During the Workhorse Homecoming Rally I had the opportunity to speak with several folks from Workhorse about the Brake Recall and caliper issues. Let me tell you all right now IF YOU AREN'T USING BRAKES ON YOUR TOAD YOU WILL PAY. The number 1 problem with RV brake failures is caused by not having supplemental brakes on your tow car. It may stop with the RV brake but a lot of heat is being generated under there.
These guys can look at a rotor, caliper or brake pad and it will tell them what happened. Even the color on the rotors is considered. I saw plenty of pictures of rotors, calipers and pads and these guys know what to look for.
The brake issue has been discussed and finally I fully understand what is happening. I couldn't put my finger on why the problem has been intermittent. The Bosch calipers used on the w 20 and w22 chassis have a problem. The calipers have two 66 mm pistons in each one that pushes the brake pads and slides the calipers to brake the coach. Read what a caliper is and how it works here:
Shop manual for automotive brake systems - Google Books
The pistons in the problem calipers are made of phenolic "Bakelite" material. I'll call it "p". This material is used because it does not transfer heat from the pads to the brake fluid in the caliper as much as metal pistons. On heavy vehicles this helps prevent boiling the brake fluid.
The phenolic pistons fit tight in the bore. There are millions of cars, trucks, busses and RVs using this type caliper. Unfortunately the p pistons are subject to swelling due to water absorption. These pistons are used on many cars and trucks with no problems because the vehicles are driven daily and the brakes are heated up more often thereby boiling some of the water out of the fluid. Brake fluid is formulated so it can absorb the water getting into the system.This also helps keep deposits/corrosion off the caliper pistons. Unfortunately the water in the fluid will drastically reduce the brake fluid boiling point. Daily, or weekly use helps prevent corrosion on the caliper slides and guide pins.
RVs are not driven every day. Some sit for months without being moved. As they sit the brake fluid absorbs moisture from the air right through the brake lines and seals. The water settles to the lowest point, the calipers. We're not talking about large amounts of water here. Very small amounts. If the calipers aren't heated from driving and braking the fluid starts to separate. The water is absorbed by the p pistons and they expand. When you are dealing with only .003 clearance between the piston and caliper bore a little swelling can go a long way. When we drive a vehicle with old brake fluid that fluid contains water and those pistons are going to swell.
Then we get in and drive through our city and we brake a lot. The heat from braking causes more swelling of the caliper piston. When the piston doesn't release it is due to the swelling. When it cools down, the swelling goes down some and the pistons release. You may not have the problem again on that caliper for thousands of miles.
The caliper has to slide in order for both brake pads to put equal pressure on both sides of the the brake rotor. The caliper slides on slides guided by pins. The slides and pins require lubrication, especially on a RV that sits for months without being driven. If the caliper isn't used for a long period of time the surface of the caliper slide corrodes. If the pins are not lubricated they also corrode. Combine swollen caliper pistons and corroded pins and slides and you have "sticking calipers".
There have been a significant number of problems with these calipers on Workhorse w20 and w22 chassis. It is a sporadic event. It usually involves only one wheel at a time. If you use your RV a lot you are not as likely to have any problem. If you live in a hot dry climate you are not as likely to have trouble. If you flush your brake fluid and replace with fresh DOT III fluid you are not as likely to have trouble. I recommend Ford DOT III high performance or Raybestos Super Stop fluid. Never put DOT 4 or 5 or any synthetic fluid in Workhorse brakes.
If you never change your brake fluid, park for long periods of time, have no brakes on your toad and live in a damp climate you are heading down a slippery slope.
Workhorse recently sent out letters to "REGISTERED OWNERS" of W20 and W22 chassis alerting them to watch for signs of sticking calipers. If you are not registered as the "current owner" of your chassis you need to get on the Workhorse web page and change the owner to you. Dealers are suppose to do this for you but not all dealers do it for you.
PRODUCTS Several people at this rally were not registered as the owners. Workhorse checked rally attendance information with the owner database.
There is a recall that will be implemented in the fall. They are going to bring in "every w20 and w22 chassis" regardless of the year they were made and replace all 4 calipers. Yes I know it says through 2007 but they are still installing the same old style calipers on the chassis today because they don't have the new caliper parts. I saw it today at the factory and talked with the engineer. You guys with the later model chassis aren't likely to have any issue because your fluid is fresh and the calipers lubricated but you will need to have the calipers replaced once the recall is initiated. As of today the recall is on over 49,000 RVs.
The new calipers will have metal pistons. They are currently negotiating with someone to have the new pistons made. The new, or refurbished calipers, will have the metal pistons.
IF there is damage to your rotors or your ABS sensors due to caliper failure Workhorse will replace those as well at their cost. You are thinking, "hey this will be a great thing because I'll get new brakes free". Nope. If they inspect your old calipers and determine they have failed and caused damage to a rotor or ABS sensor you will get those replace free. If you simply have cracked rotors and your calipers have not failed you will pay for the rotors and pads. Their thinking is that this damage could have been done by riding the brakes. If your caliper pins and slides are badly corroded and haven't been properly lubricated you are responsible. They can look at the calipers and identify if there is a caliper failure issue. The caliper will have a white residue on the piston seals. There will have be scuffed walls in the caliper bore or the pistons. The rotor will have signs of metal transfer from the pads being stuck to the rotors if the calipers have been sticking. You will get free calipers with the recall but the rest is subject to the determination of whether the old caliper has failed.
Workhorse has a team sitting in the factory right now looking at the thousands of claims already filed by folks saying their calipers failed causing damage to their brakes. They aren't just saying they will refund money spent if you have a brake issue. It has to be found that a caliper failure caused the problem.
Many folks are out here on Workhorse chassis and have never had a brake problem. The issues I mentioned are the ones that make a difference.
Workhorse is telling folks that if you have a brake caliper hang up. Stop. Let the caliper cool down. Once it cools the piston will release and you can drive on. IF the caliper fails to release call the Workhorse roadside assistance number on the letter. They are advising people to follow the instructions on the letter they sent out:
http://nhthqnwws111.odi.nhtsa.dot.go...9V225-8575.pdf
It is critical that we all pay attention to the warning signs in the letter to be safe.
Hope this helps some of you.
Jerry Newberry
Brake recall
Linear Mode
