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Discussion Starter #1
Well lets begin with bike configuration.. I have stock calipers and pads, SS lines and a banjo bleeder at the master cyliner.. The problem began a couple of months ago.. Mushy Brakes... The brakes were great until.. I went down a couple of months ago..nothing serious but since then I have been trying to get some decent braking back, and I can't.. I have bled to the point I should have a 50 gallon drum in my garage for brake fluid..They feel good for a little while until they heat up..Then pow mushy brakes.. I have heard this is common on the 929 but wanted to verify before I replace the master cylinder.. HELP does any one have some experience in this matter...I have searched the knowledge base and came up empty.. I don't have any leaks in the system and I assure you there is no air coming out when I bleed the calipers or the banjo.. I suspect it might be trapped in the master cylinder but can't get it out///
 

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Discussion Starter #3
2000 miles or so They look brand new when I pulled them and I meaured today they are wearing evenly...Thanks for the suggestion any more? I gotta get this brake thing fixed before the 24th going to jennings...
 

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Check the pistons in the calipers. Take the pads out and pump the brake lever a few times. If the pistons tend to move out a bit and but then suck back inside the caliper to their original position then you need to do a rebuild of the calipers. That involves purchasing new seals for the calipers and cleaning the pistons (all very easy to do). Cost for all of the seals will be about $80 from Ron Ayers.

I had the same problem as you did with mush brakes. I would clean them all up and would have great brakes for about half a day or so. After that they would get mushy and the lever would pull almost back to the bar. I rebuilt the calipers and now they work just like new. I also bead blasted the rotors again to remove any pad material left on the rotors. That has nothing to do with the brakes being mushy, but I was installing new pads at the time as well and wanted to insure I had optimal grip between the pads and the rotors.

Edit: FYI, the outside pistons on the calipers were fine on my 929 but the inside pistons were sticking. You need to insure all 4 pistons are freely moving. They should all push out and stay out when you pump the lever.
 

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I've also heard that the stock piston seals in the calipers are to blame, I'm happy with my SS lines setup at the moment, but as soon as they start going off I'll be replacing the seals.

the SS lines helped heaps though.

Ben.
 

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Two things i noticed with mine:

1. pads wore unevenly causing brakes to feel mushy. Once replaced, brakes firmed up. You can try replacing the pads. If they don't make a difference, you will have a spare set for when you need them.

2. one of the best tips i received was to remove the anti rattle leaf spring clips on the back sides of the calipers, you know, the stainless steel clips held in place by the same pins that keep brake pads in calipers. Your pads may rattle a bit but the lever feel is much firmer without them. Personally, i don't notice any rattle but i run my bike at track only. Chances are your brakes will run a bit cooler without these too (at the track where repeated hard braking occurs anyway). I was surprised at how much of a difference this made in lever feel. This is super easy to do. Just remove them and go for a spin to see if you feel any improvement.

I think rebuilding your calipers would be good also but a bit more labor intensive. I am a bit lazy and would rather only do this if necessary. I believe Abtech, used to rebuild his several times a season to keep brakes in peak condition.
 

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I think your problem is just the old reliable 929/954 hard to bleed master cylinder problem. Once you get air in it's very hard to shift by normal bleeding - pumping the lever. It's a bitch for example sometimes to get fluid into the system if you drain the master cylinder so that it has to get the air out and prime itself.
It's just possible something is off at your master cylinder (that it got dirt in when you fell and needs seals) but the chances are it'll come right immediately if you vacuum bleed from the calliper while pumping the lever at the same time. You absolutely don't need to routinely change calliper or master cylinder seals for normal wear and tear - only if they have somehow got damaged.
You really don't need a vac bleeder either, they seem to go too fast for most people anyway - I posted a write up on on the old site on how to do it using a 300ml disposable BD syringe from a drug store and some 3mm bore silicone tubing. Seal the bleed nipple thread with a narrow strip of teflon tape if you vacuum bleed or it'll pull air around the thread.
 

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Discussion Starter #9
Thanks to all for the great advice...i have learned alot..lfg929 however hit the nail on the head. On my right caliper (rider view) I had two pistons not extending and would retract on there own once the brake handle was released, on the left there was one for sure and another I think freed itself as i pumped the handle..I am having a little trouble finding a seal kit to rebuild the calipers any suggestions..Also if by chance you accidently over travel the piston and fluid leaks out...Have you damaged the seal or can the piston be reinstalled?? Once again I thank all of you for sharing your experience and helping me with this it has definately been a pain in my arse..
 
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