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Discussion Starter #1
'95 M900.
Had the usual squeeking rear brake (when applied) and read somewhere a possible cure was to place thin shims (coke can..)between the caliper pistons and the pads. Did this...no differance.
tried some sinter-free pads (Ferrodo)...cured the squeeking, but now I get the rear brake binding after a 20 or 30 minute ride. Calipers very hot, but doesn't seem to release disc. I dissassembled the calipers, pistons OK, seals OK, no dirt. I then disassembled the master cylinder, seals OK. Re-flushed the system with new fluid and, statically, the rear brake works OK, locking the disc when applied and releasing the disc when the lever is released.
Notes :
1: Sinter free disc pads were thicker than old ones.
2: Caliper pistons sit further back in the caliper body than before.
3: Disc thickness under size at 3.15mm to 3.20mm (minimum 3.6mm according to Haynes)
...Any ideas, guys ?
I'm thinking the softer pads are creating more friction and maybe boiling the brake fluid(?) causing expansion and forcing the pistons to lock around the disc...but shouldn't the fluid expand up into the reservoir in this case ????
I think I'll put the sintered disc pads back in and see if it makes any differance (as well as changing out rear disc....)
Anyone else seen this phenomenon before ?
Cheers,
...Simon
 
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Discussion Starter #3
Hi Howie,
The freeplay..is that before the pushrod hits the master cylinder piston ?
I have about 2 to 3 mm of pushrod movement before the pistons lock on the rear wheel, however I'm not too sure whether this is freeplay or just the movement in the piston/pads to disc, as the lever return spring kind of masks the pushrod freeplay (if it exists)...any easy way to check this ?
Thanks......Simon
 

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free play is the amount of travel before the pushrod starts moving the piston. this is needed to assure the compensating port in the master works, avoiding pressure build-up.
 
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Discussion Starter #5
I'd go back to the stock pads, champer the edges, apply anti-squeel compound (not a coke can) to the back of the pads.

That's what I did with mine to cure the brake squeel. Everyone said the squeel would come back, but it's been several months now and it is still quiet.
 
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Discussion Starter #6
First, good call on the brake fluid boiling. Make sure you're using high temp brake fluid such as Motul 300 or its equivalent. Second I would recommend applying a thin coat of moly grease and/or anti-seize to the pins to make sure the pads aren't hanging up on the pins and staying stuck to the rotor, causing drag and heat build up. It would also be worthwile to make sure the piston is moving freely in the bore of the caliper. If it is binding at all it will not retract fully and the pads will remain touching the rotor and cause heat build up. Hope this helps!
 
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Discussion Starter #7
Thanks for the help, guys...
I checked the lever freeplay this morning and found it compressing the piston slightly when there was no movement in the lever, ie as is. I adjusted freeplay to 1.5mm (thanks Howie ;)) and will give her a go !
Thanks SoCalMonster for the tip on chamfering...I'd tried this a few months back and found this worked for a while (however, this latest problem may have caused brake squeal as well...).
Pistons checked out OK, but if the seals are suspect, does anyone have a good source for master / caliper seal kits ?
The local shops down here don't seem to carry any.
Cheers,
...Simon
 

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Pistons checked out OK, but if the seals are suspect, does anyone have a good source for master / caliper seal kits ? The local shops down here don't seem to carry any. Cheers, Simon
I was told by TAW that brembo didn't do replacement seals, so I've got a rear caliper and master cylinder on the shelf for those who need them. They're like $70 for the caliper and $40 for the master cylinder. Not that spendy, given shop rates for rebuilds.
 
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