My 1951 M37 build thread....

[chicklin]

Well, still too early to lock up the tool box. The bearing cups must be pressed in all the way in order set the correct bearing preloads. You said they were pressed in when you pulled it back apart. This had to leave a huge amount of end play in the worm shaft assembly. I'm not understanding how extra gaskets helped that out as that is quite impossible. Adding gaskets would make even more end play. Obviously you were not able to detect the end play because the drum shaft & brass gear was already in place. Adding shim to one side would cause the worm to run out of center of the brass drum shaft gear, a BAD set up that will cause you trouble, broken gear teeth. The worm shaft bearing retainers should be shimmed an equal amount on both retainers so the worm is held in a centered position. The amount of shim needed is determined by the worm shaft rotating resistance by hand; when the preload is correct, it will take a good firm grasp of your hand to turn the shaft. This set up procedure must be done prior to installing the worm shaft oil seals into the retainers, seals will make the shaft turn tight, making it impossible to get bearing preload correct. This must be done before the drum shaft & brass gear are installed into the housing. Otherwise you will get a false sense of turning resistance, you need to feel the resistance within the worm shaft assembly only, without oil seals. Once the proper shim pack is chosen & correct preload is established, remove the bearing retainers & the worm shaft from the housing, install the drum shaft with brass gear into the housing followed by the worm assembly. This time install the worm shaft oil seals into the retainers, being sure the correct # of gaskets are placed under each retainer, coat all gaskets with a good quality gasket sealer & do the final assembly. Failure to follow through on all this correctly will cause you GRIEF.

I'm not sure where you're gettting that there would be a huge amount of end play in the worm shaft. Actually, it should be quite the opposite. If everything was tight before I took it back apart and noticed the bearings had already sunk into place, then shimming it would be the correct action.

I'm not getting where all this online information about gear box building is coming from; this is the 2nd explanation I've given this week about improper set ups. Both situations were similar, proper procedures for bearing set up was omitted from the build instruction in both cases as I understand it. I think I'd be looking elsewhere for direction. The other situation was with a transfer case build up, that guy would have experienced a catastropic failure in the rear drive unit if he hadn't ask for further instruction. He wasn't even close to doing it correctly. Correct bearing & preload settings at build up are absolutely imperative to long running components, cutting corners just isn't smart, it will cost you in $$$ & frustration.

One more thing, did you align the end housings with each other when you did the final assembly? If not, your troubles aren't even over when you correct the bearing preload issue already at hand. Alignment is of utmost importance, premature wear & oil leaking will be the result of improper alignment.

Yes, I made sure to align the housings.

[MSeriesRebuild]

Only you know for sure what you have done, I'm only going on what you have written. You said you put extra shim under 1 retainer. If you used more shims under one retainer than the other, the worm is off center with the brass gear in the direction opposite from where the extra shims were used. This situation creates an incorrect set up, & will cause stress on the brass gear. You haven't clarified if you actually did a preload set up as I described, from your original posting, 1 could only assume you didn't go through the procedure to correctly accomplish that since the cups weren't pressed in completely. If you did, it was no longer correct after the cup position changed. Don't forget this can't be accomplished correctly with the oil seals or the drum shaft in place.

[chicklin]

Only you know for sure what you have done, I'm only going on what you have written. You said you put extra shim under 1 retainer. If you used more shims under one retainer than the other, the worm is off center with the brass gear in the direction opposite from where the extra shims were used. This situation creates an incorrect set up, & will cause stress on the brass gear. You haven't clarified if you actually did a preload set up as I described, from your original posting, 1 could only assume you didn't go through the procedure to correctly accomplish that since the cups weren't pressed in completely. If you did, it was no longer correct after the cup position changed. Don't forget this can't be accomplished correctly with the oil seals or the drum shaft in place.

Well, it's working. No leaks, no noises, no vibration, no heat. If it's off a little, I can live with it or revisit at another date. It won't get used much, if at all.

Next thing up is to revisit the brake shoe adjustment. I'm having a hell of a time getting it to stop well. I have a new MC, WC's all around and new rubber lines. I kept the old shoes and drums. The shoes had plenty of meat and I cleaned them with brake cleaner. The drums are, of course, out of round but they weren't scored too bad and it should still stop okay even if they aren't like new.

I've read through the manual but I'm not clear on the major adjustment piece. I get what the minor adjusters do as that's what I've been playing with thus far, but I get the feeling my shoes are not centered correctly. I've done this by feel on both of my M715's with no troubles, but these are different. Any tips?

[MSeriesRebuild]

Equal pressure must be applied over the entire length of the shoe to get good brakes, it won't be easy to accomplish that adjustment with out of round drums. Depending on how much they are out of round, the pedal may be be pushed back out at you when you apply the brakes. You won't ever get a good shoe to drum clearance set up with warped drums. When you think you are about perfect, there will be that tight spot when you turn the hub. If you intend to try that anyway, you will just have to play with all 4 adjusters till you get as good as you can with what you have. Don't expect good brakes though.

