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Discussion Starter #1
Hi all, been ages since I've posted... I've finally dug the old st4s out the back of the shed! Been doing some upgrades. Gone for the DD headlight kit, 999 4 pad calipers and ABM handle bar kit. I've bought some st3 master cylinders but I want to change the clutch side seals, but mainly the rugger boot for the push rod off the lever.

My question is, does brembo do a kit? Or does anyone have a part number for a kit?

Cheers.
 

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I'd be interested in that info too. I haven't been able to find a seal kit for the masters that are on the ST3.
 

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Discussion Starter #3
I'm starting to lean towards the Brembo PS12 110436292 kit? The number on the master is 4F28+ 12. I think the 12 is the bore diameter?
 

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Mr Leakered
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I am sorry, but I don't recall if the small pivot ST masters are rebuildable. Maybe take some pics and check in with Steve at bevelheaven.com?

I know the large pivots were easily rebuildable. I replaced them with 996 masters though. Quite nice.

One thing. Even though DOT 5.1 is compatible, I found that it shrinks the seals a bit and will weep. Stick with a good DOT 4. If you are running DOT 5.1 now, my swap and see?

Have a good one.
 

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Discussion Starter #5
I am sorry, but I don't recall if the small pivot ST masters are rebuildable. Maybe take some pics and check in with Steve at bevelheaven.com?

I know the large pivots were easily rebuildable. I replaced them with 996 masters though. Quite nice.

One thing. Even though DOT 5.1 is compatible, I found that it shrinks the seals a bit and will weep. Stick with a good DOT 4. If you are running DOT 5.1 now, my swap and see?

Have a good one.
Well I've managed to strip the master cylinder. The part number on the piston is 10.4623.14. It's 11.9mm diameter and 36.7mm long. Think I might of found a kit, but it won't be the full kit, but all I need really is the piston, seals and boot.
987574
987575
 

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Mr Leakered
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Nice. If you got it apart, it should be rebuildable. For the 996 masters, it looks like they are hard potted.

It was said in the past that KTM sells a lot of master and caliper rebuild kits that other OEMs won't. Maybe see if you can find a cross reference there? I found this Brembo catalog ages ago. It might help you?

Have a good one.
 

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Discussion Starter #7
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So anyway, I've found a kit which is the closest I can get. The boot is useless as it's to small to fit in the piston bore.
 
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Mr Leakered
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Interesting to see this thread after today. I went for a ride on the ST3 firstly to discover that I had to go directly to fill up with fuel. It's been awhile since I took her out for a thrash. But the clutch felt funny, almost not there and by the time I got to the servo it wouldn't release to get into neutral. Then I found the fluid was very low in the clutch master cylinder.
It's been awhile since I played with the hydraulics and after I took the cap off and filled the chamber I was expecting it to be good. Wrong! 10k's later there was brake fluid dripping on my paintwork. The horror! I headed back home as I had nothing to wipe it , and I confess I was fairly quick about it. After a cleanup and a look under the cap I realized I had stupidly poured fluid in on top of the rubber insert, so I had both overfilled and underfilled in one moronic swoop.
OK it's done right now , working well, but I still don't understand why I lost fluid in the first place.
My only ideas are either it was from leaving the bike on the sidestand for too long, [causing a slight leak at the cap] albeit with a piece of wood under the stand to keep the bike as vertical as possible, because I don't like the stress on my back when I hoik it onto the centre stand, or maybe the slave is leaking down inside where I can't see it, which is probably more likely. I should probably pull the clutch and see if there's anything migrating out to the plates which would be a pain in the bum. Is that a scenario or would fluid just drop out from below the slave?
I'm guessing I need to find the problem before it gets worse and leaves me stranded. Hopefully I'll get a ride in tomorrow anyway.
 
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