Another Lost Brakes Thread

[diceman1530]

I have a 1999 36fds alpine and experinced total brake loss this weekend.When I checked the right front rotor was around 460 degrees f with my temp gun.I never have boiled brake fluid before,will it just evaporate when it gets that hot?The master cylinder was dry.After it cooled I put about 1/2 quart brake fluid in and seem to have a pedal but dont trust it so I am having it towed.My vin was not in the recall but only missed buy a few numbers.Does any body know the part numbers for the replacement calipers and a possible source and cost.It looks like the right front and left rear calipers may have bin sticking.I climbed all around under the coach a could not find a leak anywhere.
Thanks Ray Fordyce 8/30/2009

[EngineerMike]

When was last time you checked the fluid level? Sounds like you may have been low. Likewise, when was last pin slide lube on your brake calipers? That's a biannual or more frequent chore IIRC.

You'll need a full brake bleed with fresh Dot3. And IIWM I'd do a full 4 wheel-off brake inspection before doing the bleed. Sounds like that 460 degree wheel needs new bearings & bearing pack as well, probably melted the ABS sensor, and depending on what you find maybe a new rotor.

Check on the caliper pistons (internal to the caliper assembly) that may be used for your repair. There is a recall in process on all pin-slide Bosch brakes on Workhorse & some other brand chassis' for at least the last 8 years that contain a Bakelite coated piston. The Bakelite coating was used to minimize heat transfer to other parts of the assembly; however, NHTSA has found that the Bakelite will absorb water from the brake fluid and swell up when heated. That causes the piston to stick in the bore, overheating the brake, causing brake drag, possibly boiling brake fluid, blah, blah, blah. Bosch has a new caliper in manufacture to replace all 4 corners on about 49,000 motorhomes. I don't know if it will be useful, but you may want to contact Bosch for further info (click on Contact & choose a division to start). If your calipers have these pistons you might want to have them changed out for the new design when it becomes available late this year (probably November or so).

[jerry davis]

EM,

I have never lubricated my brake caliper pins.

What is the preferred lubricant and do you have to take any part of the braking system apart to do a thorough lube of the pins? Would an aerosol spray lube work adequately?

[diceman1530]

anyone have part number for the abs sensors

[EngineerMike]

Jerry- You have the Meritor 4-piston brakes, not the Bosch pin-slide two-piston calipers.

All- The pin slide lube is a wheel-off job. There are instructions on the Bosch website, and (probably more easily found on) the upper "sticky" threads on the Workhorse forum here on iRV2. I should probably steal same for the Tech Library. The doc describes lube req'd as well as whole process.

I can't vouch for the years covered, but there is a Brake Parts List on the ACA Tech Library page under Chassis & Brakes that shows Bosch caliper rebuild parts numbers as well as brake pads, rotors, bearings, ABS sensors, etc. It's a copy of a fax from WRV sent to an Alpine owner for dealing w/a brake issue.

[Dave Fernandez]

WRV changed from the Pin Slider Calibers to a fixed Caliber during the 2000 to 2001 model year change. My 2001 was manufactured in late 2000 and it has the fixed caliber.

I helped one my friends with a 2000 Alpine to service the pin sliders and we were able to lube them without removing the wheels. It took a little time about 4 hours but saved us from the back braking work of R&Ring the wheels. I think the next time we lube them it will take about 2 hours now that we have preformed this procedure at least once.

[EngineerMike]

Dave- do you know what make & model the fixed calipers are (Bosch, Meritor, etc.)? And if Bosch, do you know if the pistons are the Bakelite coated gems? We should get info on those for the Library.

Boy howdy, if someone would write up a process for wheels-on pin-slide lube, it could go on in Tech Library and save hundreds of hours of future service labor and dozens of lives and probably a few marriages.

Here is the Bosch Pin Slide Brake Manual link. I'll get this stored to the Tech Library for better availability 30 years from now.

[EngineerMike]

The only truck disc brakes I find on the Bosch website are the Zero Offset Harmonized-Truck pin-slide disc design; they have the phenolic or Bakelite coated pistons that are the subject of the massive Workhorse recall on Bosch ZOPS and ZOHT pin slide calipers. These ZOHT calipers may have been replacement calipers for the original Bosch Zero Offset Pin-Slide calipers used after the original ZOP-S recall for pin sticking issues and before WRV's switch to a different brake. The 2001 model year Alpine brochure shows Meritor 4-piston (fixed caliper) brakes, which have been used on Alpines ever after, and have solid metal pistons.

Based on the above quickie research, I'd say that any pin-slide brakes on Alpines 1997-2000 are Bosch, wither ZOPS or ZOHT, and have the "phenolic" pistons that are subject to swelling and sticking, thereby overheating a wheel. The symptoms of the recall failure are remarkably similar to Ray's original post above with wheel overheating up to a possible point of "wheel end fire."

If I had a pre-Meritor brake chassis, I'd check w/Bosch on the status of new caliper availability curing the phenolic piston freeze up problems. Perhaps they will have piston rebuild kits, new calipers w/properly designed pistons, etc. Whether there will be recall coverage is anybody's guess.

In the mean time, the biggest enemy of the phenolic piston is water in the brake fluid, which the phenolic absorbs agravating piston sticking. To minimize this- change your brake fluid often. IIWM w/those plastic coated pistons, I'd attend to full brake fluid changes every 6 months regardless starting as soon as I could get the fluid changed. Its cheap.

[woodyk]

Here is the new lubricant that Prattville RV used on my caliber slide pins--it's a clear 3 M silicone paste PN#051135-08906--it's not cheap!!

Woody

[EngineerMike]

Woody- is this the stuff?

You can find it online googling 3M Silicone Paste

[Dave Fernandez]

I used a Permatex Ultra Disc Brake Caliper Lube Hi-Temp Silicone, when we lubed the Pin Sliders on the 2000 Alpine.

http://www.permatex.com/products/Aut...ne_Formula.htm

[woodyk]

That's the stuff---how much was it on line?--Prattville RV said it cost a pretty penny for them.

Woody

Originally Posted by EngineerMike

Woody- is this the stuff?

You can find it online googling 3M Silicone Paste

[EngineerMike]

costs from $15 pre tax & delivery to $24.

I didn't read the Pin Slide manual to see if they prescribe a "special" lube, might want to take a look if this applies to you. The pictures make it look silvery when applied. (I did look at the pictures, typical engineer)

[diceman1530]

Getting towed from maryland to nj xxx dollars
4 new rotors xxx dollars
4 new calipers xxx dollars
4 new abs sensors xxx dollars
2 sets brake pads xxx dollars
4 new wheel seals xxx dollars
labor for all the above xxx dollars
DRIVING A ALPINE COACH PRICELESS!!!!!! LOL
well at least I am back on the road again,that was until the driver side wiper broke on the last trip
does it ever end ?