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8 3/4 Main Caps

BrianS

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I am working on getting the suspension back under my 68 Road Runner and along with that is putting the rear end back together. I picked up a rebuild kit from Cass over at Dr Diff and was looking it over today making sure I have everything I need and realized I have an issue. First off I need to mention I purchased the car in 10,000 pieces unfortunatly the carrier was torn apart as well. Not really a big deal except whoever took it apart failed to mark the main caps. I have Larry Shepards book on Chrysler differentials and I read for an open rear it doesn’t matter but I have a sure grip and in that case it matters what cap goes where. What is the best way to figure out what cap goes where? Worst case I can take it to the machine shop but I was hoping there was an easier way.

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Will the adjusters thread in properly if they are swapped?
 
The caps matter on every Rear axle.

Correct! The outer bearing race needs to be supported correctly and not clamped or pinched of it's centerline. If you have access to an inside caliper, it's pretty easy to tell which side came from which. You only have two choices unless you were given a pail full of caps!
 
If you trial fit them you can generally work it out. Careful inspection is required but they only fit 2 places 1 is right the other is wrong.
 
At the same time I posted this I shot Cass an email-his response below

"Install the caps finger tight to make sure the threads line up. Luckily, there are only 2 variables."

I went out and tried what Cass said and sure enough there is only one way they will fit and allow the adjusters to thread in. I tried swapping caps back and forth, adjusters back and forth ect just to make sure I wasn't celebrating prematurely and there was only one combination that allowed the adjusters to thread in.
 
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I can't believe Larry Shepard said that. It is nonsense.
You might be right. I do not like to put out incorrect quotes so I went back to the book and read that part again, and again, and again. To me it seems like an out of place one liner in the book maybe a publishers error or something. He clearly says mark the caps in the paragraph before and in the picture illustration.
 
50/50, choose wisely.
 
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