Switching Caps in 8 3/4 Case

[Rocket]

I am helping a friend with his 8 3/4. He has lost a cap from the center section. How likely will another diner cap work on his case? What I have heard is it is better to start with a new case. I know there are aftermarket caps available so it can be done. Cost of new caps may steer him to another center section.

Any experience with interchanging used or new caps is appreciated.

 

[Oldmanmopar]

You need to set the bearing adjuster in the threads so it turns freely in the threads on the carrier. The set the replacement cap on without the bolts and see if it turns freely. Once you have it pressed against and it turns free see if you can start the bolts. If you can pull the bolts against and still turn the adjuster and not bind the threads you should be good .

No promises but I have done this with success on a carrier with a cracked cap. They are threaded together but there is side movement at the bolts and alignment may be possible with holes not having a precise fit to the bolt.

 

[RustyRatRod]

You need to set the bearing adjuster in the threads so it turns freely in the threads on the carrier. The set the replacement cap on without the bolts and see if it turns freely. Once you have it pressed against and it turns free see if you can start the bolts. If you can pull the bolts against and still turn the adjuster and not bind the threads you should be good .

No promises but I have done this with success on a carrier with a cracked cap. They are threaded together but there is side movement at the bolts and alignment may be possible with holes not having a precise fit to the bolt.

What he said^^^^^

Most times, they aren't critical. ....but of course there's one in every crowd, so I would follow the procedure above. Chances are, you'll be good.

 

[Dana67Dart]

just going out on a limb here, and pure speculation. but I would assume a cap from the same series case (741, 742, 489) and if posable around the same casting / assembly date would increase the chances of a good match.

my thinking is parts made around the same time should have about the same tolerances in construction, and the same group of machinists would have machined the parts. (I know it is a long shot and most likely not necessary.)


all that being said, I think @Oldmanmopar laid out a winning strategy for you.

 

[Outsder]

Broke a cap years ago, 40 years?, rest of setup looked good, so pulled a cap off another and fit it to match. Measured good bore, and filed the cap mating surface to about 0.001"us, then honed with cylinder hone to finish. Worked fine for the rest of its days.