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Discussion Starter #1
I recently purchased a 94 RMW. Going through her and cleaning up a few small problems. How can I tell what gears I have in the back side and what ratio's would be suggested for good gas mileage and still reasonable pulling power?

I have put on 235 55 17s for tires and Impala wheels. I shocked it down with Monroe Servere Service shocks. Replaced rear drums today and took care of a little wheel well cancer!! Body is pretty clean every where, but the crappy rubberized factory undercoating trapped in some water over the years and put a hole or two in one wheel well. Got her cleaned up today. Still have a creak, only when wet, in the driver side rear. It sounds like the rear bushings are on the way out. Just another project. :rolleyes:
 
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cool...you can jack up the car, make a chalk mark on the driveshaft and one on the inside of a wheel. turn both wheels and count the rotations on the driveshaft...
 

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Discussion Starter #4
Great information...... Thanks!!!:biggrin:
 

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If your car has the tow package, (Large mechanical fan in the engine compartment. Non tow pack has dual electrics), then you should have a 2.93 rear. Base model cars have a 2.56 rear. A good compromise for towing and mileage would probably be 3.42 which was also optional for the 9c1 so ABS reluctors are readily available. Many think that you get better gas mileage with lower gears also (within reason) because so much energy is used to just get the car rolling with high gears in a heavy car. There may be an issue going to higher gears with the 2.56 gear carrier.

Sean
 

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Discussion Starter #6 (Edited)
If your car has the tow package, (Large mechanical fan in the engine compartment. Non tow pack has dual electrics), then you should have a 2.93 rear. Base model cars have a 2.56 rear. A good compromise for towing and mileage would probably be 3.42 which was also optional for the 9c1 so ABS reluctors are readily available. Many think that you get better gas mileage with lower gears also (within reason) because so much energy is used to just get the car rolling with high gears in a heavy car. There may be an issue going to higher gears with the 2.56 gear carrier.

Sean
Good info Sean..... This was exactly what I was looking for. I have the 2.56 gears. I assume the stock 3.08 gears from my Impala will not work in this rear?

ANYONE?
 

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I don't believe the 3.08's will work. That is definitely the smaller carrier. I think the cut off for the "3 series" carrier is 2.93, might be 2.73 though, not sure.

Sean
 

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Discussion Starter #8
I don't believe the 3.08's will work. That is definitely the smaller carrier. I think the cut off for the "3 series" carrier is 2.93, might be 2.73 though, not sure.

Sean
You are correct. I checked with Randy's ring and pinion. The carrier will swap out of my impala ss....... so if I upgrade the impala rear, I can drop in the original 3.08 rear into the wagon...... the plotting begins!!!
 

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Gears

I don't believe the 3.08's will work. That is definitely the smaller carrier. I think the cut off for the "3 series" carrier is 2.93, might be 2.73 though, not sure.

Sean

The 3:08 differential and pinion will work in the RMW rear end. But the Impala/Caprice/9C1 rear end (axle assembly) will NOT fit under the wagon (too short). I don't have the exact measurements handy but the wagon rear is approx 3" wider than the sedan rear.

Good luck with your swap!
 

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Discussion Starter #10
The 3:08 differential and pinion will work in the RMW rear end. But the Impala/Caprice/9C1 rear end (axle assembly) will NOT fit under the wagon (too short). I don't have the exact measurements handy but the wagon rear is approx 3" wider than the sedan rear.

Good luck with your swap!
There are several posi/limited slip carriers on ebay. If I buy one of these and put my 3.08's in it should make a better all around car with better towing and around town mileage.

Better yet I think I will upgrade the impala to a stronger spool and use the factory impala carrier and 3.08's on the wagon. If I can afford to do it.
 

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alot of people have told me if you are going to go through the trouble of doing it, got to 3.42s or 3.73 with a posi unit.... Will really wake the car up.

I've got the 2.93 in my RMW and 2.73s in my L03 car....
 

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If I buy one of these and put my 3.08's in it should make a better all around car with better towing and around town mileage.
I don't know about towing but my experience has been you will not get better mileage.



A good compromise for towing and mileage would probably be 3.42 which was also optional for the 9c1 so ABS reluctors are readily available.
Just for clarification, it was the '91-'93 9C1s that could be had with 3.42 (came with the L05 engine).

In '94, 9C1 came with either 3.23 or 3.08.
 
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