I have experinced some brake shimmy for a few months but as I didn't drive the truck that much I didn't worry about it. My son bought me a set of 17" aluminum rims for Christmas and after installation the brakes really shimmied big time. I checked the run out on the brake hub and the wheels after mounting them. Checked ok, bought new brake pads, new rotors and calipers as the pads were at the end of their limit. Turned the old rotors, installed new calipers with pads and put the wheels back on. I could tell a difference but still had a shimmy. When I wasn't using brakes, truck rode fine all the way to 95 mph, didn't try it any higher. So, I put the new rotors and bearings on--- took it down the road , a little better but still some shimmy when the brakes are applied, some times worse than others. Steering good and tight, rides good just braking a problem. Where do I look next ? Could I possibly have a bad rim that only shows up when braking ?
Help !!!

 

Hard to believe but the problem may be in your rear brakes.
Make sure they are adjusted correctly and there is no differential fluid leaking on the shoes.

 

Yep. I had the same problem and it was the rear brakes. Went away by itself though . Don't know why. I tore the brakes apart and found nothing wrong (that I could see).
Tom

 

Jacked up the rear this morning and adjusted the back drum brakes and looked for any fluid leakage. No leakage. Drove the truck and still have the shimmy.
Next ?
Thanks for the help----

 

You say you bought new rotors and had the old ones turned, which did you install?
Sort of sounds like they're still warped.

 

I installed the orginal ones after turning them. Same shimmy. Put new Rotors on and still shimmied. Man at the parts counter said that he had a friend that had same issue with Dodge truck and wound up replacing the whole braking system. Was a back brake issue but the owner didn't know for sure what caused the problem or what actually fixed it. I am at the point now of pulling the back hubs, turning them and putting new brake pads in back. I will do the Chevy big bore cylinder conversion at the same time.
Advice ?

 

Just make sure the shop doing the turning knows what they're doing.
If you can't get the drums off put the truck rear on jackstands, remove the wheels, put one lug nut back on loosely, start the engine put it in gear and slam on the brakes in both forward and reverse.

 

Yep, sounds spooky but what infidel said really works. I did it on a drum that a brake shop said "we can't get it off". Maybe leave 2 lug nuts on if you really want to be safe. Good luck, Kevin

 

Your truck probably needs new drums and shoes, just an idea tho...

Deezle1

 

Hey I read on here I believe but it is the back brakes .But it is not going to go away untill you go with disc brake convert cause the casting in all drums for so many trucks out of balance. When the shimmy stops without convert the brakes are out of adjustment (not applying shoes) just using front brakes .Mine does it also .Put a heavy trailor behind and mash brakes haaaaard to stop in a hurry and it will viberate all stuff off of dash

 

Another way to check if its the rear brakes: Drive down the road at the speed you usually experience the brake pulsation, pull out on the parking brake lever and hold it out, gently apply the parking brake. If its the rear brakes it will pulsate like usual. If it doesn't its probably in the front somewhere. Give it a shot and let us know.

 

OK fellows, here is the latest. I did the E-brake test and no shimmy, Only when I used the brake peddle. I've just finished doing a complete brake job on the front. I pulled the rear drums (lots of fun, put the rear on jack stands and tried the run and hit brake peddle --didn't work for me, although I had let the brake adjusters off before hand-- that may have hindered this method). After pulling them off, I inspected the pads, plenty of pad left but they did have small fissures in lining. Pulled the wheel cylinders off --- after inspecting them I believe that only one end piston was working-- other end stuck so that only one pad was being deployed causing the crystellized pads to "bounch" against the drums causing the shutter. Replaced the brake cylinders with the chevy one ton ones, turned the drums only a few thousants and installed new pads. Took a ride and NO MORE SHIMMY !! Brakes galore ! only problem now is that I don't think the abs is working as I'll lock up one rear wheel if I hit the brakes hard and now the abs and brake light are on.
Advice on abs light and system ? Very happy at this point !

forgot to add--- I think going from the stock steel wheels to the lighter aluminum helped the problem to show up in a bigger way.

NEW--- just got back from a short trip. ABS and brake light out ! Brakes working great !
Thanks, Guys !!!!!!

 

Sometimes using the parking brakes to determine which end the problem is on, like in your case, doesn't work since the parking brake is mechanical rather than hydraulic.

 

Touche' Infidel, I didn't even think about that!

 

Now have the best brakes ever on the truck! Only one issue remaining, every now and then I will get the shimmy back -- After I feel it , at the next stop I will push the brake pedal down good and hard and shimmy will go away. I assume this "centers" the back brake pads ?