Author Topic: Front caliper assembly ? Lube or no lube?  (Read 38583 times)

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Offline TwoTired

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Re: Front caliper assembly ? Lube or no lube?
« Reply #76 on: August 17, 2009, 11:54:54 AM »
Great that it doesn't run.
Does the material resume it's original appearance and properties when it cools down to room temperature?
What we would need is that it will still remain a barrier to water for the metal on which it is applied, before after the heat excursions.  With the Dow Corning stuff, you couldn't tell afterward that it had ever been heated.  I notice your sample doesn't glisten the same before and after the test.  But, you may be going beyond the temp that it is expected to survive without a property change.

Still looking like a good substitution, though.  It would be very interesting to see how the Dow corning stuff would fare in your test oven.  But, I'm guessing it would fare about the same.  I only went to 500F in my tests.  The display numbers on your oven are in degrees C, right?
If you have an old caliper seal, it might be interesting to see at what temp that seal gets destroyed.  To my reasoning, the grease only has to withstand the temp range that the seal can, (and not run and survive).  That, and maybe the glue used to bond the brake pad to the steel backing.

Nice work!

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Offline Gamma

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Re: Front caliper assembly ? Lube or no lube?
« Reply #77 on: August 17, 2009, 12:44:12 PM »
Yes the oven is reading in Centigrade, we use it for heat treatment of aluminium.

Although I didn't touch the grease during the experiment, it appeared to be unchanged up until at least 399C which, in our oven is approx 382C (calibration error) which is 719F.  After this it was obviously drying out (boiling off slowly) and I ended up with a crystaline powder. 
I don't have an old seal handy, but might salvage one from the rear calipers I've got.
Next time I do this I will stop at 400C and see what it looks like when it's cooled.

The boys are wondering why I'm spending so much time at the oven  ;D

Offline TwoTired

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Re: Front caliper assembly ? Lube or no lube?
« Reply #78 on: August 17, 2009, 01:13:37 PM »
The boys are wondering why I'm spending so much time at the oven  ;D

Yes. Scientific testing, Research and development, product verification do take time.  This is a concept mostly lost on today's "instant gratification" society.

Sometimes you design a test, and then realize mid test that the test itself is wrong and tainting the needed results.  Then you refine the test and start over.

You should be glad this test isn't really complex at all.  I mean, we aren't considering atmospheric pressure, temperature change rate, air-borne contaminants, substrate contamination, photonic contributions, gravitic or magnetic anomalies...etc.  ;D

Recall the "fly in the ointment" saying?  Or the movie "The Fly"?  How about Homer saying "DOH!"

 ;D ;D
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Offline MoTo-BunnY

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Re: Front caliper assembly ? Lube or no lube?
« Reply #79 on: August 17, 2009, 03:00:40 PM »
Very well done.  . .this is the kind of stuff I love the internet for. This was like a DIY Consumer's Reports test or something. . ..lol

Thank you for sharing!
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Offline Gamma

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Re: Front caliper assembly ? Lube or no lube?
« Reply #80 on: August 18, 2009, 06:27:48 AM »
I have no idea what the temperature of a working caliper is, but today I held it for 45 minutes at 250C (482F) and let it cool.  It looked exactly the same and was still slippery to touch, but it did have a slight skin on it.  So I suspect that in time, held at that temperature or above, it would eventually dry out.  The data sheet did say 200C as being the top of it's operating range.
Yes I could go on and on messing about with it, but at least it doesn't run.
« Last Edit: August 18, 2009, 08:31:58 AM by Gamma »

Offline Duke McDukiedook

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Re: Front caliper assembly ? Lube or no lube?
« Reply #81 on: August 18, 2009, 06:43:29 AM »
Don't forget cosmic rays and neutrinos, you can't forget those too.
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Offline buffalogt750

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Re: Front caliper assembly ? Lube or no lube?
« Reply #82 on: August 19, 2009, 07:43:03 AM »
I am horrified at Motorcycle Classics magazine. Latest issue has an article on rebuilding the brake caliper for their CB500 cafe project that will be given away in October. They actually recommended lubricating the caliper seal with (you may want to sit down for this) brake fluid. What can they be thinking?  One can only imagine what else they may have done to this heap. I am contacting them today to demand that they immediately withdraw my entry from this contest!
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Offline spitfire

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Re: Front caliper assembly ? Lube or no lube?
« Reply #83 on: August 19, 2009, 11:24:32 AM »
Used silicon grease when I rebuilt the brakes on my CB750F (as per the manual), after spending a fair bit of time getting rid of all the crystalised brake fluid and Aluminium oxide I thought it might help things stay a bit cleaner. Got the grease from a place that tunes bikes as everyone else just gave me blank looks when I asked for silicon grease.
That must be about 2 years ago and all seems well so far.

