Broken Pinion (1 Viewer)

[Mudkiwi]

Hi there, I was tring to tow a stuck Mitsubishi (should have left it there) and broke the pinion in the rear diff.
Is this a common thing? I thought a drive shaft or a UJ would have broken before the pinion went, any ideas on why this might have broken?

 

[crushers]

send me a larger pic to
wayne@crushersrule.com
i would like a closer look...

i have seen many a pinion let go before the ujoints. usually the pinion was not set to proper tolerances i.e. too much back lash...

 

[clintnz]

It is common on 40 series, dunno how different the 70 diffs are. The 40 series fix is to put in an anti-tramp device of some sort.

Cheers
Clint

 

[Mudkiwi]

send me a larger pic to
wayne@crushersrule.com
i would like a closer look...

No worries I will take one today and send it through.

 

[crushers]

LOL!!
when i read this i thought you snapped the pinion off the Mits...
the rear diff on a 70 series is the same as the 40,60,80,75. if there is too much play then it will break, espec if you are torquing on it trying to pull something or going rev/forward/rev as in a mud hole. the load and unload will shap it off...

 

[NZBJ71]

soft springs

From you pic it looks like you may have a light spring pack (knid hard to tell with the small size)

If you do its likely that your getting spring wrap under load.

This is a problem i have just developed also, because I have just replaced my BJ71 with a FJ40 powered by a 5l Holden EFI V8 and it has soft springs. the net result is 2 snapped pinions in 2 trips out.

Have a search in the 40 series forum for "traction bars", there are some good ideas there, alternatively there are a few guys down here that just use heavy overload springs under the pack to fight the axle wrap.

Tony