Chevy brake rotor warning

[JohnnyFry]

When I had the juddering problem, 65,000 miles ago, the mechanic at my Chevrolet dealership drove in it with me and recommended Ambulance spec pads and rotors which were about 50%.more than standard. I went for the upgrade and never had another problem. I have driven 10% grades in West Virginia and many miles long 6% grades in Colorado and New Mexico and have had zero recurrences of the problem.

[booster]

Originally Posted by tlillard23

Back to the brake rotor warning. I have the 70S on my 2007 190p. had replaced the rotors and brake pads when I got it, I I too had the rear brake pads wear out very quickly. (front looked like new, rears were past the wear groves) I measured everything last time when installing and measured everything again this time, I have the correct rotor for my application. I started checking temperatures, the rear are running 100° hotter than the front after just a few stops. front is 200s rears are 300s. both left and right.



has anyone seen higher temperatures on the rear as compared to the front? do I need to re-bleed the system maybe I have some sort of weird bias going on?
The brakes don't drag, I drove a mile or so without hitting the brakes and then coasted into a parking lot, front and rear rotors were same temperature, a little bit above ambient.

Rear brakes should pretty much always run cooler than fronts. I actually wish I could get a bit more braking on the rear of our 190.



I think there has to be something wrong with your setup, but hard to tell what at this point with limited information.


Did both sides do the same thing and wear the same?


Did both the inner and outer pads wear out or just inner or outer>


Did the rotors so any heat scrortching or blue coloring?


Any pix of the parts that you might have would also help.


When on jacks do the rear wheels spin easily by hand initially and also after a brake application and release?

[tlillard23]

See answers below
*misspoke I have the 60s, with the smaller diameter center bore, and a semi floater. The measurements on the original old rotors (that I'm using as dumbbell) and the rotors currently on the van were the same dimensions that you mentioned for the 60s

Originally Posted by booster

Rear brakes should pretty much always run cooler than fronts. I actually wish I could get a bit more braking on the rear of our 190.



I think there has to be something wrong with your setup, but hard to tell what at this point with limited information.


**Agree


Did both sides do the same thing and wear the same?


**yes, both sides (Dr/pass) wear the same and same temps.


Did both the inner and outer pads wear out or just inner or outer>


**inner were just past the low wear groove, outer had just a bit more wear grove. Fronts looked new.


Did the rotors so any heat scrortching or blue coloring?


*none that I noticed. was getting rust, so maybe some pin binding?


Any pix of the parts that you might have would also help.


*none. I cleaned up the rear rotors and reused them. I'll dig through the trash for pads.


When on jacks do the rear wheels spin easily by hand initially and also after a brake application and release?


*yes, no abnormal dragging. will recheck when home

[booster]

If the rear brakes aren't heating up until you use them to brake you probably don't have them dragging all the time. But to have them heat up more than the front would have to mean they are doing most of the braking on the very heavy van. I would think it would take a lot of effort on the pedal to stop the van adequately with mostly rear braking.


If that is the case, the problem may more likely be someplace else in the system.


I don't know if they used a separate proportioning valve in Hydroboost brake setups or not, but it they do that would be possible point to look. Proportioning may be in the ABS module.



Master cylinder could do it if the front system was faulty.


ABS module could be a cause also if plugged, faulty, or air locked on the front system.


Plugged front brake lines or "flapped" self plugging flex lines in the front or rear.


Stuck front calipers or pistons.


Air in front system lines or calipers.


The van is 17 years old and you probably don't have maintenance history on it, so might be best to do a complete brake inspection/rebuild to make sure all of it is in top condition. Also a good idea to make sure you have the same brake pad manufacturer and compound on the front and rear, preferably top end semi-metallic material. The brake fluid may even be many years old, even.



Be on the lookout for stuck rubber bushing and bellows as we have seen that they can be an issue if someone used the old oil based brake grease in them that will make them grow and stick. I had done that error based on the tube said it was fine on caliper slides, but it wasn't. An astute member here found that issue which got me to take a look and ours were also bad from the grease.

[tlillard23]

fixed it - Replaced the master cylinder, did a tech2 ABS brake bleed (bleed, abs, bleed)
Front are getting some heat now, Big difference in brake feel.

[booster]

Originally Posted by tlillard23

fixed it - Replaced the master cylinder, did a tech2 ABS brake bleed (bleed, abs, bleed)
Front are getting some heat now, Big difference in brake feel.

Glad you got it fixed relatively easily.


I need to learn how to use the Tech2 that I have for brakes, as I have never done ours when I have changed the brake fluid.

[tlillard23]

the actual tech2 is easy, do a manual bleed, then plug in tech2 it runs the pumps and such, I assume it just cycles fluid out of module, then do manual bleed again.

[booster]

Originally Posted by tlillard23

the actual tech2 is easy, do a manual bleed, then plug in tech2 it runs the pumps and such, I assume it just cycles fluid out of module, then do manual bleed again.

So you are not moving the old fluid that was in the module out by feed and bleed on the system? That is surprising to me.

[tlillard23]

you are correct. the earlier ABS had a more involved bleed procedure. I think bosche figured out people weren't doing it because it was too complicated. So now they are sucking clean fluid (from the first bleed) into the module and let the mechanic flush out the old with the second bleed

service manual says same thing. Running the "ABS bleed" from Tech 2 no wrenches required. just runs the pumps and valves.