Replacing Pinion Oil Seal

[MtnDriver]

I'm a 3-week LBC owner ('73 MGB) and having a blast with it, both driving it and working on it. Changed all the fluids (including differential) first day I had it.

Car was dry as a bone until four days ago -- I've put 1000 miles on it in three weeks *grin* -- when the differential (tube type) started slinging oil; getting thrown against the undercoating, battery boxes, etc. Tried some seal conditioner in the dif. oil, but no help; getting worse, in fact.

QUESTION: How much torque is required to get the pinion nut off? I've applied PB Blaster several times over three days and applied more force than I would think should be necessary (more than my torque wrench will register) but no movement. Haynes says 140 lb/in and Bentley only mentions torque readings for rotating the tires through the pinion. While I know things can get stuck on these little cars, increasing the force (while I'm under a car and protected only by jack stands) seems like it may not be the best answer. What am I missing?

And if I've taken the back of the propeller shaft off and drained the differential, is this a good time to replace other seals? Assume I should check the pinion bearings while I'm poking around in there.

Thanks in advance,
Tim

 

[borjis]

I think your only option may be compressed air driven tools to get that nut off.

I had everything replaced in the rear end of my 72 and it was just too much to deal with so I had somebody do it who specializes in rear end R&R.

 

[Steve_S]

As mentioned, a pneumatic impact wrench will take it right off. Mark the nut so you can torque it down to exactly the same point. Tighten too far and you will destroy the crush washer.

 

[Joelb]

I wouldn't recommend using a torque wrench as a breaker bar, you can really screw up the torque wrench.

A 1/2 inch impact wrench, electric or air, will take it right off.

Good luck

 

[MtnDriver]

Okay, so I tried a breaker bar, pneumatic impact wrench (even tried hitting it clockwise then reversing), PB BLaster, heat, and lots of cussing. Nothing has worked. In fact, I melted the synthetic retainer portion of the nut, so I've likely made it worse. Do I have any options besides re-connecting the drive shaft, adding dif. oil, and taking it to a shop? This isn't what I had in mind when I bought the car or when I bought the $6 seal I'm trying to replace! On the other hand, spending several hours trying to get a nut off seems ridiculous.

Thanks,
Tim

 

[Steve_S]

An impact hammer should make short order of that nut. How much torque is your impact hammer capable of? If it's a little electric one, it might not be enough. At a minimum you need the type used to take wheel nuts on and off.

 

[jlaird]

That nut is rated at 140 lbs, it needs a real impact wrench.