M38 Bell Crank Bolt Tourqe

[1stSgtUSMC]

107 was the majic number for me. I did 60 for the clamp bolt. Thanks fellas!

S/F
Kevin

[RonD2]

Glad to hear it Kevin.

I agree Wes, there's no torque spec in the M-38 manuals for lug nuts, but the last line of the Willys SM-1002, Table U-55, Torque Specifications says lug nuts get 60-75 foot pounds. That's what I use on my M38 and I figure it's safe.

[wesk]

but the last line of the Willys SM-1002, Table U-55, Torque Specifications says lug nuts get 60-75 foot pounds.

This is where a detailed analysis of the available data pays off. Before I could accept that torque spec I made sure it was for the same part number stud and nut. It is not so therefore that torgue spec cannot be applied without gathering more structural data on the parts to determine their differences & similarities & their yield strengths. Following are Willys part numbers.

M38 Studs & nuts:
Stud - 649877 LH
Stud - 649878 RH
Nut - A475 LH
Nut - A476 RH

CJ2A & Early CJ3A
Stud - A473 LH
Stud - A474 RH
Nut - 641952 LH
Nut - 641953 RH

CJ3A after sn 168642
Stud - A473 LH
Stud - A474 RH
Nut - 636035 LH
Nut - 635516 RH

[RonD2]

No doubt. But I think that trying to do a detailed analysis of the structural data for M38 wheel stud and nut part numbers might be mission impossible for the vast majority of average practical-minded members of this forum that rely on it for simple answers to simple questions? I know it is for me.

As much as I really like this hobby, including the challenges of sorting out fact from fiction, myth, and legend in the manuals, the interweb, and the minds of real mechanics who forgot more than I'll ever know --- researching something like that is well beyond my capability and not real high on my list. Call me lazy if you want.

Instead, how about another direct question if I may -------> are the lug nuts on your jeep torqued 92 to 101 foot-pounds? If not, what torque value are you using?

The M38 manual says "tight", and that might be good enough for the Army?

Thanks again!

[DJ]

Tight enough to keep them on ,but not so tight I can't get em off.

[wesk]

You should always try to figure who the manuals are written for before you try to interpret their meaning. The Army TM's were published with the assumption that the technician performing the tasks would have been Army trained before he started working on the jeep. In the same tune the civvy factory manuals were written with the intent that they would be used by factory trained technicians. The only manuals written for hobbyists are those that preface their data with a forward that explains they are targeted for the owner / hobbyist. Like Chilton, Haynes, Motor and Moses Ludel manuals.

Yes, I am a very experienced technician with over 55 years wrenching on vehicles and aircraft. I still wrench on both today at the ripe old age of 73. I don't claim to have a red M on my shirt. As I type this I have worked on 3 cars this week 4 different aircraft and trust me when I say I gave up remembering every number & procedure for all the different makes and models over 20 years ago. I have always preferred to use the book, get the right answer first so I only have to do it once and when I need advice I seek it from the best source I can find.

But I think that trying to do a detailed analysis of the structural data for M38 wheel stud and nut part numbers might be mission impossible for the vast majority of average practical-minded members of this forum that rely on it for simple answers to simple questions?

The fact of life here is the more technical the task you undertake the less simple the answers are! Researching is not as impossible and lengthy as you suspect! Having run a few auto shops and done a lot of brake/wheel/tire work I still have dozens of industrial spec catalogs laying around. For example as I set here and flip thru an AMMCO Tools, Inc Brake Drum & Disc spec manual for 1972-82 year models lo and behold the torque for lug nuts on the entire 72-82 Jeep line is 75 Ft Lbs except for the J20's rated at 8400 GVW which gets 130 Ft Lbs.

You may prefer to hear simple answers but in most technical applications they are just not the simple.

are the lug nuts on your jeep torqued 92 to 101 foot-pounds? If not, what torque value are you using?

Actually I seldom change the torque setting on my air gun unless I see a drastic departure in thread pitch or stud diameter or a drastic change in wheel material so the majority of the 1/2"-20 lugs I install go to 90 Ft. Lbs. which is more than adequate.

[RonD2]

Thanks Wes. Understood. That's what I'm doing: seeking information from the best source I can find (you).

The Army TM9-8012 Operators Manual says "tighten". I believe most any soldier, including cooks, clerks, and infantrymen, were licensed to operate the M38 using that TM? I can't imagine that every time a flat tire was changed a trained mechanic followed with a torque wrench, but I could be mistaken about that.

[wesk]

I can't imagine that every time a flat tire was changed a trained mechanic followed with a torque wrench, but I could be mistaken about that.

No, most military units specify under normal operating conditions the driver have the motor pool handle the wheel change. And most units either had their driver's sent to a motor pool class on the how to and some units even stenciled the torque on the wheel. Many required a motor pool work order to followup the tire change on return to post so the wheel lugs could be checked.

Most military recruits were initially trained to not reply to their Sgt when he said jump but to first be up in the air then reply. Most trained technicians when told to tighten a fastener generally reply "To what torque" before they tighten.