Rear Brake Drums keep Warping VIOLENT SHAKE (1997 Suburban 6.5TD)??

[97Suburban]

Please Help me with this horrible rear drum setup. on another set of what I understand to be high end drums, Raybestos 9531 PG Plus (Professional Grade Plus) drums. Just had this next set cut today and at 331mm and 332mm in diameter. Last set sent rear into a "violent shake" and I had to back off on shoes...

So what do I do tomorrow, go to NAPA or CarQuest or AutoZone and buy some kind of ceramic shoe or semi-metallic brake shoe????

This stupid GM setup is a waste of money and stinks....

TheBrakeMan.com said they have shoes for this but at $200 to $250 depending where you buy them, what the heck, another fortune, this Diesel business is really getting on my nerves, everyong charges a fortune for any part that says diesel???

Please help me figure out what shoes to buy tomorrow so that I can take a 12 hour trip without the drums heating up and sending the rear into a "violent shake"!!!!!! Thus, I keep paying for new front rotors due to weak or NO back braking, another expense, then injectors, remote PMD, computer, turbo arm, tires...

What are the Raybestos & NAPA grade levels, how the heck do I figure this bees nest out???

[Yukon6.2]

Hi
This is the first time i have ever heard of rear drums warping.There really isn't anything different between the diesel or gas braking systems,so price should be the same.
When you are replaceing the brake shoes are you using new hardware?That is new springs and related gizmos to hold the brake shoes to backing plate and related levers mounts ect.Also are all the pieces getting installed corectly?
Also what condition are your emergancy cables in? Could they be sticking?
The general thought are these rear brakes may not be overkill,but when adjusted properly with good parts they do work good.
I'v had GM trucks for years and have haulled big loads and have never had any problems with rear brakes,to get the best braking i have found that you need to adjust the rear shoes yourself,the automatic adjusters seem to leave a little to much space between the shoes and drums making the front brakes work harder,which can warp the front rotors.
I have heard that there are oversize brake cylinders for the rear if you are having problems stopping.
I have a k3500 tow truck which i haul real heavy loads at times,broke trucks with their trailers in tow,motorhomes,and the ocasional 5 ton truck.In 10 yrs i have replaced the shoes once,they are getting close again,but the drums never gave me any problems.
I think you have a problem somewhere that needs to be found.My thought is something is causing the brakes to stick on,causing excessive heat warping your drums.Or you got a set of elcheapo drums by mistake,reboxed in an expencive box.
Hope you find the cure.
Thomas

[97Suburban]

Thanks for the reply!
Yes, the emergency cables work great and are free, becuase, I hate to mention it, but when the brakes slowly stop working, I use the manual emergeny break method to feather some pressure to the rear.

So far, every shop I talk too that knows these suburbans, agrees that everytime you change the oil, it is a must to readjust the back brakes, becuase the value sends very little fluid to the rear and just a little wear and weak fluid makes them get weak quickly.

Some say get replace the brake valve for more fluid to the rear with the larger value.

Also, TheBrakeMan says replace with his low heat shoes to keep this common warping problem from happening, and he said never lock the emergency brake when parked and warp them (I NEVER have).

Thanks again, please educate me more

[DennisG01]

I've had my Suburban about 6 years. I *think* they're the original drums. I've never had any warping and I always use the e-brake. However, I do agree that there should be some more stopping power. I had read a TSB about having the proportioning valve replaced and I might just do that - or maybe use an adjustable one. I've been on this forum for a quite a while and can honestly say I don't recall reading anything about warping problems - on a Sub or a pick-up truck. I don't doubt you that you're having problem - and I understand how frustrating it can be. But, there's gotta be something else going on to cause you this problem.

[NutNbutGMC]

....Also, TheBrakeMan says replace with his low heat shoes to keep this common warping problem from happening, and he said never lock the emergency brake when parked and warp them (I NEVER have).

Thanks again, please educate me more

Not doubting your word but the BrakeMan is not convincing me that this is common and that HIS shoes will resolve your issue. I smell a rat with the BrakeMan's advice. Drums and shoes should not warp under any normal type condition without an external action causing the issue (as the others have stated here). Let alone the advice of the emergency brake. I "ain't" buying it at all...

Are you sure you don't have a real seal or fitting leaking down on the shoes?

[97Suburban]

Ah good point, I personally replaced the rear wheel cylinders and shoes around Jan/feb 2007.

Also, when I bought this from the dealer, the thing was stopping on the front discs and no back brakes, so the dealer replaced the rear shoes that were oil soaked and replaced the rear axle seals dec 2005.

So yes, the shoes are components are clean and dry still.

Also, I just finsished installing the newly cut drums 331mm & 332mm, but get this, BOTH drums act like they are a little out of round, this has been the characterstic ever since I bought this truck, I have to loosen up the adjuster so that as the wheel spins and the drum ob long side comes around and rubs, this STINKS, Urggg, I hate this!!!! It seems the New drums were not out of round from what I can remember Jan/feb 2008, but they went out of round fast and caused a shake also until I backed off the brake adjuster. I asked local shops about a bent axles and they said no way because I would have bigger problems.

ANY thoughts on bent axles???

[Robyn]

These trucks are notorious for warping the front brake rotors.

I have never had a Late model Burb that the brakes did not give issue.

The best rotors I have had so far were a set of the Chinese cast ones.

So far so good. The high quality NAPA ones went south in less than 6 months and the cheap crap have been working fine for over two years now. Go Figure


I have yet so see any real issues with the rear drum setups.

Good quality brake shoes seem to work well on these.
There are a few issues with the proportioning valves going south and not allowing enough pressure to the rear brakes.

Best

Robyn

[rustyk]

This is a complete WAG - I had the shudder issue years ago on a Ford, but not with the warping; I completely bled the lines - surprised to find a couple of little bubbles. That improved things somewhat.

Anyway, the real problem was a defective proportioning valve.

[6.5 Detroit Diesel]

There should be no difference between the gasser and the diesel. I am assuming you have a FF rear?

[Robyn]

There are really no differences between the brakes on a diesel Burb and a gas Burb
Its all in what was ordered on the truck when the spec sheet was written.

Anybody that is charging more $$$ for parts just because its a diesel is ripping folks off.

Many times though the diesel rigs will have a larger brake set (thus the extra cost)
This is in many cases due to the rig having been specd out with a HD tow package or other HD equipment.

Best

Robyn

[Mainous]

See this thread to make sure you understand how these brakes work:

http://www.thedieselpageforums.com/t...o+servo+brakes