replacing rear brake drums

[RGulembo]

I have replaced the rear drums two times in the last several days and the problem I still have is stopping with a chattering feel like stopping on a rough gravel road. The new drums are being checked for being out of round or warped. What gives? Any suggestions?

 

[rrausch]

Did you also change brake shoes? If so, did you make sure when you changed brake shoes that you put the leading shoe on the front and the trailing shoe on the back?

 

[RGulembo]

rear brake drums

Here is what I found out from the shop that still has my truck. The brakes on this 3/4 ton are actually 1 ton brakes. The front rotors and pads were replaced but the rear drums were turned and new pads were replaced. Apparently what has happened is that the front pads glazed over because the rear drums, even when turned were still warped. Two new sets of rear drums were ordered, one from NAPA and another from Dodge and both slipped on real easy with no adjustment. Both sets have been removed and found that when placed on the machine, they were both warped even as new. The shop has now replaced all of the brakes again, but after a five minute ride the chattering has returned once again. Any one out there had this problem as it seems that every mechanic in this shop is baffeled also?

 

[Joe G.]

What year is your truck? 4X4 or 4X2? Where are you?



According to my '95 service manual the 2500 drum brakes are 2. 5" wide with 15/16" bore in the wheel cylinders. The 3500 are 3. 5" wide with 1 1/16" bore wheel cylinders. The brakes appear to be the same if you don't measure the shoe width and wheel cylinder bore size. I don't think the single wheel drive drums (2500) will fit correctly on 3. 5" shoes. Maybe someone who knows for sure will chip in on this point. The wheel cylinders could have been replaced with the 3500 cylinders. Anyway, you should check to see if the shop knows what they are talking about.



I have never heard of a problem like this. In fact, I can't see how it is possible if the brakes are installed properly. Loose or cracked backing plates might cause something like this. Have you tried another brake shop?



I have 229K miles on my truck. The rear brake drums are the originals. I keep them adjusted so that they do their part when brakeing. No funny business even when I have to panic stop from 70 MPH.

 

[Casey Balvert]

Hmmm. At first I thought you were talking about your trailer brakes. But you are talking about the truck brakes apparently.



I ran into a problem with a customer's car years ago with a rapid pulsating feeling on braking. Like a chattering. I checked everything and machined all of his brakes, new linings. Still did it. Drove me nuts. Just for giggles I tried a set if new tires and rims we had sitting in the shop. Cured it. It was the tires. Worth a look.



Casey

 

[Jetson]

Do you have aftermarket alum. wheels?

 

[RJ2]

Last year I had my brakes replaced on a TV show they pulsated when stoping ,the test to isolate drums is to stop with the emergency brake . I had drums turned and I acquired a bad vibration problem. Had to put the original wheels back on. Went to get a tire rotation and brake check and I was told at tire kingdom the drums would not come off because of the ridge in them. I got new drums put on. The bad vibration was back, and I knew it was the same as the first time I had drums replaced. Tire kingdom said the only way to fix it was to get the premium drums ,another 150 extra. they put them on and it is pretty much back to normal. Evidently when they manufacture drums, they do not always lay them flat after turning them because of space and they warp.

 

[Matt400]

With the majority of the stopping force coming from the fronts you can isolate the fault by noting how much shake you get with the service brake vs the park brake by itself.



Take care in using the park brake this way and keep the release lever pulled.

You may find the trouble is the fronts.

Another thought is that it is very possible that the new drums were machined out of round from not being chucked up proper on the lathe.