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Thanks for the info everyone! I bought a pair from China and they didn't work right out of the box.
Here are some pics from my rebuild. Same thoughts, but had to use what they had at Lowes. The o-Rings were a bit different, but when I used the super glue, I just squeezed extra tight. I also installed an extra washer on the diaphragm side to keep o-ring in place. Added fair amount of petroleum jelly then Jb welded the end washer. Works like a champ!
After dremelling nubs, cleaned and jellied-up!
Ingredients. Brass washer in Hardware in bag, on racks.
Before glue. Make sure to squeeze hard! Should be flush with lip when done. Clean edges with isopropyl alcohol.
The first one I did is still a wee-bit slow. I didn't squeeze hard enough to get 100%, but the other is perfect.
Eliminating thelse leaks also eliminata Ted the brake pedal creep that I had at stoplights.
I have a vacuum switch out of my '77. It is by all tests leaking. I took it apart quite easily by using a Dremel diamond grinding bit to take the crimp off the end of the control rod. Thanks to all involved in this thread. I really appreciate it.
My question is, I can see how the crimp and the washer allow the control rod to PULL the spool back INTO the valve but what extends the spool? Seems to me the rod and washer would just extend and leave the spool behind. I would have expected another washer and a crimp at the other end of the spool to push it the other way.
The rubber seals on my spool are worn quite a bit and leak. I tried cleaning and applying silicon seal grease but it didn't help. Air still leaks past the seals into the bypass channel and out the end. I might try making a new spool from Delrin with standard O-rings.
Any explanation would help.
Thanks
I fixed the first switch mentioned above As suggested using the O-ring addition, glue and a self made larger washer at each end to keep the O-ring in position.
. I figured out after looking at the second switch that there IS, as expected, supposed to be another crimp in the rod below the spool so the rod can push the spool back up with no vacuum applied.. My switch was stuck in the pulled-in position and the rod could not return it. After some careful measurements I added a tiny C-clip to the rod and a bit of JBweld to hold it in position partway down the rod. I was working through one of the hose ports to get at the rod..(I should have been a brain surgeon :-). Anyway the first one is moving in both directions and holding vacuum now.
On to the second one. Since the spool moves in both directions on the second one I assume all it will need is the O-ring treatment to be successful.
Thanks again for the method of fixing these.
