Fixing 9" Ford Pinion Leaks:

Nothing is more annoying than a nasty oil spot on your clean driveway or garage floor. In this case a newly rebuilt 9" centersection in our project Bronco started seeping oil almost as soon as it was filled with oil.

Here is the annoying spot on the shop floor:


A little investigating led me to determine the oil was leaking out of the pinion or seal area:




I started the process by removing the pinion nut using my 18 volt Craftsman cordless impact wrench. If you have never used a cordless impact wrench, you are missing out because I cannot live without mine:


I had replaced the pinion seal, but I re-used the pinion yoke even though there were a few small grooves in it. It was most likely the culprit. A call to Randy's Ring & Pinion got me a new yoke, pinion seal, and pinion nut. There are repair sleeves for the yokes, but they are only $5.00 cheaper than a whole new yoke, which cost me about $50.00:


I cleaned the splines on the pinion with some brake cleaner to remove any remaining oil:


I next smeared some silicone on the inside of the yoke as I have seen the yokes leak through the splines:


I did the same on the pinion nut:


Some bearing grease was smeared on the sealing surface of the yoke to keep the seal from burning up from being dry:


I didn't replace the pinion seal because it had just been replaced, and the vehicle did not run at all. I placed the yoke back on the pinion and seated it as far as it would go by pushing on it:


The pinion nut was then replaced and threaded on by hand:


There are different ways of making sure that the pinion bearing has the correct amount of pre-load such as counting threads, or turns of the pinion nut. I have a different method: While tightening the pinion nut with the impact wrench, I pull on the yoke to see if there is any play on the assembly. I slowly keep tightening the nut until a slight amount of resistance is felt, and then I go 1/16th of a turn more which is the correct amount of pre-load on the pinion bearing. The cordless impact WILL NOT crush the crush sleeve any further than it is. I have used this method on dozens and dozens of 9" centersections and I have never had one fail yet:

The best part of the whole process is the clean floor.

.

I've successfully used this method many times too with no ill effects (although most recommend not to do it without a new crush sleeve.) Glad that you mentioned the silicone on the splines as I found that to be a problem also.

Now when I rebuild a 9", I use shim washers instead of the crush sleeve and really don't need to worry about crush when doing the above repair.

Great, thanks! Didnt know you could do this without pulling the pinion and replacing the crush sleeve.
Mine was leaking through the pinion nut I thought, must have been the splines. Needed rebuilding anyway, hope it doesnt leak now, but if it does I can fix it.

Very cool!