90RS305

Alright, I've had my 90' for about a year and a half now, and the entire time I was under the impression I had 2.73's in the rear. After looking a little more closly at THIS LIST I noticed that it said the 1990's with the 5 speed had 3.08's. Is this true?!?! I know it's not posi, but having the 3.08's would explain a few things, like the fact I got my stock LO3 to pull a 15.3 out of it's butt, and how I can roast my tires....err tire....SOO easily. Is there anything physically on my car that I can look at to confirm the gear ratio? I would love solid proof of this if possible. Any info would be GREATLY appreciated!
Man, all the post about my 2.73's......

Bruce (90RS305)

RB83L69

Take off the cover and look.

Have you changed your rear end grease lately? Then you need to. Great excuse for taking off the cover. Whilr you're there taking care of the neglect and overdue scheduled maintenence, count the teeth; or look on the edge of the ring gear, the teeth count is usually stamped there.

ede

there's no way to know if they've been changed or not and like rb said it's time to change the oil anyway

johnjm22

How did you get a stock LO3 to run a 15.3? I have a hard time beliving that.

90RS305

I know, but it's true. I had the slip to prove it but unfortunatly it got lost when I moved The gear oil was changed about 3 months before I bought it so yeah it does need to be changed, so when I count teeth how many = what gear? I know it's the stock rearend though, so is the info on the tech data page correct? Thats my biggest question...

Bruce (90RS305)

RB83L69

Count the ring, count the pinion, divide the ring by the pinion

kd5boc

Without having to open anything...you can also jack up the back end, and turn your wheels.

Mark the driveshaft with chalk, and have a buddy turn the wheels 1 complete revolution (making sure to have both wheels turning) or leave one wheel on the ground and turn the other one 2 revolutions. Then just count how many times the driveshaft turns...quick and can be done in less than 5 minutes. You won't have the exact munber, but with all the info we have on these cars, you will be able to tell "which" rear-end you have.

drop-top IROC

If everything is stock, you likely have the 3.08 rear if it's a 5 speed. That was generally the standard issue for 5 speeds. 700R4's got the basic 2.73. Check RPO codes and/or 3 digit stamp on the axle tube to be certain.

90RS305

Kewl! :rockon: thanks for your help guys! I'm gonna change the gear oil here in the next couple weeks so I'm just gonna count to be sure, but I'm bout' positive now it's 3.08's. Kinda kewl to know....

Bruce (90RS305)