brake shoe adjusting

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m37jarhead
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brake shoe adjusting

Post by m37jarhead »

Tm9-8031-2 page 246, paragraph 169, section i says to refer to TM 9-840 for adjustment of brake shoes.
I don't have TM 9-840 so can anyone give me the proper proceedure for adjusting the anchor bolts AND
the brake shoe cam adjusters??
Any help appreciated.
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Re: brake shoe adjusting

Post by cuz »

The TM 9-8031-2 was published in 1953 while the 840 was still the Operator's manual. The TM 9-8030 published in 1955 replaced the TM 9-840. Just go to TM 9-8030 Page 331 for all brake servicing and adjustments. Or since TM 9-2320-212-20 replaced the TM 9-8030 in Nov 73 you can use it starting on page 2-143. I like the two mid fifties TM's the 8031-2 and the 8030 best of all the TMs'

The brake adjusting procedures are three each and different. One is a minor adjustment done in the field using only the upper cam adjusters. The second is a major adjustment for new shoes using all four adjusters and a feeler gauge. The third is a major adjustment for worn shoes that have lost their taper using all 4 adjusters and a feeler gauge. If you do not have a copy of the two newer manuals then let me know and I'll email you the pages.
Wes K
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54 M37, 66 M101, 45MB, 51 M38, 60 CJ5, 46 T3-C
MVPA 22099

Disclaimer: Any data posted is for general info only and may not be M37 specific or meet with the approval of some esteemed gurus.
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Re: brake shoe adjusting

Post by MSeriesRebuild »

m37jarhead wrote:Tm9-8031-2 page 246, paragraph 169, section i says to refer to TM 9-840 for adjustment of brake shoes.
I don't have TM 9-840 so can anyone give me the proper proceedure for adjusting the anchor bolts AND
the brake shoe cam adjusters??
Any help appreciated.
The procedure in the manuals isn't worth much unless you are dealing with 100% NEW EVERYTHING. The thing they don't take into consideration is worn drums or slightly out of round drums, it doesn't work with turned drums either. When these issues come into play and they always will, going by the listed procedures will not make it happen. Neither is the feeler gauge worth 2 cents for the same reason.

All things considered, there is 1 way to do it. Remove the drum inspection cover, turn the drum so you see the bottom end of 1 shoe lining. Adjust that anchor bolt until the lining nears the drum surface, turn the drum so the upper end of the same lining is visible. Adjust the cam out until the lining nearly touches at that end. The next steps are critical, turn the drum back and forth viewing both ends of the lining making minor adjustments to both get the lining as close as possible to the drum without major dragging taking place. Keep in mind that the bottom end of the lining is near the shoe pivot point and the top end is being forced outward by the wheel cylinder, thus the bottom end will be closer than the top end when an ideal adjustment is reached. You can view the final adjustment by pulling the top end out with the cam until the drum is locked, if you see a gap between the drum and the lining when the drum is locked, the adjustment is not balanced correctly, more tweaking will be necessary. The ideal adjustment is achieved when the whole length of the lining is in contact with the drum just as the drum gets tight and can no longer be rotated by hand. At this point back off the cam adjustment slightly so the drum can be rotated by hand. A minor tight spot or 2 as the drum is rotated by hand is normal on most trucks as very few perfectly round drums exist. The adjustment is very close to perfect at this point. Get all 4 wheels adjusted to this stage, now you can do a road test. Drive a couple of miles applying brakes normally several times, if they feel good and you have a nearly full pedal, you are close. Check the drums for excessive heating by carefully feeling them with you finger tips, if they are hot to the point of burning your fingers, you may need to back off the cam adjustment slightly on that wheel, if some are barely warm, you can tighten the cam adjustment slightly. It may take 3-4 road test trips to get all just right. This is the only method of getting adjustments the best they can be, don't do it when you have to try and hurry the process, it takes a while to get through it, it is the only method that works well as far as getting the best braking possible with an all original system.

