Chevy Roadtrek Front Brake Judder Fix

[peteco]

This post describes a fix to my mild brake judder/vibration issue that started on my 2006 Roadtrek 210P. I had replaced the front brake pads and rotors, and rear pads in 2014 at about 50,000 miles with Hawk brakes. That improved my braking tremendously and eliminated my juddering/vibrating on hard or long downhill braking. But in 2021 at 130,000 miles I noticed some slight juddering occuring on hevy/hot braking. I had read about the issue with uneven brake material transfer to the rotors. THis is what causes juddeirng in most instances in my opinion. Many like to blame the rotors warping, but I do not think that is the problem on our heavy Chevy Roadtreks. I had read about a guy with a BMW with this problem, and he sanded his rotors pretty heavily and it fixed his problem. I thought I would try that before looking at getting new brakes. It has been a year and 10,000 miles since I did this fix and the brakes still work perfectly. This writeup has more in it than just the brake work.

I had interacted with Booster on this and had planned to post earlier but never got to it. He mentioned it in this post:

https://www.classbforum.com/forums/f5/brake-problem-rt-05c210p-1875.html
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Roadtrek Brake Service, Rotor Refinish, May 2021

Just got back from test drive and bedding the brakes. Followed Hawk procedure: 10 stops from 35, 3 stops from 45 mph. I never fully stop though. 15 minutes driving to cool off.

Not even a hint of wobble or vibration. Just a dead straight stop,

Here is my theory of what caused the previous wobble. The front rotors had developed an uneven burnish or transfer of brake material to the rotor. So the brakes grabbed slightly unevenly. This uneven braking coupled with the poor steering system design and some cumulative looseness from the individual parts: tie rods, idler, pitman arms, idler bracket. Yet after a few stops the wobble decreased or even went away. So somehow the rotor evens itself up from heat or brake material transfer. I think that most “warped rotor” situations are not warped at all but uneven rotor surface condition.

Theory on why this uneven rotor surface occurred: I tend to baby my vehicle and brakes. Anticipate traffic signals, engine brake, etc. This is evident by the pads lasting so long, with 65k on these and plenty of pad left. My other cars usually have minimal brake wear also. I need to rethink my braking habits. It would probably help to do some heavy braking occasionally. Perhaps do a bedding once a month too.

Measurements:
Both front rotors: thickness (1.495”), thickness variation (0.001” max), runout (0.002”). Hawk rotors.
Left rear rotor: thickness (1.123”), thickness variation (0.001” max), runout (0.004”). Original rotor.
Right rear rotor: thickness (1.128”), thickness variation (0.001” max), runout (0.006”). Original rotor. A little over spec (0.005”) but I didn’t think it was worth the effort to remove and index or turn.
Front Hawk pads: 5/16” thick
Rear Hawk pad: 3/16” thick

I measured front runout after reinstalling the rotors. Got the same runout numbers.

 

[peteco]

So here’s what I did.
Removed front rotors. Made a jig to hold the rotor.

 

[peteco]

Use a file to remove some of the rust from the inner and outer lip. Removing this rust prevents it from clogging up the sandpaper.

 

[peteco]

Sanded rotors with 80 grit sandpaper. The 6” sander is run at very slow speed using the Harbor Freight speed controller. This works great to slow down the speed of tools. Also used a right-angle drill holding a small 3M brake sanding disk. This sanding disk got the areas close to the raised outer and inner edges. The trick is to sand at very slow speed and remove the burnish without digging in.

 

[peteco]

The first picture is after trying to sand by hand. Didn’t do much. The 2nd picture shows about half way through sanding.

 

[peteco]

I kept on sanding until there was no burnish remains remaining. Took about 20-25 minutes per rotor. This worked fine but next time I may consider getting the rotors turned.

 

[peteco]

I also sanded the glazed surface of the pads using 100 grit sandpaper.

Before reinstalling the rotors I lubricated the front wheel bearings.

I reinstalled the rotors and bracket. The calipers were sliding fine on the Permatex Silicone Ceramic Extreme Brake Parts Lubricant I had used last time. Permatex sent me this for free after I complained about the swelled bushings from their synthetic Permatex Ultra Disc Brake Caliper Lube. I can’t believe they still sell the synthetic stuff. I still relubed the front caliper pins.

For the rear I still had the old Permatex Ultra lube in there. The rear slides still moved freely. The rear caliper apparently does not have a bushing in it, even though the picture in the Service Manual shows a bushing. The rubber pin bellows did have chunky grease in it. I had new bellows so I changed them out. I cleaned out the pin bores and relubed with the Permatex Silicone. Had some new clips so I put them in also. I lightly sanded the rear rotor surface.

The thin metal backing on one of the pads had completely broken free of the rivets, though the rivet does keep the backing from sliding. Recall I had a problem before with the backing. Hawk had sent me new pads, which I still have but want to wear these out first. I “glued” the backing on with CRC Disc Brake Quiet; put this on and clamped the pad and backing for 30 minutes.

I had previously bought these Carlson Drag Reduction Clips but had not installed. The reviews looked pretty good so I installed. They are tricky and a hassle to install. Especially since I had used CRC Disc Brake Quiet on the back of the pads, which made it messy too. I found I needed this CRC previously to prevent squeal. Once I got the caliper on it looked like the clips work well to spread the pads to minimize rubbing on the rotor. It will be interesting to see how the pads wear now. Note that the rears pads have worn much more than the fronts.

 

[peteco]

I finished by replacing the brake fluid. I use a Motiv pressure bleeder. I used three 32 oz bottles to get clear fluid flowing. After bleeding I found the pedal still a little soft. This has happened before also. So my wife helped me do a pedal bleed (pump 3x, hold, crack bleeder, repeat 3x). What surprised me was that the fluid that came out at first was dirty. I guess the pedal bleed stirs up some old fluid in the caliper piston bore that the pressure bleed flow bypasses.

 

[peteco]

Status update. This original brake rotor sanding rework was done May 2021. Have driven 18000 miles since then. I have had no front brake judder since then. The brake pads and front rotors (Hawk brand, see other posts) were installed in 2015, 83000 miles ago.

Front pads are presently at 5/16-inch. New front pads are 7/16 thick, so only 2/16 wear in 83,000 miles. This is pretty amazing for brakes that stop the vehicle much better than the OEM ones.

I did have to replace the rear brake pads as one pad was getting close to the limit. The others were worn as well but not as much. Not sure why the rear pads wore out faster, as the fronts carry most of the braking load. When I replaced the rear pads I did a sanding of the disks to remove burnish and face edge rust, just like I had done the front rotors in 2021.

I checked rotor thickness and I still have a fair amount of thickness remaining (both front and rear). I estimate the rotors can go at least another 50,000 miles. Checked runout as well and they are within specs.

As I mentioned, these brakes stop the vehicle noticeably better than the original ones. Even if they were completely worn out now I would replace with the same.

 

[norv]

View attachment 14265

 

[peteco]

View attachment 14265

 

[jjrbus]

Nice write up, thanks for taking the time and effort to do it. Reminds me of my old neighbor Joe Podwica, great guy, fleet mechanic. Every now and then I would see him sanding down rotors. In those days rotors were 10$ and I thought it was a waste of time, well rotors aren't 10$ anymore!