View Full Version : Bent axle shaft?

12-21-2011, 10:24 AM
I have a 93 GMC 3500 van I use for work. I just got it recently and don't know much about it's history. My rear drum brakes have issues. They pulse rear bad, sometimes to the point one wheel will lock up. Usually it is the worst at speeds of less than 15mph. Sometimes they are fine though. I don't know much about drum brakes but I have been playing with the adjusters and have not made much headway. I replace one drum because I thought it was warped (it was the one that was doing most of the locking up). Now the other side is worse. I noticed the other day while laying under the van and spinning one of the rear wheels that the drum move up and down in relation to the backing plate. The rear axle is a semi float. Could the ends of both of the shafts be bent? I would imagine it it's a 14 bolt. I should check though.

12-21-2011, 10:30 AM
Could be bent. I'd say unlikely though.

Are all the springs and hardware new? I'd try that first. A weak spring can casuse what your describing. The hardware kits are not that expensive either and often overlooked when doing a brake job.

12-21-2011, 11:03 AM
The hardware appears to be pretty new. The adjuster moves easily and the springs are barely coated in brake dust. The drums are pretty new, no lips on the inside. I just replaced the one drum on Monday. Just because the springs are new does not mean whoever installed them did not bend them during the install.

12-21-2011, 12:53 PM
Some mechanics will hammer the shit out of a drum to get them off. I've seen a lot of bent drums. I've seen bad ones out of the box. I'd have them machined. A lot of Napas will do it.

12-21-2011, 01:28 PM
Another thing I forgot to mention is that the previous owner would load the thing floor to ceiling with fire wood. Carrying that much weight may have overloaded the axle. I guess I need to pull the drums and spin the axle and see if it bent. If it is straight then I'll have the drums machined.

12-22-2011, 01:10 PM
If it locks up more when you first drive it for the day i would say its moisture in the shoe linings. When they get a little heat in them the moisture goes away. But if not its most likely worn drums and hardwhare.

12-22-2011, 02:44 PM
Get a dial indicator with a magnetic base, perform a run out check on the axle flange's edge and see if there truly is "hop" in the axle shaft before you tear stuff apart. You may find that it is in the drum.

12-23-2011, 11:08 AM
I used to own a dial indicator on a magnetic base. I think gonecheenin has it.

12-24-2011, 01:16 AM
Where are you at? I have a few and the vicegrip style as well.

12-24-2011, 11:01 AM
Vice grips and a coat hanger. If its bent you'll know it.