Topic: Front caliper assembly ? Lube or no lube?

[Toxic]

So I have been reading and searching and I don't know why some guys put lube on the front caliper seal and piston.
Specific caliper assembly lube is available.
The Honda manual says nothing about doing this.

On page 142 of the Honda Manual it explains the operation of the piston within the caliper.
The seal deforms as the piston is pushed outward applying the pressure to the brake pad allowing it to make contact with the disk.  When the pressure is released ie: you let go of the brake lever the deformed seal returns to the normal position thus retracting the caliper piston.

It would seem applying lube to the seal and piston would interfer with the above operation of the seal.

Granted installation would be allot easier with a little lube.

[Gamma]

I'm going to assemble mine with a spalsh of DOT 3 brake fluid, then if I can't get pure silicon grease for the back of the fixed pad, I'm going to use a teenie bit of Copperslip on the back.
http://i192.photobucket.com/albums/z293/galaxy8155/DSC02448.jpg[/img]]

[Duke McDukiedook]

No, you want to use brake assembly lube if you are using DOT 3 brake fluid.
You are setting yourself up for corrosion problems if you use DOT 3 fluid as an assembly lube.

You could use a silicone assembly lube if you have new lines and completely cleaned everything out for DOT5 brake fluid.

Read this thread
http://forums.sohc4.net/index.php?topic=55318.0

[Toxic]

Thanks for that link but it still doesn't make sense why you would lube the seal and piston considering the way Honda describes how the seal functions.  If you lube the seal would it not distort the way it supposed to in order to retract the piston.

 

[Toxic]

Well this much is clear... you shouldn't use brake fluid to lube.

This was taken from TT's post in the above link and it makes sense but not when you consider how Honda says the seal is to function.

You lube the caliper seal with the assembly lube.
The caliper seal divides the DOT3 area with the outside atmosphere.  Whatever you lube the seal with, it must be compatible with DOT3.
If you use DOT 3 to lube the seal, some of it is then outside the seal in contact with atmosphere.
DOT 3 will pull water out of the atmosphere and place it in contact with the metal parts that will then begin to corrode.
Brake parts assembly lube does NOT attract moisture from the atmosphere.  In fact, it acts as a barrier to prevent moisture from contacting the metal parts of the caliper.
Brake parts assembly lube blends easily with DOT3 on the inside of the caliper.

You decide which is the correct lubricant for the application.

Also if we were to use some sort of lube, would it not say so in the Honda shop manual?

[Duke McDukiedook]

The lube is just to help you get the piston in the caliper and maybe wet the surface of the seal.
Kinda like putting a little oil on the rubber gaskets when you put on an oil filter.

[Gamma]

I don't disagree with the reasoning on corrosion from hydroscopic activity of brake fluid.  However, I'm a glutton for punishment.  These calipers were in the open scrap yard for probably 20 years so they will out live me, even if I use a little brake fluid on the seal.

[TwoTired]

I don't disagree with the reasoning on corrosion from hydroscopic activity of brake fluid.  However, I'm a glutton for punishment.  These calipers were in the open scrap yard for probably 20 years so they will out live me, even if I use a little brake fluid on the seal.

Two years, you'll have caliper binding/retraction issues and will have to rebuild the caliper again.  Must be a glutton for maintenance! 
BTDT, and I live in an arid climate!  (although, I do ride in what rain we do get, when I get caught.)

[Toxic]

The lube is just to help you get the piston in the caliper and maybe wet the surface of the seal.
Kinda like putting a little oil on the rubber gaskets when you put on an oil filter.

It's not at all like putting oil on the rubber gasket of an oil filter.  The difference is in the way this caliper seal has to distort in order the caliper piston to retract.
Sure the lube will make the assembly much easier and I get the part about the lube providing a barrier to prevent moisture from getting into the system.
The piston is going to slide just fine in the caliper but with lube on the seal I don't see how it is going to function as per the Honda manual. You probably won't the retraction you should be getting which could be the reason for some people complaining of the rotor getting excessively hot. If the piston doesn't fully retract and is making slight contact with the rotor you are bound to have some build up of heat.

Not trying to be argumentative, just trying to understand the system.

Ultimately we all make our own choices.

[Duke McDukiedook]

I used assembly lube on the piston/seal and the Dow silicone grease on the dome/puck on my rebuild and I have had zero problems so far.
No squealing either and I am using the EBC pads.

Ultimately it is your choice how you want to do this, but when Lloyd and others recommend a certain way of doing things, I tend to listen and take notes.

