Fawndeuce

Hi guys,
I just had my master rebuilt and sleeved, I reinstalled and filled it but have seeping from between the brass block and the big nut on the end of the master, same brass block as before, no previous issues.
I had annealed and reused my old washers, had the seeping, got new washers, same issue at the same place.
How much torque can I use on the banjo bolt without risk of cracking the brass block? How can i tell if I've already cracked it? Looks fine to the naked eye.

Thanks,
Paul

CaptainEgg

I would start with replacing the block and washers. How much torque have you put to it?

jim lockwood

My memory sez the recommended torque on that bolt is ~60 ft-lbs. My concern wouldn't be about fracturing the brass block; it likely will just crush slightly, if that. Rather I'd be concerned about stripping the threads in the MC.

Fawndeuce

Thanks guys,
I could see 60 lbs on the nut in the end of the master, but wouldn't 60lbs be excessive on the banjo bolt?
I've also noticed that the new washer that I used between the block and nut is thicker than the original, may not be compressing into the groves machined in the block?
Finally got it back from the rebuilder Terry, I'm not sure exactly how much torque, I could try with a torque wrench, I'm guessing over 30ft/lbs?
I'd just try a new block and washers, but I'd have to order from CC or others, to Canada expensive with shipping and will take God knows how long to get here, the car is still off the road.


Paul

GTOguy

I agree about the brass being bulletproof and the worry being the cast iron. 60 foot pounds seems excessive as hell to me. To the OP: tighten it more. You may need to remove the block and lap it on a flat piece of glass with some emery cloth or draw it down the length of a bastard file to true it up if it's distorted. I have run into a lot of sealing issues with newer copper washers.....they are harder than the old stuff.

65GGvert

You need to try just a little tighter if you're sure it's not seeping from the line over to the bottom of the bolt

Bacci

I am busy right now and cannot research but do recall I had the same problem and it was the copper washers I was using were not soft enough. I would hesitate to keep tightening the bolt until you verify the correct washers being used. I may have used the old one to correct my leak???

dplotkin

That is because there is not as much copper in copper washers as there once was, no different than pennies.

Dan

Pilot Dan

If you have no imperfections in the brass block or nut (you can true with a small file), I would remove the big nut and carefully examine the casting in that area in case it may have been damaged (cracked in the sleeving process and fluid is weeping. It has happened to other folks..........hopefully not your problem.

jim lockwood

It may very well be. But looking at the size of the bolt, I don't see that 60 ft-lbs seems unreasonable.

What I dimly remember is having difficulty finding a torque spec. If you know of one, I'd love to find out for sure what it is.

VETT457

I recently replaced mine and torqued it to 45 ft-lbs. It's a 7/16-20 bolt and I assumed it's not better than grade 5

Fawndeuce

Thanks guys, unfortunately no chance to work on it tonight.
Last night I left it for a few hours and then put a mirror under the master and block, also ran a Kleenex under the master and big nut again, bone dry. The block was also dry, but there was a drip, the leak is definitely at the washer between the big nut and the block.
I'm going to take it apart again tomorrow night, I think I'll anneal the new washer to soften it up, then reassemble and torque it down with a torque wrench to about 45 ft/lbs feeling as it goes.
I'll be curious to first see when I take it apart if any of the concentric rings have actually been pressed into the new washer? I would bet hardly at all, if anything at all.


Paul

65GGvert

Your car, but a lot of work when a slight tightening would most likely fix the leak. It's all metal on metal, it has to be tight.

GTOguy

First, it's a hollow bolt, so don't go crazy. Just tight. Second, as a pro, I have OFTEN re-used 40 to 100 year old copper washers on old cars to actually fix a poor sealing leak due to inferior modern parts. So re-using the old washers and re-torquing just may be the answer here. In industry, I stopped using the new washers supplied in brake caliper re-build kits 300 years ago to avoid seepage. The originals went right back on, and never leaked.

65GGvert

He said he tried using the old washers first, but it seeped. New washers did the same.

62vetteman

The torque specification for that bolt is shown in the AIM ( section 5 sheet 2 pages B90-91 ). It is 25 to 30 ft. lbs.

Fawndeuce

Hi again guys,
So it appears that with your input, I've fixed it, it's been several hours now and everything is bone dry, even after pumping the brakes several times.
Here's what worked for me, your mileage may vary...

The new washer was not compressing at all, I had estimated about 35ft/lbs and it was still seeping, sure enough when I pulled it apart again, the imprints from the concentric circles from the block and big nut were light. I had really felt that I was at or near the max as far as torque, an 11" boxend on it with some muscle, it was done.

I looked over the old washer again, but I'm guessing that it had been reused many many times, may even have been from '62, just too thin and didn't even puff up at all after annealing.

I ran the new washer over 220 then 400 on a smooth surface, I also lightly ran the brass block on both sides to verify if it was flat, the corners were just slightly high, but all came good.
I then heated the washer with a propane torch to anneal it, got it cherry red for about 20seconds, then air cool, as soon as it was cool enough to touch, I quickly put it on the block and put a couple of drops of brake fluid on both washers, then torqued to 35ft/lbs, (had not seen Vetteman's post, I also had not found the spec in the AIM). I could feel the washer slightly compress, I could also feel that at 35 ft/lb I was at the max.

Fingers crossed, thanks again for the help! I love this forum for input on these types of obscure questions, in my line of work we call this "tribal knowledge", or in other words, stuff old guys know!


Paul

Fawndeuce

Hi again guys,
Got the new wheel cylinders and hoses installed, then I cludged together this adapter with parts on hand so that I could use my Motive bleeder to flush everything out and bleed.
I had an old master cap with a broken tab on it, I used air hose fittings with steel washers in and out to sandwich the plastic cap, then sealed it all with some leftover JB Weld for plastic.
The cap threads were quite worn at the edge, couldn't use an oring or thicker gasket, so I cut one out of a thin cardboard file folder and then put non hardening Hylomar on both sides of it, I used some wire to help the cap sty put, it sure wern't purdy, but it got 'er done!


Paul

AGs61Vette

Hi All,

I replaced the master cylinder in my '61 and had a drip at the block. I kept a plastic lid under the block to catch the drip. Everyday I would torque the banjo bolt down a little more and check for drips. My magic number was 40 ft-lbs.

dplotkin

I'm currently dealing with a seeping piston stop bolt on the bottom of a Bendix master adapted to my 60 Chrysler 300 F. Jeff knows some of the saga. My use of Dot 5 along with the issues the OP and others have faced, good metal to metal sealing is my problem. I'll loosen and tighten again, can barely get to it - I'm close to using a wad of JB weld on the God forsaken thing.

I used stainless lines on another car, not sure I'd do that again either. You know that old adage about every action having an opposite reaction? That 'taint no BS. Especially with these relics.

Dan