brakes Forums

zaskar

Last w/e, when driving home, one (if not both) of the rear calipers stuck on. The wheels didn't lock but due to loss of forward speed, they were obviously jamming on.
Luckily, this happened within 1/2 mile of base site and I managed to limp home. Trouble is, I recon the brake fluid boiled cos I lost peddle altogether!
Also, once we had stopped, I noticed that brake fluid had been forced up through the master cyclinder reservoir which was over-flowing, I presume because of excess pressure in the system due to boiling and expansion at the rear calipers.
I've got 2 new calipers on order (thankfully got a good deal!) but I'm starting to wonder if the fluid being forced back past the master cyclinder rubbers might have damaged them?
Once things cooled off, I had full peddle again within about 1 hour and no pressure warning lights on the dash but i can't help wondering about the master cyclinder rubbers?
Any thoughts?

LC1962

Hi Zaskar

Your RV isn't Ford based by any chance is it?

We had this happen on one of ours and we have heard of at least 3 others...luckily our fluid didn't reach boiling point and James was able to remove the wheels and free the calipers.

He says its highly possible that the rubbers in the MC could have been affected but you won't know without bleeding the system through and testing to see if you can maintain pressure..... he's got me looking into it as to the cause as it seems to be a common fault on Ford trucks (too much of a co-incidence for his liking) He doesn't think its down to the calipers, muttered something about a valve - will report back if I find anything.

Cheers
Linda

zaskar

des

Hi Linda. I have a chevy/workhorse chassis, with truly awful brakes. any thoughts on how to improve? des

LC1962

Hi Des

Seems to follow with Chevy based A class, our Itasca Suncruiser was dreadful....had to virtually stand on the brake pedal to stop it..it eventually went to a body builder with very big leg muscles who didn't find it a problem Laughing

I shall consult the Oracle when he comes in for his lunch.

Zaskar..I will add chevy to the investigation list too

zaskar

LC1962

You'd be amazed how some people drive these things Zaskar, I posted a while back about a customer who bought one of our RVs then had it "chipped" because the rev limiter cut in at 90mph (and he was towing a trailer too!) Shocked

I wonder if he's still alive? Confused

olley · Campsite DB Admin

Hi Zaskar, brake fluid is hydroscopic, it absorbs water/condensation, and its this which boils in old fluid.

It turns to steam and you loose your pedal completely, after its cooled down its turns back to water and you get your pedal back.

The master cylinder allows fluid to return back to the reservoir when you release the pedal, so the steam pressure could easily have pushed the fluid over the top, I think it unlikely that the seals are damaged.

I would advise changing your brake fluid, the best way is a pressure bleeder but I have been told that you can't get one with an adaptor to fit the top of RV reservoirs, maybe Linda can confirm this? failing that its the old fashioned way. Laughing

Olley

zaskar

kands · Account Deactivated

Hi zaskar
I would agree with Olley about the water in the fluid. I had it happen in a RR car once, totally lost pedal (and RR use two completely independent braking systems to supply fluid to each of the four wheels Shocked

), but if the water finds its way to the caliper end, which it does, then the problem you described will manifest itself mate. Before changing calipers I would give it a complete change of fluid and look to see what comes out, I bet you see some foreign matter in there, and then give the RV a good test. Maybe a short drive out to Huntingdon on Friday will do the trick Laughing

The other brake issue with RR was that the flexible pipes used to break down internally and then little "flaps" of rubber would act as non return valves and the rear (usually) brakes would slowly lock on.... They then go on to cause a fire it not spotted soon enough