Brake caliper service question.

[popkat]

None of the Powerhouse seals I've fitted have been tapered, you put them in either way round, this seems to prove they don't need to be.

It's possible that over time the seals can wear to a taper, example : last year I rebuilt a pair of brake calipers from a ZX6R (they had never been apart before), half the seals were tapered and half not, they were not in any order, just random, I put them back in as that's what the customer wanted, the lever had a lot of travel probably due to the seals in this case dragging the pistons back, the brake worked put was far from ideal. If I had put the tapered seals in the other way round they most probably would have caused a dragging/binding brake. I told my customer he needed new seals which he was going to have a go at himself. Not seen him since so never knew the outcome.

[sirch345]

can anyone else confirm this?

This came up a thread a couple of weeks ago IIRC

Let me see if I can find it.
http://www.vtr1000.org/phpBB3/viewtopic ... 30#p374128

(:-})

You certainly do have your eye on the ball Carl well done in remembering that link

Quote taken from the link Cybercarl posted:-

The seals need to be fitted the correct way round -- they can be put in back to front. You will need to remove the pistons to check. There is a slight angle on the seals that is not visible to the eye. The way to check is to install the seal and then with your finger moving from closed end of the bore outwards you will feel the lip of the seal as your finger passes over it. If you do not feel the lip then they are installed back to front and there is a chance of that piston leaking brake fluid. In fact for years Ducati would not sell brake seal kits to the public because a set were installed incorrectly resulting in an accident in the States. They would only sell complete calipers to the public. They would only supply brake seal kits to dealers who could ensure they were fitted correctly.

Not wishing to sound like I'm doubting you Thunderbolt, as that could explain why my front brakes are binding every so slightly. The only thing that I find rather strange is that I can't see any mention of this in the Honda Workshop Manual, surely if the caliper seals needed to go in a certain way around it would be stated in the Manual.
I wonder what our members from the Superhawk forum think, can any of you shed any light on this I wonder

Getting back to my bike, I have now bled the system again and tried tying the lever in against the bar over night then bleeding them again, neither of these have really changed much, they're still binding very slightly. When I tied the brake lever back against the handlebar and left it over night, in the morning I found the brake lever had gone slack in the leash, is this normal I didn't tie it back over tight as suggested.

Chris.

[thunderbolt]

The seals need to be fitted the correct way round -- they can be put in back to front. You will need to remove the pistons to check. There is a slight angle on the seals that is not visible to the eye. The way to check is to install the seal and then with your finger moving from closed end of the bore outwards you will feel the lip of the seal as your finger passes over it. If you do not feel the lip then they are installed back to front and there is a chance of that piston leaking brake fluid. In fact for years Ducati would not sell brake seal kits to the public because a set were installed incorrectly resulting in an accident in the States. They would only sell complete calipers to the public. They would only supply brake seal kits to dealers who could ensure they were fitted correctly.

Not wishing to sound like I'm doubting you Thunderbolt, as that could explain why my front brakes are binding every so slightly. The only thing that I find rather strange is that I can't see any mention of this in the Honda Workshop Manual, surely if the caliper seals needed to go in a certain way around it would be stated in the Manual.
Chris.

Chris, the comments I made above were a generalisation and applied to Ducati brakes. The main point I was trying to make was that the raised lip (or edge of seal) should be able to be felt by running your finger over the seal from the inside of the piston bore to towards the out edge of the caliper. Not all manufacturers are going to necessarily manufacture their callipers the same way. I have just finished fitting the 954 callipers and M/C to my '03 model and took measurements of the new seals before fitting them and they were perfectly square. But when I fitted the inner seal to its groove I could feel the lip when running my finger over it. I then pulled the seal out and inserted it the other way round and I could also feel the lip that way as well. So on closer inspection of the groove the seal goes into I could see that Nissin had made the lower edge of the groove on an angle which pushes one side of the seal up to create the lip. Hence why there is no instruction in the Honda Manual about it. BTW my new brakes on the front are impressive to say the least. I have never had a set of the VTR calipers apart but assume that Nissin uses the same principle on them as well, i.e. groove for seal is not square but with the lower edge at an angle (trapezium).

Hope this makes things more clear.

[sirch345]

The seals need to be fitted the correct way round -- they can be put in back to front. You will need to remove the pistons to check. There is a slight angle on the seals that is not visible to the eye. The way to check is to install the seal and then with your finger moving from closed end of the bore outwards you will feel the lip of the seal as your finger passes over it. If you do not feel the lip then they are installed back to front and there is a chance of that piston leaking brake fluid. In fact for years Ducati would not sell brake seal kits to the public because a set were installed incorrectly resulting in an accident in the States. They would only sell complete calipers to the public. They would only supply brake seal kits to dealers who could ensure they were fitted correctly.

Not wishing to sound like I'm doubting you Thunderbolt, as that could explain why my front brakes are binding every so slightly. The only thing that I find rather strange is that I can't see any mention of this in the Honda Workshop Manual, surely if the caliper seals needed to go in a certain way around it would be stated in the Manual.
Chris.

