Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Wed Mar 16, 2016 2:24 pm Post subject: Master cylinder question
Been a while since I was here. It has actually been about a year since I even need with the Jeep. So anyway, I was taking the pedal cross shaft and pedals off because i have a LOT of play in the brake pedal arm (turned out that I need a new cross shaft AND brake pedal arm - I already have new bracket). That's when I saw the brake fluid leaking from the boot. So after I realized that would have to order parts, I shifted my attention to the master cylinder. I pulled it off and tie it down. I cleaned it up and replaced the cups on reassembly. I cleaned all of the ports which had a bunch of crap in them. Ok, so here's my question. I thought that one of the ports in the bottom of the reservoir was plugged, but when I ran a drill bit down into it, it was not drilled all the way through. The one I am referring to is the 5/32" hole in the middle of the reservoir looking straight down into the filler hole. Is this supposed to be drilled through also? That would explain my brake problems if so. _________________ Matt
1953 M38a1
1964 USMC M38a1
'51 USMC M100 trailer, '54 M100 trailer, '90 M101a1 trailer
Http://wilfreeman.wordpress.com (M38a1 build blog)
http://m38a1usmc.wordpress.com (USMC M38a1 rebuild blog)
Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Wed Mar 16, 2016 5:34 pm Post subject:
I think there are two holes, feed and return. I wouldn't go drilling them oversize, just clean them so they are open. If the bore in the cylinder is pitted from rust, cut your losses and buy a new master. John
Joined: Nov 19, 2010 Posts: 107 Location: ITALY - TUSCANY
Posted: Thu Mar 17, 2016 2:29 am Post subject:
Matt, I checked 2 of my "spare" (read take-off) master cylinders. Both have a shallow indent approximately in line with the center of the filler opening. Really look like tooling marks from when the filler opening was bored out and threaded. I'd say definitely not supposed to be a through hole. That's my story and I'm sticking to it. David _________________ David Manning
1952 M38A1, 1953 M38A1, 1954 M38-A1, 1952 M100
Photos on Page 10 of Members Albums.
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Thu Mar 17, 2016 6:17 am Post subject:
Thanks guys, man, I thought had found my problem there! Oh well. The bite and everything looked good on it - just figured it needed new cups bc it was leaking. Then i saw that partial hole. I went ahead and ordered a bunch of parts to get everything back up to snuff for the convoy at the rally ina few weeks. _________________ Matt
1953 M38a1
1964 USMC M38a1
'51 USMC M100 trailer, '54 M100 trailer, '90 M101a1 trailer
Http://wilfreeman.wordpress.com (M38a1 build blog)
http://m38a1usmc.wordpress.com (USMC M38a1 rebuild blog)
I think there are two holes, feed and return. I wouldn't go drilling them oversize, just clean them so they are open. If the bore in the cylinder is pitted from rust, cut your losses and buy a new master. John
I used to work with some guys that had rare antique cars that contained parts that were unobtainium including wheel and master cylinders. When the cylinders were ruined from pitting, they took the cylinders to a machine shop and they bored them out and pressed in a liner made of stainless steel. I think there are now shops that specialize in doing this kind of work.
thats affirm on the boring of brake cylinders. try and check out "white post restorations in virginia" i live in the philippines and needed a new cet of cylinders for my j24a. there are none to be had here. i ended up buying one from japan . the most expensive master cylinder in the world! over 450 $ !!!! a friend was visiting from the states and i had the retrogrades on my bench, he offered to take them back to conus and white post has them now 400$ to repair resleeve two wheel cylinders and the master cylinder. i couldnt bear to throw them away after shelling out all that coin on new ones. they've done work for me before and have been very satisfied so far.
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Mon Mar 28, 2016 9:07 am Post subject:
Come to find out, the "unfinished" hole I was referring to actually has a very small hole inside the 5/32" partially drilled hole that is drilled through. I found a diagram online that showed this to be a bypass hole. I used a welding tip file to clean this hole out, as I didn't have a drill bit small enough. Mine WAS plugged.
I installed an NOS kit in the master cylinder, bled it and installed in the Jeep. I must have had the steel lines installed off center, because when I pressed the pedal, brake fluid leaked out like a sieve! I tightened them and got the same result. When I pulled the lines back off, you could see indentions on the brass y fitting mating surfaces. I figure this is why it is not sealing. I am going to replace the brake lines that connect to the master cylinder today since they are rusty on the outside. I will have to order a new y fitting though. The Denton rally is coming very fast - I am hoping I can get the brake issue resolved before April 14th! _________________ Matt
1953 M38a1
1964 USMC M38a1
'51 USMC M100 trailer, '54 M100 trailer, '90 M101a1 trailer
Http://wilfreeman.wordpress.com (M38a1 build blog)
http://m38a1usmc.wordpress.com (USMC M38a1 rebuild blog)
Joined: Nov 19, 2010 Posts: 107 Location: ITALY - TUSCANY
Posted: Mon Mar 28, 2016 9:25 am Post subject: MASTER CYLINDER
Matt, did you make sure to use the soft copper washers on either side of the fitting?They act as a gasket. dwm _________________ David Manning
1952 M38A1, 1953 M38A1, 1954 M38-A1, 1952 M100
Photos on Page 10 of Members Albums.
Joined: Mar 13, 2006 Posts: 1079 Location: Richburg, SC
Posted: Mon Mar 28, 2016 10:00 am Post subject:
Yes sir - I installed new ones. It was leaking at one of them also, but that leak stopped after a thorough tightening. After I replace the lines, I'll hook them up to check for leaks before I order a new y fitting, but I am guessing I will have to buy a new one because of the indentions in it causing the leak. _________________ Matt
1953 M38a1
1964 USMC M38a1
'51 USMC M100 trailer, '54 M100 trailer, '90 M101a1 trailer
Http://wilfreeman.wordpress.com (M38a1 build blog)
http://m38a1usmc.wordpress.com (USMC M38a1 rebuild blog)
thats affirm on the boring of brake cylinders. try and check out "white post restorations in virginia"
White Post is the place that I was thinking of but I couldn't remember the name. I was in a car club with the owner of White Post over 30 years ago. I still remember the 3 wheel Morgan that he used to drive around! IIRC he also had supercharged Cord! (drool!)
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