As many will know the KVA has the reputation of being the most difficult of the GT40 replicas to build. I think the main reasons for this is the decided lack of information on assembly of the kit and the fact that only the bodyshell and chassis and a few other minor parts were available from the manufacturer. The KVA was the first on the scene in the UK and quite a few "kits" were sold. As little help was available to builders in the early days many of the "kits"are still turning up today being completed by perhaps their second, third or even fourth owner. Really the KVA is no more difficult to put together than any other kit, the only difference is that you have to source the various bits yourself rather than obtaining them from the one source, the kit manufacturer. Whilst this may be very convenient it is obviously not going to be the cheapest way of purchasing the majority of parts that you will need. This is intended to be the first of a series of articles which will be published here in Fortyfication which will take you through the various stages in building a GT40 replica based on the KVA bodyshell and chassis kit. The various assembly notes are to be based on the KVA but will in essence will be very similar, if not the same, for any other GT40 replica kit build.
As with any project the first thing that you should do is put your tools away, pick up a pen and paper and plan what you are going to do. This will save you many hours of abortive work and much wasted money in obtaining the wrong parts. Because the KVA is just a chassis and bodyshell you are virtually compelled to do this anyway. As with any project of this sort it is always a good idea to seek the advice of those who have already built a GT40 replica and of course that is were the club can play its part. You must decide what kind of GT40 you are going to build, is it going to be as near the original in looks etc. as possible ? Or is it going to be as fast and maneuverable as possible and will it be used on the road only or on the track only or perhaps more commonly a bit of both. Are you going to make a show car or just one that is very tidy ?. You must ask yourself all these questions and many more so that you can decide such things as what state of tune will the engine have. This will determine several other parts like clutch and gearbox and will also have an affect on wheels, drive shafts and many other parts. If you go through this exercise and can come up with an outline of the specification of usage and finish that you think you want then you are well on the way towards a successful build. Many people still change their minds more than once during the building phase but I'm convinced that most of these changes are either made because little if any planning was done first off or that they enjoy the building part so much they don't want to finish the job and move onto driving the car, which will bring up a whole new set of problems for you to tackle.
If you have a KVA one of the first things to do is to identify which chassis you have. Here I shall be describing the construction based on a "C" type chassis as that was the best of the chassis suppied and most of the earlier chassis arrangements are usually altered by their owners to improve performance and be similar to the "C" type. How do you recognise the "C" type chassis ? this is a question that I am always being asked. The easiest way is to look at the rear suspension. Fig 1 shows a typical "C" type rear suspension. The engine mounts and rear framework to support the transaxle and rear fibreglass varied considerably but the basic suspension is the same on all "C" type chassis. The front suspension is a double "A" frame and uses a Ford Granada upright. The suspension units themselves are standard 2.25" ID coil springs over dampers and any manufacture of the correct length and spring strength is suitable. More on dampers and spring ratings in a later article. Fig 2 shows the front suspension assembly on the "C" type.
Having identified the chassis you might have to check a few things out and perhaps make some modifications and/or additions to the chassis. The chassis that I have had engine mounts that when the engine was fitted brought the tops of the Weber carbs above the line of the bodyshell, this can be seen in the picture shown in Fig 3. I lowered the engine mounts which were welded to the chassis but kept them essentially the same as shown, in hindsight I should have made a new set of mountings that bolted to the chassis so that they could be removed for easier access when fitting the engine/gearbox assembly. Another thing that I had to do was add some mountings to carry the steering rack. The steering rack that I used was from the Ford Cortina and all that is necessary to get it to fit is to cut about ½ inch off each threaded end to reduce the overall length by 1" , you can use the steering rack from the Ford Escort but that needs extension pieces made and fitted as it is too short as standard. Many other racks could be used and the only criteria is that they are the correct length, can be made to fit the track rod ends which have to be suitable to fit the Ford Granada uprights. You have to position the steering rack so that the steering column can be easily coupled and to avoid bump steer. Some might not know what "bump steer" is, well its when the wheels are steered by the suspension as it moves up and down, this is obviously an undesirable feature. The reason for bump steer is basic geometry and I won't go into that as I'm sure you won't want to start remembering all that from your school days. As neither the Cortina or Escort racks are exactly correct for the geometry (and I don't know of any rack that is exactly right) you have to position the rack so that you don't get any significant movement of the steering over the range of suspension movement that it will be working over. This should only be around 3" of vertical movement and not the total movement that the pivots will allow. Offer the steering rack up and fit the track rod end to the uprights and then move the suspension through the movement range that is required and check for bump steer movement, when you have this correct note the steering rack position and plan the mountings to suit. The mounting that I added for my steering rack were supported off the lower chassis members but again in hindsight I should have mounted them from the upper chassis members as that would have given me more space for the pedal assembly to be fitted later. I also had to add mountings for the steering column and I changed the cross member below the rear bulkhead window from ¾ inch square tubing to 1½ inch square tubing so as to provide a good solid fixing for the seat belts and make paneling easier. Other mounting brackets were added to support the rod gear linkage , tanks and air conditioning unit. I guess the comments that I have made about the arrangements that I should have made on the engine mounts and steering rack mountings are both things that could have been avoided with a little better planning so you can see how important it is to spend plenty of time planning prior to starting your build. Other manufacturers chassis have most of the brackets already fitted, however the engine mounts on some are still rather high but I will write further on that subject in a later article. You should still check all mountings very carefully as they are easily added at this stage but very difficult later. Now the chassis is ready for painting but more on that next time. To be continued.
