Rear caliper E-brake lever sticking.

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Bruce2
Posts: 6845
Joined: Sat Oct 13, 2001 3:01 am

Rear caliper E-brake lever sticking.

Post by Bruce2 » Sat Dec 29, 2001 8:39 am

I've got a problem with one of the E-brake levers sticking when the car isn't driven for extended periods. I took the whole mechanisim apart a couple of years ago and cleaned it up and greased the pivot. But its back again. I sprayed some WD-40 and worked it last night, but its not as free as the other one. Any ideas on how to free it up good and stop it from reocurring?

94teener
Posts: 129
Joined: Sat Sep 22, 2001 2:01 am

Rear caliper E-brake lever sticking.

Post by 94teener » Sat Dec 29, 2001 11:51 am

It might be that the brake caliper piston is sticking in the cylinder, rather than anything to do with the lever.
As you know, a little corrosion occurs in the braking system if the old fluid is not flushed out and replaced every year or so, especially when a car sits idle for weeks at a time. Every caliper I have ever rebuilt had rust spots or rings on the pistons. The only reason for ever rebuilding calipers is because of piston surface corrosion. The seals never wear out.
Phil

Bruce2
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Rear caliper E-brake lever sticking.

Post by Bruce2 » Sun Dec 30, 2001 6:26 am

I went to silicone fluid 7 years ago to prevent corosion. The last time the lever stuck (98), I took the whole caliper apart and the piston and bore were spotless. It was the lever at that time.

94teener
Posts: 129
Joined: Sat Sep 22, 2001 2:01 am

Rear caliper E-brake lever sticking.

Post by 94teener » Sun Dec 30, 2001 10:07 am

Looks like I am wrong in this case. I suspect you will have to take the lever mechanizm apart again, perhaps polish and lube all of the metal contact surfaces.
Phil

Bruce2
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Rear caliper E-brake lever sticking.

Post by Bruce2 » Mon Dec 31, 2001 6:11 pm

Didn't do a damn thing to the calipers or MC. I just cleaned out the DOT3 crap and poured in the DOT5. MC is probably a Brazilian one. Front calipers are ATE with ATE seals, rear calipers are whatever comes stock on a 914 (ATE?) Hoses are original. Haven't seen any problems like you describe. Drove the car through Vegas a year and a half ago when the temp was 120.2, brakes felt no different. Converted my new 2001 Mexican Bug to DOT 5 too. Wonder what kind of seals they use?
As for silicone still absorbing water, I disagree. Moisture in the air will still find its way into the resevior through the vent, but it will not absorb into the fluid like DOT3. I live in a very damp climate, and one of my DOT 3 cars requires a new MC every 2-3 years due to corrosion. The DOT5 car is going on 7 years without any repairs to the hyd system (only that sticking lever)

I checked the lever last night and it returns ok now. Not as good as the other, but good enough.

ray greenwood
Posts: 1941
Joined: Thu Jul 19, 2001 2:01 am

Rear caliper E-brake lever sticking.

Post by ray greenwood » Tue Jan 01, 2002 2:09 am

Just a note, silicone fluid does not prevent rust. It prevents the absorption and emulsification of water into the fluid which lowers the boiling pt....and causes rust. But it doesn't keep water from entering the system as vapor/condensation. Question: What did you replace your caliper and master cylinder seals with? DOT 5 silicone fluid is incompatable with stock seals. Stock seals are BUNA-N. Silicone needs to use EPDM. Some later master-cyls and caliper seals were made with EPR which is a variant of EPDM and usually works OK with both fluids. One of the characteristics of seal attack by silicone fluid is swelling and sticking of the seals. They will begin to disintegrate if you live or drive in hot climate....been there...had it happen to me. Ray

ray greenwood
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Rear caliper E-brake lever sticking.

Post by ray greenwood » Wed Jan 02, 2002 3:06 pm

As I noted...and probably was not clear, silicone is not hygroscopic, so therefore does not ABSORB water...but carries and mixes with condensation just the same. The absorption of water into brake fluid was intentional in the design of brake fluid. This was to prevent compressable pockets of liquid (not that water is really compressable, but does tend to have a differntial compared to brake fluid surrounding it, an creates pockets of steam vapor unless mixed at the molecular level...hence the miscability of regular brake fluid). DOT 5 silicone fluid was not designed to prevent rust, and will not any more than 3 and 4. Dot 3 and 4 only cause rust when mositure is at a high saturation point. At that point...rust is the least of your worries, as the boiling point will be down in the 180's. Dot 5 is designed to have a much higher boiling point and exhibit less fade in high performance vehicles. That is the purpose of it. It should have no problems with the brake lines...but it will sooner or later...usually sooner, eat the seals of they are not compatible. The usual first symptom is locking of calipers...or non-retraction. When the master cylinder succumbs...the seals literally crumble. Brand of brake part has nothing to do with seal material...as all manufacturers have made seals of various types. You would do well to disassemble and inspect to see what you find. A lot of the latest vehicles...starting I'm not sure when, but probably the 80's, almost all went to EPR seals and should have no problems. I've been here before. The failure is ugly. It will require something in the neighborhood of flushing with MEK to get all of the residual from any brake-fluid and associated black seal sludge out of a system. This is also why they reccommend replacing hoses when changing fluid types, as the hoses will die from MEK, MIBK or hexane/benzene based cleaners. Ray

TomB
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Rear caliper E-brake lever sticking.

