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1500 midget master cylinder

jim79

Senior Member
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Near death experience today- no brakes. I have always has a little leak onto the pedals but today it let go. My question is: Is there an aftermarket/performance option or is the same style but new option sufficent?
My new best friend is the emrgency brake handle, saved my butt. :frown:
 

Gerard

Luke Skywalker
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The style MC you have is dual circuit, meaning you should have a backup function to the system, should one circuit fail. It does require you have a working shuttle valve (the 5 port brass distribution valve you have in the engine bay). Do you know for certain it is the MC that gave way and not a wheel cylinder, low fluid level, flex hose of fatigued/cracked hard line.

I would examine the entire system to try to determine where the failure occurred and why. My thought is that if the MC actually did fail, the entire system should be examined anyway.

This style MC is complicated to rebuild <span style="font-style: italic">correctly</span> and in my experience, usually done incorrect by the shade tree mechanic. If you plan to rebuild it yourself, make sure that:

1. If it has been rebuilt in the past, the the piston exiting the front of the MC (the part the pushrod enters) is not damaged an any way. It needs to be smooth/blemish free and highly polished, other wise your new seals with still leak.
2. the link between the forward and aft piston is intact and functional. This is a sliding link that is sometime broken, twisted or bent, that will prevent proper functioning.
3. Determine if the lip and or cup seals failed, causing a breach.
4. If the bore is pitted (almost always are), that it can be honed out within seal tolerance. If not, either have it sleeved or buy a new MC.

As to alternatives, you can probably find something that can be retrofitted with some modifications. Something in the Tilton line may work.

That should get you started.
 
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J

jim79

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Just got done looking under the hood. It looks like my occasional drip got bigger.The front resevoir was empty and the rear was 3/4 full. So I'm assuming that my shuittle valve isnt functioning correctly? As for the red brake warning light, that thing has been stuck on since I broke the switch. :blush: I guess I never thought I'd need it. The master cylinder was rebuilt 6 years ago by myself. I remember it was slightly pitted back then.
I think I need a new switch,proportion valve and new master cylinder.
As you can tell, this really scared the crap out of me. As I get older, all the danger lights and warnings seem to be things I take more serious.
Again, any opinions on the new master cylinders? I assume better than remanufactured? I would love to put a tilton on that car but it'd probably blow all the lines and wheel cylinder at the same time(or throw me threw the windshield).LOL.
Thanks for the reply,
James
 
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jim79

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I hate spelling errors. (through the windshield I meant). Im mourduring the queens language yuk yuk yuk
 

Gerard

Luke Skywalker
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"The front one empty" could mean you just have air in there, and that could have caused the loss of braking. I would start by seeing if you can refill it and get some pressure back. I suspect you will. The leak you speak of, is typically caused by the scarred (external) piston. There is a seal at the front of the bore, which is solely to keep bypass fluid from exiting the MC. If that piston is not smooth, it'll never seal and will always leak, no matter what else you do. If that is damaged, and you have pitting, those need to be corrected. You can look into whether a Speedi-sleeve is available, which will restore that surface. I have also been able to polish up that surface, if it is not too deeply scarred. After that, I recommend you have the cylinder brass sleeved. I do ALL of my master cylinders that way and I never have a problem with them after that, no matter how long they sit. I even have new or new condition ones sleeved as they will be trouble free for a much longer period of time. Especially in Michigan! (I spent my early years in the Detroit area)

Some of the repro ones aren't great. Either they're not made correctly or won't last more than 6 months. So I personally prefer restoring an original Lockheed, than replacing with an reproduction. I can send you to the right guy for sleeving, should you decide to do that but he won't do one that's been badly handled, because you sometimes can just not make them right. YMMV

P.S. Fluid dripping down the pedal is really bad too, because your foot can slip, the end result being as bad as no brakes at all.
 
G

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Here's how I handle brakes on old cars:

New M/C
New hoses
New Wheel cylinders
Rebuild calipers


Do it all right the first time and you're done.

Piece meal it and you'll be fighting it when you could be driving it.
 
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J

jim79

Senior Member
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Did you put a new water pump, radiator, hose,new fuel tank fuel pump ,fuel lines, carb, etc? At some point you used used parts(piece mealing). It's the nature of restoration.

Everything was new in my brakes system except the master cylinder and shuttle valve. Hindsight = Shouldve got a new master cylinder 6 years ago but it might have leaked by now also?
Thanks for all the advice. I might contact you about the brass sleeving trick.
James
 

Morris

Yoda
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You can order a brand new MC from advanceauto.com. Plus I think they are having a 20% off sale. I have no idea of the quality. I just saw it the other day while looking for something else.
 

Jim_Gruber

Yoda
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From the pics at the Advance Auto site the MC they are showing for a '68 Sprite Mk4 is a single not a dual master. More research needed to see if product shown for later years is a correct Dual Master.
 

Morris

Yoda
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IIRC, the list the correct master for the 1500... which, IIRC, is also the correct master for all dual circuit cars??? It seems that I was looking up '74 for some reason, and that looked like it was a dual circuit.

It's been awhile since I looked at that stuff.
 

Gerard

Luke Skywalker
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Bugeye to '62 are tandem, combined clutch brake 7/8" MC
'62 - '66 are same except 3/4" bore
'67 is separate clutch and brake MC, single circuit brake.
'68 onward is dual circuit brake. However, there are two different size bores for the clutch MC's
 
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