spf72

my 64 rear brake cylinder is leaking and when I pulled it I was surprised by the build up of "gunk" - that's my technical term. I normally would just buy a new part but all of the replacements are made in China. Just something wrong in putting a China part on an old corvette. It looks like a pretty straight forward rebuild although I don't want to waste time and destroy another set of brake shoes if they usually leak. Opinions?

LouieM

This is an easy job that I've done many times. Definitely avoid Chinese brake parts!

GTOguy

If not pitted or badly worn, super easy. Hell, you don't even need to unbolt it from the car to hone it out and put a kit in it! Agree, stick with USA parts if possible!

juanvaldez

Like they said, easy. You need a GM kit and a brake cylinder hone. I would take the wheel cylinders off if possible. Might as well do 'em all at the same time, if one is bad they all so will be. Nothing but soap and water, brake cleaner or brake fluid to clean with.

Can you get O.E.M wheel cylinders? Like other have said, time is money. The cylinders are pretty cheap. I usually try to just replace cylinder unless I can't get 'em.

DUB

Yep and they will continue to leak and fail in time due to the properties of the DOT 3 brake fluid and it not being bled out from time to time.

My response is somewhat 'slanted'. I repair these...so my time to hone and rebuild a wheel cylinder would he higher than if I replaced it. And seeing how many of my customers are looking for a 'deal' and I do not want to spend time and not get paid...I would replace them.

AS for putting China part on your car....get used to it.... know I have. And that is when I buy AC Delco parts that they are made in China in some cases. Not all parts from China are crap...it has everything to do with their quality control.

And you might be surprised that if you go an buy a seal kit...where it may come from.

DUB

LouieM

If the caliper bores are too pitted, then you can buy stainless steel-sleeved factory-original calipers from several CF vendors. I've used Muskegon Brake for this several times in the past. They will even SS sleeve your very own calipers if you want, at least they used to offer this service.

0Willcox Corvette

If it were my car, the first thing I'd do is run a hone through it (with some oil) and then inspect it for pits. Tiny pits can be honed out, larger ones will deem the core useless. Most of the time a good hone and an new seal kit will do the job. You should be able to get the seal kit from your local parts store.

IMHO-

Willcox

juanvaldez

Remember, all you wheel cylinders are like that!

0Willcox Corvette

Good point.. and instead of heading to the wood shed multiple times it'd be a good idea to do them all and bleed one time.

Willcox

DZAUTO

One thing that is misunderstood and people are often misled, is in regard to pits inside wheel cylinders. SOME non-knowledgeable mechanics tell customers that if the wheel cylinder has pits, it should be replaced. WELLLLLLLLLLLLLL, maybe so, maybe no. IT TOTALLY DEPENDS ON WHERE THE PITS ARE LOCATED INSIDE THE CYLINDER!!!! If the pits are NOT in the area where the piston cups move in and out, then the cylinder can be rebuilt and saved! REMEMBER THAT!!!!! If the pits are in the center of the cylinder, IT DOES NOT MATTER!!!! And last, as pointed out above, the small pits can be removed by honing. I use a wheel cylinder hone chucked up in an AIR (NOT electric) drill, under running water (or a 5gal bucket) an constantly move the hone in and out to produce a very nice surface. After honing in the water, I immediately dry it with compressed air and wipe the bore with brake fluid.

SWCDuke

Chances are all the hydraulic components have sludge buildup and possibly corrosion. Have the wheel cylinders and m/c ever been rebuilt in the 52 years this car has been on the road?

The sludge is probably wear particles from the seals. They cause the fluid to darken and eventually drop out. Chances are the m/c has sludge buildup at the bottom, too, if it has not been rebuilt or replaced in the last 10 to 20 years.

Rebuild all the hydraulic components, flush out the pipes with denatured alcohol and thoroughly dry with compressed air.

A complete hydraulic rebuild is a good time to switch to silicone fluid, but you should disassemble any store bought parts that are assembled with conventional fluid, clean with alcohol and reassemble with silicone fluid. If brake hose age is unknown replace them and flush with alcohol since the ends are swagged on with conventional fluid as a lubricant.

Periodic fluid changes will purge the system of wear particles. With conventional fluid it should be done every two to five years to also flush moisture out of the system that can cause internal corrosion. Silicone fluid won't absorb moisture, but flushing every 5-10 years will purge wear particles.

Bores should be honed using conventional brake fluid as a lubricant, NOT OIL! Then if using silicone fluid clean the bores with alcohol and lubricate with silicone fluid for assembly.

If you do a complete hydraulic system rebuild and then maintain it properly as above the system should last for decades.

