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76 midget master cylinder

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Tipsy

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So now I've rebuilt my switch assembly and am trying to bleed the system. I put on speedbleeders so I can do it myself. But I'm now discovering no fluid is being pushed out the back half of the master. Is this due to air being allowed into the master? (Moss has a video about bench bleeding the master because you can never get air out of the master) Or did I just not realize that the rear brakes were never working in the first place? And I should rebuild master? Or can I just dissassemble master, clean out any crud (I'm sure that's the issue) and reassemble?
Thanks!
Jeff
 
Well first and foremost replace those flex hoes. The rear one is particularly prone to collapsing and shows no external signs of doing so.
 
There is a plastic bearing in those that is a real pain to extract. Often, you may have to destroy it to get it out (the rebuild kit does come with one).

Just be prepared.....it's not as simple as a normal master cylinder. I chose to just buy a new one.

The bore may also be pretty worn.....they seem to wear easy. I've thrown away a few that the bores were too beat up .

There was said to be a problem with some of the Moss master cylinders, but that issue has been resolved (the the new Moss master cylinders in my car is fine....no problem)
 
Jeff, I just posted on your switch post. As Nial says, you really can't dismantle until you take out the plastic piece - and you have to destroy it. Rebuild kits are (to my mind) cheap enough that it is worth a try before buying a new one.

That said, take off the side nuts and clean those out - that is where I found most of the crud. Then see if anything comes out (before you even put it on the car) then see if it flows through the splitter and so on.

Have you changed the rubber hoses?
 
Thanks guys. I have not yet replaced rubber hoses. Wanted to be sure master was functioning first. I've ordered the rebuild kit and will attempt that this weekend. There is no fluid coming from the back half of the master at all. So either the master is clogged or that part of the piston inside the master is not working. I do get good pressure from the front section of the master.
 
Get some red brake parts grease. That stuff is awesome!

Also, just use a propane torch to melt the plastic piece out of the bore. It's quick, easy, and it will not destroy your plunger or bore.
 
Tipsy said:
Thanks guys. I have not yet replaced rubber hoses. Wanted to be sure master was functioning first. I've ordered the rebuild kit and will attempt that this weekend. There is no fluid coming from the back half of the master at all. So either the master is clogged or that part of the piston inside the master is not working. I do get good pressure from the front section of the master.
Click to expand...

The two pistons are linked together with a sliding pin. Sometimes the pin can break. This would leave the rear piston inoperable.

The key to success in rebuilding one of these MC's (besides the usual pitted bore issues) is that the portion of the front piston that passes to the outside must be in perfect condition. If it is scratched, scored, gouged etc., the master cylinder will leak out the front. These are often damaged during disassembly while attempting to remove the deep set pair of circlips. That surface has to seal against the last lip seal in the stepped bore, so make sure it is free of defects and polished to new condition. It should look like a fresh crank journal when you're done.
 
Well, you were correct. Difficult to get apart but I managed. Only to discover as you said, the sliding pin connecting the two parts was broken partially. It looks like a cotter pin but sort of hourglass shaped. One of the legs was broken. I guess I will return my rebuild kit and get a replacement master. Can't find anywhere to buy that joining piece and there is definitely some scoring and damage to the other parts too.
 
Tipsy said:
Well, you were correct. Difficult to get apart but I managed. Only to discover as you said, the sliding pin connecting the two parts was broken partially. It looks like a cotter pin but sort of hourglass shaped. One of the legs was broken. I guess I will return my rebuild kit and get a replacement master. Can't find anywhere to buy that joining piece and there is definitely some scoring and damage to the other parts too.
Click to expand...

If it is scored don't even try to buy the part - time to replace.
 
I have a new condition OEM Lockheed MC if you are interested. I was keeping it for a future project, but I have enough on my plate already, so will likely never use it.
 
So Gerald, opinions, 1)rebuild my leaking 11 y.o Lockeed Dual Master via Sierra or 2) Find a NOS Lockeed Master 3) Usual Suppliers Chinese or Indian Made new junk.

Thinking # 1 is probably my best alternative followed by #2. And no, the list can't inform my better half they know the source of those mysterious marks that appear on her white tile kitchen floor and carpets on the basement stairs after I've driven Bugsy with my Topsiders on. I put a piece of paper towel on the carpet the other day underneath the clutch and brake pedals only to find it quickly absorbing a whole lot of brake fluid that's gathered on the carpet and transfers easily to shoes.

The fix for the summer will be a piece of carboard down there, check fluids regularly, and get it torn apart and rebuilt this Fall.
 
Jim_Gruber said:
So Gerald, opinions, 1)rebuild my leaking 11 y.o Lockeed Dual Master via Sierra or 2) Find a NOS Lockeed Master 3) Usual Suppliers Chinese or Indian Made new junk.
Click to expand...

Hi Jim,

Well, in my opinion, 3 is not an option.

I had an extra set (both brake and clutch) that were done by Sierra. They were never installed, but I sold those already. Sierra would be my first choice, but I'm not sure if he does them anymore and they are such a PiA do do, though I'm sure he'd do one for me if I asked. I have several Lockheed cores if you didn't want to yank yours out and wait for it to come back.

The one I have is pristine in every respect, but sleeving even a brand new one is probably the best option for longevity and trouble free service. All my cars are done with sleeved MC and have been for well over a dozen years. None have required rebuilding ever again. As I mentioned previously, the key to this particular one not leaking on you feet is a pristine surface on the front portion of the piston that passes externally. New seals will not help if there is any scoring/blemishes. The reason being is that there is a fluid port in the front of the MC (see pic), between the front bore piston and the external seal, so it's normal to have some fluid in that area. Just like any other lip seal, the surface it rides on is critical to it's functioning properly. I don't know if they make a Speedi-sleeve that size, but that is your only other option to correct it.


LockheedMCPORT.jpg


Original Lockheed MC

LockheedMC.jpg
 
Thanks Gerard for the update. I sent you a note. And based on everything I've heard the advice is very sound.
 
Jim_Gruber said:
Thanks Gerard for the update. I sent you a note.
Click to expand...

Jim, haven't received anything from you
 
Sent to the Contact us e-mail address on your WebSite. It has not bounced back.
 
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