# brakes



## zaskar (Jun 6, 2005)

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?


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## LC1962 (Oct 6, 2005)

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


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## zaskar (Jun 6, 2005)

LC1962 said:


> Hi Zaskar
> 
> Your RV isn't Ford based by any chance is it?
> 
> ...


Nice one Linda, thanks.
Mines a Chevy based GBM Landau. It happened last year in France and I was able to strip down/clean/rebiuld (nice on the side of the Autoroute!) but now it's happened again I recon it's definately new caliper time! Have checked for a balance or load valve but can't find anything. I'm gonna replace ALL the fluid and see what happens at the peddle.
Fingers crossed!!!!!!!!!!!!


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## des (Aug 13, 2005)

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


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## LC1962 (Oct 6, 2005)

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 :lol: 

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

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


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## zaskar (Jun 6, 2005)

LC1962 said:


> 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


Funny but I've heard loads of people say this (on RV AMERICA as well) but i've never found it to be the case. 
Ok, they're not red hot, but it's a 7 1/2 tonner, not a Ferrari !
Perhaps i just drive slower or break earlier.


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## LC1962 (Oct 6, 2005)

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!) 8O 
I wonder if he's still alive? :?


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## olley (May 1, 2005)

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. :lol: 

Olley


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## zaskar (Jun 6, 2005)

olley said:


> ...........Olley


Nice one mate! Thanks for the info. Pretty much confirmed what I either suspected or hoped for. 
Looks like ffiona's gonna need a new left leg!


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## 88927 (May 10, 2005)

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 8O 8O 8O ), 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 :lol: :lol: :lol:
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 :? :? :? , but as your brakes returned to normal once it had cooled I suspect it is not this but the water issue mate....

Good luck with it and let us know how you get on.....

Keith

Ps, I asked the MOT guy if he thought the brakes on our Rockwood were ok on the tester and he said that once he realised he had to stand on the peddle he managed to lock the wheels, but did agree that a lot of leg power was involved although everything worked well..... maybe Chevy's are like Fords Linda......


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## 97993 (Mar 5, 2006)

The old fashioned way can damage m/cyl seals as the pedal is used when bleeding in places it has not been to before and can turn seals inside out,
do one caliper at a time and clamp off flexi in the normal manner ,when the new caliper is fitted open bleed screw and allow to gravity feed itself, it may take a minuet or two and as you need to change fluid allow it to run for as long as you think is reqd to refresh fluid in the pipe work to that caliper, lock off bleed screw and pressure test, move onto the next one and repeat, you will find gravity bleeding very sucsesfull and so will most of you out there if you ever have to break into fluid lines gravity bleeding is the most reliable ,
having said that on rare ocasions only a pressure bleeder will do
hope this helps 
My apologies to the trade for giving up one of the best kept secrets, but a friend in need and all that *avoid pumping that pedal if at all possible*
Geo


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## LC1962 (Oct 6, 2005)

olley said:


> 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. :lol:
> 
> Olley


Hi Olley

We don't use a pressure bleeder so wouldn't know. JC does the gravity bit as explained by Geo.

Des, I asked about your Chevy brakes and he says he's never driven a Chevy based MH where the brakes haven't been "vague", the 2001 C Class we're currently using is the same - looks like it is how it is.

Incidentally I read some very interesting info on the Ford-trucks.com forum re rear brakes sticking...looks like Ford have known for some time about such problems but failed to act until 2005! I'm trying to find a similar site re Chevy trucks.


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## olley (May 1, 2005)

Hi linda you lot are so behind the times :lol: 

One advantage of a pressure bleeder is that you can completely drain the system down, before replacing with new fluid, and be sure of refilling without trouble.

When I have not had one and I have had to replace brake pipes, it can be an absolute pig to get a pedal. 

Give me air brakes anytime.

Olley


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## LC1962 (Oct 6, 2005)

olley said:


> Hi linda you lot are so behind the times :lol:
> 
> Olley


 :lol: :lol: What do you expect from a man who builds aircooled engines for a living?

We had one when we owned the garage but never bothered to replace it when it wore out...for the amount of times it would get used didn't see the point...there is a lot of choice language when it IS needed though.

Perhaps we'll get a replacement one day.......but I want a new computer first :roll: still running Windows 98 with a hampster at the helm


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## damondunc (Feb 14, 2006)

*RV brakes*

One really common fault on rv's especially chevy's is internally collapsed brake hoses allowing fluid to reach the calipers under pressure but not allowing it to return to the master cylinder when the brakes are released hence giving the impression of seized calipers. If you have a sticking brake jack the offending wheel slightly off the ground and undo the bleed nipple slightly, if you get a jet of fluid and the brake then releases it's almost certainly the brake hose at fault. Ford has most certainly had a problem with overheated fluid some ford calipers have phenolic resin pistons to reduce heat transfer to the brake fluid, be sure to change the brake fluid completely on caliper replacement as recon calipers normally have metal pistons! Cheers Duncan.


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## 100251 (Jul 28, 2006)

*American RV*

Damondunc has described exactly a problem I had with my Chevvy (a P30 chassis)

What a great site this is , with or without a pennant!
Skywriter3 Begat 2 begat 1


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## Steptoe (Nov 8, 2005)

Don't have an RV but as I do most of my own tinkering I have found this a most useful thread, especially Geo's tip about single handed gravity bleeding...Mrs S works nights so it can cause problems when I need some pumping done 8O


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## zaskar (Jun 6, 2005)

Here we go again!!!!!!!!

Off to Scotland on Saturday so I thought I'd take the rig out last night and make sure everything was ok after replacing the rear calipers.
Wouldn't you know it, the fronts have now decided to jam on (should have replaced all 4 - that'll teach me!).  
Pulled into Knutsford services with the front off side dammed near on fire and a VERY worried looking pump attendant! 8O 
Got to shoot off to Canock after lunch for 2 front calipers and fit them before weekend......why does it always go pear shaped just before my holidays! :? 

Dont want to refurbish the 4 old calipers myself but would like to know of a firm which could (dependant on price) rather than just throw them away.
Any ideas guys?


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