Another Brake Failure and ABS controller cooling...

[ninerguru]

First of all, I want to thank all contributors to this forum. It is invaluable to be able to share problem and solutions on our beloved coaches.

Ever since we purchased our 2003 HR Admiral SE in May of this year, I have been following with great detail and angst, the problems that seem to be inherent to the W2x WH chassis family and hoping that it would not happen to our coach.

Coming home on Sunday, Sept. 14, the dreaded smell of burnt brake linings permeated the inside of the MH. We had been traveling for about 1 hr and 10 minutes and had stopped at a campground about 1/2 hr from the house to dump our tanks. It took about 10 minutes to dump the tanks and we were on the road with about 25 minutes left to go. The smell started after we restarted our trip from the campground.

After getting home, the pedal had gone soft, telling me I had boiled over the fluid. We were towing my track car on an Al trailer with 4 wheel electric brakes. MH has about 15K miles and runs like a top and well within the GCWR.

I had seen this post before Okay-- Where is the ABS? and I started thinking if heat had anything to do with my problem.

We had stopped for about 10 minutes after running for a while and I wonder if the proximity of the exhaust to the ABS controller could have heat soaked it and send it into "cardiac shock"

Since air is free, and having a spare length of 2" brake cooling hose from my track car, I decided to force feed some cool air to the ABS controller. I made a strap of sheetmetal to hold the front of the hose against a panel under the chassis and then gently bent the hose and tie-wrapped it to flow air to the top of the controller. Added a screen to keep junk out.

I don't know if this will help, but it certainly can't hurt. I know that electronic components like to remain cool and perhaps a slight raise in temperature could send the controller into failure mode...

I have a couple of pictures that I like to post but it seems I don't have permission to create an album. Could any one help?

I have also reported the problem to the NHTSA, figured that if enough of us report them, they will eventually have to do something.

Please let me know if you need additional info on the problem. I now need to inspect brakes and change brake fluid. BTW, we usually change brake fluid on our track car at least 2x/year. It is a cheap, but critical part of regular maintenance.

Lou

[ninerguru]

First of all, I want to thank all contributors to this forum. It is invaluable to be able to share problem and solutions on our beloved coaches.

Ever since we purchased our 2003 HR Admiral SE in May of this year, I have been following with great detail and angst, the problems that seem to be inherent to the W2x WH chassis family and hoping that it would not happen to our coach.

Coming home on Sunday, Sept. 14, the dreaded smell of burnt brake linings permeated the inside of the MH. We had been traveling for about 1 hr and 10 minutes and had stopped at a campground about 1/2 hr from the house to dump our tanks. It took about 10 minutes to dump the tanks and we were on the road with about 25 minutes left to go. The smell started after we restarted our trip from the campground.

After getting home, the pedal had gone soft, telling me I had boiled over the fluid. We were towing my track car on an Al trailer with 4 wheel electric brakes. MH has about 15K miles and runs like a top and well within the GCWR.

I had seen this post before Okay-- Where is the ABS? and I started thinking if heat had anything to do with my problem.

We had stopped for about 10 minutes after running for a while and I wonder if the proximity of the exhaust to the ABS controller could have heat soaked it and send it into "cardiac shock"

Since air is free, and having a spare length of 2" brake cooling hose from my track car, I decided to force feed some cool air to the ABS controller. I made a strap of sheetmetal to hold the front of the hose against a panel under the chassis and then gently bent the hose and tie-wrapped it to flow air to the top of the controller. Added a screen to keep junk out.

I don't know if this will help, but it certainly can't hurt. I know that electronic components like to remain cool and perhaps a slight raise in temperature could send the controller into failure mode...

I have a couple of pictures that I like to post but it seems I don't have permission to create an album. Could any one help?

I have also reported the problem to the NHTSA, figured that if enough of us report them, they will eventually have to do something.

Please let me know if you need additional info on the problem. I now need to inspect brakes and change brake fluid. BTW, we usually change brake fluid on our track car at least 2x/year. It is a cheap, but critical part of regular maintenance.

Lou

[Max Hubrich]

Hi Lou,

Sounds like a neat plan to me--

To post pictures please "Go Here". Monoco Momma will help if you still have problems, just send her a note (PM-private message). I finally got the hang of it after a long period of frustration.

Welcome to this forum, you'll love it!!

[ninerguru]

Thanks to Duner for pointing me to Photobucket. As I mentioned in my previous post, I made a forced air feed to the top of the ABS controller. I also elevated the steel plate that was laying on top of it to allow air flow, and bent down the OEM integrated air scoop in the heat shield to catch some more air.

I got a couple of additional ideas... Wire up a small 12v fan to be activated when the engine cooling fans go on, like when sitting in traffic. Also, car racing supplies carry an exhaust pipe wrap specifically made to keep the exhaust heat in the pipes. Since the exhaust runs so close to the controller, might be worth the $15 in insulation... Lou

[Thudman]

DriVer:

Where is the ABS controller on our 38G?

Thudman

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Thudman:
Where is the ABS controller on our 38G? </div></BLOCKQUOTE>Thudman, I believe you're looking at it in the picture above. The W20 and W22 are basically the same in this regard.

