# 12 bolt Diff what outer seals/bearings do i need?



## Destro23 (Aug 4, 2016)

When i got my 68 Lemans convertible (GTO Tribute/clone car) there was a rumble in the rear after it warmed it... i changed and filled the diff with fluid and fluid now leaks out of the axel on passenger side.... to make a long story short... the diff pin bolt is broken inside the diff so i can't take it apart to fix the rear outer seal. i've now been able to drill through the bolt but it still won't come out. So i'm taking it to a local shop.

i've been told to replace outer wheel bearings as well.. i just dont know what to order while we have this open. And am not sure if this is original diff of car.

stamped on the gears INSIDE of rear end: 3869788 15-41 GM
google says it's : 2.73:1 - 41/15 teeth on gears Positraction

Casting numbers on rear:

CH K 067 E
CH = 2.73:1 ~ 12-bolt Positraction 

thanks for any help/advice while i have it open.


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## Pinion head (Jan 3, 2015)

5707's on the axle bearings, Timken is what I use.
8660S on the axle seals. National brand seals.

If axles are spalled (pitted) or a deep groove has been chewed into the bearing surface on the C-clip axle, it's time to replace the axles. Some folks will say, oh no you can get by with a $30 axle saver bearing, but I personally have examined many axle saver bearings that have failed. Axle saver bearings also have much smaller diam & width rollers, just not good.

to remove the broken pin bolt,hopefully the shop has a Matco differential pin bolt removal tool. I first bought this specialty tool 90's & have cloned it several times with correct thread size cap screw & long 1/8" drill bit. Also check the cross shaft, make sure it's is not chewed under where the spider gears ride. Many times, the reason a small pin bolt has broken, is due to spider gear(s) dragging along a rough surface (versus) smooth machined surface on the crooks shaft. The spider gear can actually seized on the worn surface of the cross shaft & cause the entire crosshaft to spin and snap the pin bolt. Some care needs to be taken to examine the cross shaft & it's mating holes in the carrier. If either are worn, they need to be replaced. Get into that position, I have several dozen nice condition 12 bolt 3 series carriers, as well as single track only cross shafts with no wear.


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## Destro23 (Aug 4, 2016)

Thanks Pinion Head for the numbers... now the only problem i'm having is locating the Bolt. Napa had one but it's to short the one from napa is 2" this one broke at the 2" mark.

update... the shop has drilled through the pin completely and even had to drill a hole right next to it to remove the last bit of the bolt. Now the whole cross pin won't budge out of there! there is no more bolt holding it in. and it's not budging out of there. There is a little play on the axles when i have the tire and drum off. Not sure where to go from here. 

its looking more and more like the whole rear needs to be redone.

i've ordered Yukon cross pin shaft and  Yukon Cross Pin Bolt


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