Parking Brake…

Parking Brake…Dec. 2014

Stayed in a RV park in Orlando, Florida that was to far away from any stores to walk or bike, so I’d have to drive my RV once every two weeks to a couple stores to accomplish my necessary shopping. On one of those trips, I parked where I usually do, put the shift lever into park, let up on the brake pedal and the rig started rolling. Damn. Checked the P-B lamp on the dash, and it’s dark. Repeatedly bang the shift lever into P-B position and…nothing. So, have a new parking brake issue. It’s not like the last issue (see below) where the P-B would apply while the shift lever was in drive or something, this time it would just not apply. I now know enough about this system that I expected I could figure out what was wrong on my own so in my spare time, when I was bored, I’d look at it underneath the rig once in a while. And since it wasn’t an emergency, I would just park judiciously until it’s fixed, I wasn’t in much of a hurry. Only needed to chock the wheels at the RV park.

Before I really got to work on it much there came the day I fell off my bike and injured my shoulder and hip. Threw my back out too. Now it was difficult for me to climb under the rig because it’s on very soft sand so I can’t use a creeper and the shoulder prevented doing the military crawl. And I quickly discovered that my shoulder won’t allow me to do much overhead work under there either. But the looking around I did do showed that there wasn’t a fluid leak (it’s a hydraulic system), the brake shoe and assembly looked fine, the cable was connected, etc. Also, the valve that actuates the brake is very reliable and was just replaced three years ago or so. So, not finding anything on my own I set about trying to find someone to fix it since I couldn’t with my bad shoulder. Called a couple places but their comments about the problem didn’t give me a feeling of confidence in their knowledge. Asked around the RV park and didn’t get much help there. One guy someone said was the guy did stop by but he was outta there as soon as I told him it’s a diesel RV with a Bendix hydraulic brake system. There are tons of Chevy chassis’ out there with a very poorly designed P-B system that fail all the time, mine isn’t like that, but the Chevy system is all he knew.

Finally, got a recommendation for a shop north of Orlando. Called them up, checked them out, and they sounded great. Paul’s Auto and Truck Repair. Didn’t take the tech long to discover that the clamp holding the heavy armored and sheathed cable up near the shift lever was loose. Allowing the cable assembly to move when I shifted into P-B. It must stay clamped to actuate the P-B valve. Once it was clamped down solid, the P-B worked fine. Whew. Glad I got that fixed. And for under $100 it was worth it.

But the repair didn’t hold long. The next several days, I drove from Orlando to Van Horn Texas and it worked fine along the way a number of times, but failed in a McD’s parking lot in Van Horn just after I arrived. Shoot. Since I planned on staying there for a few days, I asked around and found a hydraulic mechanic, just sorta bumped into him at a thrift shop while I was jawin’ with the owner. The guy was right there visiting. He came over to the park and basically found the problem in 15 minutes. Same as at the shop in Florida…cable had come loose from its cable clamp. My shoulder was still holding me back so I was happy to pay the guy to fix it again. He really reefed on the clamp screws this time and I hope it works longer. But soon I’ll be able to reclamp it myself anyway so I won’t have to pay anyone. I think it might need a shim plate to change the angle the cable now has. You can kind of see where it’s straining a bit when you take it out of P-B and put it in Drive and visa versa. Wiggles a bit too much…which is causing the clamp screws to loosen up. I’ll take a look here soon and try to come up with a backyard mechanics fix for it.

In this picture you can see the black P-B cable held onto the bracket with a two bolt half pipe clamp. That’s where it’s been loosening. You can see the slot in the clamp. There’s a matching embossment that’s part of the cable and it suppose to keep it fixed in place. That long silver metallic part is what you can see moving erratically when you shift. That’s what I think is causing the clamp to loosen up.


Parking Brake…Sept. 2011

This is a reprise from the travel section of my blog but I thought it is good background for the parking brake (PB) problem.

