Tips For Rebuilding Rack Piston
Rack Piston Seal
Replace all rack piston seals before installing ball bearings!
I had to install the big teflon seal on the rack piston twice. The first time I must have stretched it slightly as it had a bit of a bulge. When I tried to install into the rack piston into the casing, that bulge snagged and I ended up cutting off a sliver of teflon. I should have known, because the piston met resistance and I pushed too hard. For my second teflon seal (I had to buy ANOTHER seal kit to replace it!) I soaked the seal first in boiling water to expand it slightly with heat. It went onto the piston easier and there was less bulge when cooled. For insertion I suggest using an engine piston ring compressor to avoid damaging the seal.
Rack Piston Ball Bearings
Installing the ball bearings into the rack piston really is the catch. I had issue with the grease causing drag so that after 8 or 10 bearings had been inserted, they refused to stay in their track and would pop up. Here is how I was able to complete this leg:
I inserted just the worm gear into the rack as it is supposed to go. Once fully inserted, I turned the worm until its groove matched up with the ports in the rack. This essentially completes the race within which the ball bearings move. I would insert a small amount of grease before each ball is inserted and push a ball in with a small drift pin, giving the worm gear a little bit of rotational jiggle to help with alignment and to coax the balls in. The rotational jiggle gets to be important around the 12th ball, and helps draw the bearings into the race channel. It is important that you do not allow balls past either of the two ports. You can coax the balls in and out of the channel with similar rotation of the worm shaft.
Once all balls have been inserted and the u-channel has been reinstalled, you can rotate the worm shaft out. As you remove the worm shaft, you should insert a place holder, be it the taped up 5/16 hose hutchhiperf recommends, the special tool if you can find it, or something else. Instead of the tape-wrapped tubing, I used a 1/4" drive 7/16" deep socket on an extension to fill the space, which fit perfectly and held everything in place.
The ball bearings are the real trick to this entire job. I attempted their insertion over 10 times! Every time one or more would drop out I had to start over, cleaning each bearing of grease and sorting each bearing by color. It was because of my multiple attempts (with many bad words used) that I came up with the idea to utilize the worm gear to help initial assembly.
michael j (your mileage may vary.)
1970 Chevelle SS396 - "Elektra"
Canadian built true SS, L34, bucket seats, 4 speed, Posi, console, deep fathom blue with white interior, white vinyl top and white stripes.
1980 El Camino
229 V6, 200C Metric (soon to have a 200-4R)