How to centralise your caliper

[keen]

According to Hope USA : http://www.hopegb.com/page_mep_force_38.html

Could be applied to any brakes, even w/o windows if you understand the principles.

[Nickbee]

is there a more "foolproof" way to do this other than by eye? I will be getting Hope brakes soon and have seen this video. What kind of margin of error is possible?

Thanks

[dogonfr]

I forget his screen name but the English guy with the sheeps head stuck in a lawn chair has been doing that technique for a couple years.

He also yells Hope, one in the same?

[keen]

Originally Posted by Nickbee

is there a more "foolproof" way to do this other than by eye? I will be getting Hope brakes soon and have seen this video. What kind of margin of error is possible?

Thanks

Use feeler gauges or shims against one pad to rotor - increase / decrease to center the caliper. It's still an eyeball action for the center but front to back edges will be on the money.

[Shark]

That's how I've always done mine.....
never understood why people would try shims, business cards, etc etc....
look down & center it, then snug up the bolts again, works like a charm.

[dogonfr]

Besides tightening the caliper bolts little at a time to prevent twisting the feeler gauges help stabilize the caliper. Not a ton but a little.

I use feeler gauges to adjust the lever throw/pad engagement also.

[Nickbee]

do you start by pushing the calipers all the way in? Then use the same feeler gauge on each side? I've done plenty of work on motorcycle brakes, but this centralizing stuff does not need to be done there...

[dogonfr]

Originally Posted by Nickbee

do you start by pushing the calipers all the way in? Then use the same feeler gauge on each side? I've done plenty of work on motorcycle brakes, but this centralizing stuff does not need to be done there...

Their is no need to centralize moto disc because the caliper floats on a pin. As pointed out earlier or another post MTB calipers are fixed and the pistons will not grasp the rotor in perfect unison.

[Nickbee]

With the whole pad spacing thing… If you reset both pistons all the way in, install the pads, center the caliper, then pump the brakes… In theory the pads should end up evenly spaced to the rotors right?

[keen]

Originally Posted by Nickbee

With the whole pad spacing thing… If you reset both pistons all the way in, install the pads, center the caliper, then pump the brakes… In theory the pads should end up evenly spaced to the rotors right?

In theory but pistons don't move @ the exact same time. You end up with the caliper off center and just tightening the bolts can also slighlt twist the caliper.

[Nickbee]

Awesome… So besides just looking at the caliper is there any methods besides the “poke and hope” theory. I guess the perfectionist side of me wants to understand all of this before I go to install my Hopes in the near future…

[the-one1]

Here's what I do:
Lossen the caliper bolts.
Pull the brake lever
Tighten the caliper bolts
Wallah, the caliper is now centered.
Note: this only works with post mount.

[SteveUK]

Originally Posted by the-one1

Lossen the caliper bolts.
Pull the brake lever
Tighten the caliper bolts
Wallah, the caliper is now centered.

As keen has already said, this only works if both pistons move at the same speed. Many, or even most, new calipers will have one piston moving at a different speed. This results in the caliper being off-set and, in the worst-case scenario, one piston not actually doing anything at all.

[Nickbee]

Originally Posted by the-one1

Here's what I do:
Lossen the caliper bolts.
Pull the brake lever
Tighten the caliper bolts
Wallah, the caliper is now centered.
Note: this only works with post mount.

If you watch Hope’s video this is exactly what they tell you not to do…

[Nickbee]

It is interesting how both Avid and Marta will have you squeeze the brake lever to center the calipers and Hope recommends against it. Is that something in the design?

[OldMTBfreak]

You are better off manualy centering the caliper with the pistons fully retracted. Then squeeze the lever a couple of times and observe the pads. If one is closer than the other, use a screwdriver and force the piston with the least gap back into the caliper. Give the lever a couple of squeezes. Observe the pads again. The gap should be the same. Repeat if necessary. I have XTR disc's, I have to do this once a month or so. With 2 pistons, you will ALWAYS have a lazy piston.

[keen]

Originally Posted by Nickbee

Awesome… So besides just looking at the caliper is there any methods besides the “poke and hope” theory. I guess the perfectionist side of me wants to understand all of this before I go to install my Hopes in the near future…

As already mentioned : Use feeler gauges or shims against one pad to rotor - increase / decrease to center the caliper. It's still an eyeball action for the center but front to back edges will be on the money.

