Zf parking brake tailshaft

[nickcox]

Hi everyone. New to this forum. Been a member of several Mercedes and vw forums. Love old merc and vw idi diesel.Own quite a few. So... that leads to my purchase of a 1991 Super Duty 7.3 idi 5 spd. 10 ft flat bed. It's a bit rough but over all solid. Paid 1k for it.

So far I've done quite a few repairs. Finally got it road worthy. Just wanted share my resent woes dealing with a "death wobble". Any speeds above 40 mph the truck would go into an uncontrolable shake. Very violent. Checked everthing in the front end. Read a bunch of posts about the wobble. Rechecked everything. Finnally just decided to get some used tires for the front. Old tires looked fine.... anyways Problem fixed. I can take her to 60 mph no problem.

Here's my forum post. I've been having trouble finding much info about the zf tailshaft parking brake housing. On my truck I can shake the drum at u-joint #1 up and down...more than I think it should. The housing has a sticker stating it was rebuilt in 2004 by Precision builders in Mo. States oil capacity is 4.1 oz. I removed the driveshaft and the drum. The brake shoes looked new. No wetness on the shoes. With the drum removed I can pull the shaft approx 1/8'' back and forth (axial?) It seems excessive. Next I pulled the plug above the arm with the cable. No fluid came out. It smelled a little toasty. I added 1.5 oz of merc V.

Questions: How to I change to oil in the parking brake unit? Should oil run out of fill plug? Is there a drain plug? What should the endplay be of the tail shaft? I'm guessing mine has to much play. I don't notice adnormal noise

Thanks for reading.. I'm just running into trouble finding info. Would greatly appreciate any help.

 

[towcat]

welcome to the site. you read right on the fill cap. my suggestion is to put back in 10/40 motor oil rather than ATF. that's the orig spec. you should have extremely small perceptible in/out play in the bearings. only recently has rebuild parts been made available to the aftermarket to repair these units. most of the time, it's too late to repair the unit due to the meager amount of oil, the indication of failure( speedo stops working) and the lack of rebuildable cores. post up any questions. I have over 15 frustrating years dealing with these brakes. 99% of the failures is due to the unit overheating due to the brake being left engaged while vehicle is in motion.

 

[nickcox]

Thanks towcat. Would you say my unit is probably toast? Is there anyway to correct it with out rebuilding? Should oil be flowing out of the fill plug and is there a drain plug?

 

[G. Mann]

ALERT !!!

The symptoms just described are typical of the rear bearings failed on a ZF 5 speed with driveshaft parking brake.

That part of the ZF has it's own oil supply. When the transmission oil is changed, it does NOT change the tail shaft oil. There is no drain plug for the tail shaft. You have to suck out the oil from the fill port which is hard to see and hard to find till you once find it.. Middle of the shaft, drivers side, on mine, it's an allen plug.

Pretty common for the tail shaft to lose oil, then run the bearings dry, then bearings seize and break off the tailshaft, drop the drive shaft, and raise hell in general.

The free play you are having at the shaft, with the brake drum off is NOT normal. Description you gave says, bearings are toast.

New tail shaft parts are damn hard to find, from my experience. Perhaps Towcat has a source...

I could be wrong.. but try this. Pull the fill plug and try to suck out oil from the tail shaft housing. [small nylon line hooked to an electric fuel pump worked for me. If you get oil out, I'll be surprised..

There was a Ford service bulletin on the tail housing and oil.. not many trucks use the drive shaft so it doesn't get much attention.

The oil should be auto trans fluid per Ford. Not heavy gear oil.

 

[towcat]

http://www.allstategear.com/ZFParkingBrake.html


http://www.ptcinc.ca/parts/ford_brake_park.html

 

[nickcox]

Wow thanks for the info... is rebuilding the unit possible for a diy person? Or is it something I should just find a used one? Also should fluid flowing out of fill plug? I just added a little but not enough to go past plug... I need to use the truck for a a few things then I can park and fix it.

 

[towcat]

i'd run it if it's not leaking fluid. just don't forget about it.

 

[nickcox]

Every thing was dry underneath the drum.... should fluid run out of the fill plug or.... just 4 oz total?

It is a bit scarey seeing the prices of those units online.

So towcat... with your experance with these things, you would continue running it? I'm not plannimg on driving much currently. But who knows...

 

[towcat]

i fill mime until the oil runs out.
if you are not using the truck for long, use it as long as there is no leaks. but do down it for repairs at your earliest opportunity. usually the units are burned up junk when most notice there is a problem. as a result, most units are ****** materials.

 

[nickcox]

I'm sure this isn't a new thought.... is there anyway to put something cheaper and more reliable than the current unit? I like to repair the unit but I don't want to down the truck.... does anyone have a unit to sell?

 

[stuborn nut]

I may be able to come by one don't know what kind of shape it's in. I just pulled the zf out of in front of it. I can swing by and take a look at the unit before the briars take over again. I believe it is a '89 460cid truck is there anything special I need to look for?

 

[FarmerFrank]

I have a used one I'd sell. Seems to be in good shape, I can't feel any bearing play but I also didn't pull the drum off.

Pm me if your interested

 

[nickcox]

Hey stuborn.. I'm not sure about this, but I believe there are different spline teeth number. I feel like I read from the late80s to the early 90s are the same.

I guess I'm looking for a unit the has lttle to no endplay and hopefully doesn't. That way I can tear into the one on my the truck.

Pm sent to farmerfrank.

 

[towcat]

zf parking brake for the F450 uses the same spline count shaft gas or diesel.