I'm new to the car hobby thing and I'm having trouble with getting the right rear end for my camaro.It's a 92 rs 305 tbi 5 speed manual tranny.The thing is the old man I bought the car from had put a 2.73 rear end in it because the old 3.08 had gone bad.I found a 3.23 rear with disc brakes at the junk yard and put that on my car,but now it revs alot higher than before and my speedometer is way off.I'd like to know if any one can tell me if a 3.42,3.73 or wich rear would work best on my car and what's the best way to tell wich rear end I'm looking at,the only way I can tell is by finding the numbers stamped on the diff.I don't know anything about rear ends and any info you guys can give me would help out.Thanks.

 

Is the 3.23 rear end you found a 10 bolt? Or the 9 bolt?

Either way, it gives you a numerical advantage. You must have noticed the car being faster?

For the speedo, you can get these little plastic gear that will replace the one in your VSS, and your speedo will be correct again. I forget the website, but another member will probably chime in. Also, they will be able to tell you what color gear you need to buy too get it fixed.

Another option is, if your new rear came off a car at the JY, maybe that car has the proper gears in it's VSS? It might be too old tho IDK. Sorry I cant really help.

 

10 bolt vs. 9 bolt will be obvious as hell by simply counting the diff cover bolts

most all were 10 bolt but some were 9 i have never seen one in person yet, so apparently none were cold in the central IL region haha


as far as ratio goes you have three options


pull the diff cover and look

give the stamping codes off the pass side axle tube to us and see if one of us can decode them
or decode them at the chevy dealer parts counter if you know the year make model the axle is from

or do the driveshaft vs. tire revolution count trick and do the divsion math to get the ratio

3.42 is great with non Od trannies, 3.73 or deeper is great with OD trannies

daily drivers that is


yes your speedo will be affected if you dont have the factory ratio axle under it

as well as tire height

and other things

to fix it you will have to replace the speedo gears in the tranny tailshaft housing


there are online tire height/axle ratio/RPM calculators to determine what RPM at a given speed you will get with a given axle ratio and either 1:1 or .70:1 final transmission ratio

 

Thanks for the advice guys it really helps out,just one more thing,do you think I should keep this rear end, like I said before it's a 3.23 out of a 86 camaro at least that what the Haynes repair manual says.The stamp on the rear passenger side axle is 8PQ and it is a 10 bolt.Or would a 3.42 work better?

 

3.23 and 3.42 are so close to the same especially with a stock drivetrain that it doesnt matter

i would worry about more important things really


good luck!