Really the caliper can be slightly off center as the two pistons move independantly. The caliper / pads have to be exactly parallel to the rotor or it can cause : lack of power, have excessive noise, mushy lever and in the end un-even pad wear.

[the-one1]

Originally Posted by Nickbee

If you watch Hope’s video this is exactly what they tell you not to do…

Hehe. I did watch it, but I wasn't listening.
In any case, the fluid will flow to the piston with the least resistance.

[Nickbee]

Originally Posted by OldMTBfreak

You are better off manualy centering the caliper with the pistons fully retracted. Then squeeze the lever a couple of times and observe the pads. If one is closer than the other, use a screwdriver and force the piston with the least gap back into the caliper. Give the lever a couple of squeezes. Observe the pads again. The gap should be the same. Repeat if necessary. I have XTR disc's, I have to do this once a month or so. With 2 pistons, you will ALWAYS have a lazy piston.

Thanks! All this talk helps.. I might have to do a photo thread of the install once I get my new Hope brakes.

[pagey]

Here's what I do:
Lossen the caliper bolts.
Pull the brake lever
Tighten the caliper bolts
Wallah, the caliper is now centered.
Note: this only works with post mount.

The only thing I add is putting a business card on both sides of the rotor. It leaves a perfect size gap

[SteveUK]

Originally Posted by pagey

The only thing I add is putting a business card on both sides of the rotor. It leaves a perfect size gap

The piston seals will automatically re-compensate for this gap the first time the lever is pulled after the cards have been removed. It may be useful in setting up a cable actuated set-up, but is pointless for a hydraulic one.

[Nickbee]

I got my X2 pros on.

http://forums.mtbr.com/showthread.php?t=570577

I lined up everything by eye. As the British dude said, it might take you a few tries but you'll get it!

Thanks again for this post!

[archer]

I've found that eyeballing the Hayes is about the only way even thought they say to squeeze them down on the rotor and tighten. THEN they say check for rub and adjust and there is always massive rub because tightening the bolts makes the caliper walk.

[herbn]

ok, if one piston is lazy,wouldn't centering by eye end up with the disc being flexed over by the non lazy piston? I do center by eye and it can be a little tricky to see the light between the pads and the disc,it would have been kind of cool if the video was clear enough and well lit enough so you could see that nice even space of light between the pads and the rotor.

[Nickbee]

Originally Posted by herbn

ok, if one piston is lazy,wouldn't centering by eye end up with the disc being flexed over by the non lazy piston? I do center by eye and it can be a little tricky to see the light between the pads and the disc,it would have been kind of cool if the video was clear enough and well lit enough so you could see that nice even space of light between the pads and the rotor.

I’m not an expert, but at that point wouldn’t it be time for a rebuild?

[herbn]

they're saying even new calipers will have a lazy piston, i don't think i've found that,but then again it's been quite a few years since i used hope brakes.I still won't flip my bike over,something i started with hopes(back then) my brakes would change if i flipped the bike for any reason,like fixing a tire. I figured ,i don't flip my motorcycle,i don't flip my car, so i don't flip my bicycle.

[Nickbee]

Interesting about flipping your bike over. I am not storing my bike upside down now but will be soon to make more room in my garage. It was my impression that if a brake was properly bled it should not affect things. Mmmmmmmmmmmm?

[dogonfr]

Originally Posted by archer

THEN they say check for rub and adjust and there is always massive rub because tightening the bolts makes the caliper walk.

You missed the part that says to snug the bolts alternating one to the other till tight.

This should be done on anything that has more than 1 securing bolt that needs aligning because the holes are not the exact snug size as the securing bolt or stud.

[dogonfr]

Originally Posted by herbn

they're saying even new calipers will have a lazy piston, i don't think i've found that,but then again it's been quite a few years since i used hope brakes.I still won't flip my bike over,something i started with hopes(back then) my brakes would change if i flipped the bike for any reason,like fixing a tire. I figured ,i don't flip my motorcycle,i don't flip my car, so i don't flip my bicycle.

Your on track.

Their is always the potential for a lazy piston, seal stickshon, worn piston, ever so slight over bore, poor transfer of fluid to opposite piston. Motos use a floating caliper so it can always evenly grasp the rotor.

[Nickbee]

Originally Posted by dogonfr

Your on track.

Their is always the potential for a lazy piston, seal stickshon, worn piston, ever so slight over bore, poor transfer of fluid to opposite piston. Motos use a floating caliper so it can always evenly grasp the rotor.

