200 ft/lbs torque to much for the pinion nut

Thunderbird712 · Post by **Thunderbird712** » Sun Aug 17, 2014 10:23 am

After replacing the front and rear diff pinion seals I torque the nuts down to 200 to 220 ft/lbs and now I cant roll my frame telling me its torqued to much. I do have to figure out which diff was causing the problem or possibly both but is a lower torque setting for these nuts possible? To note these seals were never replaced since I had the jeep. Also I have never taken them apart. The diffs were operating fine with no noise or obvious signs of issues during an inspection before I started my restoration. So I have no idea what they were torqued to before. The other thing to point out is there is no felt seal in the rear diff. Would this cause the issue?

Thunderbird712 · Post by **Thunderbird712** » Sun Aug 17, 2014 10:25 am

Sorry in case some one misses my signature it is a m38a1

OKCM38CDN · Post by **OKCM38CDN** » Sun Aug 17, 2014 11:34 am

If I remember correctly the torque is 200-220 ft/lbs...

try that...

Thunderbird712 · Post by **Thunderbird712** » Sun Aug 17, 2014 12:53 pm

You know I forgot to mention that I had tried that. I saw a previous post by WesK about using the 120 ft/lbs and that the 200 was to set everything. At 120 everything works fine. I continued to read up on it more and kept seeing the 200 #. I am just not fimiliar enough to say 120 will be enough. I do however believe what Wes said is ok. Thats why i wanted to post the question to see if anyone else had gone with the lower torque value. Still reading through some more posts, other forums, and other literature on the diffs to learn. Thanks!

wilfreeman · Post by **wilfreeman** » Tue Aug 19, 2014 2:45 pm

I racked mine down with a ½" impact, not even thinking about how much torque it was putting out, now I can't even get the nut back off to torque it correctly. I probably galled the threads. I will try again with a ¾" impact when I get the chance to work on it again - already tried a few methods I have found on the net with no success. Just think about it before you do anything as dumb as me! I would go with the 120# and see if you have the correct play, then go from there.

Post by **wesk** » Tue Aug 19, 2014 6:09 pm

I don't recall advocating 120 on the axle companion flanges. I recall that 120 was for the transfer case front and rear companion flanges.

The book calls for 200 to 220 ft Lbs then insuring the bearing is shimmed properly to maintain a rotating friction of 10-25 In Lbs. That is not a lot of rotating resistance and if set correctly to that spec the pinion should turn with no more then 10-25 In Lbs of rotational torque. I am betting your bearing preload is much higher than 10-25 In Lbs.

jimm · Post by **jimm** » Tue Aug 19, 2014 9:11 pm

I agree with Wes that your pinion assembly is probably not shimmed correctly. You have to measure the torque to turn it without the differential installed in the axle, i.e., no other load on it than the bearing preload. It can be tricky to measure that low of torque because you need to do it as you are rotating the pinion slowly but smoothly (breakaway torque will be a little higher than rotating torque).
Since the assembly is made up of very stiff pieces of steel and cast iron, a little shimming goes a long way. You want to creep up on the right amount of shims from no drag/preload. More shims are the equivalent of making the case longer (or the shaft shorter) and increase the preload. When you get close to the correct preload torque, adding the thinnest shim (.003") will make a noticeable difference. You may even have to take out some and add others, e.g. minus one .005" plus two .003", to get the increment you need.

Thunderbird712 · Post by **Thunderbird712** » Wed Aug 20, 2014 4:18 pm

While I was reading up on the issue I came across this previous post

http://www.willysmjeeps.com/v2/modules. ... pic&t=6761

First off I misread the torque value in the post. Second I could be wrong in my assumption it was about the diffs. That was the only post i read mentioning a lower torque value so i tried it as well as asked the question about it. Anyway as I said the rears have never been taken apart by me and the last owner was the greek army. So they could have been previous rebuild incorrectly but I have never had any issues with them. I got my answer about the torque. I have some more stuff to figure out before I go ahead and take things all part. Thanks for the help.

Post by **wesk** » Wed Aug 20, 2014 8:39 pm

Looks like Hal was the culprit in both posts. Hal, the torque is not 120 Ft. Lbs!

OKCM38CDN · Post by **OKCM38CDN** » Wed Aug 20, 2014 9:18 pm

Sorry, I am mistaken, I read one thing and made an assumption, well you know what happens when you do that...

Post by **wesk** » Wed Aug 20, 2014 9:29 pm

No apology needed. I'll go ahead and correct the two posts with incorrect torques.

jimm · Post by **jimm** » Wed Aug 20, 2014 9:45 pm

wesk wrote: The book calls for 200 to 220 ft Lbs

Wes,
Just for clarity, which book are you referring to? The civvy repair manual? I can find no reference to a specific torque for the yoke nut nor the preload drag in either of the M38 and M38A1 power train manuals (TM 9-8014B and 9-8015-2, respectively), and don't see the yoke nut listed in the table of torques you posted from the civvy manual.

Post by **wesk** » Wed Aug 20, 2014 10:12 pm

The best book to fall back on when the TM's come up short on hard data. The Army's unit motor pools didn't rebuild axles. They order a depot overhauled unit and exchanged it. That's why the field level TM's lack so much hard data. The Army depot doing the overhauls would have had in house pubs which would include Willys and Spicer factory manuals to address the overhaul issues.

That is why I loaded the important chapters from the civvy manuals in my photo album. Some day I'll get them all scanned and PDF'd and loaded on the downloads page. I have advised the use of the civvy factory manuals to backup our inadequate TM's ever since day one (2002) of this web site and day 1 (1996) of the M38 Yahoo group.

The TM 9-8015-1 and TM 9-1804B both only address the pinion bearing preload as a check for slight drag and adjust shims as needed note.

TM 9-8015-2 on page 180/181
TM 9-1804B on page 132

In the old referenced post you mentioned replacing the 3/4-16NF-2 nut every time which is really not required unless the Hug Nut fails a run-on torque test.

jimm · Post by **jimm** » Thu Aug 21, 2014 10:02 pm

I thought that was the book you meant. I bought a copy after we rebuilt our axles, so I must have used your scanned info, which was very helpful at the time.

'Twern't me that mentioned replacing the nut every time - that was Bretto

If you had to replace it after one use, you'd go through a bunch of 'em just trying to get the pre-load set!