What gearbox / rear diff - BIG power?

[20vK]

Hi Guys,

I'm just in the process of trying to buy the engine and transmission for my project car (mk2 golf), after finding out that my 1.8, 4-pot 20vT engine won't be any good for me.

The basis will be a 5cyl 20v, but I'm still trying to learn about the boxes / rear dif.

I'm looking for a 6 speed quattro set-up, which will need to take a huge amount of power/torque (think dahlback +)

I know that in the VW world, we have to match up transfer box ratios with real haldex diff ratios, so is it the same for torsen set-ps, or can I mix and match from the audi engine/box range?

I am looking for the strongest set-up possible, and there is no issue of mounting the parts, as it's all hanging off semi space-frames.

What do you guys suggest, and where is the best place to source the gear from?

Also, is there any way to incorporate the newish 40:60 (front:rear) power ratio that I've read about into this? With the engine way up front, it would be nice to balance it out with a bit more power from up the rear!

Many thanks,

Rich

[Error404]

pretty sure 034 do a 75:25 centre diff - Thats all i can help with i'm afraid!

[gnutz2]

All i did was buy a 6 speed ABY avant and used the whole setup out of that, have a look.

http://www.s2forum.com/forum/showthread.php?t=19402&page=9

I`m think that you need to match the back diff to the front one but im not completely sure. i dont think you will have any issues with loss of traction to warrant any changes in the setup.

As for stronger boxes, if it breaks get another one. But i think youre looking at serious money for a racing box

[Faheemo]

pretty sure 034 do a 75:25 centre diff - Thats all i can help with i'm afraid!

that would be the stasis torsen center diff ..

[20vK]

Thanks for the answers, guys

gnutz2 - I've previously looked through your thread and build. Really nice to see some "proper" engineering. You've done a cracking job - can't wait to see that on the road - very similar to the project I had in mind, so I'm a little gutted, to be honest! However it's nice to see that it can actually be done - I wasn't sure if I'd have to extend the front wings or shorten the wheelbase to fit everything in!

Does anyone have any idea what the torque limit is you can put through the quattro boxes, before they fail, and do you know what it is that fails?

I would probably get some straight cut custom ratio gears made up, as long as it is not the selectors or casings that fail.

Thanks for your answers and help - much appreciated.

Rich

[Error404]

i think its the input shaft that will break with big torque figures.... IIRC the S4 bi-turbo box has a nigh-on indestructable flexishaft input, don' know whether that could be incorporated?

[20vK]

Ahhh... good to know.

I assume that getting it replicated in a "hard as nails" steel by my engineering shop may remedy that.

[Error404]

i think the flexibility is the key to the indestructability

Maybe Titanium? (if you can afford it)

[shortsport]

Here,s a helpfull site

http://www.elektro.com/~audi/01E/

[20vK]

Great site! Thanks for that - some bedtime reading (when BT don't deliver my wireless router today, because I'm at work, trying to earn money to pay for their broadband service. Why they won't deliver to my work address, I just don't know. OK rant over)!

Will do a good bit of research on the boxes to see at what torque they are failing. If anyone can let me know if they have had a failure (on a quattro) and what torque they were putting through it, that would be great.

Thanks,

Rich

[quattronutter]

i think its more down to how the box has been treated with regards to failure,some are running nigh on 600bhp without problems,just make sure you have a good box,if it breaks just fix or replace it

[20vK]

I'm looking at up to double that, with stupid torque. If I don't modify the box internals, I'll be forever changing boxes! I'm also trying to spread the torque over 10k rpm's to reduce potential damage, but I still need to start with the strongest set-up out there.

p.s. I don't have £40k to spend on a custom box, so please don't suggest it!

[Error404]

if you are looking at upwards of 1000bhp you are really better off trying to convert a big old yank autobox to mate up with the engine TBH. At that kind of power, engines and gearboxes are regular wear and tear items... even sequential dog-boxes capable of holding that kind of crazy torque will pop on a regular basis.... £40k is chicken feed in the grand scheme of what you are talking about IMHO mate

[20vK]

I realise that - But there's not a cat in hells chance I'm having an auto box on a track car!

There's always a cheaper way to do something. The whole car is going to cost me around £30k to build, which for the power we are talking about IS peanuts (rather than chicken feed). That's the currency I work in, I'm afraid!

I seem to remember Gemballa or Ruff have built a 1000bhp motor. Maybe a porsche box is the way forward? For some reason, I thought the Audi gear was tougher, or at least had the potential for toughness - The VW boys are just about to put around 700bhp through standard 4 motion box and haldex gear.

[Sweeper]

I can get you a gearbox , that can hold about 600HP for one year in rally stages.

The local subaru rally team can make one. Cost around 5000GBP in your money . They put gears in original gearbox casting.

Btw , I asked if they can make one that can hold 900HP for a friend of mine from Russia. They replied that there it can't be done becouse it will not last long if you abuse it.