Why not use a floating caliper on bikes? Too much weight? complexity?

[dogonfr]

Originally Posted by Nickbee

Why not use a floating caliper on bikes? Too much weight? complexity?

Thats an excellent question which has never been answered.

Their have been some mechanical versions but the tolerances were poor so the caliper would rock and cock when applied causing binding. My guess is tolerances for such a small brake set up would be expensive plus with all the weight weenies be a tad heavy. Tooling, testing. manufacture would bring the price sky high then your looking at maybe 3-4 years till it's profitable and the process is in play and lighter but price of components has also gone up so might as well charge a few extra ducates.

[nuj]

hello, i've just adjusted my shimano none series hyrdaulic brakes. one piston doesnt move the same as the other, so what i did, i removed the pads, sprayed some wd-40 and wiped the excess cleaner and then retracted the piston. returned everything in their proper place and then pumped the lever. works every time

[archer]

Originally Posted by dogonfr

You missed the part that says to snug the bolts alternating one to the other till tight.

This should be done on anything that has more than 1 securing bolt that needs aligning because the holes are not the exact snug size as the securing bolt or stud.

Nope, been there done that.
The calipers walk even when you alternate tightening the bolts gradually, maybe not quite as much but still visible.

[archer]

Originally Posted by nuj

hello, i've just adjusted my shimano none series hyrdaulic brakes. one piston doesnt move the same as the other, so what i did, i removed the pads, sprayed some wd-40 and wiped the excess cleaner and then retracted the piston. returned everything in their proper place and then pumped the lever. works every time

WD-40 isn't a cleaner it is a Moisture Displacing Lubricant, emphasis on the MD part of MDL. It can dry to a varnish like consistancy. I wouldn't reccomend it for this application (or for use on firearms.)

[jeffscott]

Originally Posted by SteveUK

The piston seals will automatically re-compensate for this gap the first time the lever is pulled after the cards have been removed. It may be useful in setting up a cable actuated set-up, but is pointless for a hydraulic one.

Not at all pointless....

First of all if the brakes are working fairly well, ie no sticky piston, then this method will find the center of the piston movement....This is ideal.

If however one or both of the pistons are sticky then this will "center" caliper way over on to the sticky side, and this will result in brake drag....

Once that happens you have to remove the pads, and wheel, clean up the caliper and fix the cause sticky pistons....

Then you might as well eyball the caliper into the center, then start the whole damn process all over again.

[SteveUK]

I think there's a misunderstanding here. I was replying to the assertion that the gap between the pads and the rotor can be widened (for clearance) by setting the caliper up with card placed in between them. It's nothing to do with centralising.

We're assuming that the caliper is correctly algned - so that the rotor runs plumb through the middle of the slot - yes? OK, so then you put a card on either side of the rotor and pump the pistons out; yes? For arguments sake, both pistons/pads extend equally and the rotor remains central, with both pads contacting at the same time. Now, when the lever is released and the pads are retracted, the gap between the pads and the rotor is going to be, say 1mm. As soon as the lever is pulled again, the pistons/pads will need to be pushed that 1mm before they contact the rotor, but the seals are only going to retract them by the amount they are designed to, thus eliminating the extra space originally created by the card. It's basically just exaggerating the self-adjusting process for pad wear.

[jeffscott]

Originally Posted by SteveUK

As keen has already said, this only works if both pistons move at the same speed. Many, or even most, new calipers will have one piston moving at a different speed. This results in the caliper being off-set and, in the worst-case scenario, one piston not actually doing anything at all.

The procedure you refer to here centers the pad motion about the rotor, not the caliper about the rotor...

Works fine if the pistons are not too sticky....If to sticky clean recenter by eyeball and start again.

[SteveUK]

Jeff, will you please understand the context in which I make my posts. You appear to be wanting to contradict me, but saying the same thing as me (in a round-about sort of way).

[jeffscott]

Originally Posted by SteveUK

Jeff, will you please understand the context in which I make my posts. You appear to be wanting to contradict me, but saying the same thing as me (in a round-about sort of way).

My point is this, the common trick of using businees cards to center the caliper works, and has a point...

It centers and aligns the pads about the rotors, to get the card in there the pistons have to be pushed in, and that might be just enough to clear the sticky piston....

[SteveUK]

I'm still not sure we're talking about the same thing here. Does the process you're describing involve sliding cards between the rotor and one pad, so that the opposite pad has to extend more?

