Brake wheel cylinder AH HA!

[Keith_J]

I had discovered why so many wheel cylinders are leaking, cheap cylindrical springs without cup expanders. I had always thought these were rebuildable/repairable but checking the parts manual, I found the SMR is PAOZZ, meaning a stocked item that is replaced and DISPOSED at unit level, not repairable.

Just another case of some supplier selling inferior parts to the government.

 

[avengeusa]

hmmmm, I know a guy who owns a factory that makes seals.....

 

[Katahdin]

Are the NAPA Rebuild kits any better? Just wondering if I should go through them or a surplus dealer.

 

[swbradley1]

At the risk of starting a war is it better to rebuild or buy NOS? I'm sure my one truck with no brakes has a leaking wheel cylinder and if I have to mess with one it wounded like a good time to do them all.

sw

 

[gringeltaube]

I had discovered why so many wheel cylinders are leaking, cheap cylindrical springs without cup expanders. .......................

Remember: KISS..... To my knowledge they had those "cheap" springs as you call them, since M-35s do exist and they usually don't leak.... until cylinder wall corrosion and pitting takes place. Even the best expanders won't help then.
The problem is humidity and condensation occurring behind (outside) the rubber cups and causing corrosion of the cylinder.

Here are my : if you want any WC (rebuilt or new, NOS or "aftermarket", expander-spring- or not) to last for decades and stay dry(!) don't install them as they come out of the box! Pull out the pistons, lubricate them with silicone grease and re-install, then put plenty of silicon grease in the cavity between piston and dust boot, eventually glue the dust boot and rods in place using PU-adhesive and change brake fluid from time to time, if it isn't DOT5!


G.

 

[Keith_J]

Are the NAPA Rebuild kits any better? Just wondering if I should go through them or a surplus dealer.

IDENTICAL to OD Iron. Good to go! Thanks for the source!

 

[Keith_J]

Remember: KISS..... To my knowledge they had those "cheap" springs as you call them, since M-35s do exist and they usually don't leak.... until cylinder wall corrosion takes place. Even the best expanders won't help then.

Here are my : if you want any WC (rebuilt or new, NOS or "aftermarket") to last for decades and stay dry(!) don't install them as they come! Use lots of silicon grease to assemble the pistons and links, glue the dust boots in place with PU-adhesive and don't forget to change brake fluid from time to time, especially if it isn't DOT5!


G.

Actually, silicon brake fluid is good enough lube for the pistons. The problem with corrosion/leaking is more likely when the master cylinder has the poppet check valve instead of the breather line. This allows negative pressure to build in the master cylinder. This can cause the influx of water in the wheel cylinders.

I have yet to see any wheel cylinder that took more than 30 seconds of fine honing to restore proper finish. Never have seen corrosion with DOT 5, amazing. On other vehicles, I have seen rusted WC to the point it was pitted, far beyond repair.

Silicone DOT 5 is far better than any glycol, IMHO. It just won't absorb humidity. Glycols have a tenacious affinity for water but also have higher bulk modulus, making for better "feel" especially in servo drum brakes. The Deuce and larger have non-servo brakes, meaning DOT 5 is perfect. Now CUCVs? Especially M1009s which don't have the load-proportional rear brake line regulator? Caveat emptor. I have witnessed one lock up and heard about another.

Drive safe and do your PMCS! Don't be afraid to hone your wheel cylinders, kits are available at NAPA, see above.

 

[gringeltaube]

Actually, silicon brake fluid is good enough lube for the pistons.
..................

Even if you had easy access to DOT5...... AND if you never would drive through water over the axles ....AND, AND ..... there is no guaranty that the brake fluid INSIDE the cups will keep the piston completely lubed all around since travel is minimal when brake shoes are correctly adjusted !!
So condensation and galvanic corrosion WILL take place sooner or later if the boot is not completely sealed and there is no silicone (grease) present OUTSIDE the cup, to preserve all metal surfaces involved.

