How I did the brake job…2005
Well, I got the brakes fixed today finally. Cost me $534 for the master cylinder (new) plus all the fluid and stuff. They have been getting worse for a long time, meaning that over time the symptoms became hard to ignore. The first problem I had with them was the day I drove the rig off the consignment lot back in July of 2004. The brakes ‘Stuck’. But that problem went away immediately after I stuck my foot under the brake pedal and pulled up. Months later, March 2005, I went down into Death Valley using my brakes instead of downshifting on a long 6% grade, that was an experience. They overheated badly and I lost all brakes for a while while they cooled down. That’s when I started downshifting on a long hill to slow the RV instead of using the brakes exclusively. After several miles of driving after I reached the valley floor the brakes seemed to heal themselves. I think because the fluid cooled down enough and the moisture bubbles in it had migrated up and out of the system.
After that little fiasco, I didn’t have much trouble until mid-October when in downtown Elkhart, the brakes just went down to the floor. Even then I had brakes but only manual, no power assist. Kind of hard to press them, but I did have brakes. Topping off the brake fluid seemed to help. Since then I had been monitoring the brake fluid level carefully for months and usually I’d have to top of the reservoir whenever I checked. So I was just very careful driving before I got here in Dos Cabezas, Arizona. About 400 miles before I got here, adding brake fluid to the reservoir didn’t seem to help any more. So, time to fix them. After I was all set up and getting online, I spent a hell of a lot of time just trying to find the part. Freightliner repair department had them, but you had to buy both the master cylinder and the booster, $888. And for them to do the job? $2800 firm. NO WAY. So I spent HOURS on the internet trying to find a rebuilt or new master cylinder, based on the symptoms. The problem is that it’s hard to know exactly which part number I have for my RV and nearly all auto sales places insist that you select a CAR to order a master cylinder. I have a RV, not a car! Butts.
Anyway, it’s taken nearly a month to find the part number, find a place that sells them, learn all I can about changing them, ordering and installing the part, and then bleeding the system. I learned a lot and I’m happy I had the experience, I just wouldn’t want to do it too often. Lucky that the weather here is so nice. 68F to 75F every day almost.
Back when I was driving around the country (Indiana to Arizona), I did have some brakes and initially pumping the pedal would return assisted brakes, but eventually I really had to press hard on the pedal. Pumping on them stopped being helpful. So I got in the habit of decelerating early by downshifting. Not one time did I ever need to panic stop. And I avoided places in big cities or other areas where I may be put in a tight squeeze and need lots of quick braking action. And I had a fall back position. In an emergency, I could slam my shift lever into ‘Park Brake’ position, which would apply the driveline brake. The tranni doesn’t have a parking pawl. Never had to do this while driving but I did test it in a few parking lots and at some stop signs to check that it worked…it did.
After I got settled in Dos Cabezas, where I might add there was a competent mechanic who offered to remove and reinstall my master cylinder, I checked with a local Freightliner repair facility (in Willcox, Arizona). They would only sell a new MC, no rebuilds, and they would only sell the MC with a power booster. This is a secondary part that attaches to the MC and using hydraulic pressure provided by the power steering pump, assists the braking action. They were asking $888 for the two parts. I also asked for a quote for them to do the job. They wanted $2800, which included the parts costs. Well, the mechanic at the ranch I was at could do the job plus bleed and refill the system. I offered him $200, and he accepted $20 down, pulling off the MC in about 20 minutes (this was after we tested and he found a huge leak coming from the junction of the MC and power booster). I wanted to avoid having to spend $888 so I spent many hours trying to find some business on the internet that would sell me a new master cylinder for a Freightliner chassis. Or a rebuild kit, or a rebuilt MC. The biggest problem is figuring out the correct part number for the MC installed on a RV. The MC in a RV is usually (so I was told) a custom part made only for that RV manufacturer. This is not true. My MC is a standard part made by Bendix and there is just a Part Number chase that you have to do to figure out which one it is. Turns out that all MCs, like nearly all metal devices attached to a mobile chassis, have a casting number cast right into the medal. That and the diameter of the piston (guesstimates are acceptable) are all you really need to find the right part. And then there is the problem of the way most internet auto business are set up. They care about cars mostly so they don’t provide any way to select a part without selecting a car!
But eventually I found a place that had an ‘Ask the Experts’ email button which I used to explain my situation. After a couple of back and forth emails, getting the correct casting number and piston diameter and such, we had a Bendix part number and I ordered the MC. After shipping it came to $487. After brake fluid and such it came in at around $530. I didn’t bother with the core as the shipping would have nearly cost as much as I’d gotten in return. I didn’t search for a used MC at a RV salvage place after several mechanics told me that using a used MC wasn’t something you’d want to do.
