84Toyota4x4
Well-Known Member
I haven't had to do too much with hydro boost brakes before since I have never owned anything that has had them, nor did any of the shops I worked at service vehicles that would have had them. That said, my fiancee's family has a 32' GM chassis motorhome (mid 90s with about 20K miles on it) that I did some brake work on in the past which is supposedly giving them problems, so if you guys could lend a little insight, I would appreciate it.
The story goes like this. A few years ago someone wanted to take it over the pass and when they were getting ready to leave, it had a stuck front caliper from sitting. I got under there and got the caliper moving well enough so they could drive it on that trip. It went over and came back with no other problems, but then it sat for another year or so.
The next time someone planned to take it, remembering it had problems last time that were only "patch repaired", they decided to test drive it first. It again had problems with the front calipers sticking. I was then recruited to put new brakes on it. I got calipers, pads, and rotors from Napa, all "heavy duty" grade stuff for the proper chassis code (which slips my mind now). I repacked the front wheel bearings, slapped the new parts on, put fresh fluid in the master, and bled the front calipers until I saw good clean fluid coming out.
After that, I test drove it about 10 miles and had no problems. It was then taken on a trip to eastern WA up and over the pass with no issues at all both ways. A few months down the road, it was taken on another trip (different driver from the first two eastern WA trips) up north with no problems, but about 1 mile from home on the way back, the driver started noticing a problem with the brake pedal "feeling soft". He gets it almost all the way home and says the pedal "went to the floor" as he was pulling into the driveway and he "almost couldn't stop", but he was able to "pump the brakes to get it to stop". He also claims it felt like the front brakes weren't working at all.
I went out to look at it and didn't see any signs of leaking, both PS and brake fluids were full, etc. I hopped in and the pedal felt fine with the engine off, I started the engine and the pedal still felt fine. I drove it in the driveway and the pedal felt fine, it stopped fine, etc. I drove it forward and used just the parking brake to stop it, then the pedal, and there was a noticeable difference in how it stopped which to me says the front brakes were working fine. I then took it out on the street, drove it around for 15 miles or so up and down hills and used the brakes more than I would typically driving it, and every time I hit the brakes, the pedal felt fine, no pulling, etc. In fact, I even got the ABS to come on at one point going downhill and slamming on the brakes.
Now then, my only theory about this is that the driver was just too heavy on the brakes in traffic, they got hot, and he was experiencing brake fade from the heat. He did say they were in stop and go traffic all the way down 9 when they came home, and that they took the semi twisty back roads from 9 the rest of the way to their house. I asked him if it was possible they were just too hot, but he insists there is a problem with the brakes and some kind of failure. I recommended he take it to a shop since I couldn't see or replicate a problem with it, but I'm wondering if there is anything else I can do in the mean time. It seems odd that the problem would come and go, and it's awful coincidental that he had been driving it in "harsh" conditions before the issue arose as well.
So, what are your thoughts? Could it have just been brake fade from stop and go? Could it have some kind of intermittent internal failure? I got to thinking about it again since I was considering taking it out for a weekend trip, but I want to be sure I have looked over everything and I can say with a little more certainty what exactly happened.
~T.J.
PS - Sorry for the long-ass post...
The story goes like this. A few years ago someone wanted to take it over the pass and when they were getting ready to leave, it had a stuck front caliper from sitting. I got under there and got the caliper moving well enough so they could drive it on that trip. It went over and came back with no other problems, but then it sat for another year or so.
The next time someone planned to take it, remembering it had problems last time that were only "patch repaired", they decided to test drive it first. It again had problems with the front calipers sticking. I was then recruited to put new brakes on it. I got calipers, pads, and rotors from Napa, all "heavy duty" grade stuff for the proper chassis code (which slips my mind now). I repacked the front wheel bearings, slapped the new parts on, put fresh fluid in the master, and bled the front calipers until I saw good clean fluid coming out.
After that, I test drove it about 10 miles and had no problems. It was then taken on a trip to eastern WA up and over the pass with no issues at all both ways. A few months down the road, it was taken on another trip (different driver from the first two eastern WA trips) up north with no problems, but about 1 mile from home on the way back, the driver started noticing a problem with the brake pedal "feeling soft". He gets it almost all the way home and says the pedal "went to the floor" as he was pulling into the driveway and he "almost couldn't stop", but he was able to "pump the brakes to get it to stop". He also claims it felt like the front brakes weren't working at all.
I went out to look at it and didn't see any signs of leaking, both PS and brake fluids were full, etc. I hopped in and the pedal felt fine with the engine off, I started the engine and the pedal still felt fine. I drove it in the driveway and the pedal felt fine, it stopped fine, etc. I drove it forward and used just the parking brake to stop it, then the pedal, and there was a noticeable difference in how it stopped which to me says the front brakes were working fine. I then took it out on the street, drove it around for 15 miles or so up and down hills and used the brakes more than I would typically driving it, and every time I hit the brakes, the pedal felt fine, no pulling, etc. In fact, I even got the ABS to come on at one point going downhill and slamming on the brakes.
Now then, my only theory about this is that the driver was just too heavy on the brakes in traffic, they got hot, and he was experiencing brake fade from the heat. He did say they were in stop and go traffic all the way down 9 when they came home, and that they took the semi twisty back roads from 9 the rest of the way to their house. I asked him if it was possible they were just too hot, but he insists there is a problem with the brakes and some kind of failure. I recommended he take it to a shop since I couldn't see or replicate a problem with it, but I'm wondering if there is anything else I can do in the mean time. It seems odd that the problem would come and go, and it's awful coincidental that he had been driving it in "harsh" conditions before the issue arose as well.
So, what are your thoughts? Could it have just been brake fade from stop and go? Could it have some kind of intermittent internal failure? I got to thinking about it again since I was considering taking it out for a weekend trip, but I want to be sure I have looked over everything and I can say with a little more certainty what exactly happened.
~T.J.
PS - Sorry for the long-ass post...
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