Replacing wheel seals in RV Dually
D Vautier 12-2013
My son got a 1978 RV camper built up on a Ford Econoline chassis. I think it's the same as an F350. Lots of things were not working but the immediate problem was a leaking rear wheel cylinder. It was leaking bad. The former owner had a big bottle of brake fluid right next to the master cylinder so he could keep filling it up at every stop. Replacing a rear wheel cylinder on a dually brake is a difficult job for sure but things can be and usually are even more difficult when the vehicle is old.
There is a lot of data available on how to do this job but you have to piece information together to get a good picture of what to do. In this page I hope to help a little bit on how to deal with some possibly really difficult things.
I removed the hub cap first. It took me quite some time just to do this since the hub cap was rusted on. I designed a special tool puller from wire with little hooks to get the hub cap off and not get it all bend up. The 8 lug bolts came next but they were easy to get loose. Then I jacked up the vehicle and used two sturdy jack stands and removed both wheels. I then took out the axle with it's many bolts. Next came the axle nut that does require a special socket ($28). No way around that one.
There is a little retainer pin on some nuts that has to be removed before taking off the wheel nut. The outside bearing slips out and the big ugly wheel drum bearing combination unit then comes off. It's heavy. Beyond the drum I found a broken spring, leaking wheel cylinder, bad wheel seal and axle oil all over the place. More uglies.
After cleaning everything up, I found pictures of the brake and I then removed the shoes, springs and cylinder. The easiest way to remove the cylinder is by also removing the back plate (4 big nuts) which gives you much more room to work and get the old cylinder out. New cylinders and a spring sets are abundantly available. The hard part to get is the wheel seal (D6UZ1175A) for this model. I replaced the cylinder, gravity bled the brake for now, practiced adjusting the brake shoes and put all the shoes back. I had to wait a week to get my seal. Now comes the hard part.
The old seal is almost impossible to hammer out from inside because the inner bearing is right in the way. If you hammer out the seal by hammering on the rear bearing it could ruin the bearing. We tried to pry it, hammer it and wedge it out. Alas, to no avail. Finally I got my coal chisel to work and managed to remove it in pieces. You could just pull the bearing but that would require some really special stuff.
I did not damage the seal casing but when we pried at the bearing we bent up the oil drip catcher a bit. Seals have to be pressed in. You can't hammer them in so I spent some time looking around my junk pile for a way to come up with a press. I found several plates, an idler wheel and a spring compressor threaded shaft. That got the job done.
I had my son help me with the rest. We got the drum back on, adjusted and bled the brakes, reinstalled everything fine. So good luck to all you how fix old RVs.