Drum brakes over-adjusting and getting hot after rebuild

[CruiserTrash]

Update: Just did about 400 miles from Denver to Steamboat Springs, wheeled a big loop through Wyoming, then drove back home. Heavy use of the parking brake on the trails, some spots I had to stop facing up steep loose hills and really cranked the brake up as much as I could. The takeaway is: no overadjusting. At one point the brake pedal felt a little stiff (drums were not hot though) and I backed off the adjusters each by about 4 teeth just in case. The washer and larger c-clip make pushing the adjuster arm out of the way more difficult - this is the only drawback I've found. You really have to get in there with a flashlight, make sure your tool is contacting the adjuster arm, and push the heck out of it to clear it from the star wheel ... but it's not too terrible. Just different than how it was before.

 

[mbx118]

I have no doubt that the previous posters in this thread did this, but after having the same problem and fixing it by adjusting the bellcranks I figured I would point this out. There's a screw on the back of the bellcrank that sets the tension on the cable inside the drum. If it's too tight (screwed in too far) it will tighten the actuator cable, cause the shoes to drag, especially as the starwheel will continue to adjust the drums outwards like usual. Same goes if the parking brake cable is too tight. Obligatory FSM excerpt.

 

[mbx118]

After confidently proclaiming that I had the answer above, I was of course wrong. They dragged less but still overadjusted when I lifted the rear end and pulled the handbrake repeatedly and then freed when I spun the adjuster back in. I did switch to OEM shoes, also from cruiser outfitters and took some measurements new vs old. No overadjusting now when I jack up the rear end and pull the parking brake as hard as I can repeatedly. Fingers crossed.

You can see below the non OEM adjuster peg thing is 2 mm different, further outboard on both detents. Could have used the micrometer a little better. Also the actuator arm (not adjuster) is much tighter to the shoe now in the axial dimension. Hard to believe 2mm is the difference here but maybe drums are just that fiddly.

The metal web is about 0.25 mm thicker, but I don't think that could make a difference. Got both horseshoe clips at 1.5 mm.

The non OEM shoes:

OEM Shoes:

 

[CruiserTrash]

After confidently proclaiming that I had the answer above, I was of course wrong. They dragged less but still overadjusted when I lifted the rear end and pulled the handbrake repeatedly and then freed when I spun the adjuster back in. I did switch to OEM shoes, also from cruiser outfitters and took some measurements new vs old. No overadjusting now when I jack up the rear end and pull the parking brake as hard as I can repeatedly. Fingers crossed.

You can see below the non OEM adjuster peg thing is 2 mm different, further outboard on both detents. Could have used the micrometer a little better. Also the actuator arm (not adjuster) is much tighter to the shoe now in the axial dimension. Hard to believe 2mm is the difference here but maybe drums are just that fiddly.

The metal web is about 0.25 mm thicker, but I don't think that could make a difference. Got both horseshoe clips at 1.5 mm.

The non OEM shoes:

View attachment 3947352View attachment 3947353


OEM Shoes:
View attachment 3947354View attachment 3947355

Further up this thread there was talk about where the adjuster sits and the difference in that part of the posts. On the aftermarket post there’s a chamfer and on the OEM post it’s a flat. The chamfer would allow more axial play in the adjuster level, while the flat would limit its axial movement.

I’m still of the mindset that the problem lies there. The lever has to move axially, out and around the next tooth on the star wheel. If the chamfer allows too much of that movement, the lever is going to go out and around, and grab another tooth even when it’s not supposed to. The flat on the OEM post combined with the detent for the outermost clip would still allow some axial play, but not as much - possibly only enough play to grab star wheel teeth when the lever is supposed to, but not enough play to allow the level to grab another tooth when it shouldn’t.

Also to further update from my last post where I said the shoes stopped over adjusting: that was wrong. They still do it. I’m very close to just buying new drums and new shoes, both Toyota and not aftermarket. To put a further point on it, I was experimenting with different thickness clips on the very end of that post, and all that was to circumvent issues with that flat versus chamfer issue. Or so I think.

@cruiseroutfit Penny for your thoughts? I just think the post on the aftermarket 60 Series brake shoes allows too much movement. My previous experiments in using washers and different clips were bandaids for the real problem.

 

[DrRock]

All, I would also confirm that your e brake bell crank is adjusted properly. When one replaces the shoes, the bell crank adjustment would be set for a set of worn shoes if adjustments were made over the lifetime of the old shoes. This would lead to the new shoes potentially having some tension put in them, leading to brake drag.

 

[CruiserTrash]

All, I would also confirm that your e brake bell crank is adjusted properly. When one replaces the shoes, the bell crank adjustment would be set for a set of worn shoes if adjustments were made over the lifetime of the old shoes. This would lead to the new shoes potentially having some tension put in them, leading to brake drag.

Great point. I definitely followed FSM procedure for setting those. I had the bellcranks completely apart and on my workbench at the time, and reinstalled them from scratch.

 

[HectJDM]

I have the same and it drives me crazy

 

[cruiseroutfit]

Further up this thread there was talk about where the adjuster sits and the difference in that part of the posts. On the aftermarket post there’s a chamfer and on the OEM post it’s a flat. The chamfer would allow more axial play in the adjuster level, while the flat would limit its axial movement.

I’m still of the mindset that the problem lies there. The lever has to move axially, out and around the next tooth on the star wheel. If the chamfer allows too much of that movement, the lever is going to go out and around, and grab another tooth even when it’s not supposed to. The flat on the OEM post combined with the detent for the outermost clip would still allow some axial play, but not as much - possibly only enough play to grab star wheel teeth when the lever is supposed to, but not enough play to allow the level to grab another tooth when it shouldn’t.

Also to further update from my last post where I said the shoes stopped over adjusting: that was wrong. They still do it. I’m very close to just buying new drums and new shoes, both Toyota and not aftermarket. To put a further point on it, I was experimenting with different thickness clips on the very end of that post, and all that was to circumvent issues with that flat versus chamfer issue. Or so I think.

@cruiseroutfit Penny for your thoughts? I just think the post on the aftermarket 60 Series brake shoes allows too much movement. My previous experiments in using washers and different clips were bandaids for the real problem.

I'll have to pull some from stock the next time I'm at the shop and take a look and see. We've sold hundreds (thousands?) of those shoes over the decades, same ones I run on my FJ40 (FF 60 rear axle), my HJ61, BJ74, etc... I've not ever noticed any issues. I'll definitely dig into it personal or have our parts engineer look it over.

 

[CruiserTrash]

I'll have to pull some from stock the next time I'm at the shop and take a look and see. We've sold hundreds (thousands?) of those shoes over the decades, same ones I run on my FJ40 (FF 60 rear axle), my HJ61, BJ74, etc... I've not ever noticed any issues. I'll definitely dig into it personal or have our parts engineer look it over.

Really appreciate that. It seems to be the (so far) only identifiable common link between people having this issue. My own personal engineering brain can’t find another thing that would be causing the issue.

I will say the brakes work ok even with the issue. Yes they over adjust, there’s too much drag, the shoes wear at an accelerated rate, the drums are full of brake dust, and we’ll see how the inside surface of my drums look when I pull them apart next week. But they work. The danger here is a wheel seizing or - as was the case for me last year - everything gets so hot and the heat cycling bucks the lug nuts loose.

If it turns out that somebody finds another possible cause for the problem that’s great. Not trying to pick on you Kurt!