Chris, the comments I made above were a generalisation and applied to Ducati brakes. The main point I was trying to make was that the raised lip (or edge of seal) should be able to be felt by running your finger over the seal from the inside of the piston bore to towards the out edge of the caliper. Not all manufacturers are going to necessarily manufacture their callipers the same way. I have just finished fitting the 954 callipers and M/C to my '03 model and took measurements of the new seals before fitting them and they were perfectly square. But when I fitted the inner seal to its groove I could feel the lip when running my finger over it. I then pulled the seal out and inserted it the other way round and I could also feel the lip that way as well. So on closer inspection of the groove the seal goes into I could see that Nissin had made the lower edge of the groove on an angle which pushes one side of the seal up to create the lip. Hence why there is no instruction in the Honda Manual about it. BTW my new brakes on the front are impressive to say the least. I have never had a set of the VTR calipers apart but assume that Nissin uses the same principle on them as well, i.e. groove for seal is not square but with the lower edge at an angle (trapezium).

Hope this makes things more clear.

Don, thanks for getting back to me on this subject. I can see what you are getting at regarding the trapezium on your 954 calipers. If the Firestorm calipers are the same, I agree that would explain why there is no mention of fitting new seals a particular way round in the Honda Workshop Manual, due to them not being tapered when new. Also that could explain why my brakes are binding very slightly if I have managed to re-fit some of the old seals in back to front, as without a doubt the old seals will have moulded themselves to the seal groove shape.

I must admit I'm a bit annoyed to find the brakes are binding very slightly, as they certainly were not before I pulled them apart. I was trying to make them better if anything, not worse.

If I end up taking the calipers apart again I will fit a new set of seals this time.

Good to hear you're happy with your new brake set-up
Although I can't say I've heard anyone who's done that mod say they were not happy with it.

Cheers,

Chris.

[thunderbolt]

Don, thanks for getting back to me on this subject. I can see what you are getting at regarding the trapezium on your 954 calipers. If the Firestorm calipers are the same, I agree that would explain why there is no mention of fitting new seals a particular way round in the Honda Workshop Manual, due to them not being tapered when new. Also that could explain why my brakes are binding very slightly if I have managed to re-fit some of the old seals in back to front, as without a doubt the old seals will have moulded themselves to the seal groove shape.

I must admit I'm a bit annoyed to find the brakes are binding very slightly, as they certainly were not before I pulled them apart. I was trying to make them better if anything, not worse.

If I end up taking the calipers apart again I will fit a new set of seals this time.

Good to hear you're happy with your new brake set-up
Although I can't say I've heard anyone who's done that mod say they were not happy with it.

Cheers,

Chris.

I understand the frustration of replacing old pads with new and then finding that you have a binding situation in the front end. With my bike I rebuilt both front callipers, new seals all round including the ones that go between the two halves, rebuilt M/C, connected up existing Teflon lines and fitted new Nissin HH OEM pads. I can hear a slight scraping sound when I spin the front wheel, which is the metal pads touching on the disc as the wheel spins. But having said that when I give the wheel a good spins it rotates at least three revolutions till it comes to a stop. Hope you sort your issues out soon.

When you replaced the pads did you push the pistons all the way back in to their bores and then let the fluid push them back out to their natural/normal position. It's worth trying that before pulling the callipers to rebuild them. Did you check the relief hole in the M/C to see if it is clear?

[kev64]

I think, with all the effort youve gone to, i would go down the route of fitting new pads,
and as said push all pistons back, insert pads, get them onto the discs and bleed again

[sirch345]

I understand the frustration of replacing old pads with new and then finding that you have a binding situation in the front end. With my bike I rebuilt both front callipers, new seals all round including the ones that go between the two halves, rebuilt M/C, connected up existing Teflon lines and fitted new Nissin HH OEM pads. I can hear a slight scraping sound when I spin the front wheel, which is the metal pads touching on the disc as the wheel spins. But having said that when I give the wheel a good spins it rotates at least three revolutions till it comes to a stop. Hope you sort your issues out soon.

When you replaced the pads did you push the pistons all the way back in to their bores and then let the fluid push them back out to their natural/normal position. It's worth trying that before pulling the callipers to rebuild them. Did you check the relief hole in the M/C to see if it is clear?

Don, your front brakes certainly have had the full works, good job
I must admit I've not fancied going down the route of 954 calipers (or that type of calipers from another Honda model) simply because of grinding material off the calipers to make them fit, but I'm guessing there is more than enough material there to do so safely. I know some have split the amount taken off the calipers by taking half of that amount from the fork legs top mounting bracket, but I would rather not touch the top caliper mounting bracket, like yourself.

I haven't checked the relief hole in the M/C, I take it that's the one that allows the fluid back up into the reservoir I'm guessing I would need to strip, or at least partially strip the M/C to check that

I pushed all the pistons back in until they were flush with the face of the caliper as shown below:-



Thanks for the suggestions Don.

I think, with all the effort you've gone to, i would go down the route of fitting new pads,
and as said push all pistons back, insert pads, get them onto the discs and bleed again

Thanks for your support as well Kev

Chris.