Post by TomB » Wed Jan 02, 2002 4:36 pm

I'll stay away from the fluid discussion - that shouldn't affect the ebrake mechanical levers anyway.
Rather than the lever, you may have the shoe either sticking to the backing plate or the drum. There is a raised bump on the backing plate that guides the middle of the shoes, and if that isn't greased lightly the shoes can stick on it when left in place a while. The shoes can also stick to the drum from light rust in a damp situation. I once had a Vanagon stick so tight I had to pull the inspection plugs and rap the shoe with a drift to get it loose; just rocking the car wouldn't do it.

Bruce2
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Rear caliper E-brake lever sticking.

Post by Bruce2 » Thu Jan 03, 2002 2:11 am

Brain fade Tom, this is the 914 Porsche forum. All 914s had 4 wheel discs, never drums.

ray greenwood
Posts: 1941
Joined: Thu Jul 19, 2001 2:01 am

Rear caliper E-brake lever sticking.

Post by ray greenwood » Thu Jan 03, 2002 11:24 am

The fact that the retraction action (coool I made a rhyme!) is in part (they do have a spring) due to the distortion of the caliper seal...this is why I would disassemble and inspect. Dot 5 makes some variants of Buna soft (swelling and pressure collapse) and others hard as a rock (usually causing cracking and leakage) either way, lack of elasticity can casue sticking. The difference is in Buna N (more synthetic ingredients than natural) and plain Buna which is also a synthetic, but a little different. With the importance of brakes, if you didn't specifically...with before hand knowlege...change the seals to match the fluid....it would be good caution to check. I would hate to see you hit something...but usually the brakes will lock up totally at a light one day when they fail...leaving you imobile. Ray

Bruce2
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Joined: Sat Oct 13, 2001 3:01 am

Rear caliper E-brake lever sticking.

Post by Bruce2 » Thu Jan 03, 2002 8:54 pm

Ray, Although your concern is admirable, your facts of the characteristics of brake fluid are dead wrong.

"silicone is not hygroscopic, so therefore does not ABSORB water...but carries and mixes with condensation just the same"

How does it carry and mix with water if it doesn't absorb it? I tested your theory last night by pouring water into silicone fluid. It absolutely does not mix. They react the same as oil and water. The water formed a bubble at the bottom of the container. I then looked into the brake resevior of the car that's had it for 7 years to see if there were any bubbles of water. None at all.

"The absorption of water into brake fluid was intentional in the design of brake fluid"

If it were intentional then why does every auto maker recommend you flush it out every 2 years? Why do they stress the fresh fluid must come from a sealed container? The answer is to get rid of moisture laden fluid. Moisture doesn't help brakes, it destroys brakes.

"DOT 5 silicone fluid was not designed to prevent rust"

I refer you to the fine print on any container of DOT 5 fluid. Here's a quote from one of mine:
"It [DOT 5] does not absorb water like conventional formulations thereby maintaining its original boiling point and viscosity. Used properly, DOT 5 will outlast other brake fluids and reduce brake system corrosion."

To me that sounds like prevents rust. What do those words mean to you?

Racer Chris

Rear caliper E-brake lever sticking.

Post by Racer Chris » Wed Jan 09, 2002 4:03 pm

I just had to replace an e-brake cable that was sticking. The caliper was fine.
You should still bleed the brakes regularly with DOT 5 and if the seals are affected you'll see black residue in the fluid.

Chris Foley

ray greenwood
Posts: 1941
Joined: Thu Jul 19, 2001 2:01 am

Rear caliper E-brake lever sticking.

Post by ray greenwood » Wed Jan 09, 2002 7:39 pm

Bruce...I never said silicone brake fluid was hygroscopic. Dot 3 and 4 ARE...and they are designed to be that way. As I said, DOT 5...which is usually...but not always...silicone based is designed to NOT be hygroscopic...BUT it still carries water. Usually in bead and droplet form. This is not hygroscopic. The dot 5 spec silicone fluids were created for one purpose only, to carry a much higher wet boiling point. There is no way to keep water vapor from condensing in any brake fluid. The difference is, that in DOT 5, silicone based...it will not affect the boiling point like in the DOT 3 and 4...and does not have to be changed nearly as often. When the water beads contact metal...they still rust. They also still cause vapor pockets when they get hot enough to evaporate. These usually ...eventually... end up in the resoivoir...and will not homogenize with the fluid. Re-read my posts, you got my point backwards. And get this..if you poured water into the DOT-5 fluid...and saw it bead up...and not mix...you saw exactly what I described above....BUT the water is now STILL in the fluid...is it not? Every day, Caliper seals suck in moisture on retraction, and in the rain on almost every stroke...hence that nasty rust line you get. The vent in the cap to allow for expansion, allows humidity in on every brake stroke. In cool weather...it condenses...you get water beads....looks just like water in gasoline..almost. But the water is there...and rusts on exposure to metal. No effect to the boiling point with DOT 5...but rust pits kill cylinders. Most people can prevent all rust with any brake fluid, simply by flushing the moisture saturated fluid every spring, before it has time to emulsify with the mineral base of the oil. Until about 1983...this used to be in most Mercedes manuals as a dealer service requirement for this very reason. Silicone is good stuff...but unless you know exactly what kind of rubber you have in your cylinder...you are playing with your life. I'm glad the brake cable was all there was wrong. I have been researching seal materials for almost a decade trying to source slave cylinder seals for clutches and obsolete master cylinders. Be very careful what you put silicone....and even mineral based fluids into. Ray

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