Hello,

I was coasting to a stop in neutral today and it felt like the clutch engaged a bit. Looked under car to find a puddle of gear oil and a hole in the rear differential cover. Had it towed back to my house to check it. One of the ring gear bolts was sheered off and all the other bolts were loose. I’ve never done any work on rear differentials. The bolt head had about 1/2” of thread left on it. What would the process be to fix it? Here are a few pics.




Hole in cover.

Sheered bolt.

Looked okay except for some gouged on the outer edges where the bolt head got kicked around.


Close up of sheered off bolt.

 

Someone has been in there are that is a Richmond Gear gear-set. My guess is that they didn't torque the bolts. Best bet is to purchase a new set of bolts and replace them all. Note that they are left hand thread.

Torque spec is 89 ft/lb.

RBob.

 

I can remove and replace the bolts without removing the gear set right? And idea best way to remove the piece of the bolt that is still in there?

 

Put the carrier on the bench and use a RH twist drill bit. Once it grabs into the bolt it should back the bolt right out since it wasn't galled or seized. You might need a carbide bit to bit into the grade 8/9 bolt

 

I was able to back the broken bolt out with a pick. As soon as the new bolts arrive (no one in town has them) I can put this thing back together. Thanks for your input, I appreciate it.



I felt like a surgeon removing a bullet from my patient.

 

And use RED Loctite on the threads after cleaning them with solvent. Carb or brake cleaner will work for that.

 

I’ve got it all cleaned up. How long after the bolts are installed with the red lock tight do I need to wait until I fill it with oil and drive it?

 

Loctite cures in the absence of air. By the time you have everything back together and the cover on, you should be able to fill with gear oil.
Synthetic gear oil (and additives) eat right through regular silicone. To prevent any future leaks, use Permatex Max Gear Oil Resistance RTV.


While you are in there, count thee teeth on both gears and you can figure your gear ratio.

 

I thought the part number on the gears correlates to a Richmond 3.73 gear set, but I will count the teeth to verify. Hooked to the t56 the ratio seems perfect to me. The new cover came with a gasket, I was just planning on using that. Or should I use the parmatex gasket maker you suggested?

 

If the gasket is a thick fiber gasket, just use that. If it isn't then get one and skip the RTV. That stuff makes a mess wherever it is used.

RBob.

 

Personally, I glue the gasket to the cover with the RTV. None on the diff flange side. That way the gasket comes off with the cover next time. In most cases where RTV is used, you want to glue the gasket to the part that comes off.

 

41 teeth on the ring gear and 11 on the pinon so confirmed 3.73. New bolts arrived. Got them torqued to 89 ft lbs., about to slap the cover on and fill her up. Thanks again for all the help.