[thunderbolt]

Chris, see picture below:



You would need to remove the reservoir, rubber pipe and connector to the M/C. This could be a bit messy, use plenty of rags around the M/C to protect the bike.

Using a steel bristle from a steel bristled brush stuck into the end of a matchstick poke the wire through the small hole and while working the piston back and forth wiggle the wire around inside the small hole to clear it of any muck.

Good Luck.

[sirch345]

Chris, see picture below:



You would need to remove the reservoir, rubber pipe and connector to the M/C. This could be a bit messy, use plenty of rags around the M/C to protect the bike.

Using a steel bristle from a steel bristled brush stuck into the end of a matchstick poke the wire through the small hole and while working the piston back and forth wiggle the wire around inside the small hole to clear it of any muck.

Good Luck.

Don, many thanks for the photo and for the advice on checking/clearing the relief hole. I take it I'm safe to do that without damaging the piston seal with the wire

I actually got around to putting the front of the bike up on the paddock stand today. I can only get approximately three quarters of one full turn when giving the front wheel a good hard spin, so not good

Cheers,

Chris.

[thunderbolt]

Chris remove each caliper in turn and give the wheel a good spin and see if you can work out which caliper is at fault.

If you probe gently with the match stick tool you should be able to detect if it is touching on a soft material (rubber) or a harder material (aluminium).

[Pete.L]

Chris,
I'm thinking it's your seals causing the problem. Either A, they haven't seated evenly in the groove or B, because they were old seals they have deformed slightly and not been put back in the same way around.
I used to take the seals out of my bikes on a regular basis when I was an all year rider. Muck and/or corrosion always managed to get past the dust seal eventually and build up along side the brake seals, resulting in a dragging caliper. I can tell you from experience they do deform over time.
I'd be pretty confident a new set of seals will fix your predicament. Or, if it is just the seals needing to reseat themselves correctly, maybe a good old thrashing and some hard braking will help speed up the process

Pete.l

[sirch345]

Chris remove each caliper in turn and give the wheel a good spin and see if you can work out which caliper is at fault.

If you probe gently with the match stick tool you should be able to detect if it is touching on a soft material (rubber) or a harder material (aluminium).

Don, I have now removed each caliper in turn to see which caliper is binding, it's both of them not just the one.

Before I either remove the calipers to pull apart again, or before I check the relief hole, I'm going to open one of bleed valves on the calipers and see if the wheel then spins free. My way of thinking is, if it doesn't change anything then it must be something to do with the seals. If the wheel then spins free then I will go about checking the relief hole.

Thanks for getting back to me on the piston seal information when using the matchstick tool

Chris,
I'm thinking it's your seals causing the problem. Either A, they haven't seated evenly in the groove or B, because they were old seals they have deformed slightly and not been put back in the same way around.
I used to take the seals out of my bikes on a regular basis when I was an all year rider. Muck and/or corrosion always managed to get past the dust seal eventually and build up along side the brake seals, resulting in a dragging caliper. I can tell you from experience they do deform over time.
I'd be pretty confident a new set of seals will fix your predicament. Or, if it is just the seals needing to reseat themselves correctly, maybe a good old thrashing and some hard braking will help speed up the process

Pete.l

Pete, I'm inclined to be thinking along your lines too re: it being something to do with the caliper seals, seeing as that is the only thing I have touched and I didn't have this problem before, but I'm also wondering if the relief valve (as Don suggests) could be the problem seeing as the piston and seal in the master cylinder has had a right good workout from me bleeding the brakes, as the piston and seal travel further in the master cylinder then, than it does when in normal use IIRC (but you probably know that anyway), so may be it could have stirred up some dirt.

Thanks for your reply

Chris.

[sirch345]

Before I either remove the calipers to pull apart again, or before I check the relief hole, I'm going to open one of bleed valves on the calipers and see if the wheel then spins free. My way of thinking is, if it doesn't change anything then it must be something to do with the seals. If the wheel then spins free then I will go about checking the relief hole.

Chris.

Update
I opened one of the bleed nipples today, the brakes stayed the same, still binding,

Chris.

[Pete.L]

Update
I opened one of the bleed nipples today, the brakes stayed the same, still binding,

So definitly no pressure in the hydrolics then

Just had a thought. I had a dust seal unseat itself when installing a piston once. It managed to jamm istelf between the caliper wall and the piston and that caused the pads to drag on the discs.
I've never installed them dry since then, alway put a little oil on them to help them slide on the piston at install.
Happyt Hunting Chris.

Pete.l

[thunderbolt]

Update
I opened one of the bleed nipples today, the brakes stayed the same, still binding,

So definitly no pressure in the hydrolics then

Just had a thought. I had a dust seal unseat itself when installing a piston once. It managed to jamm istelf between the caliper wall and the piston and that caused the pads to drag on the discs.
I've never installed them dry since then, alway put a little oil on them to help them slide on the piston at install.
Happyt Hunting Chris.

Pete.l

Yes I agree completely.

I coat the main (inner) piston seal with DOT 4 brake fluid and the dust (outer) seal with PBR rubber grease. I believe some people use silicon grease. I then insert the pistons with a twisting motion after coating the piston with brake fluid. It works for me.