Master Cylinder Rebuild

[Baron3-6]

So, I've replaced the front flex lines (and one small section of steel line fused to the old flex line) and am bleeding the brakes...lots of pumping, bleeding, and constantly topping off the master cylinder later....still soft pedal...I have no bubbles at the bleeders, but small bubbles forming in the master cylinder reservoir now. I'm thinking either I just have ton of air from replacing the lines and need to keep bleeding, or my master cylinder is starting to go.

I have the Napa rebuild kit for it (UP1).....but I've also noticed that complete master cylinders are around $80...so:

Anyone rebuilt one? and is it more of a pain in the a$$ that $80 for the new one would be worth it.

NAPA AUTO PARTS

 

[Roller]

I usually go with the complete rebuilt unit. By the time you clean and rebuild the old one, assuming it is rebuildable, the cost of one ready to go is worth it.

Frank

 

[hndrsonj]

You know you can install split master cylinders from a late 70's early 80's chevy truck cheap and update the safety of the system while doing it? I'll dig out my stuff tonight and find the info (doing this is my weekend project anyway).

 

[poppop]

I have rebuilt many master cylinders just not on M37's. Rebuild is fine if it hones out clean and will be cheaper. But if you don't get a shiny surface on the complete bore it will not hold up. If it were me I would hone my master and evte its condition and go from there.

 

[pwrwagonfire]

Did you open the vent line on the top of the MC when you were bleeding? I was having the same thing as you are having happen until I did that...bleed like a dream, then closed it afterwards.


I was given advice on here a couple years ago not to re-build; I'm sure once would be fine, but hone that out too many times and it gets pretty out of spec!

Let us know how it goes!

 

[hndrsonj]

Here's what I am installing this weekend.

M37 master cylinder manual

 

[Baron3-6]

pwrwagonfire,

Is this the valve you're referring to? (see pic)
It didn't mention this in the TM I've got on bleeding but that makes sense....

Thanks!

 

[emr]

FYI I have brand new Deuce and 5 ton master cylinders, deuce 50... 5 ton 80 plus ship from Nj, I need a phone number and zip if interested, ...

 

[pwrwagonfire]

pwrwagonfire,

Is this the valve you're referring to? (see pic)
It didn't mention this in the TM I've got on bleeding but that makes sense....

Thanks!

Yup! Thats the valve. The manual talked about opening that valve when using a power bleeder, so I figured what the ****, might as well try it, and it worked!

 

[Baron3-6]

Well I didn't end up using the valve, although it sounds like it makes things much easier. I looked at mine, covered in rust, looking rather frail, and heard my inner voice say to me "if you try to open this you will **** this up so bad only a weekend and $100 at the Napa will fix it"......and this time for once, I listened.

I bled each line in order about 8 times over and after lots of pumping....I got the pedal to stiffen about 1/2 way to the floor, ideally should be 1/3. I'll let it sit a few days and then give it one more good bleed. At least she has enough brakes for a good victory lap around the neighborhood!

Paint is coming nicely too!

 

[pwrwagonfire]

Well I didn't end up using the valve, although it sounds like it makes things much easier. I looked at mine, covered in rust, looking rather frail, and heard my inner voice say to me "if you try to open this you will **** this up so bad only a weekend and $100 at the Napa will fix it"......and this time for once, I listened.

You're lucky...I usually don't pay attention to this voice until its too late!!

 

[g2065g]

NAPA AUTO PARTS

This kit looks identical to the m35 kit. Is it the same or just the same parts but different diameter? Trying to find a Part number at NAPA for the m35 so I can try to get one local.

Will this work for rebuilding a m35a2 MC?

 

[doghead]

Looks correct, but can't tell or sure.

 

[g2065g]

That kit is only 18 bucks at NAPA. I will see if I can get one here local and compare sizes. I will post what I find out.

The kit is about half the diameter of the m35 cylinder. No go.