Building the KVA GT40
by Ken Saunders
Carrying on from part one of this series let me continue on with a few more thoughts on the chassis. It is a good idea to decide at this stage where you will be mounting the battery as this is a heavy item it will need to be supported directly off the chassis. Ideally the battery should be as close as possible to the engine starter motor so as to minimise the voltage drop in the leads. It is advisable to keep the sill line space for fuel tanks and therefore the remainder of the space on the nearside along side the engine is the best place for the battery as on the opposite side, the offside, the space will be traversed by the gear shift linkage limiting the usable space. This nearside space is not totally ideal as access will be limited but as most batteries these days are sealed for life and require no maintenance that is certainly the best position available on the KVA. A steel plate can be welded between the lower chassis rails in this area to act as a platform onto which the battery can be fitted. Once all the brackets and modifications are done to the chassis it can be thoroughly cleaned and prepared for its protective coating. Many builders have their chassis powder coated but in my experience this is not the best coating to use. Rarely is the powder evenly applied prior to baking and the corners usually have the thinnest coating and these are really where you want the best protection. Powder produces a very hard finish coating but this will chip and is difficult to patch. I have used a red oxide primer and then a coat of transport polyurethane paint which is ideal as it can be painted on by brush and leaves no brush marks. This paint produces a plastic type surface finish and whilst it is a softer finish than powder coating it has the major advantage that it can be touched up if it gets chipped or scratched and the patch will blend into the original finish without showing. Make sure that you don't paint any of the threads on the suspension adjusters, these should be lightly greased. If you decide to have suspension components chrome plated be aware that this process can embrittle the metal, however the plating company should be able to resolve this as long as you remind them that it is undesirable in these components. If you can mount the chassis onto a platform so that it is at a comfortable working height it will certainly make the construction easier. The panelling on the underside of the chassis can be fitted, it is best to tip the chassis onto its side to carry out this operation and it is also advisable to use seal end pop rivets around 4mm diameter or better still M4 screws. I used 12swg aluminium sheet to give the flooring a little extra strength but you could use thinner sheet if you are careful where you put your feet as you get in and out of the car. You can of course use sheet steel for the flooring but I suggest you get coated sheet to provide some extra corrosion protection, I would suggest 16swg as a minimum and for additional support and rigidity 14swg sheet. Once you have cut the sheets to size and have drilled them and the chassis with fixings every 2" - 3" the panels should be fitted using a jointing compound to weather seal between the chassis and the panelling. It is also important not to have any bare steel in contact with bare aluminium as this will cause corrosion. The centre section of the bodywork sometimes referred to as the spider needs to be fitted and to ensure that this is fitted into the correct position you can either take measurements or better to fit the front and rear sections and the suspension and wheels as well so that you ensure that the wheels appear in the centre of the wheel arches. A good tip here is to pop rivet the various sections of fibreglass together using small strips of metal as the joiners this keeps all the sections in their relevant positions so that you can position them correctly onto the chassis. The pop rivet holes in the fibreglass are easily filled at a later stage. You will need to remove the front and rear sections and the wheels and suspension after this exercise so they need not be mounted to solidly at this stage. When you have decided the position of the spider you will need to fit the doors and check that the windscreen fits the aperture before to finally tighten the bolts as you may find that you need to fit packing under the mounting points to get the various parts to line up correctly. Remember it is rare for glass fibre sections to mate exactly on first fitting but as long as they are within 2 - 3 millimeters you will be able to achieve a good final fit. Once the spider is fitted you can locate the dash panel which in turn will allow you to locate the top end of the steering column, the bottom end is dictated to some extent by the steering rack however you do have to include one or two universal joints in the linkage so as to provide a collapsible feature for protection in case of accident. As most cars constructed today will be subjected to the SVA test this feature will be one of the checks that are made. I used the steering column from the Triumph Dolomite as this is telescopic but you can use more or less any column provided it can be coupled up to the steering rack acceptably. As I had mounted the steering rack at low level I had to shape the aluminium panelling over the steering rack and this more or less precluded me from using a floor mounted pedal box as I would not be able to get it far enough forward to suit my long legs. As I have already mentioned, in hindsight I should have mounted the steering rack high as that would have allowed more room for the pedal box but as this is one of my winter mods I am having third thoughts as it seems almost impossible to get a floor mounted pedal box far enough forward to allow someone my length (6'-2") to use them and it is therefore better for me to leave them at low level and modify the pendant pedals to provide me with a better pedal layout to allow me to heel and toe, this being almost impossible with my present setup. If you intend