[jeffscott]

Originally Posted by SteveUK

I'm still not sure we're talking about the same thing here. Does the process you're describing involve sliding cards between the rotor and one pad, so that the opposite pad has to extend more?

no.

[SteveUK]

Useful response, thanks. I'm not trying to argue with you here, I'm just trying to understand this business card thing. To me, it seems like a waste of time. It doesn't do anything to influence the alignment of the caliper as it's basically the same as not using business cards, but setting up with a thicker rotor. As soon as the normal rotor is fitted, the seals will compensate for the extra space. In the meantime, the thicker rotor has not in any way influenced the alignment of anything.

[jeffscott]

Originally Posted by the-one1

Here's what I do:
Lossen the caliper bolts.
Pull the brake lever
Tighten the caliper bolts
Wallah, the caliper is now centered.
Note: this only works with post mount.

Steve add the business cards to the above and figure it out.

[boomn]

Originally Posted by jeffscott

Steve add the business cards to the above and figure it out.

you still appear to have missed the point of what this thread is talking about.

[SteveUK]

Originally Posted by jeffscott

Steve add the business cards to the above and figure it out.

I understand what the method is supposed to achieve, it's just that I see a flaw in it. I agree that the loosen bolts-pull lever- tighten bolts method should align the pads to the rotor, but it doesn't account for a sticking piston which will leave the caliper off-center and, in the worst-case scenario will leave only one side of the caliper doing the work. As I've already explained, adding card between the pads and rotor makes zero difference to anything. In the case of a totally stuck piston, it would actually be causative of a problem.

You're trying to patronise me by insisting that the insertion of card actually does something to the spacing of the pads; but it doesn't (once the brake is operated after the card has been removed).

[jeffscott]

Originally Posted by SteveUK

I understand what the method is supposed to achieve, it's just that I see a flaw in it. I agree that the loosen bolts-pull lever- tighten bolts method should align the pads to the rotor, but it doesn't account for a sticking piston which will leave the caliper off-center and, in the worst-case scenario will leave only one side of the caliper doing the work. As I've already explained, adding card between the pads and rotor makes zero difference to anything. In the case of a totally stuck piston, it would actually be causative of a problem.

You're trying to patronise me by insisting that the insertion of card actually does something to the spacing of the pads; but it doesn't (once the brake is operated after the card has been removed).

Not at all in the if the simple fix doesn't fix the problem you have a sticky piston, get it yet the method is useful and has a point. Simple.

And no if it is a stuck piston the cause of the problem is what ever got the thing stuck in the first place not the method....

Geez open your mind a bit.

[SteveUK]

Originally Posted by jeffscott

Not at all in the if the simple fix doesn't fix the problem you have a sticky piston, get it yet the method is useful and has a point. Simple.

And no if it is a stuck piston the cause of the problem is what ever got the thing stuck in the first place not the method....

Geez open your mind a bit.

Seriously, Jeff, that's not even English.

[boomn]

Originally Posted by jeffscott

Not at all in the if the simple fix doesn't fix the problem you have a sticky piston, get it yet the method is useful and has a point. Simple.

And no if it is a stuck piston the cause of the problem is what ever got the thing stuck in the first place not the method....

Geez open your mind a bit.

Nope, you still missed it. Going all the way back to the OP, the issue in question isn't stuck pistons or really obviously sticking pistons that don't function correctly. The issue is that every brake caliper has one piston that is slightly "stickier" or slower than the other. The fact that one piston usually moves slower than the other means that using the pistons to align the caliper for you may not actually center the caliper over the rotor.

You also keep missing the point that if you do the card trick, as soon as you actually engage the brake it ignores the extra spacing you added with the card and resets itself to the width of the rotor. That is what hydraulic brakes do... they constantly reset their spacing based on the current rotor thickness and pad thickness

[jeffscott]

Originally Posted by boomn

Nope, you still missed it. Going all the way back to the OP, the issue in question isn't stuck pistons or really obviously sticking pistons that don't function correctly. The issue is that every brake caliper has one piston that is slightly "stickier" or slower than the other. The fact that one piston usually moves slower than the other means that using the pistons to align the caliper for you may not actually center the caliper over the rotor.

You also keep missing the point that if you do the card trick, as soon as you actually engage the brake it ignores the extra spacing you added with the card and resets itself to the width of the rotor. That is what hydraulic brakes do... they constantly reset their spacing based on the current rotor thickness and pad thickness

Nope Not every brake caliper has one piston that is stickier enough to matter.