Doing what I explained above gives you extra insurance in any case, for many years! It has worked well for me and others who do a lot of fording, in a part of this world where DOT5 still is completely unknown/unavailable!

G.

 

[stumps]

Are the NAPA Rebuild kits any better? Just wondering if I should go through them or a surplus dealer.

The OD Iron kits look beautiful. They are new, and they have the proper expander springs.

About $6 bucks each.

-Chuck

 

[stumps]

At the risk of starting a war is it better to rebuild or buy NOS? I'm sure my one truck with no brakes has a leaking wheel cylinder and if I have to mess with one it wounded like a good time to do them all.

sw

Get a brake cylinder hone, and rebuild. I have never found a brake cylinder that was too far gone for that method. Most of the rust that may exist is inside of the space between the cylinder seal surfaces, and as such doesn't matter.

Also, if you buy a complete wheel cylinder, you won't know, unless you take it apart, if it has the right spring inside of it.

-Chuck

 

[TexAndy]

Get a brake cylinder hone, and rebuild. I have never found a brake cylinder that was too far gone for that method. Most of the rust that may exist is inside of the space between the cylinder seal surfaces, and as such doesn't matter.

Also, if you buy a complete wheel cylinder, you won't know, unless you take it apart, if it has the right spring inside of it.

-Chuck

This. A wheel cylinder rebuild takes about 10 or 15 minutes. Not hard at all.

 

[gringeltaube]

...... A wheel cylinder rebuild takes about 10 or 15 minutes. Not hard at all.

WOW! That is FAST! What's the trick....? - or do you not count the time to get it out and back in place again...?

G.

 

[TexRdnec]

WOW! That is FAST! What's the trick....? - or do you not count the time to get it out and back in place again...?

G.

i'm a big fan of the rolley eye smiley but i like to reserve its use for a time when something cannot be naturally assumed. in this case, immediate access to the brake cylinder

but you know, it's whateva...

 

[swbradley1]

Thanks guys. I'll buy a hone. Gives me an excuse to get more tools.

Like I needed and excuse......

 

[SgtHatred]

Are the NAPA Rebuild kits any better? Just wondering if I should go through them or a surplus dealer.

Does anyone know the part number for these on NAPAOnline.com?

Thanks!

 

[lavarok]

The OD Iron kits look beautiful. They are new, and they have the proper expander springs.

About $6 bucks each.

-Chuck

Super easy job once the brake drum is removed. I was pleasantly surprised how easy it was to rebuild and the OD kits work perfect. Get a honing tool...they are cheap and for the extra couple minutes it takes to hone, you will have piece of mind of a job well done.

 

[jasonjc]

Here is what the inside of the wheel cylinder may look like. All 6 looked like this one. But the brakes were working good.

 

[markmontana]

This cylinder came from a truck that was rebuilt only a few hundred miles ago. While sitting out in the yard, it lost brakes. It was obvious which wheel was leaking- inner tire was wet. The rubber piston cap not installed correctly- so dirt got thru. Be sure to get those rubber on tight... I've seen more than one that was partly open.

 

[Heavysteven]

All,
What is a honing tool? Is it used to remove rust from inside the cylinder? Where would you purchase one from? Is there a ccertain size?

Update found at Harbor Frieght good to go

 

[Crazyguyla]

Get a brake cylinder hone, and rebuild. I have never found a brake cylinder that was too far gone for that method. Most of the rust that may exist is inside of the space between the cylinder seal surfaces, and as such doesn't matter.

-Chuck

Chuck,

You can have at this wheel cylinder for rebuild. Short of a press, the cups wont budge. This is the example of a wheel cylinder to far gone to rebuild. I have totally rebuilt the brake system from the master cylinder to wheel cylinders. Everything from the MC to the wheel cylinders was clogged with rust.
The fun of bending steel brake line and double flares. Stil have 5 wheel cylinders to replace and the airpack. Then I should have brakes

Marcus