You said you cleaned the lining, you may have cleaned what was on the surface, what is soaked into the lining is still there & will hamper braking ability until you get all new linings to go along with a leak free system.

Cutting corners will only cause you grief, $$, redo time, & lots of frustration. It doesn't matter where you are working on a gear box, engine, electricals, or brakes. It's pretty much a pay it now or pay it later kind of thing. You may well pay more later, because of other things that suffered as a result of the short cuts.

[chicklin]

Cutting corners will only cause you grief, $$, redo time, & lots of frustration. It doesn't matter where you are working on a gear box, engine, electricals, or brakes. It's pretty much a pay it now or pay it later kind of thing. You may well pay more later, because of other things that suffered as a result of the short cuts.

Well, of course new shoes and turned (or new) drums would be better, but until then I'd like to get what I have working better. This is a toy, not a daily driver or a full-on restoration, so I'm going to try and make the equipment on hand work as well as possible before investing the money into new parts.

I'll fiddle with the adjusters some more and probably take the drum off to get a better idea of how each one affects the shoe.

[refit1701]

I don't think you can turn those drums, they are thin already. Brakes are so very important, we don't want to see you get hurt if they don't do their job well enough. Money spent on brakes is never wasted. I coughed up enough to redo my entire system and as such has put me behind on the rest of the project.

Charles is just giving you the benefit of his experience, like he does for all of us here.

I'm following your project with carefully!

[chicklin]

I don't think you can turn those drums, they are thin already. Brakes are so very important, we don't want to see you get hurt if they don't do their job well enough. Money spent on brakes is never wasted. I coughed up enough to redo my entire system and as such has put me behind on the rest of the project.

Charles is just giving you the benefit of his experience, like he does for all of us here.

I'm following your project with carefully!

Agreed, they are very important which is why I'm not putting this thing on the road until they work correctly. I just want to make sure I've exhausted all possibilities with the current equipment before laying out the cash for new shoes and/or drums.

The two M715's I've owned had shoes and drums in similar condition and I was able to adjust them so I could lock them up on dry pavement. I realize this brake system is set up a little different, so I may never get to that point, but it's got to be better than what I'm getting now. It's taking me 1-2 lengths of the truck to stop at 10-15 mph on a slight downhill grade. That's not acceptable even for worn components, in my opinion, so I'd like to try adjusting them first.

[MSeriesRebuild]

A M715 has a very different system from a M37, much thicker drums also. Turning a M37 drum is pretty much fruitless because 99 out of 100 will go past spec before they true up. If you do this they will warp again as soon as they heat up a little to worse than they were to start with, time & $$ wasted. I haven't seen a new drum in years, so good luck hunting those. About the only hope is some decent take-offs, also rare these days. The absolute best thing with brakes on a M37 is to convert to the disc system. I would be holding on to my $$ toward that end instead of spending anything on the drum system if it were me.

[DJ]

Looking at Midewst Military's website ,looks like John has a whole crate full of NOS drums.

DJ

[chicklin]

Yikes, a whole set of drums and shoes is going to run close to $1000. I think I'll play with the ones I've got some more.

[MSeriesRebuild]

If John has some new ones available, you should expect the cost to be on the high side as they are extremely rare. Another issue that should be checked into is this; certainly these have been many years in storage, drums will warp in storage if not stored properly. This is truth, if they are stacked, the weight of the ones on top will warp the ones on the bottom. I got some brand new 5-ton drums a while back that looked great, weren't any good at all as they were warped totally beyond use because of incorrect storage. John is pretty thorough & I would assume he has checked this, however I personally would not buy them unless he signed off on them as being not warped. As old as they are, the chance of issues is simply too great of a risk otherwise.

I don't know what his cost is for shoes, we have new shoes for $35 each with riveted linings.

[knattrass]

Charles - your usual gold plated response! I wondered about warpage.

[DAP]

I have some used takeoffs but don't know how to tell condition. Make me an offer. Shipping is the killer. I am 1 hours south of Charlotte, NC so if you can drive pick up thenyou can even look at drums and pick what you want.

[MSeriesRebuild]

I also have a huge amount of take-off drums, I didn't figure you wanted to drive from Mo to pick up though. Hey I wish you would haul them away.

[chicklin]

I also have a huge amount of take-off drums, I didn't figure you wanted to drive from Mo to pick up though. Hey I wish you would haul them away.

As much as I'd love to visit North Carolina, I think I'll pass.

Ordered canvas top, seat covers and decals yesterday. I'm planning on painting this weekend so it should actually start to look like a real M37 pretty soon. I'll take some pics when it's done.