Back of truck bounces while braking??
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Senior Member
Joined: Jul 2000
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From: Houston, by way of every major city in America.
Back of truck bounces while braking??
I don't know if anyone remembers my previous rear bounce(while braking) Now it has gotten to the point where you can see the bed going up and down in the rear view mirror. The bounce is also much more severe. Has this happened to anyone?? It's driving me insane,LMAO......What is it??? Anti-lock brake sensor going bad? Drums out of round? I have had little annoying brake issues since I owned this thing,but this is too much...Help out if you can,,,,98
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Joined: Feb 2000
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From: Kalamazoo, MI, USA
Drums get hot-spots (changes in the molecular make-up of the iron) that get very hard and don't wear the same as the remainder of the (softer) part of the drum. This escalates the "condition" (can't use the word "problem" now-a-days) since the hot spot continues to get hotter due to it's being the first thing that the shoes contact (or at a higher level of interference/force).
Common "fix"es for this condition is to "turn" (lathe-cut) the drum -- and better "fixes" are grinding the drum instead.
The result, however, is that you're taking precious material (losing heat-sinking ability) away during either action. I personally prefer shake to giving up soak ability (material) -- but there is a level at which I do cry 'uncle' -- and from your description, I'd have cried 'uncle' miles ago with your set-up.
Another downfall of turning drums is that the shoes then don't 'fit' the drum (since the radius is now bigger) -- and the shoes then touch first in the center of the shoe -- which results in either or both of two things:
a) a spongy brake -- due to the initial contact in the center of the shoe -- whereupon the shoe needs to actually deflect (deform) in order to contact the remainder of the shoe with the drum, or
b) the initial contact with the center of the shoe(s) with the drum causes localized heating (rather than having it spread out across the full shoe pattern) and you start the hot-spotting all over again -- only quicker.
Drums are cheap -- and so are shoes -- you can probably do a reline and re-drum for $200 and an afternoon of beer and male-bonding.
Don't scrimp on the lining.
Better?
Do a search on my ID and Brakes for more tips & traps.
Common "fix"es for this condition is to "turn" (lathe-cut) the drum -- and better "fixes" are grinding the drum instead.
The result, however, is that you're taking precious material (losing heat-sinking ability) away during either action. I personally prefer shake to giving up soak ability (material) -- but there is a level at which I do cry 'uncle' -- and from your description, I'd have cried 'uncle' miles ago with your set-up.
Another downfall of turning drums is that the shoes then don't 'fit' the drum (since the radius is now bigger) -- and the shoes then touch first in the center of the shoe -- which results in either or both of two things:
a) a spongy brake -- due to the initial contact in the center of the shoe -- whereupon the shoe needs to actually deflect (deform) in order to contact the remainder of the shoe with the drum, or
b) the initial contact with the center of the shoe(s) with the drum causes localized heating (rather than having it spread out across the full shoe pattern) and you start the hot-spotting all over again -- only quicker.
Drums are cheap -- and so are shoes -- you can probably do a reline and re-drum for $200 and an afternoon of beer and male-bonding.
Don't scrimp on the lining.
Better?
Do a search on my ID and Brakes for more tips & traps.
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Senior Member
Joined: Jul 2000
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From: Houston, by way of every major city in America.
That will be sufficient,thank you
I'll head out for new drums and shoes as soon as I can,lol. What would be the best shoes in your opinion? Only the best for my baby What's funny is I thought it was the front rotors warping on me again.(before the bouncing started,that is) It would have this kind of pulsating feeling,but the not in the pedal,,,Thanks for the great explanation,Y2K! Damn,and just painted those drums last week,they're quite sharp looking,lol.,,,,,98
Senior Member
Joined: Feb 2000
Posts: 1,544
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From: Kalamazoo, MI, USA
I haven't been THAT close to the hardware in years -- but there are basically only a few lining manufacturers that provide OEM-level lining -- and they all sell aftermarket lining under myriad lables.
The trick is to find out what the OEM lining friction codes are (like EE, EF, FF, GG, GH, HH, etc) -- and make sure that your replacement lining AT LEAST have the same rating.
Next, I'd look for flagship lining brands by Bendix, Abex, Carlisle (top three that come to mind) -- and I'd use NEW as opposed to RELINED -- only due to the expectation that the shoe geometry will be better with new shoes.
Don't rule out the front brakes as your culprit -- as similar conditions apply to rotors -- and they are usually the origin for such complaints, since the front brakes do as much as 75% of the braking of the vehicle (but drums are the cheapest part).
The trick is to find out what the OEM lining friction codes are (like EE, EF, FF, GG, GH, HH, etc) -- and make sure that your replacement lining AT LEAST have the same rating.
Next, I'd look for flagship lining brands by Bendix, Abex, Carlisle (top three that come to mind) -- and I'd use NEW as opposed to RELINED -- only due to the expectation that the shoe geometry will be better with new shoes.
Don't rule out the front brakes as your culprit -- as similar conditions apply to rotors -- and they are usually the origin for such complaints, since the front brakes do as much as 75% of the braking of the vehicle (but drums are the cheapest part).