05 Tundra with rear brake noise

I have a 05 DC with 19k miles and ever since the truck has had around 8k miles the rear brakes emit a loud moaning sound when you go to stop and get down to about 4 mph or slower. Two dealers have checked and cleaned the dust off and one replaced rear drums and they still do it badly. It is loud enough that other drivers will turn and look at you. Would some different shoes help this like high performance. Had them checked again yesterday and was told they still looked great and the noise was normal. BS, I have never owned a vehicle that made that much brake noise. Suggestions?

Reply to
Dad-x-2
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snipped-for-privacy@webtv.net sez:

Hmmmmm, interesting. My '04 DC has started doing the same this winter (I have about 25k miles on it). I'm running studded snows that have relatively aggressive tread patterns (noisy) and was wondering if they were inducing some low speed vibration that set things off. Are you still on the OEM tires?

I pulled the drums and blew all of the dust out with the compressor which helped for a while but its back. I made sure to check for hydraulic slave cylinder and/or axle seal leaks at the time but it all was nice and dry. It seems to be affected by moisture as it doesn't do it when things are wet from snow melt and such. I'm curious on why it has started now with my driving patterns/habits unchanged since I've had it for over two years now. Normal? Baloney, it didn't do it before. I can mitigate the symptoms by braking with more pressure in coming to a stop but that bugs me.

The next thing I'm going to do is pull the drums again, inspect the wear surfaces and make sure the automatic adjusters are doing the right thing (for grins, I may try swapping the drums too just to change the braking directional forces on them).

The other thing I suspect may be in play is the load sensing & proportioning valve. I installed air bags on the rear over a year ago and usually run them at the minimum recommended 10psi when unloaded so ride height isn't affected. I think I'll try pressuring up to 50 psi to get the back end up higher. That should lower the pressure to the rear drums through the proportioning valve on braking so it'll be interesting to see if it changes anything.

I'll keep ya posted on what works or doesn't work ...

Good diagnosin' to ya, VLJ

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Reply to
vlj

Well, it certainly isn't normal. Keep taking it back to the dealership and demanding action. If necessary, contact the district rep. Maybe Toyota changed the compound of the brake shoe lining, or maybe they changed suppliers...in any case, they need to make it right.

I do not like the idea of air bags or any other helper springs in the back. The rear brake proportioning valve allows more braking effort from the rears when more load gives the rear tires more traction. The proportioning valve senses the load on the rear by the height of the bed above the axle. Helper springs of any type raise the bed under load and do not allow the rears to provide as much braking as they should.

Ken

Reply to
Ken Shelton

Ken Shelton sez:

Yesterday, I pulled the rear drums off, blew the dust of and cleaned everything up so I could have a good look at things. The only abnormal condition I found (in both drums) is "banding" in the very center of the friction surface contact/wear area showing uneven pressure exerted by the brake shoes. (I have pictures I can email if you want to see them).

I laid a straightedge on the shoes themselves with a bright flashlight on the back side and this showed the contact surface of the shoe to be "dished" with light coming from the other side in the middle and decreasing out to the sides.

This leads me to believe that the steel backing plates of the shoes themselves aren't thick enough nor sufficiently reinforced from the center rib out to keep the outside of the shoes from deflecting under load. This causes the center of the shoes to wear more quickly than the outsides. Once worn and under light braking pressure, only the outsides of the shoes are in contact with the drum instead of the full shoe and this results in the vibration or "moan" on braking.

I bet replacement of the brake shoes (and turning of the drums too) would make it immediately go away. I'll find out how enthusiastic my local dealer will be to take such measures.

That's true, but the beauty of air bags is that you can adjust the pressure in them. I installed them since I'll be using a slide-in camper that when fully provisioned will be right at the vehicle's maximum payload capacity. Once you turn off the road to go many more miles back in to camp, being able to pressure up and get more clearance and suspension travel is a good thing. Once back on the pavement, the pressure can be bled off to have all of the aforementioned benefits of more braking in the rear.

Good wrenchin' & off-roadin' to ya, VLJ

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Reply to
vlj

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