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Sticking front brake lever


cabbage

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Hi. I need a little help please.

 

I've run a search on this but couldn't find anything.

 

I've just replaced the fork seals on my r1100rt. The fork oil had run all over the brake pads. After cleaning the front calipers thoroughly I installed new brake pads.

 

When I apply the front brake and then release the lever, the lever does not return to the fully out position but stops about an inch short, the brakes are still locked onto the discs in this position. If I push the lever fully out the brakes release.

 

Any ideas? I suspect this is at the master cylinder end of things and not the calipers as they release quite happily when the lever is in the fully out position.

 

Cabbage

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Consider that the hoses may be old. An old hose will swell and close the inner dia. When you press the master it forces the fluid thru but the return flow has no force behind it and may be restricted by the smaller ID. It usually "bleeds" back after a bit and releases the calipers.

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David McClain

I've had the same problem on my 96RT. After inspecting the right handlebar assembly I noticed a small accumalation of brake fluid in and around it. Road grime and dust made its way to the lever pivot screw. I removed the screw and cleaned it now the lever returns to its proper position. Now all I've got to do is to rebuild/replace the master cylinder!

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From a prior thread:

 

If you remove the plastic cap on the front master cylinder (after removing the one phillips screw) and pull back on the rubber boot I think you will find a bunch of dried brake fluid and other crud under there. This is caused by slow seepage of brake fluid past the last seal of the plunger and eventually build-up of material here will prevent the plunger from extending fully, causing exactly the symptom you describe. Pretty common problem on that vintage bike.

 

The cure is simple and inexpensive. Remove the piston (make sure to remove the lockscrew on the side of the master cylinder first), clean out the bore of the master cylinder with some 400-800 grit sandpaper (flush it out well when done!) and install a rebuild kit (p/n 32722332037, about 40 bucks.) You may not really need the rebuild kit but given the age of the bike I'd throw one in while I'm in there. When you're done refill with brake fluid then move the master cylinder around while pumping the lever and you'll be able to get any air out, bleeding from the caliper probably won't be necessary. Of course place something over the tank during the whole operation begin to end as brake fluid will destroy paint in short order.

 

After the above work you'll have a crisp front brake lever back.

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Problem solved. The pivot pin has a plastic sleeve over its central length. I removed this and hey presto returns to normal. I don't know if this bit is essential but there is no play in the lever on the pivot shaft.

 

However, as no good deed goes unpunished, I discovered a leak on the master cylinder so now it's a strip down of that.

 

Thanks for all your suggestions.

 

Cabbage

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Clive Liddell

Cabbage,

That plastic sleeve is supposed to be there. Just wipe a trace of your favourite lube on it and replace it. When you clean up the crud (tech term) I found that a slight leak that I had went away.

 

HTH

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I stripped down the master cylinder, thoroughly cleaned the piston and seals, I then used fine quality wire wool to clean up the cylinder bore followed by a polish with autosol for good measure. Lubed the seals with fresh brake fluid, reassembled - no more leaks - Hurrah!!

 

Left the plastic sleeve off the pivot, just ridden 50 miles, no adverse effects.

 

Cheers Guys

 

Cabbage

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