age

ok... I've read the thread below regarding the choice between the 3.73/3.42 gears for the automatic.. but how about for the T5?

I've swapped out my 700R4 for the T5, and realize that with a 5th gear, and different ratios, the 3.73's might be a better choice.. or would the 3.42's still be a better all around gear?

I'm using the car for autocrossing, and the occasional stop light derby.. I'm seriously considering 3.73's.. but I don't wanna go to 3.42s from 3.23s and not notice any difference.. it would just be a waste of time and money.

age!

92 L98

Baz89RS

If your asking about the final drive ratio's, then there wouldn't be much difference between a stick and an auto. Your 5th gear with the T5 is you overdrive as is the 4th gear of the automatic. The extra gear is spread out before the 1:1 trans ratio. Meaning that because you have a t5 or t56 doesn't mean that your final drive ratio will be much lower then an auto.

Having said all that, I went to 3.73's with my auto and wish that I got 4.11's. Ofcourse I don't do any highway driving or autocrossing. So I think you should at least get 3.73's.....

99Hawk120

Not true. The T5, the T56, and the 700R4 all have a 1:1 gear. It's 4th in the T5/T56 and 3rd in the 700R4.

There are several different T5 trannies floating around, at least one of which has a .63 5th gear, which is lower than the 700R4's 4th gear. The 94-97 T56 also has a 0.5:1 6th gear, and that is MUCH lower.

A lot of LT1/LS1 guys run 4.11 gears in the rear, and that 0.5:1 6th gear is why they can get away with it.

That said, I'd do 3.73s in the 5-speed. The 4.11s are noticeably weaker and probably a bit too much gear. If you have a T56 6-speed,
run 4.11s unless you are running past a certain trap speed (what, will depend on your tire size and redline--ended up being approximately ~117 for my car). It's probably a moot point, the 10-bolt will self destruct ling before you run 118mph trap speeds with a stick shift.

FYI, I'm running 3.89s in my car ('96 T56, Ford 9", ZZ4 motor with 6000rpm redline, 27" tall tires).

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"Beware he who would deny you access to information, for in his heart, he dreams himself your master"

'84 Black Camaro Sport Coupe ZZ4 350 M6 -- '84 Olds Cutlass Supreme 231 A3
'91 Medium Blue Metallic Z28 400 A4 -- '99 Navy Blue Metallic Firehawk #120 346 M6

FlashGTA

With the TPI I'd stay with 3.42's. If you have a heavily modified car that breathes up top then 3.73's.

SSC

Yea this is the major focal point.
If your engine has been optimized for high end performance 3:73's would be great.
I say this because there not much difference between 3:23's and 3:42's and you might feel like you wasted your dough
You will be needing more rpm to reach a certain speed so if your engine is up to the job go for the 3:73's. But dont be supprised if you find yourself using 2nd gear to take off in.

merf23

I now have a 3.27 9bolt with the T5/0.73 5th. I plan on going to the 3.73's with a 0.62 5th gear. This will maintain the same highway RPM with better overall performance.
The T5 5th gears are very easy to change. They are located in the tailshaft...about a 45min job once the trans is on the bench.

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1984 Z28 (L69) monochrome tangerine orange with IROC decals and hood
1987 IROC wheels with Goodyear GSC's
305 from 87 IROC with 1994 LT1 cam (203/208 .450/.460")
performer intake
Qjet from 73 Olds
dynomax cat-back, gutted cat
no emissions controls --> passed emissions testing
non WC T-5 with 0.73 5th
3.27 nine-bolt

JohnnyIroc

iTrader: (3)

3.73's are the only way to go if you are planning for a good et and mph at the track. Ive driven my brothers formula with 3.45 gears at the track and it only passes the finish line at 4300-4500 rpms at around 90-92 mph. Dont waste your time with 3.42's but do plan on having good tires if your going to get 3.73 gears. Good luck

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88 IROC-Z 350 TPI 5 speed
Performance Resource Chip, Flowmaster American Thunder cat back exhaust, B&M Ripper shifter, MSD coil, TB bypass, TPIS MAT relocation kit , AC Delco 160* t-stat, Richmond 3.73 gears, March Power & Amp pullies, Home made Ram Air, Steve Spohn SFC's, LCA's, and LCA relocation brackets , Panhard bar, TPIS AFPR, Ported plenum by Daniel Burk, Mac Test pipe
Best et: 14.232(all times with 305)
Best mph: 97.76
Best 60': 2.063
http://hometown.aol.com/famioso15/johnnyiroc.html