liam.mccaffrey
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| posted on 25/2/11 at 12:44 PM |
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Transaxles
what transaxle options are available for massive (600HP+) power and torque levels. Obviuosly cost going to be high.
Any one had any experience? I'm looking at GT40 sites and like.
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MakeEverything
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| posted on 25/2/11 at 12:56 PM |
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UN1 should take a fair hammering, but i think for the larger torque figures the primary shaft needs to be replaced for a single piece which is
stringer.
Failing that, Porsche transaxle should do the job?
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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orton1966
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| posted on 25/2/11 at 03:22 PM |
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Audi?
There must be some suitable Audi options although some will require the output for the rear wheels removing but I believe this is possible
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coyoteboy
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| posted on 25/2/11 at 03:37 PM |
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Pretty much just the audi/porsche ones in the UK AFAIK (the US folk do a few), the TDi 2wd boxes should handle the torque of a nice 4-500 hp v8
without much issue, but higher than that and I think you're in unknown territory with stock gearboxes. You can't take a 4wd box and mod it
(you can, but it's designed to split torque so bad idea!)
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v8kid
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| posted on 25/2/11 at 03:41 PM |
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I use an upgraded UN1 with LSD but the cost was quite high about £4k. Also it is not so easy to change ratios as other boxes. Plus in order to get the
input shaft below the output shaft the gearbox has to be inverted which I found tricky to say the least. Gearchange is H pattern and not fast.
Hewland is £10k secondhand try the hillclimb sites they are available, have better gearchange and more ratios available.
As far as I know it is impossible to invert an Audi box so you will end up with an unacceptably high CofG
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
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coyoteboy
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| posted on 25/2/11 at 03:48 PM |
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quote:
As far as I know it is impossible to invert an Audi box so you will end up with an unacceptably high CofG
Unacceptably surely depends on what you're running it in, what your purposes are and how much you want to spend?
[Edited on 25/2/11 by coyoteboy]
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v8kid
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| posted on 25/2/11 at 05:27 PM |
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Oh yes absolutely I stand corrected of not being sufficiently specific!
However in the context of this forum surely it is reasonable to assume that we are talking of lightweight sporting machines with low CofG? Not getting
into the argument of all the benefits of low CofG here I'm assuming its a given.
Also the original post is for 600hp and that is not going to be cheap.
If you reckon it is I wish you all the luck in the world but consider all the other implications. For example braking. High CofG gives more front
weight transfer under heavy braking into a corner perhaps. More front weight transfer means there is less weight on the rear wheels to resist
cornering forces. But the mass is the same at the rear pushing straight on when the car is at an angle trying to corner.
Corner entry oversteer results going off the road backwards. It does not have such an effect in the original saloon cos there is more mass upfront
causing the front wheels to wash out and the two balance.
I think you will get trashed on corners by the original saloon unless you concentrate on getting the rear end weight lower. It can be done other ways,
angling the engine forwards drops the weight as does lowering the whole lot and running the driveshafts at an angle but both options will probably
require dry sumping - come to think about it thats possibly the cheapest option! Your photo looks as if when dry sumped the bottom of the engine will
be at the same level as the bottom of the gearbox which is ideal.
CV life will be compromised but they are cheap and even at 10% of original life is still OK for a fun car.
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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liam.mccaffrey
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| posted on 25/2/11 at 06:19 PM |
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a lot of good info, its not for a lightweight machine,
CoG not really an issue as it will be an inprovement on stock what ever i do.
This is one of those extreme future projects but it doesn't hurt to dream does it
Merc Vito midi Supervan anyone?
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scootz
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| posted on 25/2/11 at 06:31 PM |
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The Audi 01X box (and it's other TDi siblings) will spit the dummy out at those figures.
I have also read that disabling the rear drive on an Audi 4x4 box is not the answer either (sorry - can't remember why, but a search of the GT40
forums should explain why).
The traditional way would be to bag a Porsche G50 and invert it like the Ultima boys do. If you shop around, you'll pick one up for £2k-ish.
It's common, so you may even find an adaptor plate for your chosen application.
Other than that and you're into the big-money of Hewland, etc!
It's Evolution Baby!
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Theshed
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| posted on 25/2/11 at 06:43 PM |
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Elite do a nice 6 speed for £6k - very pleasant folks they are too. Without being (too) pedantic torque is the issue for gearboxes and not BHP.
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liam.mccaffrey
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| posted on 25/2/11 at 06:48 PM |
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I know its torque that does damage, be pedantic all you want 
It will be high torque application though also
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Theshed
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| posted on 25/2/11 at 06:57 PM |
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Road or race? I picked up a second hand Xtrac LMP gearbox for my toy. I have seen quite a few old Indy g/boxes for sale - they should cope... If you
could bear to drop a couple of hundred BHP the Hewland FTR is very cheap - Often found second hand. For the road it seems to be
Porche/audi/Subaru/Renault. You can buy a modernized ZF gearbox from the states or a modern forgery from Quaife. There is an australian company that
makes very strong transaxles for off roading Albin?
