A4 launch Help

[coupe00]

Ya I agree, modifying the suspension to take advantage of the power you're putting down is money better spent. Wider isn't always better. And in some cases going to a bigger wheel and tire can be heavier, more unsprung weight, and slows the car down. The downside to getting the power to the ground is the weak 7.5 rearend these cars come with. I really don't recommend much in the way of traction modifications until the rearend is upgraded to a 12 bolt or 9 inch. The stock 7.5 simply cannot take that kind of punishment for very long, especially from a 6 speed. GM really dropped the ball when it came to that part of the car.

you can put a ford 9 inch in for our rearends?

[Firebirdjones]

Yes, Moser, Strange, Currie, all make bolt in 9 inch rearends and 12 bolt rearends for the 4th gen F-body, complete with torque arm mounts etc...
You can buy just the housing and assemble it yourself, or you can buy it complete and ready to drop in with ABS and traction control provisions etc...Larry.

[The Scientist]

What is the differences and for what applications would you choose the 9 inch or 12 bolt?

[Firebirdjones]

Thats personal preference. I have built both 9 inch and 12 bolts, but I really prefer the 12 bolt. Simply put, I have 3 other cars with factory 12 bolts and just like them. It was the rearend of choice for the muscle cars of the 60's and early 70's. Plus the fact that I like to keep my cars all GM, and the 9 inch takes a little more HP to turn.
Plus I go out of my way to make the 12 bolt look like a factory 4th gen install just as GM should have done it, with date codes stamped on the axle tubes etc....but I'm a freak Myself and a buddy of mine went through the trouble to weld correct style brake line tabs onto the axle tubes, (it seems the aftermarket leaves this little detail out ) among other little details to make it look like a factory deal.

9 inchers are nice for gear changes if you frequently change the gears, but I don't know of many street cars that do that. 9 inch offers a little more strength do to the pinion gears relationship to the ring gear, but again, this also robs a little HP to the wheels. Is that little bit of extra strength really needed in a street car? I don't think so.
I have found a 12 bolt with a 33 spline Eaton posi, and 33 spline axles (c-clip eliminator) will take just about anything I can throw at it without complaint. If you want to get more serious a spool with larger axles is always an option, but not that streetable.
As an example, my 72 SS 454 chevelle has a factory 12 bolt, I run a moroso brute strength posi unit with stock spline (30 spline) axles, although the axles are made by moser and not tapered like the stockers, so they are slightly stronger than stockers. This rearend has been together since 1988 with tons of dragstrip passes, car weighs 4,108 lbs. and cuts 1.5 60 foot times at 11.40's,,,,118 mph. 12 bolt doesn't give me problems at all.
Larry.

[Silver Streak]

I have been in a Camaro with a 12 bolt.. and it HOWLS when you're driving.. and at speed yelling practically isn't even an option.. I thought that is how they were... was this just a bad install?

[Firebirdjones]

Yes, something is not setup properly. Also what can contribute to that is eurothane bushings in the control arms and torque arm. Some people even run solid bushings. These types of bushings transmit more noise throughout the car. Most everyone upgrades to eurothane bushings for the trans mount and torque arm mount, and this is the start of the problem. Then they mount solid or tubular control arms/pan hard bar, this transmits more noise, then of course a eurothane bushing in the control arms/pan hard bar will transmit even more noise. Every car is a little different as far as this is concerned but it seems to be common for people to upgrade to this stuff before a rearend is even done.
If you couple this with a rearend where the backlash and/or pinion depth was not setup properly then,,,,yes,,,you can have a car that sounds like a school bus, some worse than others. Mine have always been quiet,,,just takes time to setup. Larry.

[iggz]

so ive been looking at a few stalls... yank 3000 series for 525 dollars.. would this be a good converter to get or should i go higher?

also is this ok for my 3.23 rear end?

oh i just remembered when im in first gear accelerating hard.. there appears to be a grinding noise coming from what sounds liek the transmission.. could this possibly be the TC on its way out? if so id gladly replace it with a higher stall one.

[Firebirdjones]

Not familiar with Yank, although alot of people here like them and use them. The price don't seem bad, say as compared to a Vigilante, which is what I have been contemplating.
Stall speed would vary depending on what you want to put up with, the cam you are running or plan to run or change in the furture, gears etc...
I can tell you that on stock cam LS1's I see alot of people going with 3,000-3,600 stalls. Some even higher. A good cooler is a must. I personally would try to keep in mind what future plans for the car are and go from there. I do know with a Vigilante you get 1 free restall within the first year of purchase,,,so if you get something you are not happy with, or you change the camshaft within that time frame, restall it to something more to your liking. But these converters run in the $800 range. Larry.