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View Full Version : 8.5" posi - Cross Pin stuck in posi



cad
02-26-2006, 08:15 PM
Hello all,
This weekend I was attempting to pull the axles from my 1978 8.5" GM posi rear end and could not get the cross pin (crosspin) out (the big one in the spider gears) from the center of the diff.
It would only come out of its spot just past where the retainer bolt hole was almost fully visible. It isn't seized in the posi....I think the spider gear, or gears, are causing the issue.
We beat on it with a big hammer and big drift for quite a while....no luck.
The rear end has been apart twice before (once when bought to put in 4.10s, and a little later to fix that shoddy job with the 4.10s in it now). But, it has been 10 years now since it's been apart.
I wonder if the crosspin is bent, or if it is galled badly due to drag racing....I can't find many examples on the internet, except for breaking the retainer bolt (which did happen).
Anyone have experience with this? I don't "need" to spend a gazillion dollars for a new rear end.
It has held up to a ton of abuse. I just want ideas, or similar experiences from those that were able to fix it.
Thanks
Clark

cad
02-27-2006, 11:06 AM
I talked to a couple techs that I know. Both say that the spider gears and cross pin are galled to the point that the pin will not slide out. Both recommended BIG hammers. Like 5 pounders. Potential is there to break the case. I have access to spare diffs. The alternative is to slide the pin back into its position and install a new retainer bolt and run it the way it is.
I am glad it is still a month until spring.....

MarkM66
02-27-2006, 11:41 AM
Did you try an air hammer?

cad
02-27-2006, 07:56 PM
In order to get a better angle on the rear end, we pulled the rear end out before dinner.
Here are some pics. Ultimately, it took a big hammer and a 4" grinder with a cutoff wheel.
www.doukas.us/crosspin.htm

I am going to look into the Powertrax locker at Summit (http://store.summitracing.com/default.asp?Ntt=powertrax&x=32&y=8&searchinresults=false&Ntk=KeywordSearch&DDS=1&N=115&target=egnsearch.asp).

malihoochie
03-22-2006, 11:26 AM
I was in the same boat once, years ago with a 7.5" rear. After alot of sweat & tears it ended - the same way as yours. I beat on that pin 'til it would not go forward or back, then I paniced and in the end I cut the pin off. I got the rearend all apart & spent a long time cleaning out the metal debris that came as a result of the cutoff wheel. I hope to never go through that again. Best of luck to you!