How to replace pinion seal

[steveh326]

OK this may be a stupid question, but how do you replace the front pinion seal? Mine is leaking... I think I see how to do it, but having never replaced one, would like to check with the experts before I tear it apart.

thanks in advance...

 

[bigb427]

Basically you unbolt and remove the driveshaft, remove the pinion flange which is held on by the big nut, then remove and replace the seal being careful not to damage the new seal when installing it.

Next you need to reinstall the flange which is where it becomes somewhat technical. There is more than one method of doing this, but I will post the preferred method in which you can reuse the pinion bearing crush sleeve.

The preferred method involves using an inch pound torque wrench with a gauge, not the "click" type to measure the pinion bearing preload after tightening the pinion nut. This is the actual amount of rotational force it takes to rotate the pinion gear. It should not freewheel or have any looseness in the pinion bearings.

The wheels and brake drums should be removed and preferably the axles also. You will need some means of holding the pinion flange and a breaker bar with a cheater bar to give at least 3 ft length to tighten the pinion nut by hand. Do not tighten the nut with an impact wrench. The actual torque of the nut is not important but it can easily be in the 250- 300FT/LB range. When you feel there is no more loosness be sure to make small movements tightening the pinion nut then check the preload with the inch/pound torque wrench. It should take 10-15 inch pounds to keep the pinion gear rotating. Note that there will be an initial "break away" reading that will be higher than what is required to keep it rotating. If you tighten it too much to where the preload is too high, you will need to replace the crush sleeve. If this happens you will need another new seal and a new crush sleeve, then you will go back to the beginning of the procedure of tightening the pinion nut after replacing the seal and crush sleeve.

 

[steveh326]

thanks Big, very clear instructions.

 

[Anonymous]

This info needs to be saved. Great write up.

 

[RyanG85]

If its just a leaky seal, I take a hammer and a sharp punch and make three locating marks. One on the pinion, one on the nut and one on the yoke. Make the marks in line with each other so you know the location of the nut to the pinion and yoke to pinion. I then take my digital caliper (or dial caliper) and measure from the end of the pinion to the top of the nut. With the marks and the depth, you know exactly where to reinstall the nut. Now you can tear it apart, clean everything, pop the new seal in and reinstall. Only use this method if its simply a leaking seal.

 

[steveh326]

OK, pinion seal, axle bearings and seals are done. Waiting on some brake hardware before I can put the new shoes back on. While I wait, I figured as long as I went this far with the rear end I oughta change out the fluid. Does it just take GL5 or something else in there?

Thanks in advance. Now that some pieces of this car are going back together I guess it's time I get a manual of some sort.

 

[RustyRed]

Thanks in advance. Now that some pieces of this car are going back together I guess it's time I get a manual of some sort.

Ford shop manual like the one linked below is much better than Hayes or Chilton. I have the later two but find them pretty much useless and only use the shop manual for the most part.

http://www.ebay.com/itm/1966-Mustang-Fa ... re&vxp=mtr

Depending on how much / what you are doing...I have also found the body assembly manual and the electrical assembly manual to be invaluable as well.

 

[RustyRed]

By the way, buy the actual book and not the CD version.

For my Trans Am I bought the CD manual and it's a pain when you are actually standing in the garage wanting to look at something. I have since purchased one of the two manuals for the TA in book form...need to chase down the other book and then plan to throw the CD away.