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8 3/4 case repair question.....

bandit67

bandit67

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My neighbors family has a 68 with a 489 case and Suregrip. It appears a piece of the pinion broke off , got into the ring gear and snapped off one of the two main caps. Bent the crap out of the two bolts. Can a used main cap be used to repair or were they machined specifically to the case. They are planning to install a kit with all new bearing , gears and seals. The clutch chunk and case appear to be ok. thanks...
 
They are machined to the case. So a replacement will likely not fit right. Easiest to get another case.
 
So you think they are line bored from the get go. That could be so. But thought we had swapped some caps back in the day.
 
blue69runner said:
So you think they are line bored from the get go. That could be so. But thought we had swapped some caps back in the day.
Click to expand...

They absolutely are bored as an assembly... You might get away with it but the proper way is to treat it like a connecting rod & resize it.. There are aftermarket caps sold for some rearends & those specify resizing the bore...

As mentioned find another case....
 
BTW this is a case

Screen Shot 2021-06-21 at 10.17.06 PM.png


This is a carrier

Screen Shot 2021-06-21 at 10.17.38 PM.png
 
If you have some mics to measure with it's worth a try..... just might get lucky but I would feel better with another case. And measuring the replacement would be a good idea too....
 
489 cases are cheap. just get another. by the time you find a cap and have it machined you will be way to deep in the rear to make sense. get another I have several
 
Last edited:
They think they may have found another 489 case. But for my curiosity , what case WAS the normal used in a 68 GTX, thanks.....
 
You also have to remember that the cases and bearing saddles are threaded for the bearing adjusters and as such are a matched set. That’s another reason why you need to match mark them before you remove them.
 
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