Outer Limits 4x4 Board

Was climbin under the zook today to swap some wheels and i noticed some dents on the back of the diff pumpkin. dinted from the inside. So i drained the oil and out came some busted welds. so i stick little finger in drain hole and there are some more rather large metal bits still in there so out comes the center.

This diff was still working fine and it took a second look to figure out what had broken. well the bits of metal floating about in the housing were the grade 11 bolts that hold the ctr together. Ive never busted a diff like this before.

Cant get the rest of the bolts out to replace them so should i just puddle weld the diff together filling in the bolt holes or weld up another ctr and swap over the crownwheel or both and carry the other as a spare?

Thanx



pics

You can get broken bolts / studs removed if you have to. Take it to an engine builder /cylinder head reco joint and they probably will have bolt disintegrator ( shades of Marvin the Martian ).

It uses a hollow brass electrode, water and a transformer to arc the broken part out. Commonly used to remove studs etc and save motors.

Not that this is your best options - only mentioning it "just in case".

who built your diff?

the bolts look like they were over tightened. and have sheared off (incorrect torque).

alway remember, TIGHT IS TIGHT AND BROKEN IS TOO TIGHT

best bet is to get a new centre. if you try and fix it you might be lucky and it'll last. but with your "sierra luck" you'll only break it, doing even more carnage$$$$$$$$$$$$$$$$$$

ok i got the broken bolts out. Bought new High Tensile 8.8 bolts and bolted it back together. the shock loading of the welded ctr and grippy tyres have sheared the heads off the bolts. been turning to hard on the tar and with the ammount of tread the old silverstones have on the road wont help.

just need to get mate to set up the backlash again and Should be back on the road tomorrow afternoon. Fingers crossed.

Hmmm, interesting.

I know of these bolts loosening in welded diff cars but not all shearing. I vote with Muggins- over-tightened (or inconsistently tightened)

Steve.

Just a thought - would reaming the casting holes and using shoulder bolts be a better option ?

Less chance of the parts moving against each other and fretting.

Don't know anything about Zook diffs however so might not be practical.

Just a thought - would reaming the casting holes and using shoulder bolts be a better option ?

What do you mean shoulder bolts? do you mean bolts with a round contact surface under the bolt head?

As you can see its a cross between a dowel and a bolt. Used in engineering to provide precise location between parts and prevent movement which can sometimes occur with threads.