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View Full Version : 12 Bolt Rearend Seal - Where To Get Them?



bigboi
04-11-2010, 02:34 PM
I have a 12 bolt rear end. I have a hunch the seal on the front of the differential is leaking. The seal I am referring to is the one that the yoke sticks into.

How do I go about replacing this seal? Do I have to pull the whole differential apart to replace this seal?

It sure is creating a mess under the back of my car... Darn oil all over the exhaust pipes and spattered underneath the car... Ugh!

Brian

big gear head
04-11-2010, 06:43 PM
This is the pinion seal. Youo need to check the bearings and pinion nut. Many times when this seal starts leaking it is because the nut backed off or the bearings went bad. If you can move the yoke up and down or side to side then there is a problem other than the seal.

You can pick up a seal at most auto parts stores, but the seal that they give you will be for a truck 12 bolt. It will work, but you need to be carefull when you install it. This seal will sometimes make contact with the outer pinion bearing and this can cause problems. When you drive the seal in don't drive it in all the way. Leave it out anout 1/8 to 1/16 iinch. Smear some RTV around the outside of the seal before you drive it in.

There is more, but I'm needing to go for now.

JeffT
04-12-2010, 01:31 PM
How do I go about replacing this seal? Do I have to pull the whole differential apart to replace this seal?
Brian


To do it correctly, yes, you need to tear it all the way down. Inspect the bearings for and replace as needed. Also, check the yoke where the seal rides for a groove. Sometimes you can find a repair sleeve that will work to fix the groove, otherwise, replace the yoke.

When you put the pinion back in you will tighten the nut to a specific bearing preload, usually 12-15 inch pounds for used bearings and 25-30 inch pounds for new bearings. This is the reason you need to tear it all down to fix correctly. You can't measure the preload accuratly with the diff, axles etc...still in place.

With that said, a lot of people just zip the nut off and replace the seal/yoke and zip a new nut back on and roll on. Sometimes it works for awhile and sometimes it doesn't. Your choice.

big gear head
04-12-2010, 05:41 PM
I've had good luck installing the yoke with a new nut and torquing it to 150 foot pounds. I did some tests and found that 150 is best. It is tight enough to keep everything together, but not tight enough to change the bearing preload. If you measure the bearing preload when you take it apart you will find that it is about 5 inch pounds or less. It is very hard to set it the same with a new chrush spacer.

When you put the yoke back on be sure that you smear some RTV into the splines of the yoke (not the pinion shaft) first.