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Old 20-01-2008, 04:30 PM
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Default brake prob

Got a bizarre problem with a bmw k100lt wondering if anyone else has had same issues.

In a straight line brakes are 100% but if you turn to left or right you lose pressure or go backwards again turning you lose pressure. Its non abs or maybe used to be but has had gubbins removed. Its had a new master cyclinder I have routed two braided hoses to each caliper direct from the master and it still does it. The pistons must be moving back into the brembo calipers when manouvering.
Its dodgy to say the least even something daft like turning round is hard work. You end up building the brakes back up again.

Gonna try a differant set of calipers from another bm see if that sorts it.
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Old 20-01-2008, 05:42 PM
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Are you sure all ABS bits have been removed, loadsa **** here, dunno if this may help



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Old 20-01-2008, 06:07 PM
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Yep ran the braided hoses to the calipers myself just a bog standard setup.
Its gotta be the calipers it seems the pistons are springing back in themselves when the bike is moved but why it only does it when you go backwards or turn the bars is beyond me the wheel ect seems tight calipers aint loose ect got me puzzled
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Old 20-01-2008, 07:24 PM
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warped disk/disks?
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Old 20-01-2008, 08:15 PM
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borked wheel bearings or spindle, putting side force on the caliper when not going in a straight line ?
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Old 20-01-2008, 08:23 PM
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If I understand correctly..on the straight the brakes work ok...(when you don't need them much) on a corner or rolling backwards you have to pump them...In other words when you tilt the bike? or when you turn the bars?..it sounds as if you have air getting into the system...if it's when you turn the bars, could it be pipe dressing causing a pull on the connections or stressing a pinhole to allow air in...maybe a very close look will show some traces of fluid or abrasion...braided hoses are harder to trace leaks when they finally get them...John
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Old 20-01-2008, 09:43 PM
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Quote:
If I understand correctly..on the straight the brakes work ok...(when you don't need them much) on a corner or rolling backwards you have to pump them...In other words when you tilt the bike? or when you turn the bars?..it sounds as if you have air getting into the system...if it's when you turn the bars, could it be pipe dressing causing a pull on the connections or stressing a pinhole to allow air in...maybe a very close look will show some traces of fluid or abrasion...braided hoses are harder to trace leaks when they finally get them...John
Yep thought of that thats why I replaced the master cyclinder dumped the origional braided hoses replaced with known workin ones and ran independant hoses to each caliper from the master cyclinder.

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borked wheel bearings or spindle, putting side force on the caliper when not going in a straight line ?
Interesting but it does it at walking pace aswell today me and a mate replaced and bled everyting up literally bounced it off the mainstand and pow no front breaks at all until pumped again going to investigate the front wheel ect again its a real mind number. Its odd full break when built up turn tilt or reverse nothing. At standstill everything lines up good ect.

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warped disk/disks?
Gonna check them again aswell if there goosed they will push the pistons back in quick spin though and they were straight and not binding 1st time round. And when your riding with the break on no pulseing ect as you get when there warped.

mucho hair pullin going on here with it.
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Last edited by jabba; 20-01-2008 at 09:45 PM.
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Old 20-01-2008, 10:48 PM
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im with borg - knackered bearing / loose wheel.

turn steering, wheel wobbles, pushes disc onto pad, no brakes.

Backwards, wheel wobbles out of its slot that its worn, same effect.
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Old 21-01-2008, 12:31 PM
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I'D GO WITH BORG AND ABOVE.. (NOT GO WITH THEM IN A SEXUAL WAY YOU UNDERSTAND)
oh hell caps
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Old 21-01-2008, 06:42 PM
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I know nothing about BMW K series stuff.

But.....

Had the same problem with an XJ550. Turned out it was the slidy bits in the floating calipers worn to buggery.

So, if it's got floating calipers, that might be worth a look too.
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Old 22-01-2008, 12:40 PM
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Sorted I could kick myself there was a bolt through the end of the spindle where you usually have a hole to put a screwdriver through or something it was stopping the spindle from tightening up all the way the things you miss for god sake.

Thanks people after much brake bleeding ect it was that god awful now in the bin should have been thrown in the sea to rot bolt.
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