to fit servos to the brakes then it is worth making the front bulkhead from 12 SWG aluminium as that will be strong enough to mount them onto. There are some very nice pedal box assemblies available on the market, Rally Design offer both pendant and floor mounted units that are very reasonably priced. Rally Design can be found at Units 9/10 North Quay, Upper Brents Industrial Estate, Faversham, Kent. England. ME13 7DZ. Tel : +44 (0)1 795 531 871 Fax: + 44 (0)1 795 539 930. Alternatively if you have the facilities you could make your own or modify one from the scrap yard to suit. I seem to have drifted onto the brakes but certainly at this stage the brake piping should be installed before you are tempted to do remainder of the panelling which whilst providing visible growth to your project doesn't help much as the panelling usually gets in the way when installing some of the lesser visible parts. The brake pipes can terminate on the panelling at the front wheels although you should ensure that the mounting is solid or they will crack out with the movement. On the rear wheels you will require brackets on the chassis to support the ends of the rigid piping. I would recommend that you use copper/nickel piping which is slightly more expensive than copper or steel pipes but is strong and does not corrode and should therefore never require replacing. If you decide to include servos then 1.6 : 1 ratio remote servos are the units that are usually fitted and can be obtained from many and its well worth shopping around. If you have a pedal ratio of around 6:1, that is the distance from the cylinder connection point to the pedal is six times that of the distance from the pivot to the cylinder connection point, then you don't
really need servos. It won't hurt of course if you do fit them, it will just mean you don't need to push the pedal very hard. I found that when driving on the track, servos are prone to sticking, only for a short time, but when you brake right into a corner if the brakes don't come off instantly when you release them it does cause some problems as you turn in !!!. Needless to say I have now removed the servos and after initially thinking the pedal was a little heavy I have now adjusted to the weight and find the brakes more controllable than with the servos. If you fit servos you will need to install a vacumn pipe from the engine bay to the servos and whilst the connections onto the servos and the engine should be flexible the pipe in between will be more reliable if solid. 15mm copper piping is ideal for this but make sure it does leak before you panel it in. Whilst I am dealing with pipes there are a few others that should be installed at this stage. There are three pipes to run from the radiator to the engine bay, the main cooling feed and return pipes which can be 35mm copper pipes between the engine and the radiator and a breather pipe which needs to be about ¼" bore copper pipe from the top of the radiator to the header tank in the engine bay. This breather pipe allows a small bypass flow from the radiator to the header tank and prevents any build up of air in the radiator causing an air lock in the system, this being a common problem encountered in GT40 replicas as well as other similar layout vehicles. The water pipes can either be run down the passengers side on the cabin or an easier route is directly down through the centre of the car. Unfortunately on my car which is illustrated here I decided to run the pipes down the passenger side sill and made myself a lot more work with the complex bends required to route them around the chassis, I am rectifying this on the new car (a GTD) that I am presently building. A three inch wide tunnel around four inches high to cover and contain these pipes can be made from an inverted U section of aluminium sheet. This can be produced by bending carefully over a length of 3" rain water piping. The feed and return pipes should be separated by a layer of insulation material to prevent the cool return water being heated by the hot feed pipe. I use high density polystyrene foam which can also be used to create a box around the pipes to prevent the heat from them contributing to the passenger compartment temperature. An alternatively insulator is self expanding foam that comes in aerosol, however whilst this is sometimes easier to use it does not have the same insulation properties as the high density expanded polystyrene. Other pipes to consider at this time are those required for air conditioning, even if you don't intend to install it at this time it is well worth installing the pipes from under the dashboard and the radiator area and engine bay at this stage as they will be much more difficult to install later. A ½" bore pipe is required from the dash unit (evaporator) to the compressor in the engine bay and a 5/16" bore pipe is required from the condenser in front of the main radiator to the compressor in the engine bay a further 5/16" bore pipe is required from the evaporator under the dash to the receiver / dryer and condenser in the radiator area. These can be either solid or flexible, however you should ensure that any joints are suitable for around 160 psi pressure. On the KVA the air conditioning compressor can be mounted on the nearside of the engine whilst on some other replicas such as the Tornado TS40 it may have to be mounted on the offside due to space limitations. The air conditioning pipes should be run to the appropriate side of the engine bay from under the dash panel, again final connections onto the air conditioning compressor will need to be flexible and it is advisable to make all pipe connections onto equipment flexible. You will also require two " bore heater pipe hoses from the engine bay to the heater unit under the dash. As far as the brake pipes, vacuum pipe and air conditioning pipes are concerned they can be run down either side of the inner sills however space should be left on the offside for the gear shift mechanism and some space has to be allocated for the wiring harness. You can see that there are quite a lot of