Is there a way to tell a gear ratio of a stock differential with out removing it? A stamp? Number? Going to the junk yard and turning the wheels my not always be an option.

I want to pull my rear (24 spline) differential and have it rebuilt. No one i know of in town does this so i gotta send it to Utah. I'D like to grab one out of the junk yard so I'm not parked for a month while it gets rebuilt. Anything I should be looking for? Other than my locker my differential gearing is stock. My front diff (10 spline) is stock. Do RRC and Discoveries have different gear ratios for different years options etc?

 

All the usa spec rrc and disco had the same ratio. 3.54 if memory serves.

 

They should all be the same gear ratio unless someone upgraded. You could always rebuild the diff yourself, its not that hard.

 

It's the pinion bearing I don't get. I've read the rave. I don't get it

 

The pinion depth and preload have to be readjusted after replacing the bearing. Both are accomplished with different thickness shims. There's a fair amount of trial and err involvedso its a good idea to use a setup race. Basically take the old race and grind down the outside to it drops in/out easily. Then you can add a shim, check it, and adjust. Once you get it dialed in, install the new race, and tighten it all up. Obviously thats an oversimplified version but its not too tough.
I think Ashcroft Transmissions has some good info on their website too.

 

That does help actually. Simple is good. Now you have me thinking about doing it.

 

i think 3.54 pretty much standard on all but the series models

 

Its not too hard, just a lot of info to wrap your brain around if you are going into it with no prior knowledge, like I was. Once you tear into it and get the pieces out their relationship to eachother starts to all make sense. You'll need some basic tools to get started, probably less than $100 worth.
-Dial indicator and magnetic base
-Inch/pound beam style torque wrench. This is the one I used. You want the beam style so you can watch what the preload is.
-You'll need to make a tool to adjust the bearing cap nuts. Basically a piece of flat stock with two bolts sticking out of it.
-Some yellow gear marking compound
-Digital caliper/micrometer helps as well to keep track of shim thicknesses.

 

You'll probably want new bearings/races for everything in there as well. Lucky8 has everything you need. Buy one shimpack from them, should be enough along with the current shims in your diffs to do two diffs.

I will say that rebuilding diffs isn't for everybody. There is a certain amount of upfront investment needed and a learning curve. For me it was worth it. I like knowing how to work on things and being able to do things myself. I know have everything I need to rebuild my diffs anytime I want.
I also went all out when I rebuilt mine. I installed Ashcroft lockers and Ashcroft 4.12 gears. I replaced all bearings/races. I replaced all the crown wheel bolts, carrier bearing bolts, and pinion bolt. I figured as long as I was in there!

 

Yea it's really easy to get a case of the "might as wells". I know I don't want to change gear ratios as I still want to do a fair amount of highway driving. I like the 75 MPH RPM's where they are. I already have a Detroit locker in the rear diff so I don't have to buy that. The bearings/shims and tools seems my only major expense. Still for 50 bucks I may just stick the Jy unit in there so I can take my time. Gonna review the rave again with your simplified explaination and see if it clicks.