Brakes Again

[Ellis Kinney]

1954 Super MTA. Left brake will not disengage. I have rebuilt the brakes, new balls, polished the ramps, new springs, set the rod to 1 3/16 as per the owner's manual. The tractor runs fine until I touch the brakes, jerks the tractor left and doesn't want to disengage. If I hit the left brake a couple of times it will free up somewhat but drags and heats up. Really dumb question, Is there such a thing as a spacer a few thousandths thick to use?? Can these brakes be re surfaced like a flywheel? Could the three springs be weak? Thanks, Ellis

 

[wwoodrow]

1954 Super MTA. Left brake will not disengage. I have rebuilt the brakes, new balls, polished the ramps, new springs, set the rod to 1 3/16 as per the owner's manual. The tractor runs fine until I touch the brakes, jerks the tractor left and doesn't want to disengage. If I hit the left brake a couple of times it will free up somewhat but drags and heats up. Really dumb question, Is there such a thing as a spacer a few thousandths thick to use?? Can these brakes be re surfaced like a flywheel? Could the three springs be weak? Thanks, Ellis

Not familiar with that tractor but had issues with brake shafts seizing before. Took brakes apart a few times before I realized it was the shaft.

 

[Janicholson]

The brakes can be super sensitive and lock up (as you have experienced). They have self energizing (servo) action. as the friction plates rotate and the pedal is pushed, the rotation+friction cause the expander plates to rotate in relation to each other. This rotation ramps the balls up "slope" adding to the pressure applied. Sometimes the issue is contaminated oily discs, sometimes it is rough friction surfaces on the expander (both sides) and the pinion carrier disc at the tractor frame as well as the outer cast housing of the brake. Smoothing all 4 of these surfaces with an electric sander with 350 grit can make them less grabby. A third issue is excess clearance in the mechanism. they work best if the total clearance is more than. .045 and less than .070". The housing can be machined to achieve this. With the housing on the bench placed so the open side is up, all parts (except the pinion carrier on the frame) are placed inside correctly, then a measurement is made from a straightedge down the the "top" friction disc. If much more than 1/16" (.062") they tend to lock up. Jim

 

[Ellis Kinney]

Jim, Would there be any kind of lubricant that I could use on the ball ramps, or would that not make a difference? Ellis

 

[Janicholson]

Jim, Would there be any kind of lubricant that I could use on the ball ramps, or would that not make a difference? Ellis

Dry film PTFE lube like Tri Flo is good if all the other ideas are good. The ball/ramp lube doesn't help much to get it to stop locking. Jim

 

[300guy]

Hey Jim you helped me with my brakes a few years ago when my 300 left one was locking up. You told me to look at the pinion shaft teeth and see if they were smooth and allowed the brakes to slide easily. Mine had high and ow spots in the pinion teeth, so I took the pinion off and used a Dremel tool to smooth out and even the gear teeth.

 

[countryman]

Rust is the big guy here! metal brake pad surfaces clean and smooth, clean break splines that's hard to do! coat with Anti-Zies, i use dry lube on the balls and their surfaces, springs weak loose can, I sand blasted everything in & out, masked contact surfaces used two-part epoxy paint from Napa car store. My Super M snowplow tractor was the worst! On assembly seal coat the brake housing to tractor, close off bottom bolt hole with a bolt, use good rubbers, this will all help keep rain & moisture out because the brake housings are great for condensation.

Hello everybody

 

[Ellis Kinney]

Would it be possible to take the housing to a machine shop and have a few thousandths milled off? Ellis

 

[Dieseltech]

1954 Super MTA. Left brake will not disengage. I have rebuilt the brakes, new balls, polished the ramps, new springs, set the rod to 1 3/16 as per the owner's manual. The tractor runs fine until I touch the brakes, jerks the tractor left and doesn't want to disengage. If I hit the left brake a couple of times it will free up somewhat but drags and heats up. Really dumb question, Is there such a thing as a spacer a few thousandths thick to use?? Can these brakes be re surfaced like a flywheel? Could the three springs be weak? Thanks, Ellis

When I put new discs in my 560 it did that too, the fix for me was one NEW disc and one USED disc. This allowed a bit more clearance needed to stop them locking up. The new discs were thicker than usual.

 

[BarnyardEngineering]

Would it be possible to take the housing to a machine shop and have a few thousandths milled off? Ellis

Yes. The clearance specification is out there somewhere. Stack all the components into the housing (drum) and measure the clearance across the top. Little bit of simple math, and a couple passes in the mill.

We had the problem of the mechanism over-extending and locking the brakes, but you could usually kick the pedal back with your heel and it would release. Worst case you stop and back up and it would release.

 

[Ellis Kinney]

Upon further inspection I have measured like Jim said and come up with .019 to .023 depending on where I measure. I think I need one slightly used disc like Dieseltech recommended. This might give me between 45 and 70 thousandths. Anybody have a SLIGHTLY used one?? Thanks, Ellis

 

[Dieseltech]

Upon further inspection I have measured like Jim said and come up with .019 to .023 depending on where I measure. I think I need one slightly used disc like Dieseltech recommended. This might give me between 45 and 70 thousandths. Anybody have a SLIGHTLY used one?? Thanks, Ellis

Or add a .020 shim on each bolt to move the cover away for more clearance until the discs wear a bit.

 

[Ellis Kinney]

Or add a .020 shim on each bolt to move the cover away for more clearance until the discs wear a bit.

Thanks, I am also looking for a piece of 26 gauge tin. Ellis

 

[BarnyardEngineering]

Upon further inspection I have measured like Jim said and come up with .019 to .023 depending on where I measure. I think I need one slightly used disc like Dieseltech recommended. This might give me between 45 and 70 thousandths. Anybody have a SLIGHTLY used one?? Thanks, Ellis

Interesting. I've never heard of TOO LITTLE clearance. That could explain the odd behavior you're experiencing. I've never had them to where you couldn't get them to unlock...

Wonder if they're making the new discs thicker... the aftermarket disks were always a little thin... not much, if any, thicker than worn discs.

 

[Dieseltech]

Interesting. I've never heard of TOO LITTLE clearance. That could explain the odd behavior you're experiencing. I've never had them to where you couldn't get them to unlock...

Wonder if they're making the new discs thicker... the aftermarket disks were always a little thin... not much, if any, thicker than worn discs.

The new discs I got for my 560 at the time were thicker. That's why mine started working OK with one NEW and one USED disc.