pipes to run around the chassis and through the passenger space and these are best installed whilst the minimum amount of panelling is fitted so that you have the best access. All pipes should be fixed at regular intervals to prevent movement and any fatigue cracking that might occur, needless to say it is important to ensure that all joints are sound as leaks could cause you many hours work and grazed knuckles to rectify when all the panelling and equipment is installed. You will notice that I have included two heater isolation valves in the heater piping this is to ensure that the heat exchanger in the under dash unit remains cold when the cooler is in use. If this gets hot through convection then the effectiveness of the cooling will be diminished. The Under dash unit which I have illustrated here is a combined heating and cooling unit as is usually used in GT40 replicas and this module also contains two blower units which are each dual speed which providing three levels of air flow through the heat / cool unit. I shall be dealing with air conditioning systems in a later article but have included this information so that you can see what piping is required should you opt to make provision for an air conditioning system. Most members who have GT40's and who use them regularly will tell you that they can get very hot in the passenger compartment and I would say that air conditioning is almost an essential in a GT40. Whilst there is still a lot of basic construction work to go I will be dealing with engine builds and then coupling to transaxles in the next article.
Watch this space !!!! To be continued
Building the KVA Part 3
by Ken Saunders
In part three of this series I have moved away from the main body of the GT40 and will be dealing with the various options for the engine as I believe that you should aim to fit the engine and gearbox assembly as soon as possible in the assembly of the GT40. Many people in the UK have been tempted into using the Rover V8 engine in replicas, however having personally gone down this route in the early days I can assure you that you will spend as much if not more on the Rover engine than you would do on a Ford V8 and whatever you do to it your money would be better spent financially and performance wise by going for the Ford V8. Some builders have used various other engines but in general the same comments apply and those with small two to three litre engines really do lack any resemblance of the performance that the GT40 should have. A few builders have used the Chevrolet V8 engine and this certainly has something going for it as there is a larger selection of tuning parts available for the Chevrolet than the Ford. From the financial standpoint the Ford V8 engine either the 289, 302 or 351 are valued highest as these are considered more original, which of course they are. I am therefore going to deal with the Ford V8 engine and leave those who wish to travel the alternative routes to their own resources. Although a lot of the comments made will equally apply to other choices. The most commonly selected engine is the 302 Winsor although the 289 and 351 are equally as good a power horse for the GT40. The marine engine is sometimes used, the advantages that it offers are probably minimal and its additional weight probably negates its advantages in a GT40. My view is that bigger is best but then I've only got a 302 in mine at present !. The Cleveland engines are slightly longer, heavier and stronger than the Winsor engines but because of the physical size and general lack of space in the back of the GT40 Mk1 and Mk3 they are not often used. I would point out that they can be fitted into any of the replicas as long as you are prepared to carry out a little extra work on the chassis as it's a bit of a shoehorn job. It is quite an attractive engine to use as its robust construction makes it quite easy to tune to very high power levels without major strengthening. Several kit manufacturers mount their engines very high in the chassis mainly to get around the problem of alignment of the drive shafts. This seems to be the wrong way to tackling the problem as you should mount the engine as low as possible to lower the centre of gravity as much as possible and then tackle the problem of the drive shafts. This is certainly not the easiest approach which is almost certainly why the kit manufacturers have taken that route, thus making the kits easier to construct by their purchasers. In my experience the best solution is rarely the easiest. I will however, deal with fitting the engine to the gearbox and into the car in a later article. I will restrict the rest of this article to the Ford 302 Winsor engine although most if not all of the comments apply to the other Winsor and Cleveland engines and for that matter most V8 engines. Let me first deal with the question that I get asked mostly and that is "where do I get my engine from". Here you have two alternatives, buy one ready to use or build one yourself. If you go with the first option then you have a large selection of suppliers who offer every state of tune and performance that you could wish for, however like most things that you buy "ready to go", they cost considerably more than if you assemble them yourself. In the UK the choices are limited as the number of American engine suppliers is small, however the choice in the USA is considerable and these days with plastic credit transfers etc. it is very easy to purchase an engine in the USA and get the supplier to ship it over to you here. The cost of doing this is certainly not prohibitive and it will probably cost you less to buy an engine in the USA and shipping it over than it will to buy one from one of the engine suppliers in the UK. The alternative option is to build an engine for yourself and this is not quite as daunting as you might at first think, after all you have decided to take on building a GT40 replica which is probably the most difficult replica to build so an engine should be a simple task !. First off unless you intend to build one from all new parts you