Don't care if I center the caliper over the rotor I wan to get the pads centered over the rotor.

Yeah so the pads go back, shat that forced ione to do is push the pistons back into the caliper, and often that is enough to clean up the problem.

Really hydralic brakes actually self adjust geez your kidding maybe that is why I only after re center when my pistons get sticky.

Point is the method sometimes works it is dead simple and people do it.

50% of my sticky pistons I fix shoving a knife in between the pads and pushing the pistons in a nd out a few times...the rest need a good clean,

If I get drag I just center the caliper so the pads don't drag, easy works great, unless of course I have sticky pistons...

So you see some times one piston is just not stickier enough to matter.

[keen]

Retract both pistons / pads completely in the caliper now align the caliper so the rotor is dead center of the pad . You can eyeball this or use shims / feeler gauges to make sure the rotor and pad are parallel - shim both sides to keep parallel . An absolute center is not a must but having the rotor to pads parallel is. Real world pistons don't move @ the same time. Pistons use square cut o-rings to retract the pads when brake pressure is not applied - Real world - pad movement / retraction is inconsistant beacuse cycle brakes are so small. Can you pump the levers and have perfect pad to rotor position ? Not really - I center my caliper, apply the brake several times then flex the rotor opposite the slowert piston to set the pad position.

[tduro]

Wow. I spent quite a lot of time reading this entire post and still have no idea how to adjust my juicy's.

I just replaced my rear rotor and it rubs constantly. The wheel spins "ok", but nowhere near as well as my other bike with rim brakes. Can anyone point me to a thread that explains how to adjust juicy's to get a really free spin?

[mtbnozpikr]

It worked for me. I just had to make sure that I pushed the calipers in and now my calipers are centralized like they should be. Thanks for posting

[Slurry]

yea this thread is confusing me too - a lot of different ideas and arguments going on.

I have some shimano IS caliper brakes that I can't get adjusted at all. After watching the video and reading a bit here, i guess i should:


1.Reset pistons
2.Reinstall pads
3.Use stupid little shims to align the rotor to the center of the caliper cutout, ignoring where the pads are.
4.Squeeze the brake lever to set the pads
5.Use the pad-pushing method shown in the video to get the pads to not rub.

Is this correct?

[SteveUK]

Originally Posted by Slurry

Is this correct?

I would say that caliper alignment is best done with the pads removed. Once the rotor is perfectly centered through thecaliper, then the pads can be fitted and the pistons/pads worked into position.

[Slurry]

Originally Posted by SteveUK

I would say that caliper alignment is best done with the pads removed. Once the rotor is perfectly centered through thecaliper, then the pads can be fitted and the pistons/pads worked into position.

Ok, I think this is what I've been having so much trouble with. The stupid little shims were driving my crazy, it seemed impossible to get anything centered as they would just mash down as i tightened the caliper bolts.

Is it ok if the pistons are not even after setting it up? I'm thinking that the video method of working the pistons into the right place might end up having one piston in or out further than the other one.

[SteveUK]

Is it ok if the pistons are not even after setting it up?

As long as both pistons are moving freely and both pads touch the rotor at the same time, then it's not a huge issue if the caliper is slightly off to one side. However, brake issues - noise, vibrations, poor performance and vague lever feel - are typically caused by the pads not being parallel to the rotor; something which would be caused, for example, by too many shims on one of the caliper mounting tabs. The caliper is basically twisted over the rotor, causing the pads to twist in the caliper and the rotor to twist between the pads.

[jeffscott]

Yeah be real careful I have ruined umpteen dozen brakes using chain lube on the seals, geez maybe I should re think that...

So Steve what is the seal material for DOT brakes, shat is the seal material for oil brakes??

[SteveUK]

Originally Posted by jeffscott

So Steve what is the seal material for DOT brakes, shat (sic) is the seal material for oil brakes??

I understand that DOT brakes use EPDM (ethylene propylene diene Monomer) rubber; mineral oil brakes use NBR (Nitrile butadiene rubber).

(source link)

EPM, EPDM

(earlier abbreviations: APK, APTK, EPR)

Trade names:

* Buna EP® (Chem. Werke Hüls)
* Keltan® (DSM)
* Dutral® (Montecatini)
* Nordel® (DuPont)
* Vistalon® (Enjay Chemical)

EPM is a rubber manufactured as a copolymer of ethylene and propylene. Ethylene-propylene-diene rubber (EPDM) is produced using a third monomer and is particularly useful to seal phosphate-ester hydraulic fluids and in brake systems which use fluid with glycol base.

