HELP ! KVA 1989 CHASSIS TYPE C + UN1 + 302- INCLINATION OF THE REAR HALF-DRIVESHAFTS

Laurent

Supporter
Hello everyone, need a hand! I just buy and discover my kva mk1, type C chassis equipped with a 302 and a 5-speed UN1 gearbox that I have to finish. From what I've read on the forums, my half-driveshafts are extremely inclined due to the very low gearbox outputs in relation to the axle of the wheels. But raising the box in height thanks to the shock absorbers also has the effect of raising the chassis, which suddenly hits the longitudinal tubular control arms at the bottom. Has anyone managed to mount the configuration I'm talking about without returning the UN1 box? For my part, I'm thinking of modifying the longitudinal tubular control arms at the bottom by adding a bend so that it doesn't hit the chassis... (especially the bottom one) What do you think?
Does anyone have any pictures of it being done with this setup?
 

Mike Pass

Supporter
You need to raise the gearbox not the chassis. Leave the chassis as is and raise the gearbox relative to the chassis. The GTD setup is fairly similar and the gearbox is raised relative to the engine. The overall angle is about 4 degrees. To get the carburettor back level use a wedge plate under the carb to get it horizontal. The rear suspension height should be set at around 4.5 -5" chassis to ground as a starting point. I have some pics of a C type chassis at the rear. I will look them out.
Cheers
Mike
 

Laurent

Supporter
Merci Mike !!!
(j'avais d'ailleurs lu ce que vous venez de m'écrire dans une autre de vos réponses sur le sujet sur le forum..)
Si vous avez des photos d'une configuration avec un châssis de type C, je suis preneur !
 

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Ian Clark

Supporter
Hi Laurent,

It's unclear from the pictures, however the transaxle appears to be not inverted for the GT40 application. Inverting the UN1 involves flipping the differential. Also a good time to check the general health of the gearbox.

For example, you would have the same problem if you were using a ZF-5DS25 in Pantera configuration transaxle. Inverting the box raises the output shafts by 158mm, which also lowers the crankshaft centerline 79mm. Everything fits the way it should.

Also your engine appears to be nose down in the pictures. Best practice is level to .5 degree nose up to minimize coolant aeration creating air pockets in the cylinder heads... which leads to overheating and possible runaway boil overs. Don't ask me how I know:)

The Type C was the best of the KVA chassis and formed the basis of the RML GT40 built in the 80's by Ray Mallock Limited. A fantastic car

Hope this helps

Cheers
Ian
 

Mike Pass

Supporter
Here are couple of pics of a GTD rear setup for reference.
Cheers
Mike
 

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Laurent

Supporter
Thanks Mike & Ian for informations and picts ! I have to think about all the advice I receive which is unfortunately a bit contradictory!
Some tell me, if I understand correctly, to tilt backwards by 0.5 degrees, others tell me to raise the box by 4 degrees... It's going to be a long night !)
 
Hi Laurent,
The wedge plate tells a good story. The rear of the motor is higher than the front (thin end of the wedge) also the drive shafts are almost horizontal with that setup. Looks much more mechanically sympathetic for the CV joints too.
Cheers, Gus.
 

Ian Clark

Supporter
Hi Laurent,

There are three different issues being addressed here: 1) Driveshaft angles 2) Nose down motor 3) Carburetor angle. Some actions solve one or more issues or can create a new one...

The drivetrain (engine and transaxle assembly) was parallel to the chassis in the original GT40. Fortunately you have a transaxle that can be inverted so the nose down drivetrain situation will not effect your car, plus brings the driveshafts up. It's worth the trouble (cost) to flip the diff and have the drivetrain level.

Installing the motor .5 above parallel to reduce air pockets forming in the cylinder heads can also save you having to run steam passages from the back of the intake manifold to the front (there's a few threads on this somewhere).

In all cases a good header tank with bubble bleeds from the radiator and the top of the intake manifold is highly recommended IMHO.

The carburetor wedge plate is an excellent method of bringing the carburetor level with the engine. The angle in question relates to the original application of the manifold on Ford production vehicles. Truck engines were more inclined than passenger cars and as such had greater carb mounting pad angle.

