QuestionQUESTION: We "blew" the rear end out of our '41 Packard on the Great Race. We patched it together with Toyota, Dodge, and who knows what and a little machining and completed the next 4,000 miles.
It is now time to "fix" it. I have a good used replacement differential. My concern is with the pinion seal. I hesitate to replace it only because I don't want to mess around with pinion loading.
I was going to hang the "pumpkin" upside down (pinion pointing toward ground) and put some oil in the case and check for leaks. Will this work? Any suggestions?
Thanks for your time.
ANSWER: I would not hesitate to replace the pinion seal. the procedure that I would use is as follows:
1. Use a beam torque wrench and determine the turning torque of the pinion.
2. mark the pinion end and the nut so that you can line up the marks when tightening the nut.
3. Count the number of turns when removing the nut.
4. Remove pinion flange and replace the seal. Be sure to lubricate the seal lips when installing.
5. Install the nut counting the number of turns.
6. Tighten the nut until the number of turns match and the marks align.
7. Check the turning torque.
All should be well. Congratulations on competing in the Great Race. Never made that one except as a journalist covering it but did compete in One Lap America.
Brad
---------- FOLLOW-UP ----------
QUESTION: Brad:
Thanks for your very fast response....I am impressed! However, it is now confession time. Before the Great Race I had a small leak, and decided to replace the seal. Did a lot of research, and did it just as you outlined (I remember...it was exactly 10 turns to remove the nut. I had not checked the torque before, but did after. It was somewhat higher than the the 24-30 inch pounds. I attributed that to the axles, wheels, etc.
My wife is the driver (she is fearless). We push it hard, panic stopping at every stop sign, full throttle acceleration to speed. On the end of the second day we started to hear rear end whine, but kept going motto: To finish is to win). A mile from the finish, the nut came off, dropped the seal and bearing, and the pinion shaft dropped down locking up the differential.
The truth is, that pretty much shattered my confidence in replacing the seal. Others have told me that I should get a long "persuader" and just reaf on the nut. My concern is that could put undue load on the crush sleeve.
Is it possible that I did not get the nut tight enough?
Thanks so much for your time.
Pat
AnswerThe magic words, THE NUT CAME OFF! Now, does the nut look like a castlated nut but without the slots? If so that type of nut needs to be staked to the pinion shaft with a punch as a locking mechanism. Or is there a lock washer under the nut? I usually use lock tite on everything that I put together. If the nut is locked, it should not come off. My dad used to tighten the nut up just about a 1/16th of a turn beyond the original mark. Reefing up the nut on a parade/show car would probably work but with lead foot driving take some precautions. I think if it were mine, (and I drive like your wife, my 41 Ford coupe with a lightly modified flat head with Smitty's makes the most delightful sounds when pushed a bit) I would reseal it. Just my opinion. Good luck.
Brad
