Drive brake shoe/stroke measurements?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Bigtruckdrivah, May 17, 2021.

  1. Bigtruckdrivah

    Bigtruckdrivah Light Load Member

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    Got 120 day inspection last week, and the shop passed me but said the drive brakes are due soon. I’ll post a pic of the report, and maybe someone can explain it to me. I thought these still had a bunch of life left on them?

    drum brakes, 30 series chambers
     

    Attached Files:

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  3. jason6541

    jason6541 Road Train Member

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    1/4 inch is minimum lining thickness. Usually a indentation on side of shoe to indicate 1/4 inch mark. Brakes are getting a bit thin but not out of service yet
     
  4. Bigtruckdrivah

    Bigtruckdrivah Light Load Member

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    What thickness is a good stopping point. I don’t wanna take them to the min but I wanna get my $$$ out of them also lol
     
  5. jason6541

    jason6541 Road Train Member

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    I run mine to about 3/8 as far as 5/16th
     
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  6. jason6541

    jason6541 Road Train Member

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    O
     
    Last edited: May 17, 2021
  7. Rideandrepair

    Rideandrepair Road Train Member

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    Crawl underneath and Look at the backside of the shoes. You’ll see a ridge running along the outside edge of the shoes. That’s the indicater. As long as you can still see it, they’re Legal. Also run your finger inside the drum across it, if it feels bumpy, and grooved, you’ll need drums also. If the drum has a large ridge on the outer side, where the shoes aren’t in contact, the shoes could be sitting down inside the groove, making the shoes look more worn than they actually are. If only 1 drums bad on each axle. You can replace only 2, putting the new ones on rear axle, reusing the 2 good ones on the front. Tiny surface heat cracks on drums is normal. It’s not uncommon to have only a couple badly grooved drums, one on each axle. Why? I don’t know, different metals, cheaper drums? Lightweight drums vs. standard drums, tight bearing adjustments, causing heat? Ideally it shouldn’t happen, but does. Using higher metallic shoes, wears drums quicker. Semi metallic shoes, usually can re use drums once. Full metallic shoes, last longer, work better, stand up against heat better, fade less, but unfortunately tend to eat drums up quicker. Still best to use top quality shoes, and replace drums, even if it’s with every brake job. Better system, will last longer. Drums aren’t expensive these days. Old way of thinking was shoes are cheaper than drums. That’s old thinking. Better to get the best, especially if paying for Labor. IMO, even if doing work yourself. Brakes last longer, less Labor either way. Shoes are usually $50, Drums, $90-$180. Labor $300-$600, depending on Shop. TA prices on Freightliner Drums are twice the price, as Dealer. Total cost should be around $500-$1000, depending on wether you need drums. Probably a little more, if you have axle seals replaced. Just ballpark figures, based on my past experience. Get good shoes, preferably new, with Powder coating, to guard against rust jacking,(rust between shoe and lining), that causes linings to crack Merritor, Bendix, and others all make them. I use Merritors, on mine, they’re brand new, no core deposit, painted blue/green. With good drums, they last a long time. Worth a little extra $$ in the long run.
     
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  8. otterinthewater

    otterinthewater Road Train Member

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    Get one of these. It’s takes guessing out of it for the most part.

    77871CF2-00ED-4149-8372-01D689011E80.jpeg
     
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  9. AModelCat

    AModelCat Road Train Member

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    Problem when you go too thin is the accumulated crap above the rivets starts to ridge the drum.
     
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  10. Rideandrepair

    Rideandrepair Road Train Member

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    I’ve always wondered, if it was heat from rivets. What surprises me, is how the shoes aren’t distorted the same as drum. Slightly maybe. My first car, first brake job, turned the drums to the legal limit. Still had a couple grooves in them. Shoes squealed a bit at first, but wore into the grooved drums. Not ideal, but $250 for a brake drums on a $200 car was out of the question. Used ones, if you could find them were $25. Still a lot. Just one difference I’ve noticed between Trucks and Cars. It seems odd, to pull a drum off that’s deeply grooved, and yet the shoes are still pretty much worn even. Seems they’d be grooved to match the drum. Just defies Logic, to me.
     
  11. Bigtruckdrivah

    Bigtruckdrivah Light Load Member

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    Thanks for the help! I’ll probably run the truck locally for a week or 2 and get drums/shoes replaced during some down time I have scheduled to finish selling my house.
     
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