The first day (after leaving Fairbanks, AK) we made it all the way to Haines Junction, Canada. Two three hours before there, we check through the border station and around five miles after that I’m smelling something burning up in the cab of the bus. So we sniff around awhile and then I notice that the parking brake light is on. Ahh, brake pads for the parking brake are burning and the smell is getting sucked up into the cab. So I down shift from drive to 2nd, the light goes out, up shift to drive and for several miles it stays out. Then comes back on without me noticing. Until I smell burning again. This went on for sixty-seventy miles and finally, the brake pads where burned off enough that they weren’t causing a smell so I just ignored it. Not much I could do about it over 225 miles from a major town. Didn’t slow the RV down. I decided I’d just let it go until I got to the states and could get less expensive parts or service. Very expensive for stuff like this on an RV in Canada. This causes a problem of course, whenever you stop on even a slight incline, the RV would try to roll, so I’d have Kenny jump out and jamb a stop under a tire. For the first 2-3 days, I didn’t even think about just dropping the front jack when I stop.]

So I limped along with the PB malfunction from just after the Canadian border check station to Mazatlan, Mexico. Found my favorite Mexican mechanic and he starts working on it by removing the brake drum and shoes. They are not ruined. The drum has enough metal for it to be turned and the brake shoes were good enough for new pads. After that was done here in Maz at local shops, the mechanic had me start the rig several times while he tried to figure out what was going wrong with the hydraulic parking brake ‘release’ problem. The idiot light on the dash would be lit when I had it in park, and stay that way until it was dropped to 2nd gear. Then would come back on in 3rd and Drive. Also would come on in ‘Reverse’. Well, he’s not a hydraulic expert and called in another guy who is. My mechanic had thought it might be a small hydraulic control and I agreed with him, but he felt more comfortable calling in some help. The guy is huge and a shouter. Talks a lot too. Spends a couple hours under the rig having me start the rig and pull it through the gears whiles he’s watching operation. Leaves for the day. Comes back the next day for another couple hours of the same stuff. Finally, pulls out the hydraulic control my mechanic and I thought was bad to begin with. Off they go to another shop. Gets the control rebuilt and slaps it in…it seems to be working. I haven’t done a road test yet, but I’m confident. Cost was $3,000 pesos ($235USD). Would have been at least $500 in the US and probably $800 in Canada.

So, a week or two later, I head off down the road to Puerto Vallarta with a friend. Around 90-100 miles after we left Maz, I notice the PB idiot light flashing occasionally. Dammit! On guard, I watch it carefully and all it seems to do is flash occasionally. Well, that’s better then it was doing up in Canada where it would come on and stay on. But I didn’t want to temp fate so as soon as I had the time in PV, I crawled under the rig and removed the pin for the drum brake and lashed it up so it couldn’t apply even if the system failed again.

Weeks later, back in the US, the engine blew… After that fiasco, and since it was in the shop anyway, I did some serious web searching for the components of the PB system. Finally found the valve that the tech and I down in Mexico were sure was the issue, a Bendix TW-12 control valve. Same valve the hydraulic tech had ‘fixed’ in Mexico.

Didn’t take much to remove the bad one. Note the cam lever. That’s what needed to be removed and installed on the new control valve. Anyway, we ran out of time on the project that day and I left but came back the next day to have the new TW-12 installed.


Initially, when replacing the valve with the new one, the tech climbed out from under the rig and says, “It doesn’t fit right, the shift cable is twisted or too short.”


I knew that was BS, since it had been fine for 18 years. I’d told them before I ordered the new valve to hang onto the old one…just in case. They had, and when I got the owner of the shop out there, he climbs under there, looks around, crawls back out and has the tech replace the actuator plate with the one off the old control. Everything fits, I pay, and off I go. I stuck around Flagstaff for 2-3 more weeks, where the work had been done. Taking short excursions to test everything out. Even went all the way to Homolovi SP and back. The PB worked flawlessly everywhere I went. Finally, after nearly 7 years of having an intermittent issue with the PB, and finally total failure,  no more worries with the PB. I can actually park on a hill!