weekly update
I tackled the leaky hydroboost unit this week. I bought a hydroboost repair kit (mostly rubber) from
PirateJack. It came with instructions but I didn't find them particularly helpful. The two major things I used off that sheet was the diagram and the torque value for the bolts (20ft lbs.)
It was leaking from the front piston seal and you can kinda see in this pic.
I separated the Master Cylinder and since I have decent slack in the lines I just moved it out of the way leaving it hooked up. I then took the HB out and started loosening up the bolts. I left two in at the very end of their travel and once the rest were out I carefully separated the case. I didn't know if anything was going to jump out so I made sure I held onto things as it came apart.
I took off the clevis on the end of the shaft and it slid through the back half. I cleaned it up and this is what it looks like inside.
I gently pulled the "push rod & power piston assembly" (input rod assembly) out along with the spool valve and cleaned out the front half. I inspected it and it looks fine to me.
Spool valve that goes on top.
This is where the front piston seal is. It's just rubber so I picked it out, collapsed the new one and worked it in. Old on the left, new on the right.
I found two more seals on the "push rod & power piston assembly" (input rod assembly). They show a slip over tool to get those on but I just worked them with my picks being careful and I got the new ones on. New ones are pictured.
"Push rod & power piston assembly" (input rod assembly) all cleaned up. I didn't get into the piston and I'm not sure if there are any seals inside or not because the diagram was confusing on this part. The brakes actuated great before so I decided not to go to the lengths to get it apart.
This is the cap for the spool valve. Looking at the diagram showed a seal on it so I yanked it and put on a new o-ring.
The front piston seal is a lip seal like the ones I found in my tranny. I was going against the grain pushing the piston back in so I just pushed the piston up to the seal and then from the front a took a small flat-blade screw driver and worked the seal under the piston. Again, just be careful to not gouge the surface if you work it redneck style.
I then put the spool valve in and attached the two together. The instructions say to only use power steering fluid but since my system runs on ATF I just used that to lube the parts as I put them back in.
I didn't dig into the compressed gas accumulator and the diagram didn't show any seals on it anyways so I started to mate the two halves back together. The back half needed a little persuasion to get on the seals but nothing forceful. I tightened the bolts all together bringing the halves together equally.
20 ftlbs. on the bolts and it's ready to go back in the rig.
These were the only seals I used from the kit. The kit is obviously for several versions of the HB but after studying the diagram and what I found inside that's all I needed. Left side it what I replaced, the right side is what was left over.
Adjusted the clevis again to get the pedal were I wanted it (last adjustment was just a little high) and bolted it back in. Hooked up all the lines, the MC, bled it and it all works fine, no more leak.