adjusting master cylinder rod

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NAM VET
1SG
1SG
Posts: 1118
Joined: Mon Aug 22, 2016 6:27 am

adjusting master cylinder rod

Post by NAM VET »

As part of my restoration, this past spring I put in new hard and flex lines, new bleed nipples, but the master seems to work fine, so left that alone. My brakes work well, hard pedal and all, stops OK for a big drum truck. No pulling, etc. When I reinstalled my engine, I moved the clutch and brake pedal to the same height, by making the adjustment for that via the pedal shaft, where there is the locking bolt that moves the pedal up or down just a bit around the shaft. Been happy with it. I would like to have a little less "free-play" in the brake, so crawled under my M37 yesterday, and noted that my clevis/pin on the end of the master cylinder rod is actually hitting the driver's side running board support at rest. So I can't lengthen it. And besides, probably not the best thing to have happening.

So, my plan is to adjust the bolt on the shaft enough to gain some clearance between the clevis end and the support, then adjust the push rod to bring it all back to where I want it to be. After perusing the search for "clutch rod" lots of comments about adjusting it, but my question is, do I have to pull the cotter/clevis free of the pedal bracket, to turn the nut on the rod itself? I cleaned it off, put some penetrating oil on the nut on the rod, so It should turn easily.

On my other cars in past years, the end of the master rod just fit into a dimple on the end of the master's piston, and there was no issue with just turning the rod to move it in or out a bit. But I don't know if there is some precise orientation inside the master where turning the nut on the rod damages something, with the intact clevis/pin holding the rod itself.

Kind of hard to explain. Let me try this: can I just turn the nut on the push rod to change pedal "free-play", or is it more complicated than that? I presume I lengthen the rod to reduce pedal "free-play" too?

Going to change out my break-in Oil this afternoon, local chap had 8 quarts of the 10-30 Amsoil Z rod oil for me. $73 bucks. Have a bit over 600 miles on the break-in oil, with one earlier change to same at 50 miles.

All the best, NAM VET
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