Audi quattro 6 sp impreza conversion
 

One of the main thoughts for doing this was cost, I mean you can pick up a late audi O1E 6 speed gearbox for around £250. Audi boys are putting upto 1000hp through these boxes, most are problem free upto 600hp, only driveshafts snapping when running slicks seems to be a problem.
The audi box seems a logical choice as it runs the same setup as our impreza boxes, after all subaru copied Audis' quattro system in the first place.
Physical constraints are obvious, an adaptor plate needs made as does a flywheel, gearbox mountings, gear linkage and driveshafts too, not a problem to me as I am a machinist/engineer, obviously the cost of this work would push the cheque-book racer to buying an impreza sti setup.
I estimate the cost to be around £500 fitted, including a rear diff and propshaft purchase.
Interestingly the O1E of choice from the later 2.5 tdi a4/a6 is the strongest, having a "wide 1st gear" and "flexible main shaft" allowing for ridiculously hard launches, some quattros are into the 9 second 1/4 mile bracket on standard boxes. The ratios are also quite tall, where 1st to 5th almost match the uk 5 speed and 6th is fairly over driven (236mph at 7250rpm if you had the power!)
Also these boxes run a torsen centre diff (same as an ATB) fully mechanical, fully locked in when power is applied, no more spinning the front wheels while the centre viscous LSD has a think about it.
I'm interested on your thoughts, obviously not for everyone, but I didn't have the £2500 available to buy the impreza 6 speed (with no guarantees it doesn't have a problem/ would fail anyway)
Thanks

An interesting thought, how well does it fit in the 'hole' ?
Have you had the chance to measure it up?

Subscribed. I think Alyn at as performance could soon be your best friend for overcoming any problems.

Keep us all posted.

Oh it's in, tiny bit of tunnel bashing but no big deal

The only stumbling point I have is the speedo, may have to use the subaru one and drive it off a small belt. The audi is a two wire VR sensor, I can only assume the subaru one is a hall sensor? Three wires?

The audi box how I bought it and a spare subaru box beside
Attachment 58874

Very interesting.

Bespoke custom button 4140 flywheel, impreza bolt pattern, R32 golf clutch and audi O1E offset. Designed and made by me at my work (took a holiday)
Attachment 58875
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Adaptor plate in progress
Attachment 58877
Attachment 58878
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Rear diff to be mounted Saturday. Then all that remains is the prop (an audi one requires shortening) and four driveshafts to re spline.
Oh and a clutch pipe to connect and bleed and the small yet quite technical issue of the speedo. Thanks for the interest

Re 6 speed
 

Hi Good post I think this will create a lot of intrest is there any weight difference between the two boxes? Also think the price of second hand Audi boxes might go up:thumb:.

* rushes off to ebay

Audi box is certainly heavier, I mean an extra gear and a lot more strength does come at a price. For starters the centre of the audi case is made from steel! It also appears to be a proper "three shaft" box as is the way with a lot of getrag six speeds. Still I guess it's only 20kg heavier, and the weight is quite central in the car. The rear diff is of aluminium construction and is lighter than the subaru cast diff, this helps combat some of the weight gained.
The audi box is certainly as good as the sti 6 speed, dare I say it maybe stronger. Certainly a lot of ratio options available for it and price is circa £250. However flywheel, adaptor plate and driveshaft costs could be a problem for someone whom does not have the access to equipment and materials to make them.
I am certainly enjoying this project.
Once my very good condition five speed is sold it will be due me very little money, I will of gained good strength for the occasional 1/4 mile day and also possibly gained fuel economy with the tall 6th. The torsen diff also appeals to my more sideways side also. Keen to see how it puts the power down

One of the threads that lead me to doing this conversion:
http://www.s2forum.com/forum/showthread.php?t=51152

Is that 20kgs heavier than the Subaru 6 speed? They're already heavy lumps!

Audi gearbox 68kg, subaru 5 speed 61kg, subaru 6 speed 70kg. Your not going to get it for free, more steel equals a stronger box. I'll live with the 7kg increase in weight

if you need the prop balancing after the shortening, contact a company called
international marketing services, that's what they do for a living, splining, cv's yoke's prop's and balancing etc
http://www.ims-ltd.co.uk/

If this works as well as you think, you could make a small fortune if you put a package together.

No reason why it shouldn't work, I think it would be cheaper for someone to buy an sti 6 speed by the time they pay for all the bits and labour.

Definatly different from the norm. Subscribed.:thumb:

Just in from mocking up the rear diff. Measured the required prop length then measured the actual length of the prop. It's only the same! Smashing

Happy days :thumb:

You not joking, it's within millimetres, and the CV joints have loads of movement in them. Just needs a couple of spacer/ brackets on the carrier bearing. Ace

Nice project!

Subscribed :clap:

Audi 6 speed remote with push down reverse lockout. All working as it should.
Carpet and ecu is lifted just to make sure it didn't get damaged when creating a little extra room where the gear linkage goes into the box (you can see the red rubber boot in one of the pics above)
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So how much do you want to make a flywheel, adapter plate etc? :D

It's a bit of work like. The adaptor plate has to be clocked up to your gearbox and doweled in position for correct alignment, this is done once the plate is made. As for the flywheel, I had an off cut of steel at work that I used, and it was a whole days work to machine, not to mention the hours spent working out dimensions and offsets. It really depends on what VAG clutch setup you want to use, I've opted for an R32 paddle clutch as I had one kicking around left over from my golf 4motion turbo project.
Be nearer a grand for the two items for my time and materials. But with a 1 year old I just don't have any time for other peoples jobs the now.

Worth mentioning that the quattro box uses 4.11:1 final drive and all this had been planned around me using the hawk 4.11:1 rear diff I have, however for one major reason I cannot use this diff! So the audi diff and prop was purchased, luckily enough it looks like it will fit a treat.

You could try a max9924 for the VR sensor