Master Cylinder Rebuild

[Mark Hedberg]

Thanks to a post in the string from a few days ago telling me where to look, I think the master cylinder on my '64 is shot - fluid oozing around the brake pedal on the inside. I've seen some rebuild kits in the usual catalogs for about $20 - $30. Is this a job for a do-it-yourselfer, or do I need to get a "professional" to rebuild the unit (at 5-6 times the price)? Anyone have any experience with the various rebuild kits out there - do they include all necessary parts & instruction? Thanks.

Mark

[Joseph S.]

Re: Master Cylinder Rebuild

The rebuild is very easy. I redid my '66 MC using a kit from Long Island Corvette Supply but all the majors supply a kit...~$15, I think. I also honed the MC using a brake cylinder hone...worked great.

The instructions are simple, just make sure you carefully seat the seals, using plenty on brake fluid as a lubricant.

The big deal is bleeding the MC when done. I put it in a vise, installed a brass fitting on the front which attached to a flexible tube that ran back into the reservoir. Fill the reservoir and push the piston a number of times with a broad, blunt rod to get out all the air. Do that for a couple of minutes...you'll be amazed at home much air was in there.

[John H.]

Re: Master Cylinder Rebuild

When you disassemble your master cylinder, inspect the bore surface very carefully - if it shows any evidence of pitting or scratching, stop right there and send it out to have it professionally sleeved. If you haven't torn into a master cylinder before, make a sketch as you disassemble it so you know where the new parts go (seals, springs, check valve discs, etc.) - most rebuild kits don't have any instructions - just parts.

John

[Jerry Clark]

Re: Master Cylinder Rebuild

Hi Mark:

A very simple rebuild, make sure to rinse the cylinder after honing, denatured alcohol, I believe, ( it is specified on the kits).

jerry

[Mark Hedberg]

Re: Master Cylinder Rebuild

Honing? Alcohol to clean up the entire unit? I'm an absolute beginner when it comes to brakes.

[Jerry Clark]

Re: Master Cylinder Rebuild

Hi Mark:

If this rebuild makes you uncomfortable and you feel your mechanical expertise may leave something to be desireed, by all means have it done. I mean NO OFFENSE, it is only logical that if you are not content with your ability the brake system is not where you should practice. If you have ever rebuilt a wheel cylinder successfully , you should be able to do the brake master, if not, any reputable shop can perform this rebuild and it wont cost you an arm and a fender.

jer

[Wayne M.]

[Joe L.]

Re: Master Cylinder Rebuild

John and Mark------

I absolutely agree with John; if the master cylinder bore is scored, corroded or otherwise damaged IN ANY WAY, you must have it sleeved. I would not hone a master cylinder bore OR ALLOW ONE THAT I WAS GOING TO USE to be honed in any serious way. A very few well lubricated passes with the hone IS IT. Maximum. Period. Seriously honed master cylinders WILL NOT hold pressure.

If necessary, have your master cylinder sleeved with brass or stainless. This is expensive, but it's the only way to properly recondition a master cylinder with a damaged, albeit ever-so-slightly, bore.

[Joseph S.]

Re: Master Cylinder Rebuild

Hmmmm....

I think you may want to send your MC out for restoration. If you don't feel comfortable rebuilding a MC, you certainly don't want to start fooling with honing the wall. Honing is, as described previously, a polishing of the surface with care not to remove any meaningful surface material.

On the contrary, the kit I got from LICS included instructions so the install was straightforward.

If in doubt, send it out for rebuild.