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Discussion Starter #1
So it looks like Audi quattro (AWD) cars have a super narrow, yet relatively strong rear diff weighing in at about 54lbs. There are posi-trac and worm gear options available for these rear ends, and they have ratios 3.55-3.89-4.09 available in the standard gearsets. One of the common issues I see with the swap threads is the exhaust routing around the large 8.8" differential, and this really seems like it could solve that issue.

Now they are available all over ebay for about $200-300 but it is hard to tell what ratios they come with, and as the quattro cars use electronic traction control using the brakes and a clutch pack that attaches to the front of the diff. It looks like the CV on the input (pinion) side of the diff could be capped with an adapter plate to work with a regular driveshaft mount, and the swap would still require custom CV axles to be made, but that is no different from the 8.8 or CTS getrag options. The kicker for this diff is, according to ECS tuning and wavetrac, who both make LSD carriers for the audi diff, they are good to 1000whp.

Overall this has the potential to be one of the cheapest, lightest, and easiest to package options for the LS swap I am currently in the parts acquisition phase of... Just wondering why it hasn't been done, and if anyone has tried it or knows any con's associated with trying to use one :icon_cheers: Aside from having to fab a bracket, and not having many gear ratio options, is there something I'm missing here?
 

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Discussion Starter #2
Update: So I found a 2004 A8 rear diff (2.79:1 ratio) for $50 on ebay, and it appears to be in solid shape. When it shows up I will confirm the gearing, and start measuring for fabrication of a mount. This one is coming with the front rubber mount, and no rear bracket. I figure I can machine up some delrin to mount an aluminum bracket to the rear, or I can purchase a rear subframe reinforcement plate and fab a mount that bolts up to it. If it doesn't work then I'm out a whopping $65 (including shipping) but if it looks feasible, then I may have the cheapest rear diff capable of surviving the LS7 destroker I am putting together :phillyb:
 

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Discussion Starter #4 (Edited)
Destroked LS7? Audi rear end?

You have piqued my interest. I eagerly await updates.
I've read through your build threads, and I share some of your passion for bad decisions and building esoteric crap to perform :icon_cheers:

I bought a L33 block to be re-sleeved to 4.185 bore (Darton is about an hour from my house) and I purchased an LS7 blower manifold and 8-71 blower. Got a couple of Enderle hats getting ready to go while I set aside some cash for BR7 heads.



That insanity is going into my 1969 Nova, and while I was tearing down the L33, I thought, you know one of these set up to LS7 spec bore with a 3.27 stroke crank with ITB's would be kinda nice for the Miata... :haiguyths:



Currently looking for another L33 block, but depending on what I can find (they are hard to come by) the Nova, which is more of a long term project, may wind up with an RHS block for more cubes.

Either way I will be looking at running BR7 STS heads on both engines, with more of a high RPM N/A focus for the Miata. I originally wanted to put together a 427, however I think the torque would be overkill. As far as I can tell, nobody uses Audi diff because of lack of available gear ratios, however the super tall gearing should help keep 1st gear in a close ratio T56-Magnum usable, so I'm willing to give it a shot.

I'd put up some pictures of my junk (heheh) but I used photofuckit as a host before...so.... ?

Imgur ftw?
 

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Discussion Starter #5 (Edited)
So some more junk came in, although this was kinda expensive junk so I will have to put off buying heads for a while :( but for what I paid, I couldn't pass up a shot at the intake setup I wanted

Even if a few of the filter screens got kinda dinged up in shipping, I really can't complain because the seller threw in an extra throttle motor, as well as the 60lb injectors good to about 800ish flywheel horsepower in this application with 45lbs fuel pressure.


The good news is that all of the intake trumpets (which in this case are secured inside the filter screens) look to be in really good shape.

I also picked up another power steering rack to give the full de-power treatment to:


And the Audi diff showed up. Unfortunately, they shipped it with gear oil in it, and it wound up upside down in the box, so a large quantity of the oil wound up in the box via the vent tube, however, I confirmed that the gearing is indeed 2.79:1 and I will have to rebuild the setup with a Quaffe torsen carrier regardless, so I really couldn't care less about the loss of fluid. Also, it is incredibly light at 43lbs including mount with a really narrow profile.
 

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Discussion Starter #8 (Edited)
And here I was getting the impression this board was kinda dead :icon_cheers:

I've picked up a few things:



And done a few things...
Meh:


Not Meh:


Mostly I've done some interior stuff and a sound system install, I also have been getting some body parts together to improve cooling.

