Chevrolet C8 1940 Cab 11 restoration, The Netherlands

hrpearce · #1 30-07-13, 02:49

Bob is on the right track but braze don't weld. if the threads are shiny clean then you should be able to get the brass to run down at least half the thread, that will bind it all back together. You will need a heated tin of sand to bury most of the cylinder in to prevent distortion and cracking from cooling to quickly.

Lynn Eades · #2 30-07-13, 04:23

Alex, in my opinion you have to scrap it. Just too risky. How do you explain after an accident, that you thought you had done a good job of welding it?
You only have a single circuit system. It has to be right.
Sorry Alex. Just one blokes honest opinion.

Dave Mills · #3 30-07-13, 10:41

Bad luck with the master cylinder, always a good way to ruin a productive weekend of work. For what it is worth and being a mechanic myself I was always taught and practiced that you never apply heat to brake parts or steering components as it fatigues the metal/cast and it will fail over time. My advice would be to source another component and run a tap through every thread, blow it out with compressed air prior to assembly. I even run a die nut over every stud and bolt thread.
Cheers,
Dave.

Ganmain Tony · #4 30-07-13, 11:08

I agree with the other fella's Alex. Im afraid you'll have to get another one.

This is bloody frustrating and I would be very upset myself having just had it resleeved.

There may be one other option.

If you were to take it to a professional repairer and he was to say he can and will fix it, then I think you would be OK to proceed with a repair job - providing the professional does the work.

I suppose then it is a matter of cost - if the repair is as much or nearly as much as replacement - well then, go with replacement.

cletrac (RIP) · #5 30-07-13, 13:35

I think it could be repaired. It's been sleeved so there's no danger of it leaking pressure. You'd have to use a zip disc to cut the crack wider then thread the bolt in and braze it up.

Alex van de Wetering · #6 30-07-13, 16:44

Guys,

Thanks for all your comments. It was a mix of bad luck and stupidity. I thought I had partly unscrewed the stud myself when removing the master cylinder from the truck, so I never thought that screwing it back would cause this result. An expensive lesson. On checking my pics from before removing the thing I noticed the stud was already sticking out too far, so either it came from the factory like that or it happened somewhere during it's career. Anyway, there was some black sludge in the hole....a bit mud-like. As I say....next time I will definately take the time to clean the hole and thread.

I agree with all you guys.....can it be fixed?....I think so, but I would definately ask a professional shop in stead of trying myself. Is there a risk?....I think so, even though the sleeve is pretty much a closed chamber as Dave noted. The risk of it cracking again or warping during the treatment is present, so even if it can be properly welded, it could prove more expensive to get everything sorted again than to have another cylinder sleeved...
Most of all, even if It was fixed properly, I wouldn't be sitting comfortably on my way to Normandy!

So, the only sensible thing seems to be to cut my losses, look for another Master cylinder, or at least the casting, have it sleeved in Stainless again and do the same procedure again......well, without the cracking hopefully.

thanks for the feedback guys, much appreciated!
Alex

Lynn Eades · #7 31-07-13, 03:09

Alex, it is a good lesson for us all. The gunk in the hole develops a high pressure (just like a hydraulic ram)when the stud is screwed in against it. It was probably thick enough to seal, rather than exiting down the thread.
Some guys would never say anything. We learn the fastest, when we make mistakes. When we see the mistakes of others, sometimes the warning can penetrate our own skulls. (me included)