[TwoTired]

There is a lot of pressure between seal and piston that squeezes most of the lube out during assembly.  On the fluid side, some of it is dissolved by the brake fluid itself.  At any rate the seal must provide a sliding surface if it is to compensate for brake pad wear.  So over time, the assembly "lube" slowly marches out as the piston does.  Even with the lube, there is still purchase by the seal onto the piston for retraction.  I've done several, it works fine. No dragging brakes.  Far more important is the piston surface condition, the caliper groove condition, and having a compliant seal.  Compare the resiliency of a new seal with one that's 25 years old.  If it feels the same, then reuse the old one.  If it feels hardened, it probably won't distort when the piston moves and will slide instead, that will certainly effect retraction.

Are you trying so hard to talk yourself out of using assembly lube because it is difficult to find?  Have you seen the lube?  It has only slightly thicker viscosity than Dot3.  It isn't THAT much more slippery than Dot3.  It's main benefit is that it doesn't harden, evaporate or phase change with age, and is not hygroscopic, providing a barrier to water and oxygen.   The bottle I have says it is polyalkylene glycol and inhibitor, if you are keen to look up chemical properties.  By the way, DON'T use this with silicone brake fluids.

You're right though, we all make our own choices.  I've got brake parts assembly lube, and I use it on my caliper seals.  Good luck with your choice!

[hapakev]

Granted installation would be allot easier with a little lube.

Come on! nobody is going to touch that? 

[Toxic]

Thanks TT that explanation makes more sense. It fills in allot of blanks.

I have the assembly lube so that's not the issue, I was just trying to understand how the system would work if the seal is lubed and unable to distort and retract the piston.

Your explanation is logical.

I have Permatec Ultra Slick Synthetic Brake Lubricant so I'll use it.  The directions say to use it on pistons, rubber sleeves and seals.

[MoTo-BunnY]

I just don't understand with all of the many posts and tons of information on here, from long time pros that have been working on these bikes since they were new, people STILL try to use everything BUT the right lube/grease on the front brakes. . .wow.

The Dow Corning high-vacuum grease is all over the internet, for like $15 or so. It seals your brakes against water, it holds it's temp against the highest of heat your brakes will encounter. There is NOTHING at your typical auto parts store that will work anywhere near as good, even though the guys working there will try and tell you otherwise. Anything they have won't resist the high temps once your brakes heat up, and will run right out.

You are soooo setting yourself up for failure about a year or two down the road, when your brake piston will end up looking like this:

[TwoTired]

I have Permatec Ultra Slick Synthetic Brake Lubricant so I'll use it.  The directions say to use it on pistons, rubber sleeves and seals.

I couldn't find that product with an internet search.  I hope it works out for you.

[Gordon]

I have Permatec Ultra Slick Synthetic Brake Lubricant so I'll use it.  The directions say to use it on pistons, rubber sleeves and seals.

I couldn't find that product with an internet search.  I hope it works out for you.

http://www.permatex.com/products/Automotive/specialized_maintenance_repair/maintenance_repair/Permatex_Countermans_Choice_Ultra_Disc_Brake_Lube.htm

[razor02097]

hrmmmm... I used WD-40 on my finger and wiped the seal then WD-40 on rag and wiped the piston.  Its something I already had at the garage.

[Duke McDukiedook]

hrmmmm... I used WD-40 on my finger and wiped the seal then WD-40 on rag and wiped the piston.  Its something I already had at the garage.

Eeeeek! 

[hapakev]

I just don't understand with all of the many posts and tons of information on here, from long time pros that have been working on these bikes since they were new, people STILL try to use everything BUT the right lube/grease on the front brakes. . .wow.

The Dow Corning high-vacuum grease is all over the internet, for like $15 or so. It seals your brakes against water, it holds it's temp against the highest of heat your brakes will encounter. There is NOTHING at your typical auto parts store that will work anywhere near as good, even though the guys working there will try and tell you otherwise. Anything they have won't resist the high temps once your brakes heat up, and will run right out.

You are soooo setting yourself up for failure about a year or two down the road, when your brake piston will end up looking like this:

is this the stuff?

http://www.2spi.com/catalog/vac/dow.shtml

[lowmileage]

I'm getting my new seal in a day or 2.  Is this assembly lube (not the Dow stuff which I have) something that a regular parts store is going to have?

or do I have the chase the world around like I did for RU Glyde 

[Duke McDukiedook]

You'll have to do a little digging to find it and the average kid at O'reilley's won't know what the hell you are talking about.
The dude at NAPA might know.

[lowmileage]

  NAPA is 15 miles away - I was just there last week to get the RU Glyde 

[TwoTired]

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.

[Toxic]

Thanks that is great info.

Specifically this is the product I found.


The instructions say specifically it is for both the rubber seal and the piston and when applied to the back of the pads it will stop squeaks.

Good to 400F

Thanks for clearing that up.

[lowmileage]

That's the goo some people apply to the back of brake pads to prevent chatter and squeeking.  IMO, you should address why it squeeks and not mask the problem with applying that goo.  But we're getting off topic.