Who's rebuilt a master cylinder?

Hey guys,

I was flippin through a catalog the other morning and I noticed they sell master cylinder rebuild kits for my 56 Bel Air. I thought to myself........ self, could probably do that. Didn't look like there were many parts in it, which isn't a surprise.

But, my question is, has anyone out there rebuilt one, and are there any special tools or procedures that would discourage me from trying it? I love learning to do things like this as opposed to just going out and buying a new one.

 

If the bore of your MC is not pitted or rusty then it shouldn't be a big deal. You will need to hone the bore, cheap brake hone available most auto parts stores. Make sure everything is clean before assembly, lube parts with brake fluid as you assemble.

 

You should price a rebuilt first. Many times a rebuilt is about the same price as a rebuild kit. If you have a nearby NAPA try them for price. You probably wouldn't have any luck with Auto Zone or that type

 

I was wanting to do it for the experience, not necessarily a cost saving measure. But then again if a rebuilt one is cheap enough, I may go that route.

But, mine isn't leaking and seems to work fine, athough the only braking I have done is when I was backing the car down a car trailer. Stopped it no problem.

 

Rust and pits in the bottom of the MC usually determine if it can be usable after a rebuild...hone it if necessary...it's not hard to rebuild one...not many moving parts...I've done it on the side of the road...you'll have to bleed the entire brake system once done tho.

R-

 

As noted, you'll need a hone.
They don't cost much and a variable speed 3/8" drill motor is a good way to drive the hone.

Use brake fluid for a honing lubricant lubricant.

Insert the hone before turning on the drill motor.
That saves the hone and helps to keep the M/C from becoming 'bell-mouthed.'

Hone till you have a nicely finished bore.
It doesn't take much.

A black mark or stain in the bore doesn't hurt, but as Bellm says, if it's got rusty pits that don't clean up with a reasonable amount of honing, toss the M/C and get another.

Clean the honing detritus out with rubbing alcohol.
Get that at a drug store - they have sales so get 2-4 bottles and keep em on hand for jobs like this as well as cleaning up other brake components.

Most times bench bleeding the M/C will do it, if not, bleed the whole system.
Probably time for fresh fluid anyway.

If you have an old brake hone take note of the stones and make sure they're straight.
A lot of guys pull the hone too far out when they hone and that can create a bell-mouth in the bore as well as make the hone stones wear in the middle.
Replacement stones are available.

KD makes a good brake hone, if you buy one, grab a replacement set of stones while you're at it.

 

i have done quite a few mc rebuilds, now i can buy a new mc cheaper then a rebuild kit, once apon a time you could go into any auto parts store and just buy the rubbers for about $2 each, that made it $8 to rebuild your masters plus your time, i have 2 nice master here now that only need new rubbers but i,ll be damed if i,m paying $45 for a kit when i can buy a new master for $35.

 

This won't make much difference since they still make 56' master cylinders, but if you have an odd master cylinder, these are the guys to go to. They can also resleeve for different size bores.

www.brakecylinder.com

 

anyone over 50 has probably done many. along with starters, Generators, wheel cylinders. all those could be rebuilt for a couple bucks. till the parts houses figured out they could make an extra 20 bucks with black paint and a kit. after that it was almost impossible to find a kit. now it's a multi-million dollar business.

 

I would stay away from the hones that have the two or three springy legs on them.......use a ball hone instead that fits your bore.....Snap-on has 'em.....second the idea of using alcohol to keep it clean........clean is good.....clean, clean, clean.

 

You might consider measureing the bore when done - they do publish dimensional limits - not that many folks actually bother to follow them when "backyarding it"

 

Buy a new cylinder, bench bleed it, install it on the car, bleed the brakes, enjoy driving the car.
When you don't have anything else to do, take the old cylinder apart, buy a kit, rebuild it, put in in a box with a tag marked, "rebuilt" and sell it at the next swap meet you attend.

 

That's an idea too.

 

maybe if there some old guys checking this thread out who live in CA, you could give theses guys a call and see if they make new master cylinder rubbers and would sell them to us, you never know it could be a nice little mail order business suplying guys who want to rebuild there own masters, just an idea. http://www.kdlprecision.com/home.htm