Brake Shudder

[Lars Waldner]

Replaced front rotors calipers and pads 3000 miles ago. Shudder developed a month ago and got worse.
Feels like front end, as shudder is felt through steering wheel. Jacked up front end to evaluate brakes. Nothing looked worn in front suspension...all rubber bushings looked good. Calipers pads and rotors all looked new. Took rotors to NAPA and had them turned...they were warped, but not bad. Technician said the rotors looked new. Brought them home and re-installed, being careful to make sure everything was greased and torqued. Initially (1st 20 miles) no shudder, but now it is back as bad as before. I am confused. Ready to check the rears, but rears wouldn't cause the steering wheel to shudder? Rims look ok...no obvious bends or carnage. I live on a mountain, so most of my severe braking would be descending and turning, but I generally "baby" the brakes. What else do I look for?

 

[Johnsram]

Shudder can also occur through the rears...have you inspected them?

 

[Brando_SLT]

How does your brake fluid look? When was the last time it was flushed? It could be a stuck/slow piston or two.

 

[Lars Waldner]

I have not inspected the rears...but I will. Always thought the rears would not cause steering wheel shimmy...which I have. Brake fluid looks ok, but I have not drained and replaced since I basically did that when the calipers were replaced 3000 mile ago. Should I drain the fluid and replace completely?
As the shudder started, it progressed from only being noticeable while suggested it could be a warped hub or bearings. I have never experienced a warped hub, and bearings for my experience have become obvious when loading the suspension (usually front) while braking and turning while descending. This shudder is pretty much straight ahead. One thing I need to check while braking before I tear anything else apart...is to see if there is any pull to the steering wheel while braking as that might suggest a caliper piston on that side of the truck?

 

[MADDOG]

Did you season the new rotors and bed the new pads?

http://baer.com/site_images/Rotor Seasoning & Pad Bedding.pdf

 

[hotrod45]

You stated that the problem went away for twenty miles or so after working on the front. What would make you think that working on the front would make an issue in the rear go away?

 

[Lars Waldner]

I did standard "bedding" procedure...gradually build up heat with light braking followed by successively harder braking.
No, I didn't expect a rear rotor problem to go away by turning the front rotors...I didn't think the problem was with the rear rotors.
Never experienced a steering wheel shimmy with warped rear rotors.
Warped rear rotors to me would be evidenced by a shimmy coming from the rear of the truck...seat of the pants.

 

[Karlsweg]

Did you clean off any rust on face of the hub before replacing rotor and is brake hardware installed. I sound like warped rotor(s).

 

[hotrod45]

No, I didn't expect a rear rotor problem to go away by turning the front rotors...I didn't think the problem was with the rear rotors.
Never experienced a steering wheel shimmy with warped rear rotors.
Warped rear rotors to me would be evidenced by a shimmy coming from the rear of the truck...seat of the pants.

I was agreeing with you. There are things I don't know about in more modern braking systems, though. I don't know if the '03 has anti-lock brakes, but if so, are you familiar with the sound and feel of that system? I also don't know if there is a distribution block in the hydraulics for front/back. It crossed my mind that if that piston isn't centered (if there is one), you're putting all the stopping power to the front axle and getting an anti-lock response. I would hope someone who knows the system would chime in on this as to whether it's even possible.

 

[Lars Waldner]

Yes the 03 has ABS and this shudder is not the ABS pulsing. I did check the hubs for a smooth contact surface when installing the rotors. And yes the pad hardware is installed as well as re-greased. I have a hard time believing that fresh rotors could so quickly become warped? If a piston was grabbing, would that not pull the steering to that side? And would it squeak?

 

[Karlsweg]

I would pull the wheel and put lugs back on and torque them and check the runout with a dial indicator and see if they are warped again. Cheap rotors made in China warp easily and considering that these are heavy trucks it wouldn’t take much heat to warp them. Just my 2 cents also I would take it for a norm drive and quickly check the rotors with a pyrometer to see if one side is heating up more then the other. This would indicate a caliper possibly not releasing all the way.

 

[hotrod45]

I believe one of the things that I would do is to bleed the brakes. I'd be surprised if the problem involves a caliper or especially one that is hanging up, or that it is hanging up without a tell-tale twitch in one direction every time the brakes are applied. Maybe the most interesting fact is that the problem went away for twenty miles. If there isn't a runout problem with the front rotors, it really brings the hydraulics under suspicion, imo, assuming that the pistons in the calipers were moved back for removal of the caliper.

 

[Karlsweg]

It could be a rubber brake hose going bad that slowly releases the piston in the caliper. Not enough to lock the piston. And after it sits the pressure is released.

 

[Lars Waldner]

Bit the bullet and started on the rear rotors. Obviously not replaced in 16 years. To say they were hard to remove was an understatement. Soaked in Kroil and headed to NAPA to buy new rotors and calipers and pads. Rotors were definitely toast...calipers not much better. After two hours of beating, loosened the right side e-brake and eventually the rotor gave up. Installed the caliper with new pads, but left wheel off to drain and bleed the brakes. Left rotor still refuses to move even with the e-braked loosened. In the winter sometimes the e-brake has gotten stuck, and I now see that the cable lengths are different side to side. I need to even those up. Generally speaking as the orientation is opposite side to side...turning the gear through the adjustment hole down (to below the hole ) tightens the cable...yes? Once I get the left side rotor to release, I'll be able to figure this out...but for now still trying to determine how to loosen the cable. I've rotated the wheel up and then dow, and the rotor still is stuck. Guy at NAPA still swears the shudder is the front brakes and the rears would pulse through the brake pedal. Anyway, they will all be fresh shortly. Did a test of the braking on a straight hill and no obvious pulling of the wheel to either side...

 

[Lars Waldner]

I believe one of the things that I would do is to bleed the brakes. I'd be surprised if the problem involves a caliper or especially one that is hanging up, or that it is hanging up without a tell-tale twitch in one direction every time the brakes are applied. Maybe the most interesting fact is that the problem went away for twenty miles. If there isn't a runout problem with the front rotors, it really brings the hydraulics under suspicion, imo, assuming that the pistons in the calipers were moved back for removal of the caliper.

Good point...once I get the rotor to release and mount the new caliper, next step will be a drain and bleed. I can't wait to be that far along.

 

[hotrod45]