Brake shudder only after 45 mins of stop and go

Hi folks. Perhaps you can guide me into my next step. I have a 2020 DCLB sport with 48k miles. I recently developed a brake shudder only after 45 mins of stop and go traffic. I have no brake shutter driving highway speeds or local driving. The shudder goes away after an hour of regular cruising speed.

My first thought, the front rotors were warping. I replaced them along with new pads. All set I thought until the next city trip with stop and go for 30-45 minutes. Still have the shudder.

I'm was thinking a slow returning caliper. I took an infrared temp on both rotors and calipers and both front sides showed the same temp. But that was during normal driving. I always bleed the calipers until I see clear fluid.

My brake pedal does not pulse. I did not try just using the rear brakes when shuttering. I don't want to get rear-ended in stop and go traffic.

I'm off the 36K warranty but I do have the certified used 100K drivetrain warranty.

Thought ? (other them I'm long-winded)

 

Could try replacing the front caliper pins that the front pads slide back and forth on. Could also double up the springs that wrap around the pins. They are on one side of the pads and you can add a second spring to the other end on each caliper.

 

Does the shudder only happen when braking?

 

Jack each wheel off the ground. Loosen lug nuts and torque properly.

 

The shudder only happens when I'm braking when in stop ang go traffic for 30-45 mins. Fine afterwards when traffic resumes and 30 minutes go by. Got to be some heat thing. I can't isolate a slow returning caliper.

I rotate my tires at 5k at oil change time and torque my 6 lugs to 83-85 lt lbs.

 

.... Following

 

I got new pad pins and springs when I replaced the rotors and pads. I put a light wipe of brake glide on the pins as you're supposed to.

 

I've seen out of round drums cause this.

Oddly to diagnose them you simply adjust them up and see if it worsens.

 

Could simply be uneven material buildup that sorts itself out at highway speeds.

 

While you are on the road turn the parking brake handle to release, and gently pull the handle out if it is in the rear you will feel it in your hand. I kind of doubt it's the rear ones though.

 

I didn't suspect the rear drums. I'll try the parking brake thing on our next city trip.

 

It really is too new to have any suspension issues etc.

 

Intermittent shutter doesn’t point to braking issue . If u had this issue it would do it all the time . Check the drive line for any excessive play .

 

Been having a similar issue and following this thread, thought i would try the mainemah diagnosis mentioned above, slowly pulled up on the e-brake, definitely something with the rear brakes\rear end for sure.....same feeling as I get driving around town occasionally. Pulled hard on it a few times from higher speeds, more or less heat cycling the drums, p
Been a lot of years since i had a vehicle with drums, however might need to replace the drums. Weirdly intermittent, wondering if slower short drives cause more heat buildup than highway driving, therefore warping is more noticeable? Actually was kind of nice to know it was that as opposed to something else!

 

Was thinking the same. I wonder if it's actually the torque converter causing it. Try slipping the tranny in neutral while braking when this happens....it you get no more shudder, thats your answer.

 

How did you bed the new pads to the new rotors? It sounds like maybe you skipped that step and have an un-even amount of pad material deposited on the rotors during stop and go traffic.

 

Seems like you’re riding the brake pedal when braking. Overheated rotors will warp and cools down after an hour of freeway speed.

 

Update: Replaced the rear drums and still have the shutter/bucking issue ONLY after 25-45 minutes of stop and go traffic. And the shutter still happens when I pull the emergency brake gently. No shutter during normal driving and occasional braking. The rear brake shoes, springs, clips and cable look fine. No excessive dust in there. I have no idea. My mechanic has no idea either. No one turns brake drums anymore around where I live though I'd like to test drum runout on a lathe. New drums don't mean new, just different.

I'm at a lost here diagnosing this issue.

 

Is your shutter speed dependent? My 2021 has had the same intermittent stutter but it always happens around 40-45 mph. I have replaced my front rotors, adjusted the rear brakes but nothing really seems to help. Could out of round brake drums also cause enough of a balance issue at certain speeds? Since my braking vibration occurs at the same speed as an acceleration stutter my next step is a major refresh of ATF at the 50k mark.

 

Not speed dependent. Once the traffic starts moving again it shakes at any speed like 25 or 65 MPH when braking. Then no shakes after 20-30 minutes of driving without braking. That's why I suspect warped drums but not warped after they cool off ? Gremlins