Author Topic: Brake seal question  (Read 1229 times)

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Offline pookie

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Brake seal question
« on: December 06, 2015, 06:06:13 PM »
I think I put this in the wrong section yesterday, but here is my question.

I am looking at replacing my caliper seal on my front brake.  Simple and may be a stupid question, but does the seal need anything before it goes into the groove? Coat of silicone spray or grease maybe?

Manual says silicone grease on back of pads, and brake fluid inside surface of cylinder.

It seems there should be something to keep fluid from getting around the seal. Or maybe it's late and I am over thinking it...

Thanks
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Offline seanbarney41

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Re: Brake seal question
« Reply #1 on: December 06, 2015, 08:43:24 PM »
absolutely NOTHING inside the seal groove, except the seal, OK?
If it works good, it looks good...

Offline flybox1

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Re: Brake seal question
« Reply #2 on: December 07, 2015, 01:42:34 PM »

please read this...

read this before you assemble anything...

http://forums.sohc4.net/index.php/topic,56544.0.html

This thread has gotten very confused.  Lets' review.
There are four products needed to restore a caliper.
1. Brake cleaner
2. Brake parts assembly lube for the caliper seal only.
3. Dow corning High vacuum grease.
4. Brake fluid

Each has it own specific application and needs for the task to be performed.

#1 is used to get everything clean.  (given the confusion, it had to be said)
#2 is used ONLY on the seal and must be compatible with #4, as some of it will invade the brake fluid chamber.
#3 is NOT used on the seal, as that would put silicone inside the brake fluid chamber.  This is a bad thing as the compounds are incompatible.  It is used behind the brake pads and a thin coat is used on the parts of the calipers and piston that are exposed to the elements and subject to water ingression.  The Dow Grease will not mix with ANYTHING.  It is a simple barrier with the very important property that it will NOT melt when the parts get hot and then run/creep into the brake pad friction material and provide lubrication between pad and disk rotor.
#4 is what makes the hydraulic part of the brake function. (I hope that part is clear.)

The "Permatex Counterman’s Choice Ultra Disc Brake Lube" I have NOT used.
It is NOT to be used in the #2 application (directly on the caliper seal, as that would put some inside the brake fluid vessel and is clearly NOT it's intended application).

Depending on it actual composition, it may be suitable for the #3 task, IF and I stress the IF part, it will not melt/run into the brake pads.  The brake pads/rotor interface are where you WANT fiction!

Previous discussions in this forum were regarding Syl-Glyde, which I have personally tested and can pretty much guarantee that it will run/creep into the pad to rotor interface.  It only contains silicone as a minor ingredient.  The rest of this (Syl-Glyde) compound cannot take the 500F plus heat that the Dow corning grease can without doing a phase change.

The remaining question is whether Permatex Counterman’s Choice Ultra Disc Brake Lube will run/creep into the brake pads/rotor, especially when it gets hot, in this application on the Honda brake caliper.
I don't have any, I haven't tested it, you use it at your own risk.  I do know the Dow corning silicone grease DOES work properly and certainly appears to be the same stuff Honda used during production assembly.
I admit I am skeptical.  The last time a counterman recommended a product for #3 application, it was Syl-Glyde which, if he were still working behind the counter, I'd be tempted to make him eat.

+1 That's the thread I was trying to find :)
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Offline jonda500

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Re: Brake seal question
« Reply #3 on: December 07, 2015, 06:41:38 PM »
absolutely NOTHING inside the seal groove, except the seal, OK?

+1   ^this!^

John
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Offline NobleHops

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Re: Brake seal question
« Reply #4 on: December 07, 2015, 08:48:40 PM »
Do you have a Dremel? If so, chuck up a nice soft brass brush and run around that seal groove a few times scouring each side. You'll be surprised at the cloud of dried brake fluid you kick up from your nice clean caliper.

If that's not going back into service immediately, use a brake assembly lube instead of brake fluid to lube it on assembly.

WRT lube on the back of the pads, that is different stuff, must be high temp brake grease or antusqieal paste, use only the lightest smear between the antisqueal plate (if you have one) and the pad, and likewise, just a light smear on the side between the piston and the pad - only in the area that the piston bears on. A little is enough.
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Offline pookie

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Re: Brake seal question
« Reply #5 on: December 12, 2015, 05:07:52 AM »
Thanks guys.

I'd like to say I jumped right on this and buttoned everything up and it's all back on the bike.... But the sickness attached our house so I haven't yet.  I got the brake assembly lube and hope to get it all together tonight.

Thanks again
1973 Honda CB500 (project)
2003 Ducati Monster (DD)