So now that everything was all arranged, I had my new parts, fluids, and lined up help, it was time to go to work. This was in February of 2006. About this time the mechanic I had lined up bailed on me, damnit…so I decided to do it myself. Since I’d only paid him $20 to remove the MC, I wasn’t out much. Never did find out why he went all flakey on me. He wouldn’t tell his own brother either…who helped me bleed the brakes a few days later. Anyway, on with the story.
First, Bench Bleeding the new MC : I bought a bench bleeding kit from CarQuest and connected the two plastic screw in plumbing parts, 9/16″ – 18 tpi and a 1/2″ – 20 tpi, into the front and rear ports. Then attached clear tubing from the hose bibs into the reservoir and filled it with brake fluid. I used my RV kitchen steel sink to give me added leverage. Using an 18″ lever I was able to pump the air out of the MC. This required quite a bit of force, I think the lever gave me about 360 lb. of mechanical advantage.
Second, Cleaning the Booster: Before installing the MC, I needed to address the booster. The booster shaft had been pushed way far out of position when I accidentally turned on the key while the brake pedal had been depressed. This started the electric aux brake motor that pushed the rod out towards where the MC would usually be. The big piston was kind of half in/half out and the large ‘O’ ring was exposed. Using a wooden handle, I pushed the piston into position and when I released the assembly the whole thing popped out and a quart of ATF spilled out. It happened slowly enough that I was able to see how the parts were assembled and didn’t loose any parts. I took it in the shop and using alcohol as a solvent (recommended for ATF and brake fluid), cleaned the gunk out of the fine plastic mesh filter screen and cleaned all the ‘O’ rings. There are 5 of them if I remember, 3 large and 2 smaller. But they were all OK and still fresh acting…probably the result of being in an ATF fluid environment for 120,000 miles. After the booster piston was all clean, I thought I’d test it for fit. Cleaned out the booster cylinder with a clean rag and inserted the piston. It went in real easy and true, but it stuck. Thinking it would be better to not jerk it around, I left it in place. My worry was that since I had cleaned but not lubed the ‘O’ rings that could cause a leakage problem. But since the rings were in such good shape, and they swim in ATF normally, maybe my mistake wouldn’t be a problem after a few miles.
Third, Installing the MC: There are 4 bolts inserted into the booster that become studs for the MC. I left the bench bleed inserts & tubing in the reservoirs and installed the MC on those 4 bolts, leaving it loose so I could wobble the MC around to make alignment of the brake tubing easier. First I removed the rear plastic plumbing and quickly jammed the brake tube into the receiver hole and hand screwed it tight. This prevented too much fluid from escaping. Then the front plastic plumbing part was removed and the front tube installed. Then I installed and tightened down the four bolts. Now I had a primed MC installed, ready to go to the next step. Here’s what it looks like installed:
The nice clean black thing with the white plastic thing on top is the MC. The round device at the bottom is the electric braking motor. It gives boost to the MC if the engine is not running so you still have power brakes. The part above that is the brake power booster. I should mention that this brake master cylinder is in the driver’s wheel well and it was easy for me to crawl under there and work on it, after raising the rig using the center leveling jack and then blocking up the axle. There is plenty of room. Didn’t need to remove the tire or anything. I’m 5′ 7″ and 185lbs or so.
Bleeding: There wasn’t any MC bleeding needed since I’d done it in my kitchen sink previously but the old burned brake fluid needed to be pushed out at each brake cylinder. So I had a friend crack open the bleed ports at each wheel while I squirted the old, very dark brown, burned brake fluid out of the system. After about 30 minutes of bleeding and refilling the master reservoir, I was ready to test.
Testing: I started the engine and immediately noticed a howl that happens when there isn’t enough steering fluid. Ha, yes, I’d spilled a quart of ATF out of the booster cylinder when the piston popped out. So, back to the engine compartment and add a quart of ATF. B-t-w, this rig uses ATF (automatic transmission fluid) as the power steering system fluid (different then the brake fluid as it assists the brakes through the power booster). And since the steering system has a hydraulic pump, all the air that might be in the booster would be bled out just by running the engine, usually. So I ran the engine for 20-30 minutes and still had howling when I tried to steer, though not as bad as in the beginning. I gave up for the night to let it sit. Next day, I added at least 3/4 quart of ATF, didn’t see any bubbles, and after starting the engine, there was no howling. The bubbles of air had all migrated out of the steering system. The brakes seemed firm or just slightly squishy. Since it was my day to leave for Mexico, I checked all my fluid levels, looked for a leak at the MC/booster junction (none found), crossed my fingers and hit the road. Ten miles later there was no sign of any problems, brakes and steering worked fine and fluid levels were OK. Best of all there still wasn’t any sign of a fluid leak from between the MC and the booster. I was good to go. Estimate of time to do the job: 2.5 hours. And that’s by a non-expert. If I’d had Freightliner do it they would have made over $700 per hour. Freightliners estimate: $2800 includes parts. My parts cost + fluids: $530 (includes special parts like the bench bleeding kit and hose.) I’m happy with saving $2200.