Heat resistance: up to 150°C (max. 180°C in water and water steam)
Cold flexibility: down to appr. -50°C
Chemical resistance to:

* hot water and steam up to +150°C, special compounds up to +180°C;
* brake fluids on glycol base up to +150°C;
* many organic and inorganic acids;
* cleaning agents, soda and potassium alkalis;
* hydraulic fluids based on phosphate-ester (HFD-R);
* silicone oil and grease;
* many polar solvents (alcohols, ketones, esters);
* Skydrol 500 and 7000;
* ozone, ageing and weather resistant.

Not compatible with:

* mineral oil products (oils, greases and fuels).

and also (from here):

* gasoline;
* kerosene;
* aromatic and aliphatic hydrocarbons;
* halogenated solvents;
* concentrated acids;


NBR

Trade names:

* Perbunan® (Bayer AG)
* Chemigum® (Goodyear)
* Europrene N® (Enichem)
* Nipol N® (Nippon Zeon)

Nitrile rubber (NBR) is the general term for an acryl-nitrile butadiene mixed polymer. The acryl-nitrile content varies in technical products (18 to 50%) and influences the properties of the elastomer. The higher the acryl-nitrile content the better the resistance to oil and fuel. At the same time, the elasticity and the compression set is adversely affected. Often a compromise is drawn and a medium acryl-nitrile content is selected.

NBR has good mechanical properties when compared with other elastomers and a high wear resistance. NBR is not resistant to weathering and ozone.

Heat resistance: up to +100°C, shorter life +120°C (at increased temperatures the speed of ageing accelerates, ageing in oil occurs at slower rate than in hot air)
Cold flexibility: according to recipe between -20°C and -55°C
Chemical resistance to:

* aliphatic hydrocarbons (propane, butane, petroleum oil, mineral oil and grease, Diesel fuel, fuel oils);
* vegetable and mineral oils and greases;
* HFA, HFB and HFC fluids;
* many diluted acids, alkali, salt solutions at low temperatures;
* water (special compounds up to +100°C).

Not compatible with:

* fuels of high aromatic content (for super fuels a special compound must be used);
* aromatic hydrocarbons (benzene);
* chlorinated hydrocarbons (benzene);
* chlorinated hydrocarbons (trichlorethylene);
* polar solvents (ketone, acetone, acetic acid, ethylene-ester);
* strong acids;
* brake fluid with glycol base;
* ozone, weather and ageing resistant.

Originally Posted by jeffscott

Yeah be real careful I have ruined umpteen dozen brakes using chain lube on the seals, geez maybe I should re think that...

Well, as long as you're confident that your chain lube (or whetever else you use on your pistons seals) doesn't contain any of the following - for mineral oil brakes:

* fuels of high aromatic content (for super fuels a special compound must be used);
* aromatic hydrocarbons (benzene);
* chlorinated hydrocarbons (benzene);
* chlorinated hydrocarbons (trichlorethylene);
* polar solvents (ketone, acetone, acetic acid, ethylene-ester);
* strong acids;
* brake fluid with glycol base;
* ozone, weather and ageing resistant.

or for DOT brakes:

* gasoline;
* kerosene;
* aromatic and aliphatic hydrocarbons;
* halogenated solvents;
* concentrated acids;
* mineral oil products.

...then you're probably safe to just crack on as you were.

To me, it's safer (and cheaper) to stick with what I know. I know that (compatible) brake fluid is OK for lube and I know that silicone lube is good for DOT (EPDM) seals. Here's a fairly comprehensive compatibility list for EPDM. I'm sure you'll be thrilled to know that your EPDM seals are fully compatible with chocolate syrup. But would you use it to lube your seals?

[jeffscott]

Originally Posted by SteveUK

I understand that DOT brakes use EPDM (ethylene propylene diene Monomer) rubber; mineral oil brakes use NBR (Nitrile butadiene rubber).

(source link)

EPM, EPDM

(earlier abbreviations: APK, APTK, EPR)

Trade names:

* Buna EP® (Chem. Werke Hüls)
* Keltan® (DSM)
* Dutral® (Montecatini)
* Nordel® (DuPont)
* Vistalon® (Enjay Chemical)

EPM is a rubber manufactured as a copolymer of ethylene and propylene. Ethylene-propylene-diene rubber (EPDM) is produced using a third monomer and is particularly useful to seal phosphate-ester hydraulic fluids and in brake systems which use fluid with glycol base.

