One quick question. I have a 91 Camaro RS convertible with an auto and was wondering what gears I have? I did the math and I come up with 4.88's is that possible. I put is in drive not OD and went 40 MPH hour and the tack reads 2500. I have 245/50/16's. At 60 I'm spinning 3750. Is drive a 1 to 1 ratio? Ok two questions. Thanks I love this form everyone hare is super.

 

4.88 stock? Not possible. But if you are not the original owner then there is no way of knowing if a previous owner changed it.

What math are you using? The easiest way to check is to jack up the rear end, put the tranny in Neutral, then spin a rear tire by hand 1 revolution & count how many times the pinion yoke rotates.

 

Actually, I get 4.78 for the ratio.

Sounds to me like your torque convertor isn't locking up. I wil say though, the ratio from 40mph to 60 mph is identical, which would lead me to think the convertor is locked...

The easy way to know for sure is to follow BlackenedBird's suggestion, so long as the rear is limited slip...

 

Thing is, noone has ever made a 4.78:1 or a 4.88:1 gear for that axle. 4.56:1 is the uppermost limit. If you were stuck in second gear, that would be like a 4.44:1. Stuck plus a 3.08:1 swap would be 5.00:1 It could be your tach is on the way out. Go to the local auto parts store and spend $4 on a new rear cover gasket, and buy 2 quarts of 75W90 gear oil. Stamped on the perimeter of the ring gear should be 15-41 for the correct 2.73:1, or 13-40 for 3.08:1, or 9-41 for 4.56:1 That lube probably needs changing anyway, plus then you'd know exactly what you have, and diagnosis would be easier. Well worth the cost.

 

Sounds like your tach may be messing up.

 

I need some help with some of the same problem. Is the rear end from a 1987 Camaro rs v6 the same as the one in a 1992 Camaro rs v6?

 

Should have started your own thread. But thread-jack aside, they are the same basic axle. Gearing depends on which transmission each has. '87 should be 3.42:1 for either trans. '92 should be 3.42:1 for auto, 3.08:1 for stick. '92 was 28-spline, '87 was 26. But for a V6, that's fine.

 

Thanks I will remove the cover and count the teeth this weekend. Is there a problem if tork converter isn't locking up? What about in OD what should the RPM's be? It seems to me it is running fast that is assuming my tach is rite. How do I check if my torch converter isn't locking up? I have the car getting about 19.5 mpg in the city not bad for 164000 miles.

 

The method I posted above is quicker, cleaner, only requires a jack & jackstands & doesn't require buying a new gasket or refilling the fluid after it all runs out.

But....Whatever works for you, go ahead. Easy or hard & messy. Your choice.

 

I tried the turn the drive shaft and count the turns of the tire. The tire went arroiund a little over once. I am beginning to think my tach is messed up too. It is fine at an idle but gets around 4 going down the road. How do I fix that? it is going 2500 rpms in drive at 40.

 

What did you get for driveshaft revolutions per tire revolution?

 

a little over 1 like 1 and a 1/4 to 1 and a 1/3. I don't have a posi rear end. One tire spins forward and the other spins backwards.

 

Checking it the other way, as you found, is difficult. There is a way, however. You have to put jackstands under both sides of the axle. Then you have to lay under there , head under the driveshaft, one hand on each rear tire. Now, at this point it helps to have a helper person, and 2 bottles of white-out. One for you, one for them. Each of you marks each tire at the bottom. You mark a 1, they mark whatever. They turn a tire 1/4 of a turn, you mark a 2, or 2 dots, They turn it another 1/4 turn, and so on, then repeat for the other side. Once you're back at 1 on both, then mark the yoke and housing, and start turning both tires equally. It's not easy, even with the numbers you made. However, this is ignoring a prime opportunity for necessary maintenance that usually gets neglected. That gear lube isn't rated for infinite miles. It should be changed every 30K, but nobody ever does. Don't switch to synthetic if you're worried about the pinion seal suddenly developing a bad leak. And changing that is a royal PITA, what with having to properly torque a new crush sleeve.

 

You should get a MINIMUM 2 3/4 turns for a 2.73(10-bolt)/2.77(9-bolt) rear gears up to 3 3/4 driveshaft rotations for a 3.73 rear gear. 4 driveshaft rotations would give you a 4.10 (which wasn't a factory option).

It isn't rocket science. Just hafta count FULL rotations of the driveshaft. My guess (hope) is that you only counted half a rotation.

I'm gonna put my bet on you having a 3.08 gear open 10-bolt rear.

 

Well after failing at the tire turn trick I decided to remove the cover after all the car has 164000 miles on it and I bet it hasn't been changed. After reveling the ring and pinion I counted 15 and I think 40 which I come up with around 2.74. So my tach is way off. Some please steer me to a thread or something about fixing it. Oh I double checked and I do not have a posi. That's just another expense I will have to spend. Thanks for everyone's help. Now it's time to look for a set of 3.73 gears and a posi unit.