In almost all cases where we have people come in our shop saying their brakes just are not up to par, shoe to drum adjustment is the problem. Most people just do not realize what a pains taking process it is to get the best it can be. Many say they did it by the book, that just doesn't work.
Charles Talbert
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Re: brake shoe adjusting

Post by ZGjethro »

Thanks for that answer Charles. The brakes on my 52 m37 which I bought in October seem weak. I am thinking of doing a complete build of all shoes and brake cylinders. I have already replaced the leaking master cylinder. It is comforting to know out of round drums are common. I can feel my brake pedal pulse as one warped drum pushes back on the system.
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Re: brake shoe adjusting

Post by cuz »

As the availability of parts dries up one will need to make allowances for excessive machining. For example brake shoes can be shimmed to compensate for the larger diameters of the turned drums.
Wes K
wsknettl@centurytel.net

54 M37, 66 M101, 45MB, 51 M38, 60 CJ5, 46 T3-C
MVPA 22099

Disclaimer: Any data posted is for general info only and may not be M37 specific or meet with the approval of some esteemed gurus.
MSeriesRebuild
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Re: brake shoe adjusting

Post by MSeriesRebuild »

ZGjethro wrote:Thanks for that answer Charles. The brakes on my 52 m37 which I bought in October seem weak. I am thinking of doing a complete build of all shoes and brake cylinders. I have already replaced the leaking master cylinder. It is comforting to know out of round drums are common. I can feel my brake pedal pulse as one warped drum pushes back on the system.
It is common as drums are worn to the extreme, no good replacements are out there, and new drums are practically extinct. If the pedal is pushing back at you, that is extreme, likely that drum should be scraped. It will be so thin by the time enough material is removed to get it back round that it will only take a few good brake applications to get the thin metal hot enough to warp again and you are right back where you started only now with a dangerously thin drum that could easily crack and get you in some real trouble. In most cases turning is not even a smart option, and is $$ wasted.

We have tried it all, the absolute best option is to save your $$ and convert to the 4 wheel disc system. Once in place you can easily maintain this system with over the counter components that will be safe, reliable, and afford much better braking. The drum system is by in large a gone animal unless someone decides to reproduce some good quality drums, I don't see that happening and there are no new drums in any quantities that I'm aware of anywhere.

We have relining equipment, we have shimmed linings for turned drums, that is the better option there. We have also used 5/16" thick linings and radiused the ends to give a good curvature fit in turned drums, this works well, but is more difficult and time consuming to get that perfect fit. We also have new shoes that fit a good drum great, this is the best bang for the buck, except that there are practically no good drums out there anymore. All of these issues drastically affect the adjustment procedure, simply put, if components don't fit together correctly, a good adjustment set up is not possible using any procedure.

Looking at this issue from a common sense standpoint, this is my view. One must ask the question, is it smart to invest in trying to build a decent drum type original system? Why, here is the next question one must ask, will you be able to rebuild that system back to a good, reliable system when it comes time again? The next question, would it have been a smarter decision to have spent the cash more wisely such as installing the disc system, it is a very worthwhile upgrade if you plan on keeping your truck, instead of all the investment that is now lost in maintaining the soon to be impossible to upkeep original system? That is upcoming very soon unless some reproduction drums come to life. Remains to be seen if that ever happens.

We have a stock pile of take off drums, I've been threatening to scrap them just to get them gone, we search through them trying to find a get by when we have to have one. If you are in need, please come and haul them away, I'll take current scrap price for as many as you want. We have many take off backing plates with good shoes installed, all they need is a new wheel cylinder to be ready to go.
Charles Talbert
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Re: brake shoe adjusting

Post by M37UK »

Charles

How much does it cost for the disc brake system ?

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Re: brake shoe adjusting

Post by MSeriesRebuild »

M37UK wrote:Charles

How much does it cost for the disc brake system ?

Stuart
All I have are dedicated to in house projects, we have never sold disc kits for self installation. Ours is a marriage of Heli-tool and our own set up. We have worked with Heli-tool since the disc system conception. He called us in search of hubs when he was starting the project, we had 120 at the time. We crated them up and shipped them to Oregon, that is where it all began. We have had a good working relationship. I have a good many core hubs now, need to start thinking of doing the next batch before long.
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Re: brake shoe adjusting

Post by Cal_Gary »

That is some GREAT info Charles, and your timing is perfect, as I intend to do new brakes this year, and your options for going to discs will be given every consideration.
Thanks!
Gary
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Re: brake shoe adjusting

Post by jim lee »

It looks like Midwest Military is getting a run of NEW drums made up. I saw stuff about this on Facebook.

-jim lee
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