ZF 5S-42 Parking Brake Woes
 

I've got an '88 F450 with a ZF 5S-42 tranny... the version with the parking brake assembly mounted on the tail end. I've owned the truck since late '99 and have had a recurring problem with the parking brake assembly apparently leaking its fluid and the bearings subsequently frying and seizing the drive line, along with melting the plastic speedometer drive gear.:argh: I frequently check the fluid level since the first occurrence, but this is apparently not enough. :-(

The parking brake assembly has its own lubricant reservoir, and apparently something is causing the seals to wear/fail prematurely, thus causing the above mentioned problem. Has anyone had similar problems? Or, can anyone shed light on what may be causing this recurring dilemma? :humm: I'd like to find out if this is a common problem with these parking brake assemblies or if mine is a special case.

Many thanks,
Bryan

so its on the tail shaft of the tranny?? I would check your carrier bearing and your U joints to make sure your drive shaft aint moving around and ovaling out these seals...:humm:

Thanks for your reply stkdram55.

I called a shop that specializes in these trannies and found out that the brake assemblies are balanced, meaning if they are disassembled after balancing, then reassembled in a different orientation, you can end up with vibration that will wear out the seal.

I dropped the parking brake assembly on my rig and found a welcome relief... the speedo cable was broken and the parking brake is fine... my initial assessment was (fortunately) all wet. :ok1: