‘71 455/th400 442. 10 bolt 8.2 BOP rear. Went to replace rear pinion seal over the weekend, after driveshaft was reconnected and car parked back in garage, noticed a puddle of transmission fluid that night, from the th400 tail shaft.

Next up is tail shaft seal, any tricks to installing correctly, and is there typically an issue when driveshaft is removed, or did we cause ourselves more work unnecessarily. Surely it’s the latter.

 

How much leaked out, how big was the puddle? Might be worth cleaning it up well and driving it to see if there is a leak. Just removing and reinstalling the driveshaft shouldn't hurt the seal. It the rear wheels were hanging for a while that can cause a leak as the driveshaft is pulled back some on the trans yoke. In short there may not be a problem.

Good luck!!!!

 

Yes, rear in the air for about two hours. Here’s the puddle found that night.

 

Well, if your car has the original axle, that's an 8.5" ten bolt, not the 8.2". All 1971-72 Olds A-body cars came from the factory with the 8.5 axle. Also, removing the driveshaft yoke from the trans removes the seal, so trans fluid naturally dribbles out. And yeah, pulling the yoke out and reinserting it could also have disturbed the seal. As noted, I'd clean it up and drive it first to see if the seal goes back into place. If not, it's really easy to replace that seal. Just pop it out and tap a new one into place. Also it's a good idea to lightly clean up the yoke with emery cloth before reinserting it. Be sure to clean off any sanding debris first.

 

Thank you Joe, and meant to thank you earlier as well Bear. Previous posts on here helped to identify the rear as BOP 8.2. It’s surprising how a puddle of fluid may look like a quart, but could only be a third of that. I’ll clean it up, recheck fluid level and drive it. Appreciate the help guys.

 

Ah, it's that car we're talking about. Be sure you have the correct length driveshaft for that axle swap. With the rear suspension at ride height, the yoke should only be pulled about 1" out from being fully bottomed at the trans.

 

Indeed, thank you, Joe. According to the photo I posted, yoke seems to be out more than an inch. I’ll measure, are yoke, drive shaft dimensions listed in chassis service manual?

 

No, you won't find that info in the CSM, nor in the PIM - just part numbers for each application. Since your car is non-stock, that's kind of irrelevant. Unbolt the rear u-joint from the differential, push the yoke all the way into the trans, pull it out one inch, and measure any gap between the rear u-joint and the pinon yoke. Conversely, push the yoke all the way in, measure from a convenient reference point (like from the seal mounting surface on the trans to some repeatable surface on the yoke), bolt up the rear u-joint, and measure again. If the difference is outside the range of 3/4" - 1 1/4", your driveshaft is the wrong length. Unfortunately that means a custom shaft for your non-stock application.

 

Thank you Joe. PO was a chevy / pontiac guy, fortunate that he didn’t LS swap the motor and put SS badging on.

 

I put a film of moly camshaft lube on the seal lips and the yoke surface to avoid burning up the seal on initial use.

 

Pack the inside lip of the seal with Vasoline. Occasionally, pounding the seal in can knock out the small spring that’s inside the seal. While it rarely happens, it sticks when it does.

The Vasoline will hold the spring in place, and dissolve as soon as the fluid warms up. Don’t use wheel bearing grease, that’s stuff won’t dissolve.

 

Thanks Matt, may have found the problem…