TheSamba.com :: View topic - What Causes Brake Cylinders to Seize Up Over Time?

Tue Oct 17, 2017 5:23 am

Hi Guys,

I replaced the wheel cylinders, master cylinder, and brake shoes on my 68 Beetle three years ago.

This car is a daily driver and has not sat parked for more than two to three days in all that time.

My car started pulling to the right when I brake, and I inspected the brakes all the way around the other day to see what was going on.

Well, apparently the front-left wheel cylinder has seized-up, along with the right-rear wheel cylinder.

And this isn't the first time my wheel cylinders have seized-up.

They were seized-up when I bought the car ten years ago, and they were starting to seize-up three years ago when I replaced the wheel cylinders the last time.

So what causes these wheel cylinders to do this?

I'm using OEM wheel cylinders and DOT3 brake fluid with a thorough bleed ever time.

My theory is that this is design related.

The brakes are designed to allow a human leg to stop a 1,850 pound car, but the trade-off is that the brake shoes move only a few thousandths of an inch at a time.

And it's that lack of substantial movement that contributes to the cylinders seizing-up over time.

But maybe there's something I'm missing? Or am I doing something wrong?

Tue Oct 17, 2017 5:45 am

Yep great question

Tue Oct 17, 2017 6:17 am

I don't think it's design related. Getting only 3 years out of OEM wheel cylinders seems very unusual. I've never got that little service out of a wheel cylinder. What brand do you consider OEM? Are you lubricating the piston when you install it?

Tue Oct 17, 2017 6:24 am

[quote="Mudpump"]I don't think it's design related. Getting only 3 years out of OEM wheel cylinders seems very unusual. I've never got that little service out of a wheel cylinder. What brand do you consider OEM? Are you lubricating the piston when you install it?[/quote

Tue Oct 17, 2017 6:28 am

The cylinders don't come greased. What are you using to grease them? Should be using Red Rubber Grease as it doesn't degrade rubber and doesn't react to brake fluid.

Tue Oct 17, 2017 9:17 am

DOT3 and DOT4 brake fluid absorb water from the air. This can cause stuff to get rusty if the brake fluid is not changed regularly.

If you're using DOT3 or DOT4 you are supposed to replace all the brake fluid every 2 years.

Tue Oct 17, 2017 9:54 am

Just a thought but maybe it's your proximity to the Pacific Ocean..... Is your car exposed to salt water or salt spray somehow ?

Tue Oct 17, 2017 9:54 am

over heatjng from a dragging brake can seize them up. this can be from too tight brake shoe clearence, internally swollen hose (they may look find on outside, but be horribly restricted inside, preventingthe fluid from flowing backwards once pedel is released) as mentioned brake compatible grease need be used upon assembly. the master could be adjusted wrong (push rod clearence) to allow full rectraction when pedel is released.

something is wrong, tossing new cylknders at the problem may not fix it long term. so go thru the above stuff. if hoses are very old, they are suspect. with car elevated, stomp and hold the pedel down hard, then release the brake pedel and immediatly have help rotate the wheel, do this for each of the fojr wheels. if they drag immediatly after relase of pedel, then the hoses are highly suspect.

good luck, Now Stop It!

Tue Oct 17, 2017 10:34 am

I have fixed a couple of friends brakes because of this exact problem. The Cyl's were not very old but had seized.

The cars had never been driven in rain or coastal salty air.

The pistons and cyl were corroded because of dissimilar metals...That was the consensus from some of my mech buds, including myself.

As I replaced the cylinders the new cylinders had brake assembly grease already installed. The ones I removed showed no application of assembly grease!

Inspect new cylinders for brake assembly grease!

Tue Oct 17, 2017 11:00 am

I dont thinkmit is do to dissimular metals, both pistons and cylinder appear to be iron alloys. besides grease wont prevent this type of corrosion unless the grease totally electricaly isolated the two different metals.

lack of grease and the hydroscopic nature of brake fluid are probably the cause. some folks make the mistake of using brake fluid as an assembly lube for these parts, that will certainly cuase corrosion issues.

If you do a complete system rebuild replace all ruber parts, then a conversion to dot 5 silicone fluid makes good sense, kt is non hydroscopic, and wont harm paint. but before conversion al, the old rubber parts need be replaced with new.

good luck, stop sure!

Tue Oct 17, 2017 11:26 am

Are there any cons to switching to DOT5? Do all wheel cylindes, rubber lines and MC need to be replaced?

Tue Oct 17, 2017 11:42 am

vamram wrote: Are there any cons to switching to DOT5? Do all wheel cylindes, rubber lines and MC need to be replaced?