I haven't had any problems with the ABS other than with one sensor which was accidentally damaged I believe when I had my exhaust manifold gasket replaced. There wasn't any evidence that the sensors all needed replacing however I wanted a matching set so I had them all replaced.

My ABS is working great and the IP's ABS lamp is off.

[Duner]

Hey Lou, maybe you could use one of these vent adapters as a scoop....thy're only $5 here.

Glad you got those pic's posted!

[Brake-less]

Great pics. Thanks nineguru. A thought to ponder...... The control module and brake lines sure are close to that hot exhaust.

Doesn't fluid expand when heated?

Could this expansion put pressure toward the calipers and back to the master cylinder? (Einstein's action-reaction principle)

Could all this additional heat promote more moisture / condensation in the fluid?

[drrags]

Just checking in to see if you've put any more miles on your rig since this modification and have or had not any issues, or anything to report. I like your logic and I'm going to do the same mod.

[ninerguru]

Drrags, we did go out with our motor home in October to a local campground. Brakes seemed to work OK with no binding or smell of burning linings. But it could have been a combination of replacing my brake fluid after my failure. Time will tell... And perhaps, by the time I'm ready to get MH out of mothballs next Spring, a solution could be announced to resolve the caliper issue once and for all...

On a side note, my brother in law is a machinist. I've been tinkering with the idea of asking to see if anyone would had a spare set of front and rear old calipers in order to have pistons measured and duplicated in steel or aluminum to replace the metal/phenolic units that seem to be causing problems. Once you dimension the part in a numerical control machine, it should be easy to reproduce in large quantities. As I recall, I read that Chrysler had similar problems with phenolic pistons in the 70's.

Replacement should be straight forward. Remove the caliper, pop the old ones out, pop the new ones in. Bleed brakes and hope that it solves the problem. It is basically rebuilding the caliper using new pistons.

This would be much cheaper that replacing the whole caliper. But I bet OEM suppliers would choose to replace the whole caliper just because... Remember, you only need 4 pistons, and as the majority of failures have been taking place on coaches with relatively, low mileage &lt;30K miles, the piston seals could certainly be reused.

I wondered why no one has thought of this before. Braking systems are relatively simple and they are a know quantity. Basic hydraulic technology has not changed, but has been improved with ABS, disc brakes, etc.

It is common to rebuild master cylinders, calipers and brake wheel cylinders as long as the parts are available.

Something to think about... Lou

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ninerguru:
I wondered why no one has thought of this before. </div></BLOCKQUOTE>Lou, I wouldn't be so sure about that. If it's out there it's been thought about.

Implementing the design change and getting the vehicle back on the road so it meets DOT requirements is going to be in my opinion expensive.

Dale wrote about R&R'ing steel pistons on a Vette back in the day a few month ago.

[drrags]

Agreed, Lou. The caliper assembly is low-tech and is easily understood and easy to rebuild. I've machined new pistons myself for a neglected motorcycle. I too, would love to get my hands on an old caliper and have a look. Sadly, I don't have my machine shop anymore, but I still have my measuring tools. And hey, I still have machinist friends! :-)

Why shops don't do this is probably because it's simply not worth a line mechanics time to rebuild a caliper, and then also take on the responsibility and liability of a job well done. It should be assumed that the OEM is consistant in its mass-production. I mean, for example, *I* would certainly rebuild my calipers, but I wouldn't want to take the risk to rebuild someone else's.

[hawg6]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by drrags:
Agreed, Lou. The caliper assembly is low-tech and is easily understood and easy to rebuild. I've machined new pistons myself for a neglected motorcycle. I too, would love to get my hands on an old caliper and have a look. Sadly, I don't have my machine shop anymore, but I still have my measuring tools. And hey, I still have machinist friends! :-)

Why shops don't do this is probably because it's simply not worth a line mechanics time to rebuild a caliper, and then also take on the responsibility and liability of a job well done. It should be assumed that the OEM is consistant in its mass-production. I mean, for example, *I* would certainly rebuild my calipers, but I wouldn't want to take the risk to rebuild someone else's. </div></BLOCKQUOTE>There are rebuilt calipers available to replace the Bosch calipers. I replaced all four of the calipers on my MH, after two failures. The truck service center that sold me the calipers said they no longer sell or install rebuilt calipers for this Bosch design. The same parts are used on International trucks and although the service center had not installed calipers on a MH, they said the rebuilt calipers were "junk". They also said Bosch will regret the day they introduced this system, based the new caliper failures. Assume the parts I purchased are the same as the parts I took off the MH. Usually the manufactured will introduce a prefix or suffix I indicate a change in the part, but I was told the part number had not changed. Did read where the coating on the calipers has changed, but that is external. Time will tell what needs to be done to make the brakes safe? Until then we need to do the maintenance suggested by Driver.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by hawg6:
They also said Bosch will regret the day they introduced this system, based the new caliper failures .... Time will tell what needs to be done to make the brakes safe? </div></BLOCKQUOTE>hawg6, This is a very lucid understanding of what the problem is. Getting the government on board to force a solution is what we are expecting to happen soon. I just wish it would happen sooner.