Heat resistance: up to 150°C (max. 180°C in water and water steam)
Cold flexibility: down to appr. -50°C
Chemical resistance to:

* hot water and steam up to +150°C, special compounds up to +180°C;
* brake fluids on glycol base up to +150°C;
* many organic and inorganic acids;
* cleaning agents, soda and potassium alkalis;
* hydraulic fluids based on phosphate-ester (HFD-R);
* silicone oil and grease;
* many polar solvents (alcohols, ketones, esters);
* Skydrol 500 and 7000;
* ozone, ageing and weather resistant.

Not compatible with:

* mineral oil products (oils, greases and fuels).

and also (from here):

* gasoline;
* kerosene;
* aromatic and aliphatic hydrocarbons;
* halogenated solvents;
* concentrated acids;


NBR

Trade names:

* Perbunan® (Bayer AG)
* Chemigum® (Goodyear)
* Europrene N® (Enichem)
* Nipol N® (Nippon Zeon)

Nitrile rubber (NBR) is the general term for an acryl-nitrile butadiene mixed polymer. The acryl-nitrile content varies in technical products (18 to 50%) and influences the properties of the elastomer. The higher the acryl-nitrile content the better the resistance to oil and fuel. At the same time, the elasticity and the compression set is adversely affected. Often a compromise is drawn and a medium acryl-nitrile content is selected.

NBR has good mechanical properties when compared with other elastomers and a high wear resistance. NBR is not resistant to weathering and ozone.

Heat resistance: up to +100°C, shorter life +120°C (at increased temperatures the speed of ageing accelerates, ageing in oil occurs at slower rate than in hot air)
Cold flexibility: according to recipe between -20°C and -55°C
Chemical resistance to:

* aliphatic hydrocarbons (propane, butane, petroleum oil, mineral oil and grease, Diesel fuel, fuel oils);
* vegetable and mineral oils and greases;
* HFA, HFB and HFC fluids;
* many diluted acids, alkali, salt solutions at low temperatures;
* water (special compounds up to +100°C).

Not compatible with:

* fuels of high aromatic content (for super fuels a special compound must be used);
* aromatic hydrocarbons (benzene);
* chlorinated hydrocarbons (benzene);
* chlorinated hydrocarbons (trichlorethylene);
* polar solvents (ketone, acetone, acetic acid, ethylene-ester);
* strong acids;
* brake fluid with glycol base;
* ozone, weather and ageing resistant.



Well, as long as you're confident that your chain lube (or whetever else you use on your pistons seals) doesn't contain any of the following - for mineral oil brakes:

* fuels of high aromatic content (for super fuels a special compound must be used);
* aromatic hydrocarbons (benzene);
* chlorinated hydrocarbons (benzene);
* chlorinated hydrocarbons (trichlorethylene);
* polar solvents (ketone, acetone, acetic acid, ethylene-ester);
* strong acids;
* brake fluid with glycol base;
* ozone, weather and ageing resistant.

or for DOT brakes:

* gasoline;
* kerosene;
* aromatic and aliphatic hydrocarbons;
* halogenated solvents;
* concentrated acids;
* mineral oil products.

...then you're probably safe to just crack on as you were.

To me, it's safer (and cheaper) to stick with what I know. I know that (compatible) brake fluid is OK for lube and I know that silicone lube is good for DOT (EPDM) seals. Here's a fairly comprehensive compatibility list for EPDM. I'm sure you'll be thrilled to know that your EPDM seals are fully compatible with chocolate syrup. But would you use it to lube your seals?

Nice cut and paste....but EPDM is used alot for aliphatic hydrocarbons in the oil bus and works fine...

What cause the problem with EPDM is when DOT fluids are changed to oils, then the difference in concentration can cause extreme swelling...

Hence the difference a little squirt on the outside is fine, to loosen things up.

[RandyBoy]

Originally Posted by the-one1

Here's what I do:
Lossen the caliper bolts.
Pull the brake lever
Tighten the caliper bolts
Wallah, the caliper is now centered.
Note: this only works with post mount.

Voila!



What is Wallah?

[SteveUK]

Originally Posted by RandyBoy

What is Wallah?

It's an ancient aborigine term for "the wrong way".