That's the main con, you have to replace everything rubber in the system.

Also for some reason no one can really explain, DOT5 seems to eat the brake light switches.

Tue Oct 17, 2017 12:56 pm

sjbartnik wrote: vamram wrote: Are there any cons to switching to DOT5? Do all wheel cylindes, rubber lines and MC need to be replaced?

That's the main con, you have to replace everything rubber in the system.

Also for some reason no one can really explain, DOT5 seems to eat the brake light switches.

You only need replace the rubber parts, the cylinders are fine to reuse if cleaned and new rubber installed.
I have not had brake light switch problems since converting, over two decades of DOT 5 use on the Bug.

another pro conversion point is you no longer have to do regular flushing as the fluid is non hydroscopic.

Tue Oct 17, 2017 1:25 pm

Q-Dog wrote: The cylinders don't come greased. What are you using to grease them? Should be using Red Rubber Grease as it doesn't degrade rubber and doesn't react to brake fluid.

Would you mind providing a link? I have never lubed up my wheel cylinders during rebuild, but wouldn't mind trying it for future rebuilds.

This???
https://www.amazon.com/Raybestos-BAF12-Brake-Asembly-Fluid/dp/B001ANJ2GE

Tue Oct 17, 2017 1:44 pm

kangaboy wrote: Q-Dog wrote: The cylinders don't come greased. What are you using to grease them? Should be using Red Rubber Grease as it doesn't degrade rubber and doesn't react to brake fluid.

Would you mind providing a link? I have never lubed up my wheel cylinders during rebuild, but wouldn't mind trying it for future rebuilds.

This???
https://www.amazon.com/Raybestos-BAF12-Brake-Asembly-Fluid/dip/B001ANJ2GE

No, you want a paste, what you linked is a liquid. the old VW service manuals called out to use Genuine VW Brake Paste, but anybrand that is compatible with with the internal brake hydroulics will be fine. beware of grease that is sold as brake grease that is not compatible with the internal wetted parts. this type is simply a high temp grease used on non wetted parts such as caliper pins or as an anti squeak material for disc pads.

So make sure the lable states it is for use on tne wetted brake parts or pistons and rubber boots....

https://www.amazon.com/Permatex-24115-Caliper-Hi-Temp-Silicone/product-reviews/B000HBGKH4

the above link is what I use. back of bottle states it is ok to applynto pistons and rubber sleeves.

good luck, Stop Sure!

Tue Oct 17, 2017 3:27 pm

Do an internet search for "red rubber grease" and you will find several brands. And as mentioned, "brake grease" from your flaps will work as long as it says it is compatible with rubber and silicone ... some aren't.

Tue Oct 17, 2017 3:43 pm

I found this sheet in my new BRAX master cylinder. It states a "correct smearing" of this grease on the internal bits of the wheel cylinder and seals. Never heard of such a thing in 47 years of VW ownwership. Also never had a wheel cylinder seize like that. Is it a recent development from inferior materials?

Do I need to disassemble my new M/C and grease it up? I am not arguing here just amazed that I never knew.

"correct smearing" gotta love that....

Mike T

Tue Oct 17, 2017 4:07 pm

I've always just smeared a thin film of anti-seize around the piston. Probably not optimal but I've never had an issue using it.

Tue Oct 17, 2017 5:57 pm

Hi guys, thanks for all the great replies.

The thing that's really jumping out at me is the grease deal.

So if I put in a brand new wheel cylinder, it is not pre-greased?

And I need to take it apart, grease it and then reassemble it?

Is that correct?

Tue Oct 17, 2017 5:58 pm

BIGMIKEY wrote: I found this sheet in my new BRAX master cylinder. It states a "correct smearing" of this grease on the internal bits of the wheel cylinder and seals. Never heard of such a thing in 47 years of VW ownwership. Also never had a wheel cylinder seize like that. Is it a recent development from inferior materials?

Do I need to disassemble my new M/C and grease it up? I am not arguing here just amazed that I never knew.

"correct smearing" gotta love that....

Mike T

My Bentely Official VW Service Manual and several other VW service book I have state to use the brake grease or brake paste. Been using it for 40 years on my cars. same with other makes I have worked on.

one poster mentioned antisieze use, I would be hesitent to use the same antiseize that I use for my exhaust studs and such for my brakes as the container does not say it is brake system compatible. Some greases and oils will destroy the rubber brake parts, and many repair manuals state that. it could be some antisieze greases are safe, but Id not risk it unless it states on the package that it is specifically ok.

also the brake grease is handy for lubing the threads on the flare pipe threads on the cylinders and bleeder screws, helps prevent them rusting and getting stuck.

good luck