will need a "cut out" engine. This is an engine that has been literally cut out of a car. These engines are usually brought over to the UK from the USA in containers and they will have been piled high in a large shipping container during transit which means that the steel rocker covers and anything else that is vulnerable will be damaged, however this does not matter too much as you will probably wish to fit good looking rocker covers, sump, etc. and a better carb or carbs, etc. than those usually found on "cut out" engines. These engines can be obtained from several sources in the UK and the companies who offer these usually advertise regularly in the kit car and American car magazines. The standard "cut out" engine usually look like a battered version of the standard engine shown in the illustration. The first thing to do with this is to strip the engine down to the essentials that you wish to use and that basically means getting rid of the large air conditioning compressor which can be seen belt driven on the top of the engine, "you will not be able to make use of this item" the rocker covers and probably the sump, although you may wish to use this the modify but more on this later. The carb will probably be a two barrel device and the inlet manifold will be single plane and will also weight about half a ton so these are also best disposed of . The distributor might be OK but should be removed to prevent any further damage and for cleaning. The fan blades if fitted will not be required and the V8 starter will not fit when the engine is finally fitted to the transaxle for the GT40. The alternator should also be removed for cleaning and checking. The water pump should be removed and as this will be a cast iron pump and probably suspect as well as heavy, and should be disposed of. If the engine has come with a flywheel or flex plate then this will also not be required nor will any exhaust manifolds that are fitted. By the time you have removed all these bits the engine should be around half the weight that it was when you first got it. The next thing you should do is to thoroughly clean the remaining engine and you can use a good water soluble grease solvent for this purpose. The rest of the engine can then be dismantled, removing the cylinder heads and for the moment keeping them as a single unit rather than dissembling them. The engine will certainly need a re-bore and it is likely that the crankshaft will need to be re-ground, you can certainly check cylinders but if they show any signs of a lip at the top of the bore it is advisable to re-bore them. Similarly if the main or connecting rod bearings show any signs of wear then they should also be re-ground. There are many engine reconditioning workshops around and you will find one locally from your local telephone directory, they will be able to advise you wether the bores and crankshaft are OK or whether they require re-sizing. A complete re-bore and re-grind will usually cost around £200 and that usually includes the new shell bearings for the main bearings and connecting rods. Pistons are extra and two basic types are available, cast pistons and forged pistons. Forged pistons are usually shorter, lighter and stronger and should be used on any high performance engine especially if you intend to rev the engine beyond about 6.500 rpm (maximum). For most applications cast pistons are quite adequate and are less than half the price of forged pistons. Cast pistons are usually around £80 - £100 a set of eight and forged pistons can cost between £200 - £300 per set. The standard crankshaft should be adequate for all except those who are going racing seriously. If you want to go for extra strength for high power levels and higher rev engines then you will need to fit a forged steel crankshaft, cost around £800-£1000. The connecting rods should be re-sized and renovated. Most of the engine parts suppliers offer an exchange service and the new rods are usually quite good and certainly OK for moderate power levels. It is worth weighing each rod and matching all the rods to the same weight by careful removal of material, usually these re-sized rods are within acceptable weight balance for use as they come. For higher power or rev applications, performance rods should be used and many different makes and materials are available on the performance market. These cost around £600-£800 per set whereas the renovated rods will cost around £100 per set. It is essential that you decide early on what you want from the engine. You should decide what power level you want and as a guide to this the standard engine used in most GT40 replicas produces around 200 - 240 bhp and an engine with slightly better breathing will produce between 250 - 300 bhp. You can take the power level up to around 350 bhp and still retain the smoothness that is desirable for a road car but if you take it further you will start to run into a degree of unevenness at lower revs which can still be mastered on the road but is much more at home at higher revs on the race track. If you opt for an intermediate power level, which is the level most people go for, you will need to fit larger diameter valves than the standard and open out the inlet tracks, this can be tackled in two ways. The first is to get the heads ported and preferably have new larger valves fitted by one of the many specialist companies who offer this service. It is not practical to undertake this work yourself unless you have a milling machine and other specialist equipment. If you do have access to this sort of equipment then I suggest that you read one of the many engine tuning books that are available to discover the secrets of cylinder head porting. The second alternative and the one which most people opt for is to purchase a pair of new cylinder heads. The standard 302 engine is fitted with 1.45" diameter exhaust valves and 1.78" diameter inlet valves and there is a whole range of different heads available with valves up to 1.71" diameter exhaust and 2.23" diameter inlet. I would not recommend you using the really big valved