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Post by mlbv on Oct 30, 2015 18:39:53 GMT
Ever since i have had my D900, the front brake has occasionally locked on...
i first notice it when i come off the throttle and the front dives a little and i can feel that it isn't rolling as freely as it should, luckily it has never happened in the motorway as it gets hotter and hotter until the front wheel locks...
when it happens, the lever is rock hard and won't budge...
the callipers have had all new seals, and the rubbers on the sliders replaced, and the master cylinder has been rebuilt with a repair kit, as soon as i jumped on it today, the front wheel was locked again within half a mile of the bike shop...
anyone have any idea what on earth could be the problem as me and the bike repair bloke are at a loss...
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Post by GAv on Oct 30, 2015 19:18:05 GMT
Maybe one of the pads (or more) isn't seating properly. Unless a wheel bearing has gone West.
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Post by mlbv on Oct 30, 2015 20:12:31 GMT
a wheel bearing wouldn't cause the brake leaver to go rock hard, would it??
also, cracking the banjos frees it up again... and it seems to be more one side (right hand side)
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Post by chris900divvy on Oct 30, 2015 21:10:44 GMT
I've never experienced any locking at the lever with mine though I have had regular instances where the pads were sticking. I think if you have a look at the calipers sometimes corrosion can build up under the little plates which the pads sit on and that puts them in a strange position that can make them drag as they can't move freely back and forth. There's also the rubber boot which you mentioned for the sliding post, you can get a heck of a lot of corrosion under there if that rubber boot is leaking it really likes to be greased up nicely.I suppose also you could have a build up of brake dust under the seals on the piston which may be stopping it returning nicely, worth a check. I can't think of much else to be honest!
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Post by satnav on Oct 30, 2015 21:32:48 GMT
Ok, sounds like the front calipers are sticking somewhere. This is why the brake lever feels hard. Are both sticking, or just one?
This means either the sliders and/or the pistons are sticking.
I take it that when the seals were replaced you checked that the pistons were moving freely in the chamber before fitting the new seals.
If so, it is more likely to be the sliders.
It could be only happening when the brakes get warm and things start to expand when they stick.
Strip them and give everything a good clean, making sure it all works freely.
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Post by mlbv on Oct 31, 2015 0:56:13 GMT
right, before I fling probably far too much money at ebay, does anyone have any callipers for sale so I can just start again with a completely different pair, alternatively I'll just bite the bullet and spend 100 quid on the ones on ebay, is there a difference between earlier and later ones, mine is a '95 and the ones on ebay are from a 2000....
I am getting sick and tired of throwing more and more money at these brakes and nothing changing... they have been stripped down and rebuilt with new seals, taken off and new rubbers fitted to the sliders, and now the master cylinder rebuilt, and the problem still came back, and the worst thing is that it happens totally at random, it has happened five times since owning the bike over the last 1200 or so miles.. luckily each time at relatively slow speeds....
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Post by GAv on Oct 31, 2015 2:42:02 GMT
I understand your frustration but please do no forget folk on here are just trying to be helpful  If yours has a one into two line, like my Divi had, then the metal joiner the main pipe it goes into, before a union out through a hollow metal tube act as compensator valves and maybe there is a blockage on one side, also if you "crack the banjos"as you put it, I would be more than surprised if air hasn't got in the system, albeit if it is effectively only working on one side it will relieve the pressure, temporarily, however the Divvy is a big heavy ol gal and that is why there are twin discs up front of course. At first mine had the opposite, in that the lever would pull back almost to the twist grip and then suddenly grabbed on. It nearly had me off, after purchasing it and bringing it back home last January, in Wintry conditions and actually went over in the garden a couple of weeks later,(due to fluid on the tyre, on the grass) the crash bars proved their worth (my dodgy leg and ankle also acted as buffers) I took a chance on a complete set of lines,second hand off Fleabay, for the princely some of £18 , unstuck the rear caliper, bled the lot and had brakes were almost on a par with the Brembos on my VTwin Aprilias. Anyways I do hope this is of some help! |
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Post by satnav on Oct 31, 2015 8:59:17 GMT
Ok, just making sure before I moved on.