The Cobra and GT40 manifolds for Weber carbs have no angle built in and several four barrel manifolds are available with no carb angle.

The final choice of what to do about carb angle comes when you know the final choice of induction system. This could change as the build progresses.

The best use of the intake manifold at this time is to remove the carb and bolt a lifting plate in it's place for your engine crane. The drivetrain will be in and out a few times...

The nice thing about sorting the position of the drivetrain now is that all the other plumbing, wiring, linkages and shifter mechanisms etc. can be planned, test fitted and prepped for final assembly.

The great thing about this forum is the wealth of information available by searching threads or just asking. Lot's of us will be watching your car build and ready to chirp in anytime you like:)

Cheers
Ian
 

Mike Pass

Supporter
1683727254968.jpeg

1683727285826.jpeg

having compared the pics of your car and the KVA in my pic it looks to me that the gearbox is the same way up in both. The KVA in my pic worked well. Comparing the pics your gearbox is a lot lower than than the one in my pic using the round fitting on the box as reference - Pink arrows. Using the yellow line drawn between the top wishbone mounts as a reference. Also your car has a big drop in the centre of the cross bar joining the chassis side tops.
I would suggest that in the first instance you remove the crossbar so the gearbox can be raised. I would suggest making blocks (50mm?) and place them at the locations of the yellow arrows so that the driveshafts are at a sensible angle - maybe 5 degrees up or horizontal.
The crossbar will need to be modified to a straight bar as per the yellow rectangle in the pic or it may need to be raised.
I can't tell from your pic the current height of the engine in your car but once the height of the gearbox is fixed you can adjust the engine mounts to give you the best level. level is good for carb. Engine down is good for centre of gravity. GTDs have the engine angled down at the front by about 4 degrees. My GTD has run with this configuration for over 20 years. I do have a bleed line from the higher rear of the engine intake manifold to the coolant tank to bleed any bubbles. You can see the pipe and fittings in my carb pic.
I assume the cross bar was dropped to accommodate the exhaust/silencers. This would need to be addressed when all the adjustments have been made.
A friend of mine had a GTD which had the engine and gearbox lowered and it had excessive driveshaft angle (not as severe as your car) and as it was run in hillclimbs and sprints it regularly broke driveshafts - so often that he kept a spare driveshaft in the car!
Cheers
Mike
 

Laurent

Supporter
Thanks Guys !!!
Yes the cross bar was dropped to accommodate the exhaust/silencers.
IMG_6371.JPG

IMG_6366.JPG


We have all the same conclusion of reflection and modification to be made on the car !
. Do you know if it's possible to buy a carb wedge plate already built with the good angle ? i can give the carbs reference if needed...

On the pict of
JP Verweij
In which unit are the measuring tools indicated? degree? other?
 

Mike Pass

Supporter
I had mine cut to the exact angle I wanted on a milling machine. You can buy a 5 degree one or buy a spacer and then mill to your required angle. I have the centre of the aluminium wedge plate completely open. I tried a hard plastic (phenolic) spacer but they are very brittle and very hard to machine without splintering. I found the only way to machine them is to use a very small diameter mill at high rpm. I still have one somewhere but I have forgotten the angle.
Cheers
Mike
 

Ian Clark

Supporter
Hi Laurent,

Looks like you're going to have a fine KVA GT40 at the end of the day! Loads of great advice too

A bit off topic but may I ask, did the car sit for an extended period of time before you bought it? If so it would be a good idea to pull the drivetrain, separate the engine and transaxle, have a good look at engine, check to be sure all gears are present and the clutch is ok.

If anything needs attending it's more expensive to do it later...

Cheers
Ian
 

Laurent

Supporter
. Hi Ian C., the engine and transaxle are rebuilt with new parts 3 years ago, so everything start and sound correctly ! before I start taking everything apart...:)
. Thanks Ian A. for the site for the plate !
. Mike, i began to raise the gearbox as you said and i just buy a mini digital protractor to adjust the good angle... My new problem is that the Delco as well as the belt and head of the alternator touches the plate of the cockpit, I think my engine is too advanced forward... To move back 1 or 2cm to the back ...:rolleyes:
 
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