Duke

Pilot Dan

I had my original Delco wheel cylinders and master SS sleeved. No more worries even if the car sits for long periods over the winter. Honing works well if you can exercise the brakes regularly to keep the rust ridges from returning. Inactivity is the enemy here. With stainless it does not matter. We do this for Disk brake cars routinely so other than some extra cost why not for vintage drum brake cars as well.
Pilot Dan

cardo0

Having rebuilt brake cylinders myself before I learned the time saved was more valuable than the tiny cost of new cylinders. The "gunk" u find may well be the same corrosion products I found in mine and the process of removal then honing took several hours. While good experience I could have upgraded to disk brakes w/same effort. And who will see Chinese cylinders inside of a brake drum?
But on the other hand u may just want this experience for yourself. Good luck to you.

I'd have to say DUB is 100% correct here.

DUB

For what this is worth.... and this reply is from what I have seen countless times.

When having a brake part stainless steel sleeved...which is a good idea....DOES NOT make it totally impervious to wear and leaking.

I have replaced so many brake calipers that were stainless steel sleeved and leaked like crazy..and that is BOTH designs (lipped seal and O-ring).

Knowing that the movement of the seal on the brake piston is so minor...it is the presence of sludge that allows for wear on the sleeve. The rubber seals ...oddly do not seem to 'wear out'...but rather it is the pressure of these rubber seals against the stainless steel sleeve and the abrasive nature of the sludge that slowly wears down the sleeve and puts a groove in it.

SO....regardless of what part of a brake system has been stainless steel sleeved....if sludge can get between the seal and the bore...and move...it will wear out the sleeve.

How long this may take...I do not have a crystal ball to know that. But I do know that if a person keeps up on there DOT 3 fluid quality...they have a better chance of allowing the brake system to last longer...due to the opportunity of sludge and moisture to build up....and cause for the system to leak or ahve issues in performance.

DUB

Roger Walling

If you are thinking of rebuilding them, make sure the bleeder screw can be removed without breaking BEFORE going any further. (ask me why I know about this little detail)

Pilot Dan

Agree with Dub but the wear issue originates from inactivity more so than over use. Especially if you have big temperature swings which causes condensation and moisture that starts the process of rust in the first place. All of that being said, the SS sleeved wheel cylinders with Dot 4 all are still perfect and clean 8 years later. Have not touched them.

warrenmj

His '64 has drum brakes, not disc.

DUB

I AGREE if it is in regards to wheel cylinders...and then I have to politely disagree..and that is only from the numerous cars I service are being driven quite often and not just sitting a round....and this reply is mainly dealing with the brake calipers I work on and NOT wheel cylinders....which are completely different....as we know.

And I am TRULY glad that your brake system is not giving you any issues. Gotta love it when something lasts for a long time and has no problems.

DUB

Pilot Dan

Was responding to the OP in particular since this thread is about wheel cylinders and not calipers. FWIW, I have installed the SS sleeved Wheel cylinders and master combo on numerous vehicles, but 8 years is the oldest install. None have shown any problems.

rfn026

This job is going to grow exponentially. I’m going to suggest some intermediate steps but you’re probably looking at a total brake system rebuild.

Gunk: If you have a lot of gunk in your wheel cylinder then you have the same gunk throughout the entire hydraulic system. Every wheel cylinder and the master cylinder are full of this gunk.
Flush the entire system with denatured alcohol (available from amazon.com). Keep flushing until you get clear alcohol. Then fill the system with new brake fluid and bleed the brakes until you get pure brake fluid. You might get lucky here. You might also discover that the system was held together by gunk and you’ll never get a solid pedal.

Brake Fluid: White Post Restoration and Lonestar Caliper both suggest that you avoid silicone fluid. People on this forum love it. The people who rebuild brake systems for a living have found a lot of problems. About a decade ago the silicone formula was changed and the new formula seems to be no longer compatible with the rubber seals. I use DOT 3 fluid myself.

Honing: I’ve honed hundreds of wheel cylinders over the years. I no longer do it. When you hone a wheel cylinder you enlarge the bore. The seals only come in OEM size. That is a problem. How big of a problem depends on how much material you remove from the bore.

Sleeves: I’m a big advocate of sleeves. I’ve used White Post over the past few years and never had a problem. The good part is that I keep the original wheel cylinders (if that’s important to you) and the brass sleeves don’t rust from moisture.

Regular Brake Flushes: This is a big deal. If the ’64 that started this discussion had been flushed every few years none of this would have happened. You should flush the system ever two years.

Spf72 has a choice here. He can replace the leaking cylinder this week. And put the car back on the road. In a couple of weeks he can replace the next one that leaks. Over the course of the year all the wheel cylinders and the m/c will be replaced. The option is to do the m/c and all 4 w/c right now. Just get the wrenches and Visa card out and have at it.

Richard Newton
Straight Axle Alignment