We've just returned from a trip in our truck. We were stuck in a traffic back-up of 8-10 miles caused by an accident on the Interstate. The traffic was just crawling along at 5-8 mph with it being constant stop and go. After fifteen or twenty minutes, we noticed a scraping sound which was speed dependent, the faster we went the more times it occurred. It sounded like a pad dragging on the rotor disc each time it went by. It sounded like the rotor disc had a raised section on it.

My estimation of the problem was the rotor disc brake was becoming over-heated and expanded from all of the on/off application of the brakes because of the slow crawling traffic. This expanded a section of the rotor disc which was then rubbing on the brake pad each revolution, causing the scraping sound. After we were getting close to the scene of the accident, the truck started pulling to the left when the brakes were applied. I assumed this was because the rotor discs had become much hotter (expanding more) and were now having trouble passing thru the pads. Once we got by the accident and back up to Interstate speeds, all of the scrapping and pulling to the left disappeared. I assumed the rotor discs had cooled off enough to contract back to their normal size.

After several hours of driving, we were again caught in another traffic jam and we had to crawl along at a very slow speed, using the brakes all of the time. Again the same thing happened: the speed dependent scrapping sound followed, this time a pulling to the right when the brakes were applied. After getting out of the traffic and back up to highway speed, all of the problems went away.

Now my question is, can this be something easily repaired? I had the left front caliper replace about two months ago because the pad was dragging on the rotor disc and causing large quantities of red dust on the rim of the wheel. The caliper replacement fix, stopped the red dust from forming on the left front rim. I'm sure the dealer will want to replace both front or all four calipers and maybe even all four rotor discs to "fix the problem". (Because of age and health problems, I can no longer work on my own vehicles and must depend upon others to do the work.) Since it only occurs when stop and go driving is done, could it be something one "can live with" or would the excess heat cause other problems in the truck? Appreciate any thoughts, wisdom, in-sights into this problem. Thanks.

Bill

 

breaks are nothing to take risks with...

rule one when replacing a caliper.. do it in pairs.. with new pads.. and turn the rotors.. or replace them.

sounds like rotors may already to thin...
slide pins dirty/rusty/sticking.
slow driving/breaking generally do not make a great deal of heat .. if working correctly.

when the 1 caliper was replaced.. was ALL the brake lines bleed? or only One?
was both front brake pads (sets) replaced as a set... ?

 

As far as I know, only the single caliper was replaced. There was no mention made of pad replacement nor work on the rotors (turning them). I don't think any lines were bleed as it wasn't a line item on the bill. The four wheel rims were so hot that I couldn't touch them even after we had reached our destination.

 

replacing a caliper requires at lease one line bleed.... so they did not report it on the bill.. or all 4 were bleed.

all brakes were hot..... but just going down a 200 foot hill can get things Hot...

dirt/stuff in brake lines... full bleed should be done ... then a master cylinder check ..
it is possible for dirt/stuff to restrict fluid to return to master cylinder. causing a continuous drag on the brake system. but mainly the fronts... as they do 70 percent of the stopping.

just a guess here.

 

Sounds like one or both the calipers are hanging up, not floating on their pins. I would just do a full brake job if at all possible.

 

crawling along at low speed [sub 10 mph] isn't going to put much heat into your brakes, there's just not that much energy to dissipate.

I would probably look at the caliper bolts [the ones that the caliper slides on], that they are hanging up [or the caliper itself is].

 

I am in agreement that stop-and-go driving at 5 to 8 mph is not going to generate a whole lot of heat. Certainly not enough to expand or warp a rotor.