heads unless you are going racing as it will be difficult to get very large valved engines to run smoothly at lower revs. Many people go for the Ford SVO heads known as the GT40 heads, these are a good medium power head but don't be fooled by the name as they have nothing in common with anything from the GT40 programme. Another solution which has the additional advantage of reducing the weight as well as increasing the performance is to go for a pair of aluminium heads. These are usually fitted with 1.65" and 2.02" diameter valves and with the other engine parts to suit, would be used on engines in the higher power range (350 - 400bhp). The next item to consider on the heads is the valve springs. Many people buy new cylinder heads fitted complete with valves and springs all ready to use, however the springs might not be suited to the camshaft that you select. When you buy the heads the manufacturer will usually recommend a camshaft and the spring rating will be set for this cam. If you then opt for a different camshaft you should check that the spring rating is correct for use with that camshaft. If you get this wrong then you can get valve bounce and / or severe damage to the camshaft and followers (lifters). The standard rocker arms are made from pressed steel and are OK for use on the more standard engine, however they tend to flex a little and are suspect when used with higher and faster lift camshafts. It is therefore advisable to change these for a higher grade performance rocker arms. There are several different types of rocker available, from cast steel fitted with roller tips to lightweight aluminium mounted on needle roller bearings and also with roller tips. The main design features in all these alternatives is to provide strength at the lightest weight and with as low friction as possible. The push rods which transmit the camshaft lift via the cam followers (lifters) to the rocker arms should also be replaced with hardened rods as the history and material used in the original engine push rods is unknown and might fail and cause massif damage.
The cam followers (lifters) should be matched to the cam, do not be tempted to use roller cam followers on cam designed for use with hydraulic cams. Dependant upon the camshaft type and rocker arms selected you may need to fit guide plates on the cylinder heads, these are to keep the push rods in line, however if these are fitted with the wrong rocker arms or camshaft they will cause fretting of the push rods leading to their failure. By now you should understand that the cylinder heads, valves, springs, rockers, camshaft, cam followers (lifters), and push rods should be looked at and selected as a whole. There are so many different choices for the head / valve train assembly that unless you are confident in your own selection it is best to opt for one of the recommended combinations set out by the manufacturer of the cylinder heads that you have chosen. Lets look at some of the other parts that you will require. There are several choices for the sump. The standard units are OK and polished stainless steel versions are available, however you will find that when you corner at high speed the oil pressure will drop as the oil will be forced away from the oil pump pickup by the centrifugal forces. On the original GT40's the sump was modified and reduced in depth to around six inches. To maintain the oil capacity side pods were fitted and to prevent the oil from surging away from the oil pump pickup a hinged gated box was fitted around the oil pump pickup. If you have facilities to do this work yourself then you could carry out a similar modification to this on you old sump pan. There are one or two baffled sumps commercially available for Ford engines and these are an alternative. Don't forget that when the sump is reduced in depth the oil pump pickup will also need to be changed or modified to suit the revised sump. It is also advisable to fit a windage tray this is a shaped plate that fits between the sump and the crankshaft to reduce turbulence and assist with oiling, You should also get a new oil pump and the high pressure pump is certainly favourite here. Their are aluminium water pumps available at little extra cost than the standard cast iron pumps and this is also worth fitting. I will deal with the options on ignition and carburetion in the next part of this series of articles as there are many alternatives available each requiring some explanation, I will also try to tabulate some of the more popular engine alternatives and give some indication of the advantages that each offer.
I am sure that I have left out large chunks of information in this article and the others in the series and would be pleased to receive your written queries, suggestions each which I will try to expand upon and clarify. At this time I am rapidly running out of time prior to the publishing date and the brain is starting to ache with all this use so until next time .... TTFN
Building the KVA GT40
Part 4. By Ken Saunders
In part three I dealt with some of the aspects of engines. It is obvious that I skipped over a lot on this subject and I thank the members who have forwarded me comments and articles on engine building. The options when choosing or building your engine are endless and I will cover this subject again in a later article, for now I will continue with the build and look at coupling the engine up to the transaxle. The first decision that has to be made is "what transaxle to use". The most commonly used transaxle is from Renault and several units have been used. The Renault 20 and 30 were the first but later the Renault 25 and 21 units have been used. As the Ford engine is not a revvy engine it need a fairly high ratio drive to take advantage of it potential. In the following table I list the various options for the Renault transaxles, from this you can see that you really need to use one of the 3.44 : 1 ratio differential units unless you intend using the car for short circuit racing etc. where the 3.88 : 1 or even the 4.11 : 1 diffs might be more suitable.
