Thursday, September 19, 2013

ZF Side Cover Breakdown

I've been busy doing other things lately, but I had a chance to get back on the ZF today.  I finally removed the pesky side cover axle seals.  It wasn't fun, and I worried about damaging something.  It required a good whack with a big hammer and a punch to move one side slightly and then I was able to pry it out with a handheld seal puller.

I decided to replace the differential carrier needle bearings and the axle bearings.  I wasn't going to replace them, but discovered pitting.  You can see the pitting in this picture:

The side cover bearing race is pressed in.  In the picture above, the large snap ring is visible between the carrier bearing race and the ball (axle) bearing.  To remove the axle bearing and carrier bearing race, you remove the snap ring from the retaining groove, moving it back toward the carrier bearing race.  The washer should then lay flat on the carrier bearing race (very important that you don't let it get snagged in the groove and bend!), and using a short pipe or other tool, you press on the axle bearing first.  I used the aluminum wheel from my rolling car jack, which fit perfectly in the bore.  The axle bearing eventually hits the carrier bearing race and presses it out at the same time.  Keep track of the washers as a mix-up between sides would through off the ring gear alignment.  I am told that the tolerances on the bearings are good enough that as long as you don't mix up the washers, the differential alignment and lash will stay the same.

The carrier needle bearings are pressed onto the differential housing and cover.  However, you need a special tool to remove them as there isn't a lot of room behind them to seat a typical three-legged puller.  I sent the whole differential back to Pantera Performance Center and Dennis Quella pulled the bearings off, pressed on new bearings, and sent me the differential, races and axle bearings.

Here are the new bearings.  The axle bearings on the left are made in Japan and the right carrier races are Timken units made in the USA.  The new (axle) ball bearings are silky smooth compared to the worn original German bearings.

Here's the new carrier bearing, pressed on the differential side cover.  Notice the new bolts which replace the old allen bolts that tend to strip out.  I didn't notice the paint can in the background; seems like a good advertisement on accident.

I have new stainless steel hardware as well.  Dennis Quella sent me some of the longer 80mm and 100mm M8 bolts in stainless steel for the side of the two case halves (not pictured).  Make sure you use a good anti-seize lubricant on the stainless bolts used in aluminum since the bolts will tend to gall and freeze up in the aluminum without it.  

1 comment:

Richard said...

Also, SS bolts and SS nuts can also gall and seize so best to use the anti-seize lubricant on them as well.