Cheers

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« Last Edit: August 19, 2009, 11:26:15 AM by spitfire »
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Offline magconpres

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Re: Front caliper assembly ? Lube or no lube?
« Reply #84 on: April 28, 2011, 11:03:36 PM »
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.)

Great thread.
I am planning ot use Lucas Girling Rubber grease (part 64947011 for a 1/2 oz packet) on the caliper seal because I happen to have a packet (my neighbor restores Austin Healey's and gave it to me).  It says "For use on rubber components in, or near to break fluid.  No other grease to be used." on the packet, so I think it will be fine for that purpose.  I got 1 oz of the DC high vac grease off ebay for $10 (shipping incl.) that should serve me for quite a few rebuilds.

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Offline TwoTired

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Re: Front caliper assembly ? Lube or no lube?
« Reply #86 on: June 14, 2012, 10:26:47 PM »
http://www.ebay.com/itm/DOW-CORNING-Laboratory-High-Vacuum-Grease-976V-Stopcock-/280617417916?pt=LH_DefaultDomain_0&hash=item415619fcbc#ht_1861wt_1270

Is this the same dow grease referenced in this thread?

Looks to me like it is.  I never saw it in those small containers before, though.
Lloyd... (SOHC4 #11 Original Mail List)
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Offline phaedrus314

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Re: Front caliper assembly ? Lube or no lube?
« Reply #87 on: June 15, 2012, 02:08:30 AM »
Thanks TT.  Do you have an offhand guess as to how many calipers a 1 oz container would do?  Basically wondering if I'd regret not buying the bigger size.

Offline flopshot

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Re: Front caliper assembly ? Lube or no lube?
« Reply #88 on: June 15, 2012, 06:47:08 AM »
TT, how do you feel about this product in an application using silicon brake fluid ?

Offline phaedrus314

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Re: Front caliper assembly ? Lube or no lube?
« Reply #89 on: June 15, 2012, 08:47:29 AM »
I just saw another product that might work but haven't researched it yet.  It's a Silicon grease designed for the back of ceramic pads that said it  stayed in place in the extreme heats that ceramic pads produce.  Any feedback?

http://crcindustries.com/auto/?s=05361

Offline Lostboy Steve

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Re: Front caliper assembly ? Lube or no lube?
« Reply #90 on: June 15, 2012, 09:52:32 AM »
I used that green synthetic brake grease both on my "pressure" pad, and the bracket for the caliper that moves. I used the orange "goopy" crc disc brake quiet on the dead pad.
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Offline TwoTired

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Re: Front caliper assembly ? Lube or no lube?
« Reply #91 on: June 15, 2012, 11:28:30 AM »
Thanks TT.  Do you have an offhand guess as to how many calipers a 1 oz container would do?  Basically wondering if I'd regret not buying the bigger size.
Probably 5-10 calipers, as a guess.  Really, you just need a thin coating for the desired protection.
Lloyd... (SOHC4 #11 Original Mail List)
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Offline TwoTired

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Re: Front caliper assembly ? Lube or no lube?
« Reply #92 on: June 15, 2012, 11:30:56 AM »
TT, how do you feel about this product in an application using silicon brake fluid ?


I wouldn't.  The MSDS says it is 60-100% synthetic oil.  I expect it will weep/creep outward to be absorbed by the friction pad material.
Lloyd... (SOHC4 #11 Original Mail List)
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Offline TwoTired

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Re: Front caliper assembly ? Lube or no lube?
« Reply #93 on: June 15, 2012, 11:46:33 AM »
I just saw another product that might work but haven't researched it yet.  It's a Silicon grease designed for the back of ceramic pads that said it  stayed in place in the extreme heats that ceramic pads produce.  Any feedback?

http://crcindustries.com/auto/?s=05361

I haven't tested this. (I have a good supply of the correct material).   Make an aluminum foil pan and put a small amount of the test substance in the pan.  Then put the pan in an oven.  (If using a gas oven with open flame nearby, satisfy yourself that the product will not give off explosive/flammable fumes.)
Watch the product as the temperature rises.  The Dow Corning HVG will not change with temps up to 500F. (In my tests).
If what you want to use weeps, creeps, flows, vaporizes, puddles, or bursts into flame.  It is not suitable for application on SOHC4 calipers.

FYI:  http://en.wikipedia.org/wiki/Polydimethylsiloxane

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
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Offline flopshot

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Re: Front caliper assembly ? Lube or no lube?
« Reply #94 on: June 15, 2012, 12:30:23 PM »

I wouldn't.  The MSDS says it is 60-100% synthetic oil.  I expect it will weep/creep outward to be absorbed by the friction pad material.
[/quote]

Thanks.  I should have thought to look up the MSDS.