brake restoration questions

[davester]

I had a stuck brake adjuster on my 67 MKII and had a little difficulty removing my drum on one side due partly to a bit of a ridge on inside edge of drum that was hanging up on shoes. What is the maximum allowable inside drum diameter spec after resurfacing? Drums look original and un-cut so don't think I'll need to remove much and inside surface looks good.

Secondly, since my brake master looks original and has a pretty aged looking resevoir I am installing a new one. Servo will go out for a rebuild as well, so I want to flush entire system, redo all rubber gaskets and brake hoses. The standard Castrol GTLMA standard DOT 3/4 fluid (non synthetic) seems hard to find (suggestions welcome). I understand if I switch to the synthetic GTLMA new formula (easy to find) it will interact with the old style non-synthetic fluid left in the system even after a flush and cause rubber components to quickly deteriorate. Is this true, or should I just flush whatever combo of non-synthetic fluid that is in the system and renew with the synthetic after rebuilding? Thanks, Dave Gilmore

 

[Cal44]

Dave,

Flush that old crap outa' there. Brake fluid is supposed to be changed out every three years.......give or take. The new stuff is good stuff. I was using only the special German brake fluid in my Porsches.........what load o'......
I use 3/4 in the street cars as I don't race the cars stop on a dime and don't leak.

I now use the system to bleed where you push from the wheel cylinder to the master. One man operation and gets all bubbles out.

The new brake fluids are just fine. It reminds me of the myth about synth oils and how a leak would appear where there was none before. That may have occured thirty years ago but current synth oils are good. I use Brad Penn which is a semi but with extra zinc.

I would look up the specs for the brake drum but I am not in the garage.

Mike

 

[0neoffive]

them brakes etc.

Keep it as thick as you can. If the brake drums were not wobbly, just have your brake guy nip the ridge off and bead blast the glaze. OR, make one and only one micro-fine pass from the inside out. I have never found the need to thin a "Beam" brake drum. As to the servo & fluids subjects: I did have a serious issue some time back with mixed fluids turning brand new servo seals into spongy flubber. Customers were unhappy and much blame was passed around. Never found the cause or got credible responses from suppliers. Anyway, any good DOT 4 keeps things happy, but I do strongly recommend a good flush and sticking to one fluid. keepin' em' runnin' randy w