Renault five speed manual transaxle gear and differential ratios
|25 GTX||UN 1-03||3.36||2.05||1.38||1.04||0.82||3.55||3.89|
|25 V6||UN 1-04||3.36||2.05||1.38||0.96||0.76||3.55||3.89|
|25 Blindee||UN 1-06||3.36||2.05||1.38||0.96||0.76||3.55||4.11|
|25 V6 Turbo||UN1-08||3.36||2.05||1.38||0.96||0.76||3.55||3.778|
The type UN1-013 Renault 21 Turbo is the preferred transaxle for use in the GT40 replicas
although the 25 Turbo
and GTA boxes are also often used. Also note that if the GTA box is used it either has to be
inverted or the
differential reversed unless five reverse gears are required. Inverting the unit has its advantage as
it allows the
engine to be mounted lower and get a better drive shaft angle. On all boxes the selector shaft has
to be modified
to extend out of the right hand side of the gearbox so as to link up with the right hand gear
change linkage. This
can be fairly easily done but if you don't have access to a lathe you will need to get an extended
gear selector shaft
made in your local workshop. The fifth gear housing has to be modified to take the extended
shaft, take off the fifth
gear housing and dissemble and remove the selector shaft, the selector arm is fixed to the shaft by
two double spring
roll pins, then with a punch knock out the steel blanking plug on the right hand end of the casing
and fit a lip seal
to seal the new extended shaft against oil leakage. These lip seals can be obtained from one of
the many suppliers,
look in your local telephone directory, usually under the bearings & seals section. If you
don't want to do these
mods yourself or just want a modified selector shaft then have a word with Chris Cole Tel: 01952
222155 who will
probably be able to help. The preferred CV joints for the Renault transaxle are from the Ford
Granada and adaptors
have to be fitted to the Renault transaxle output shafts to couple to these. These adaptors are
available items from various sources and cost between £50-£60 each.
The transaxle type can be found on a small aluminium disk around 1-1/4" diameter which is held onto the box by one of the fixing bolts on the rear end cover of the gearbox. Unfortunately if this cover has ever been removed the disk is rarely replaced and the only way to identify the box is by checking the gear ratios.
In the early years the Citroen transaxle as this was used complete with the inboard disc brakes which at first sight looks a very good solution, however the box will not take the power of the Ford V8 or even the Rover V8 and has been the subject of many gearbox failures. Other transaxles are being used, these include the Porsche four and five speed units, of course the ZF transaxle similar or the same as the original cars but usually those from the DeTomaso Pantera with perhaps some changes to the gear ratios and its inversion to get the drive shafts at a better angle. The other unit that I have used and is very popular in South Africa is the Audi transaxle this comes in various guises but in the UK its usually fitted in the Audi 100 and 200 models, the table below lists the various options available.
Audi 100/200/9000 five speed manual transaxle gear and differential ratios
Serial Number prefix 3T
Serial Number prefix HE
Serial Number prefix HF
Serial Number prefix 3Q
|016 Serial Number
Serial Number prefix 3V
Serial Number prefix 3K
Serial Number prefix 5N
Serial Number prefix 3U
|016 Serial Number
|014 Serial Number prefix QN||3.46||1.79||1.07||0.70||3.17||4.11||0.52|
|014 Serial Number prefix 4X||3.46||1.79||1.07||0.70||3.17||4.11||0.52|
Some members have fitted the Hewland transaxle but this is usually for racing as having straight cut gears and a quick change ratio facility as well as sequential shift options makes it more suitable for this, however it has the characteristic straight cut gearbox whine and is not very suitable for normal road use.
