rear end advice

hi guys looking for some rear end gear advice here. im putting a lt1 engine with a 4l60e trans in my 80 trans am and im not sure weather to go with a 3.43 or a 3.73 . i was hoping some of you guys that upgraded to a 373 in you mid 90's camaro or bird could chime in and let me know what kind of highway rpm's and mileage you got with those gears . any help would be great . thanks

[Phantom409]

Well, I have a 93 and I'm running 4.10's in a 9" and at 80mph I run 2400 rpms with a 6 speed.
You should be a round 2000 I wold think with a 3.73.

[Kwazrollinz28]

3.73 for sure.

[1BADAIR]

i think your tires are a little taller than 4th gens
3.73 would work well

[WMCC Doug]

Hi Jimmie,

Welcome aboard! Nice looking car!

I have 3.73 gears in my '74 Z28 and am running a T-56 six speed trans. 2,000rpms is right about 80mph.

But, I know that's not the setup you're building, so I would suggest going over to www.nastyz28.com. It's a fantastic 2nd Gen Camaro website. Since your 'bird is about the same thing, their experiences should be similar. There are quite a few that have done your swap on their 2nd Gen Camaros who should be able to offer you some advise and answer your questions.

[sman]

Depending on tire size...

Im running 3.42's with a 4l60e, and converter locked, 70mph is 2150rpms by the stock tach.

[1BADAIR]

i think the stock tire is like a 225/70? thats about 27.3-4.
3.73 with a 4l60 and that tire would be 2200at 70

[sman]

How am I running so many rpms?

[JoeliusZ28]

unless youre going to be doing a lot of highway cruising i would go with a 3.73.

[kammi10]

your tach could be off just a tad spencer plus there isnt mcuh of a difference between 3.42's and 3.73's maybe 200 rpm down low

[sman]

Hmm, going data-logging on the way to school tomorrow, going to see what the computer has to say. Ive heard our tachs can be horridly inaccurate, was reading a post about someone on ls1tech where at 3000~ rpms it was off by about 500! Going to see if I can dig that up....

[prorac1]

The tach in both my 94 and 97 Camaros was off by 200 rpms. When showing 2000, im actually spinning 1800. Eric L

[1BADAIR]

plus we have like 25.6-26 inch tires

[JoeliusZ28]

I have a digital tach in my car and ive noticed that the error seems to be larger the more RPM you are turning.

[1BADAIR]

I have a digital tach in my car and ive noticed that the error seems to be larger the more RPM you are turning.

i had to finally put a real tach in my car. at idle the factory was off by 200. if i put the 3000 pill in my shift light and free reved it the light would come on with the tach at like 2000. I never knew what rpm i was launching at so i ended up putting a 5inch tach in that i remove while not at the track