Help with vehicle brake problem

[jwstewar]

This is just me reading here and taking a guess w/o actually knowing anything about truly solving the problem /forums/images/graemlins/laugh.gif. Have you checked the tire pressure? If the tires are a little low, the wheel speed sensors could be picking up that this tire is spinning faster than the others and trying to slow it down. Just a thought. At least it doesn't cost you anything to check it out.

 

[bczoom]

</font><font color="blue" class="small">( This is just me reading here and taking a guess w/o actually knowing anything about truly solving the problem /forums/images/graemlins/laugh.gif. Have you checked the tire pressure? If the tires are a little low, the wheel speed sensors could be picking up that this tire is spinning faster than the others and trying to slow it down. Just a thought. At least it doesn't cost you anything to check it out. )</font>

That is a good point. Actually, one of the places I had check the brakes pointed this out (that my tires were a little low). He added some pressure but the problem continued. I will check the TP again. If the one tire does have a slow leak or something... THAT WOULD BE A DANG EASY FIX!!

 

[Rowski]

On the side that you are having the most problem, which pad is cooked? Both the inboard and outboard pad or just one?

 

[bczoom]

Derek,

I'll have to check. I say "cooked" since they've received so much heat they're probably brittle. The pads are new so I may not have an answer until I pull them and put a micrometer on them.

Brian

 

[bczoom]

</font><font color="blue" class="small">( If the tires are a little low, the wheel speed sensors could be picking up that this tire is spinning faster than the others and trying to slow it down.)</font>

I checked the TP last night. I might have a slow leak. The tire I'm having problems with was at 24 psi. The opposite tire is 28 psi.

Now, if one tire has a lower PSI but you get the vehicle to approx. 70+ mph, will the tire with the lower PSI become more elongated (grow taller) due to gravitational force and make the TCS think it's spinning faster and apply pressure?

 

[KAB]

</font><font color="blue" class="small">( Kurt - Re. the pulsating being caused by warped rotors, wouldn't I feel that in the steering and also, wouldn't it be there all the time? Neither occurs.
)</font>

Depends on how bad the rotors are warped. In the car that I drive daily for work (600+miles/wk) they are slightly warped but do not notice it in the steering wheel or braking system most of the time. (yes, they are warped, but I am waiting for aftermarket rotors and pads to become available and figure out when I will have time to replace them.)

On the MB how does the ABS/TC system indicate that it is active? Most cars have some way of notifying the driver that it is being activated.

Somebody mentions about low tire pressure. In GM vehicles that use the ABS system to indicate low tire pressure there needs to be 12lbs of air pressure in 1 tire before it indicates a low tire. So with only a few psi of difference between tire should not cause a problem. (if so it should activate in sharper turns.)


</font><font color="blue" class="small">( First, try to isolate the problem to see if it's TCS/ABS. I'll clean the sensors and see if I can disconnect this option through a switch or fuse or something.

If the problem no longer occurs, it would lead me to believe it's TCS/ABS related and then trace it from the sensors backwards.

If that doesn't work (disconnect TCS/ABS), do a full inspection of the braking system from the pads all the way back to the master cyl. Clean everything along the way. If nothing obvious, replaces hoses and fluid and try again.

)</font>

While I was looking for a way to disconnect ABS/TC I would go ahead with a brake system inspection. This way you could make sure the system is in top notch.


When you removed the old brakes how did the lining wear look? Not inboard/outboard (unless 1 was good and the other was gone, Inconsistant wear here can be expected) but front/rear Top/bottom (per Pad) if this is not even then there is probably an issue with the mounting system.

I would also check for drag while the car is on jack stands.
There should be no drag (you already knew that /forums/images/graemlins/grin.gif).

Is there a traction control button on the dash somewhere?
Depending on the system, it will either turn off the powertrain mgmt, braking, or both parts of TC. Has no affect on ABS.

Try this forum. It looks like they might just have some good people like we have here /forums/images/graemlins/smile.gif : MB Forum

Good Luck

Kurt

 

[reb]

It sounds to me that the slow leak could very likely be your whole problem. The lower pressure would make that tire rotate faster than the others, making the computer think you have a traction problem. It would then apply the brake on that side. What bothers me is that the dealer's techs should know the system well enough to suspect that kind of problem instead of immediately looking at expensive fixes.

 

[bczoom]

Thanks again guys.

Unfortunately, I won't have any time to even look at this for awhile.

I'm going to get the tires fixed first.

 

[Lazy]

Hi
I have a 91 Chevrolet dually and the same thing happened to me. Turned out to be the rubber hose going to the caliper was collapsing and holding pressure in the caliper. I replace both hoses 3 years ago and haven’t had the problem since.

Charlie

 

[cj7]

wew.. this is a trying problem....

my 2 cents to start with is the basics..

some of which have already been mentioned.

tire pressure
clean sliding surfaces - slides etc. be sure to check under any small clips that the pads may rest on.. rust can build up under these and the pad will jam .. not being able to retrack all the way from the surface of the rotor. clean and lube (neversieze) slides and contact points.

Does one pad wear more than the other?
What about the surface of the rotor? Are they all smooth no hot spots or blisters?

beyond would be sensors or some type of computer error regarding traction control or ABS