The rods are Carrillo 6.2" rods with L19 bolts which will get combined with a Callies Dragonslayer crank in 3.62" stroke. I've been looking at pistons from Arias in 4.155" bore which would net me a 393 CID (6.5L) with 8500RPM capability and sufficient airflow to match. By dropping from the common aftermarket/LS7 4.000" stroke to a stock LS3 3.62" stroke, the max piston FPM would top out at 5430 (at the 9000 RPM hard cut) which is below the recommended max of 5500 for the rods and crank. This gives up about 45 CID, however, it should result in higher max HP and lower torque, making the car more manageable (hopefully) off the line.

Edit to fix pictures :suicide:
 

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Well Im in. That Harrop is beautiful and I came close to buying one off a forum (might be the one you have) and putting it on my LS3 swap. Just wasnt sure I could find anyone to tune it.

Keep it up!
 

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Discussion Starter #10
Well Im in. That Harrop is beautiful and I came close to buying one off a forum (might be the one you have) and putting it on my LS3 swap. Just wasnt sure I could find anyone to tune it.

Keep it up!
Thanks for the kind words :haiguyths: The harrop came from a C5R team based out of florida, they upgraded to the latest iteration, which includes an even faster turn throttle motor, and a billet manifold instead of the cast piece (I believe,maybe it is just CNC ported). The standard hurricane manifold is already a ridiculusly short throttle range which contributes to tuning difficulties, making me think the updated manifold is only good for race purposes anyway.

All in all I payed $2300 to my door for the manifold which included $600 worth of bosch injectors and $1500 worth of billet throttle horns, fuel rails, and filter screens so I feel like I made out pretty well for this one.
 

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Discussion Starter #12
Any update?
Some small progress has been made on the interior, and I finished the flyin miata depower of the extra steering rack I bought. I haven't had too much time to work on the car as of late, mainly because I have been working on a job upgrade which should allow me to spend more on the car.

One change of plans has had me hunting junk yards for a 08+ 350z/370 6 speed, as I think the tighter gearing spread and single overdrive will fit the nature and goals of my project better. Fortunately, this change should make the transmission portion of the project slightly cheaper when all is said and done.
 

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Discussion Starter #14
How'd the depower go?
Easy enough, I tig'd the pinion and found some generic plugs for the majority of the steering ports. I like them more than welding up the fittings from the hoses because they sit recessed in the ports which would leave (theoretically) more space around the steering rack for other components. I air-hammered all of the seals off the shafts and I finished it off with red high pressure mobil 1 synthetic grease which can be had for $8/2lbs at autozone over all of the moving surfaces. I adjusted the stiction tension so there is the slightest bit of drag when cycling the steering by hand. In the event that it is not enough to maintain a line, I figure it would be easier to dial a little more in then on the car versus trying to back off the lock nut and crank it out bit by bit. All in all it was a pretty easy 2hr project.
 

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Discussion Starter #15
Speaking of which, anyone know of a source for plugs for the tiny, fine-thread pitch return line fittings? Or what the thread pitch is even?
 

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Discussion Starter #16
Also now actively looking for a 350/370z/g37 transmission if anyone knows of any that are not as much as a new one -__-
 

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Discussion Starter #17
Overdue update:

So the battery took a dump and then this happened... -28lbs


Then I found a great deal on ebay, so this is happening now... -79lbs


Annnnndddd a butterfly brace is going in tomorrow...
 

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Discussion Starter #19
The Shorai is this one here:

LFX36

It is 540 CCA, 36 amp hour battery. It is considerably larger than the stock battery both in capacity, and cranking amps. I have been using it since September and with my stereo (500w amp, 10" sub, aftermarket headunit etc), headlights, A/C etc. No worries so far.

Also...

After the brace went it I noticed something... So I did a thing...

No such thing as too much bracing eh? :haiguyths:
 

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Discussion Starter #20
Just to clarify, the factory butterfly brace I pulled off and replaced, includes a rather stout formed front bar that attaches to the back "legs" of the front subframe. I cut that portion from the flimsy sheetmetal that makes up the rest of the brace and bolted it back in place as it clears the butterfly brace.

Also, the less interesting bits I did while I was off work for a week included an 5x Racing timing wheel, removing the screen from the mass air meter, new brakes and rotors all around (cheap RI **** to tide me over until I can pick up a fab-9 6 piston kit this year), new back tires, new belts and fluids.
 
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