Well Gang,
I (and I think Richard) are some of the few that have actually removed, disassembled, rebuilt, re-assembled and, reinstalled the ZF unit on our coaches. Ford, in it's infinite wisdom, says: THE ZF PARKING BRAKE IS NOT REBUILDABLE AND, YOU MUST BUY A NEW ONE!
Well, I usually like to go against the grain on things like that. To me, it's just a line in a movie called "The Score", said by Robert Dinero. In there he's talking to Edward Norton about safe cracking. He tells Ed, "Someone can build it, so, someone can "UNBUILD" it"
That was my attitude. So, I removed my ZF unit and, did some research on it. This is a very, very simple unit. all that's involved inside that unit is, a couple of seals, an o-ring or two (I've forgotten because it was a long time ago), two, rather large opposite facing Timken tapered bearings, a short shaft and, two brake shoes with an actuator, and, a drum. The bearings and races are standard in size. That is, you can get them in any auto parts store catalog. I got mine from Grainger.
Now, where it's really critical in the entire assembly is the seals. You can get cheap-o seals at your local auto parts store but, if you do, you can expect leaking, within a few miles of re-installation and that unit get's warm. I forgot all the terminology and correct name for these seals but, I used "Nitrile" seals. They were considerably more expensive than standard seals but, they're also considerably more heat tolerant too.
But, what's kind of amazing is, the way these things are put together and taken apart. I know it's hard to believe but, it's almost like their put together from the inside out. Yeah, I know, that's impossible but, in reality, it's not. You just have to realize how things fit in that little assembly.
My brake shoes were cracked and soaked with ATF so, I needed new ones. I looked at the part numbers stamped on them and, within one day, had new ones, YEAH SURE THEY'RE NOT REBUILDABLE FORD!!!!!!
I had the bearings in less than a day but, the seals, because they were special construction materials, had to come from a specialty seal supplier. That took about 3-4 days to get them. And, they were not cheap. If I recall, those two seals, ran me about $60 or more. I'd have to dig up more info to get you an actual real quote.
But, as much as it's a simple unit, it was a bit of a challenge to reassemble it. But, I finally got it. Now, here's the real kicker. There's a gasket between the back of the trans and, the ZF unit. Well, Ford has no idea what to call that gasket. They gave me the crooked puppy head look when I asked for it. I went to a couple of Ford parts houses before I found a gent who, like me, THOUGHT OUTSIDE THE BOX.
He came up with an idea. He said, "Let's try FOUR WHEEL DRIVE"! Well, he get's the zillion dollar prize. You see, the tail housing on any of the automatics in your F-53 coaches, that has that ZF parking brake, is actually configured for and, setup for, four wheel drive. That is, A TRANSFER CASE CAN ACTUALLY BOLT RIGHT UP TO IT!!
And, because of that, that's how and where we came up with the correct gasket between the ZF parking brake and the tail housing of that trans. So, as for filling it to the correct level, you can fill it even with the unit off the coach. You just have to have it level with that fill plug. That will give you the correct oil/ATF level.
After the rebuild, we drove that coach for another several thousand miles and no leaking. Our daughter and son-in-law had it for a few thousand miles and, still no leak. They just recently sold it so, I must have done something right. And, for those of you that may just want to purchase a new one or, a "remanufactured one" (since Ford says they're not rebuildable), well, you've got a couple of options. One, they're on ebay quite often for around $800.00 plus or minus for a remanufactured unit.
Ford has them, at least the last time I looked, brand spankin new, for right at, are you sitting down, $1650.00. Like stated, it's been a while so, if I recall, I rebuilt mine for around $150.00, plus or minus.So, for you do it yourselfer types, it's really not a hard job. The unit weighs around 40 or so pounds, plus or minus so, be careful in removing it and re-installing it, don't get hurt lifting it off the tail housing or, re-installing it.
Scott