Once the transaxle has been chosen it has to be fitted to the engine and the easiest way to do this is to make an adaptor plate. This fits to the rear of the engine and provides fixings at the right centres to mount the chosen transaxle. To make this you will first off need to make a template for the basic shape. First off take a tracing of the rear of the engine and mark the vertical and horizontal centre lines of the crankshaft. Then do the same for the chosen transaxle again marking the vertical and horizontal centre lines of the input shaft. Then lay one tracing over the other in the orientation that they are to be coupled in and make a composite outline of the two marking around the external and internal extremities of the tracings. From this composite tracing a template can be made, usually a fairly rigid cardboard or hardboard template is sufficient. You will then need to get a sheet of ½" thick mild steel plate large enough to cut the adaptor plate from and then mark the shape that you require using the template. Now you will spend many long hours with a hacksaw so I suggest that you get your local engineering workshop to cut this for you. They will probably cut this out with a plasma or laser cutter which will give you a very good edge finish but still might need little touching up with a file or angle grinder. On the rear of the engine are two location dowels, one on either side, and their positions have to be marked accurately onto the steel blank and then drilled to be a tight push fit. Once this is done the remainder of the fixing holes can be drilled. Don't drill the fixings until you have drilled the location dowels as you can still make adjustments if you get the location dowel hole slightly wrong. The next stage is to mark the vertical and horizontal centre lines of the crankshaft onto the adaptor plate and then offer it up to the transaxle bell housing aligning it on the gearbox input shaft vertical and horizontal centre lines. There are usually two location dowels or location dowels holes on the bell housing and these should be marked onto the adaptor plate accurately and then the dowels can be refitted and the remainder of the fixings drilled. The fixings for the bell housing have to be tapped to take the fixing bolts and bolts of the correct length have to be obtained and used for these fixings. You must ensure that the bolts extend into the full thickness of the adaptor plate but without protruding from the rear of the plate (engine side) as this might cause the plate to be pushed off the engine and thus cause a misalignment. The last stage in the manufacture of the adaptor plate is to drill and tap the fixings to mount the starter motor and these also have to be made accurately to ensure that the starter cog and the ring gear on the flywheel mesh correctly and that the starter cog when at rest clears the ring gear. If you are not confident that you can make this yourself then it is best that you buy a ready made unit from a reputable source or have one made by your local engineering or motor sports workshop.
The flywheel is the next item to tackle and the one to be used depends on the transaxle used. The one generally used on the Renault transaxles is the Ford V6 flywheel, unfortunately there are two V6 flywheels and you will need the one that has counter weighting on the rear face. The flywheel has to be redrilled to suit the fixings on the V8 crankshaft and this has to be done on an indexing head to ensure that they are very accurately positioned. If you don't have these facilities again your local engineering or motor sports workshop should be able to help. Have a word with your engine balancer first so that you get the counter weight into the correct orientation. That leads onto the next operation getting the flywheel balanced to the engine, this is most essential. One saving here is that usually the engine balancer will also be able to redrill the flywheel to suit your V8 engine and if this is the case I would definitely recommend that option. You will probably also have to fit a better clutch to that originally fitted to the flywheel that you are modifying and this will mean redrilling the flywheel to take the three location dowels and fixings to suit the clutch. This also needs to be done accurately and the clutch should be fitted before you have the complete assembly balanced. You will probably find that the engine balancer will also be able to offer you this service. Don't forget that it is best that you get the crankshaft, connecting rods, pistons, flywheel, damper, flywheel and clutch all balanced together and this is certainly essential if you are going to do any serious engine tuning. With the Audi transaxle and possibly some other units you might need to manufacture a completely new flywheel and that obviously requires the use of a fairly large and accurate lathe. The starter ring that you use will also need to be shrunk fit to the flywheel so you will need some means of heating the ring gear and cooling the flywheel.
The next item that is needed is a spigot bearing to locate and support the end of the gearbox input shaft into the end of the crankshaft. The standard bearing in the V8 crankshaft is quite large and not suitable for use with the transaxles that are used for the GT40. A holder has to be made that is a very tight push fit into the end of the crankshaft and carries a needle roller bearing of the correct size to suit the bearing on the end of the gearbox input shaft. This holder has to also carry the bearing in the correct position to suit the position that the shaft is in when the engine and transaxle are bolted together via the adaptor plate. On some cars in the past plain bearings have been used for this purpose and phosphor bronze or oilite was used as the material, however I have seen several that have been made from brass and these are certainly not at all suitable. I cannot recommend any of the plain bearing options as they are all very prone to wear and seizure which results in gearbox input shaft failures or welding of the input shaft to the crankshaft which makes changing gear and stopping rather difficult !!. When making this holder and bearing please remember to include a threaded hole in the rear end so that the bearing can be jacked out of the end of the crankshaft should it require removal or renewal. The engine and transaxle can now be coupled together and mounted into the chassis the next operation is to make the necessary mountings for the transaxle. By far the best way is to make mountings from the cross member above the gearbox and linking the two suspension tops. These should be via shock absorber mountings but remember to make these quite firm units. This is how the ZF box is mounted in the original cars and reference to the original design will help with the design of the mounting. Unfortunately most of the replica manufacturers provide mountings at the rear of the gearbox which whilst fulfilling the basic requirement is not ideal for access and simplicity of chassis design.
In the next part to this series I will try to cover some of the other options on the engine and transaxle as well as the gear shift linkage and the various options there.