Just one minor but obvious point, I take it the pads move freely on the pins.
Moving on. Gav's point was going to be my next suggestion. Never had this on a bike, but did have a spot of bother with it on a VW fastback. That is: there could be some crud in the brake line acting a bit like a none return valve, allowing you to apply pressure, but not allowing it to release it quickly.
If this is the case, chucking money at calipers on fleabay won't cure the problem.
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Post by crickleymal on Oct 31, 2015 9:02:21 GMT
I'm fairly sure I've read of this happening when a brake line starts to decay/collapse. Something to do with allowing fluid to the brake caliper but not allowing it back. IIRC it was when I frequented either the ZZR or the BMW forum. Seemed a bit odd at the time but it seemed to be a not infrequent problem.
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Post by m40man on Oct 31, 2015 9:09:03 GMT
I'm fairly sure I've read of this happening when a brake line starts to decay/collapse. Ditto. I posted same suggestion on the other thread. |
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Post by HRHpenfold on Oct 31, 2015 9:39:11 GMT
I'm fairly sure I've read of this happening when a brake line starts to decay/collapse. Ditto. I posted same suggestion on the other thread. And your probably right with your guess, The internal rubber will have flaked and be operating as a one way valve, Original Hoses are supposed to be replaced every few years, and people never do, including me, but if you have to replace seals, then it figures that it's time to change the hoses out! |
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Post by chris900divvy on Oct 31, 2015 10:42:10 GMT
I don't think the solution for the OP is to buy another set of calipers, but seems to me there's good logic in changing the brake hoses. Braided hoses do help a lot. Though I've never experienced this decay in the brake line material it sounds feasible to me that that could be the problem. Personally I'd look at cleaning up the part of the calipers where the pads sit against as corrosion under those plates can cause sticky pads too.
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Post by mlbv on Oct 31, 2015 14:56:38 GMT
oh, no, i am merely grumbling to myself, i know you guys are here to help, letting my annoyance out is just be exorcising my own demons and not to indicate my feelings towards anyone on the internet!!
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Post by mlbv on Oct 31, 2015 17:36:32 GMT
I only crack the banjos to release the pressure so that I can get the bike home, T then bleed the brakes properly, or the bike goes back to the bike shop to have something else replaced where they are bled again....
I don't think it is the pads sticking or not being able to float freely because the lever is rock hard once the discs and callipers have heated up which to me suggests that they are pushing back against a stuck piston as one would expect, if they weren't free to float, they wouldn't do this...
when I get home I will try to see if it is just one piston or both, but I have a feeling it is only the right hand calliper as I seem to get a couple of drops of fluid squirt out of that one.... Actually, as fluid should have equal pressure throughout the whole system, if I only get pressurised fluid from one side, it must be holding the pressure somewhere between that calliper and the splitter, otherwise opening any part of the system would release the pressure...
so yea, it must be the right hand side (the hose or that side of the splitter) that is blocked somehow...
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Post by mlbv on Oct 31, 2015 18:11:47 GMT
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Post by GAv on Oct 31, 2015 18:22:14 GMT
Yes m8 believe me I understand how you felt, been there have the soiled t shirts, and all I can say is that at that price including postage I would buy and try them, but it is really up to you, or maybe those on here more versed in the different model years,than me,can advise you better, just make sure you get a double banjo if they are 2 separate lines, hard to tell from the pic, Good Luck!
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Post by mlbv on Oct 31, 2015 18:36:14 GMT
they look like two lines with a banjo on each end, from the splitter to the callipers....
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Post by m40man on Oct 31, 2015 18:37:56 GMT
They should fit fine.
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Post by mlbv on Oct 31, 2015 18:48:42 GMT
sod it, bought them, if they don't fit for some reason they can go back on the bay...
