A tale of two cases, or boys watch out for your boxes

Military Trucks 1/2 ton thru 2 ton, Wanted, For Sale (NO AUCTION or EBAY), and Knowledge Base
Joe Gopan
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Re: A tale of two cases, or boys watch out for your boxes

Post by Joe Gopan » Fri Jun 12, 2020 5:46 am

You may have to helicoil or install inserts to restore fit. Grade 5 may be better in this instance,
The Transfer mounting holes was a weak spot on the Chev/GMC Banjo X-Fer. The threads would pound out of shape or cause a crack. There was an aftermarket supplier who made stronger cases because of this back in the immediate post war period, thy are now extinct.
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M35a2duece
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Re: A tale of two cases, or boys watch out for your boxes

Post by M35a2duece » Fri Jun 12, 2020 5:50 am

Joe Gopan wrote:
Fri Jun 12, 2020 5:46 am
You may have to helicoil or install inserts to restore fit. Grade 5 may be better in this instance,
The Transfer mounting holes was a weak spot on the Chev/GMC Banjo X-Fer. The threads would pound out of shape or cause a crack. There was an aftermarket supplier who made stronger cases because of this back in the immediate post war period, thy are now extinct.
Yes. Its not the wisest looking crossmember and bolting setup... that's why I wonder what to do.... right now it's almost like the low grade bolts are the fuses (guessing that's why you said grade 5 instead or 8?)... if I put in grade 5 for instance... would the bolts just rip the threads out of the cast iron? Just thinking out loud. Thanks guys!

forestry4evr
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Re: A tale of two cases, or boys watch out for your boxes

Post by forestry4evr » Fri Jun 12, 2020 5:53 am

M35a2duece wrote:
Fri Jun 12, 2020 4:51 am
So I got 7 out of 8 bolts out, one snapped off..... still haven't fought that drill and tap battle just yet... My question for you guys is when I replace the old bolts that are severely worn, should I use grade 8? Try and drill my own safety wire holes? Looks like the existing bolts were original and they appear to be very soft low grade bolts. Any suggestions?
I am certain you will get several different opinions on this, but I will provide my insight on this matter. It is my understanding that the selection of bolt grade should match the nut or threaded housing. Given that the cast iron housing is of a relatively low hardness, a relatively low hardness fastener should be used. Back in the days of our trucks, no standards for fastener hardness existed yet so we must estimate the correct fastener hardness.

It appears as though the original design has some undesirable tendencies of both breaking transfer case mounting bolts or loosening them. Even with the limiting plates installed, the bolts can still loosen up and allow the transfer case to wallow in the frame mounting. A decent corrective remedy for this situation is to use new grade 5 bolts with good new grade 5 lock washers. As a preventive maintenance regime, periodically check the tightness of the 8 bolts when under the truck to grease/check fluid levels. With the relatively low miles these old relics will be driven, this method should be adequate.

One other item to investigate is the rivets used to attach the transfer case crossmember to the frame rails. It seems that these rivets often fail allowing the crossmember to move excessively adding to the problem discussed above.

Good luck, and I hope you are enjoying your project.

Paul
1941 G4112 Chevrolet with Hercules dump bed
1942 G506 Chevrolet with Hercules dump bed

M35a2duece
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Re: A tale of two cases, or boys watch out for your boxes

Post by M35a2duece » Fri Jun 12, 2020 6:10 am

forestry4evr wrote:
Fri Jun 12, 2020 5:53 am
M35a2duece wrote:
Fri Jun 12, 2020 4:51 am
So I got 7 out of 8 bolts out, one snapped off..... still haven't fought that drill and tap battle just yet... My question for you guys is when I replace the old bolts that are severely worn, should I use grade 8? Try and drill my own safety wire holes? Looks like the existing bolts were original and they appear to be very soft low grade bolts. Any suggestions?
I am certain you will get several different opinions on this, but I will provide my insight on this matter. It is my understanding that the selection of bolt grade should match the nut or threaded housing. Given that the cast iron housing is of a relatively low hardness, a relatively low hardness fastener should be used. Back in the days of our trucks, no standards for fastener hardness existed yet so we must estimate the correct fastener hardness.

It appears as though the original design has some undesirable tendencies of both breaking transfer case mounting bolts or loosening them. Even with the limiting plates installed, the bolts can still loosen up and allow the transfer case to wallow in the frame mounting. A decent corrective remedy for this situation is to use new grade 5 bolts with good new grade 5 lock washers. As a preventive maintenance regime, periodically check the tightness of the 8 bolts when under the truck to grease/check fluid levels. With the relatively low miles these old relics will be driven, this method should be adequate.

One other item to investigate is the rivets used to attach the transfer case crossmember to the frame rails. It seems that these rivets often fail allowing the crossmember to move excessively adding to the problem discussed above.

Good luck, and I hope you are enjoying your project.

Paul
Would you just skip the safety wires then? Just use lock washers?

And yes, thank you. I am actually enjoying working on this truck a lot. I don't know why... but it just seems more fun than a lot of my previous

Joe Gopan
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Re: A tale of two cases, or boys watch out for your boxes

Post by Joe Gopan » Fri Jun 12, 2020 6:12 am

Grade 8 tends to get overused by MV'rs. Bolts stretch when tightened and the idea is to torque the bolt to be within its elastic limit, grade 8 has a higher elastic limit and in some instances a grade 8 will pull out threads due to the necessity to use more torque to tighten to it's elastic limit.
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HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
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COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

ragnar
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Re: A tale of two cases, or boys watch out for your boxes

Post by ragnar » Mon Jun 29, 2020 8:14 am

Is there a specific torque setting for the transfer case bolts? I have noticed that there is not a torque setting for most of the bolts in the G508 and G506. I wish that the engineers had provided this kind of info in the original manuals. I have a tendency to over tighten bolts. Torque limits and Torque wrenches really help reign in a guy like me with limited mechanical skills. I would really appreciate your opinions in this matter.

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Re: A tale of two cases, or boys watch out for your boxes

Post by D.R.H. » Mon Jun 29, 2020 3:31 pm

Hey Ragnar, have a look at this; https://www.boltdepot.com/fastener-info ... orque.aspx. As for the T-cases in the Chevy and Jimmy, the bolts had been either wire tied or they had little plates that were installed horizontal to the ground over two bolts and then had cotter pins placed through the heads. The little plates had either six of twelve point holes in them that just fit over the head and prevented the bolt from backing out. The bolts in my first Chevy had been tack welded to the mounts, which kept them from backing out.
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M35a2duece
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Re: A tale of two cases, or boys watch out for your boxes

Post by M35a2duece » Wed Jul 01, 2020 4:17 am

Just finished bolting my t case back in with some safety wire bolts I just made out of some 1.5 inch long grade 5s i had to cut down to 1.25. What a pain drilling them all was. Glad that's done. As for me, I have no sheet metal holders, and previously all the lock washers that were in there had snapped and fallen out, so my case was loose even tho the bolts were tight and safety wired. What im gonna try is just one regular flat washer and safety wire the bolt head to the one above it.
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