Magura master cylinder leak, bad bore

[bushwa]

You guys that have had a leaky clutch master cylinder, and found the bore of the mc to have imperfections, what did you do to fix it? I picked up the rebuild kit, but no sense in putting a new seal in a shitty bore. Anyone have luck honeing the bore to remove the imperfections? Just buy a new mc?
Thanks
Gary

 

[Xcuvator]

The bore is supposed to be hard anodized. If it is grooved it is done IMO.

 

[duggoey]

There is an extensive thread on this topic somewhere.

 

[duggoey]

http://www.cafehusky.com/threads/magura-clutch.33950/

This isnt the one I was thinking of but it more than covers the topic.

 

[bushwa]

Thanks for the link. Lots of good info there. I think I'll try cleaning up the bore and see what happens. Edit. Just ordered a flex-hone, 9.5mm Aluminium Oxide, 240 grit, intended for brake cylinder or cylinder head valve stem honing. I'll post up on the success or failure when it arrives.

 

[bushwa]

Update. Last night I removed my clutch MC, honed it out using a 1200rpm drill and the 9.5mm AlOx 240 grit hone. Used mineral oil as lube. About 20 seconds worth of in and out. Cleaned. Inspected. Honed again for about 10 seconds. Cleaned. Looked like a nice uniform aluminium bore. Reassembled with new MC piston/seals. First impression, there is slightly more lever effort. Second observation: Prior to this, I would squeeze the lever, and could watch tiny bubbles float up in the reservoir, any time I pumped and held the lever in, post bleeding, so I suspect it was pulling air in through the faulty seal, as well as letting oil out. Now, I don't see those bubbles, which makes me feel good. Rode 20km to work today in traffic and took another rip around at lunch time. Clutch action feels good, and it appears not to be leaking from the MC anymore, but I will continue to monitor it as it never was a BIG leak. Just enough to make a mess around the lever pivot with continuous use. As it is, I would use a finer hone grit (higher number) next time if available (they're special order). The 240 apparently produces a surface finish that's on the rough side of acceptable for a dynamic sealing surface. So far so good though. YMMV. Don't whine to me if you f'up your already f'd up master cylinder.

 

[duggoey]

It might not last as long as the original bore because of the anodising surface is much harder and wear resistant than Al itself. But as you know the anodising is flakey anyway so it will be ineresting to see how long it will last.

 

[bushwa]

Yea. Not much to lose in my case. Bike only had about 2500 km on it when I noticed it leaking early this summer. Can't Imagine it was wear that initiated the leak/flaking.

 

[willie]

There have quite a few reports of Magura MCs leaking on practically new bikes including mine. I expect this is a manufacturing fault rather than wear. Sounds to me you did a good job of repairing it. Little chance of it wearing out or leaking again.

 

[OlderHuskyRider]

Mine leaked(s) too, since new. Probably just continue to live with it.

 

[bushwa]

Mine left me searching for mineral oil and some surgical tubing in the middle of a 3000km trip after it leaked dry and I had no clutch. Wasn't too bad, except for starting from a stop. The 630 loaded with gear is a bit of a pig to push up to speed before dropping into gear. I'll carry a small 2oz bottle with my spare tube from now on. It's been a few more days and it's still dry tho. :-)

 

[bushwa]

This topic just popped up in the TE630 specific forum, so thought I'd post an update. Bike now has done at least 12,000 km since the repair was done. Checked fluid level a few weeks ago, still full, clutch still working fine, so the repair has lasted longer than the original set up did.

 

[rancher1]

Nice update, thanks !