I have collected a whole load of stuff from my engine, boost system and running gear rebuild on my racing van, so at some point I will be clearing my garage on unneeded parts via the ebay, they will be just another thing to add to the pile if they are no good... I am off to berlin now for a few days to see the lady, and the hoses should be here wednesday when I arrive home, with luck, they might solve the problem... I am leaning towards this flaky inner wall/one way valve thing even though I have never experienced something like this before, I find it hard to believe that both ends have been apart and rebuilt and the fault is exactly the same, if it were either the master cylinder or the callipers, I would have thought that the pulling apart and rebuilding process would have at least changed how the fault manifests itself if that's where the problem lies...
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Post by mlbv on Oct 31, 2015 19:40:08 GMT
once the new hoses are fitted, I will conduct an autopsy on the old rubber ones by cutting them into half inch slices and taking a look inside to see if there are any signs of deterioration, partly confirm whether it/they are the cause to put my mind at ease, but mainly, from my perspective as a scientist, it would be good to have a real world example that can be posted up on the site... I do this on the caddy forum quite often to give full and frank explanations of particularly weird faults and problems and exactly how to prevent them...
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Post by satnav on Oct 31, 2015 21:05:50 GMT
B*gg*r, could have done with them myself. However I think they have gone to a more deserving home. Your need being greater.
Looks like someone is breaking a 2000 Divvy if anyone wants parts.
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Post by HRHpenfold on Oct 31, 2015 21:18:53 GMT
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Post by mlbv on Oct 31, 2015 21:20:18 GMT
yea, they are from the same seller the callipers I was looking at are from, si i reckon he has a lot of other parts too...
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Post by GAv on Oct 31, 2015 21:59:26 GMT
Still havent sorted the location of those lines SatNav? Caddys yep lots of fully loaded stuff on them, particularly the 50s stuff. Regarding the lines. As far as I can tell those ones for sale are two seperate lines as opposed to these, looking at the ones on the left,  my original XJ900S ones circa 1997. They are the old ones I had on mine, sans the long line on its right top off the union metal line, which got cut off and chucked(looking at it via the screen it runs up from the left fork in effect. The one on the right is an original RSV Aprilia Mille one. Mine has colour coded blue plastic over 2 braided individual lines,  so where it goes into the master cylinder, it needs a longer banjo bolt, which has two holes to accomodate those in each banjo.  Sorry I hope I have unconfused what I meant ie the bolt holes not the Banjos themselves, or am not sounding patronising either.. |
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Post by mlbv on Oct 31, 2015 22:10:39 GMT
haha, no, vw caddy van, not caddilac!!
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Post by satnav on Nov 1, 2015 18:30:57 GMT
Hi guys. Thanks for the help. I don't NEED new braided lines. Its just they looked a bit of a bargain at £17.00
You know, something to fit later.
I've had a lower fairing which I bought cheap over a month ago, which I will get around to fitting sometime soon. Maybe.
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Post by bobh on Nov 1, 2015 22:23:07 GMT
The only time I got a similar symptom, on my D600, it was due to oxide build-up in the dust seal grooves. So even with new seals, if the grooves aren't fully cleaned out, the pistons can seize. Then you get a runaway reaction because heat builds up, everything expands and it all locks up solid.
It was quite obvious which side it was - the one with the blued disc! Fortunately it didn't warp.
But having said all that, given the symptoms in this case, I'm inclined to go with the brake pipe as the most likely cause.
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Post by mlbv on Nov 4, 2015 13:48:25 GMT
Well, a little further investigation and it is definitely both sides that are binding and eventually locking up when they get hot, cracking either banjo on the callipers releases the pressure and frees both sides off, so I am doubtful that the two lower sections being replaced will solve the problem, unless both are exhibiting the exact same fault at the exact same time... the problem must lie in the single section of hose or the master cylinder (i think....)
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Post by m40man on Nov 4, 2015 14:16:42 GMT
The lines you've bought are full-length, so I'd remain optimistic for the present.
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Post by mlbv on Nov 4, 2015 14:29:01 GMT
ah, gotcha...
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