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v8kid
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| posted on 25/2/11 at 10:28 PM |
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Theshed - Can you give us ballpark prices for those boxes
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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scootz
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| posted on 25/2/11 at 10:35 PM |
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quote:
Originally posted by Theshed
... if you could bear to drop a couple of hundred BHP the Hewland FTR is very cheap...
Where from... 
It's Evolution Baby!
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MakeEverything
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| posted on 25/2/11 at 11:27 PM |
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Id go UN1. Blow it up, then go UN1. Blow that up then.....
For c.£150 a pop, you cant go wrong. Youre not going to be flat out everywhere and rebuild kits are cheap enough.
Trouble with inverting the UN1 is the oil leaks. They start to leak anyway when the control lever shaft seals wear, so inverting it might cause you
some more problems.
Besides, if the UN1 takes power from a V8 with no problem, then it should last with a little sympathy.
[Edited on 25-2-11 by MakeEverything]
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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Theshed
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| posted on 26/2/11 at 11:39 AM |
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There is no way on earth that a Renault UN1 is going to cope with 600BHP and matching torque. Of course it would fit, of course it is cheap but you
would not be able to use all that BHP. I see no point in having a 600hp engine where you know that the first time you use it something will go. With
the standard 2 piece input shaft these gearboxes are very weak. The one piece shafts are expensive. It would be wrong to think that as they work with
a weasy old rover v8 at circa 150BHP it could cope with something stronger.
The Hewland FTR is excellent value (perhaps I should not have said cheap when we all build our cars for £250) Racecarsdirect and motorsports ads have
had examples at 2-4k not peanuts but the uprated input shaft for the UN1 is £2,000 or thereabouts (quick google).
Elite do 2 sequential 6 speeds When I asked I was steered towards the TXL 250 and told that several BMW V8 powered cars are using this with success
rated to 450ftLb is very good for the price at circa 6k
Both of the above are straight cut dog boxes and so only suitable for road use with ear plugs....
For road use the debate is endlessly repeated on GT40s.com. I do not think there is really a cheap option for 600BHP. The Porsche is a well beaten
path.
What sort of engine is this dream car presently running? Ease of finding or making adapter plates might need considering.
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MakeEverything
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| posted on 26/2/11 at 01:13 PM |
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quote:
Originally posted by Theshed
There is no way on earth that a Renault UN1 is going to cope with 600BHP and matching torque. Of course it would fit, of course it is cheap but you
would not be able to use all that BHP. I see no point in having a 600hp engine where you know that the first time you use it something will go. With
the standard 2 piece input shaft these gearboxes are very weak. The one piece shafts are expensive. It would be wrong to think that as they work with
a weasy old rover v8 at circa 150BHP it could cope with something stronger.
The renault 21 used the UN1 extensively, and as a member of the owners club, have seen a few of these cars pushing 320 and 350bhp with up to 300ft/lb
of torque. Bearing in mind that the renault 21 weighs in at well over a tonne, a stipped out mercedes vito van is looking at about 500 - 600Kg (?)
should be on the limit but within the realms of capability for the UN1.
The GT40's that i've seen which have 305 small block cheverolet engines and the UN1 push out more than the 'wheezy' RV8,
though some have been through the two piece primary and had the single piece shaft installed. That said, there are still some running on the standard
2 piece primary.
It needs to be said that Lotus also used the UN1 as a basis for their Esprit, and just replaced the primary for the single piece though ive heard that
some owners have used the standard renault transmission without failure.
I don't disagree that its not the best option, but remember that the OP not building an Ultima. All im saying is that for the cost of the
600bhp engine, its possible to use the UN1 to start with (bearing in mind the prices of some of the stronger alternatives) until the cost of the
transmission can be covered.
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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v8kid
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| posted on 26/2/11 at 05:40 PM |
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I want a Hewland for £2k for my weasy 400/400 bhp/ftlb wildcat rover!
How come when I look they are £6k?
Willing to pay commission here!
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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Theshed
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| posted on 28/2/11 at 12:52 PM |
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Ok so my unkind references to RV8 have been exposed as unjustified bigotry.......Sorry to all those who actually like pushrods! Whilst looking for my
own gearbox (browsing is so much better than working) I did see second hand FTR's for sale at the prices I suggested - they were only 6k new
(Hewland do not seem to have prices displayed on their site any more) and a lot have been made. 400ftlb is a bit steep for an FTR according to
Hewland.
I am also rather biased against the UN1 having had the joy of rebuilding 2. Both with failed input shafts (A renault master van admittedly). When the
splines strip little hard bits spray all over the place including into the gear case. However I accept that within their original limits there is
nothing much wrong with them. They are quite light in comparison to others. But my original point about building in a weak link with a 600BHP is a
good one.
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v8kid
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| posted on 28/2/11 at 01:33 PM |
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 Engine bigotry
Thats a new one for the PC crowd to get their teeth into I'm still chuckling at that one.
Seriously tho I'm looking for a better box as having spent a few £k on quaife lsd and 1 piece input shafts for the UN1 the gearchange is still
less than adequate so if you come across summat let me know - I can always sell the UN1 bits to the Lotus crowd!
Cheers!
David
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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