farmerj Posted March 23, 2005 Report Share Posted March 23, 2005 Hi guys, I recently got an '01 txt 321 - my first trials bike. Awesome! I love this bike! I'm mostly trail riding at present, and am really impressed with the torquey engine and precise handling on tight hillclimbs. On the last ride, I lost all of my rear brake fluid out of the rear caliper - somewhere. The local shop said that since the bike had been sitting for a long time that the piston seal area could have gotten corroded, allowing fluid to leak past. I disassembled and re-assembled - everything looked fine. Now I'm trying to bleed the system (I've seen the recent thread). I have no firm action when pumping the brake pedal - and I see little bubbles coming out of where the rubber boot attaches to the master cylinder. Does this mean that my master cylinder is "shot"?? Or could it be that with no pressure in the system, the (presumed) seal in the bottom of the master cylinder doesn't seat? I'll try bleeding the system again tomorrow, but thought I'd try to get some info. on my next step... Do the master cylinders have a habit of going "bad"? Can the master cylinder be rebuilt? I don't see any parts in the GG pdf manual. Thanks for letting me get initiated into this forum! I've loved following along and searching for stuff! Jeff Quote Link to comment Share on other sites More sharing options...
jaylael Posted March 26, 2005 Report Share Posted March 26, 2005 Jeff: Hope by now you have a solid rear brake pedal. You said all the fluid leaked out, but it's not clear if it came out around the rear caliper piston or not. I have seen cracked caliper housings which are maddening to diagnose. Perform the bleeding procedure with a large syringe, pushing fluid from the caliper nipple back up through the system. This will not work unless there is sufficient slack in the pushrod! Once the bleeding process is complete you should have good pedal unless the master cyl is bad or there is a cracked caliper which would leak fluid under pressure. Always eyeball the caliper and pads relative to the disc and MAKE SURE they run parallel! Often times the caliper is bent in a fall and is at an angle to the disc which will cause the rear brake to heat up and lock on! Please post your findings and let us know what is happening with it. Jay L. Quote Link to comment Share on other sites More sharing options...
farmerj Posted March 31, 2005 Author Report Share Posted March 31, 2005 Jay, Thanks for the response. I'm still struggling to get the brake response back to where it was originally - which was excellent! What a hassle! I have pushed fluid up with the syringe 3-4 times, and still couldn't get any firmness in the pedal. That is, until I loosened the brake line bolt on the master cylinder and bled it from there. Now I have some pedal, but the brake has very little stopping action - it won't lock up. I thought that maybe my problem was with the pads. One of them had a bit of brake fluid on it, which I understand ruins them. I took them off and buffed them on a wire wheel, trying to get down to "clean pad." This may not be recommended?! Now I'm not sure if they're seating squarely on the disc. But you may have given me the tip I need! This will not work unless there is sufficient slack in the pushrod! Your comment about the pushrod gives me hope that I may still have air in the line - so I will loosen the pushrod and give it another go! How do you know when it's loose enough? Do you just take the pushrod off all the way off, or ?? Thanks again for your reply! Jeff BTW - Do you elevate the front wheel or drop the rear caliper to make sure that it's at the lowest point in the system - or will this bleeding method work with the caliper bolted to the swingarm in the normal position? Quote Link to comment Share on other sites More sharing options...
jaylael Posted April 2, 2005 Report Share Posted April 2, 2005 Jeff: If you still have a spongy pedal, try elevating the rear wheel on a large block of wood or something then bleed the rear brake with the old car method of pump it up tight, then crack loose the bleeder while holding pedal. This will require at least one helper. Take care not to release the pedal with the bleeder screw open. On most sytems air will rise up, so having the back end up should allow any trapped air to escape. On some older bikes , once the system is bled, then you must tighten the pushrod up beyond what is normal to get a decent rear brake pedal. The resevoir hose is connected to a drilled hole in the master cyl. housing. The placement of this hole allows the cyl. to be refilled with fluid once the pedal is relesed, so if the rod is too tight the hole will be blocked by the m/c piston, thus preventing the fluid from refilling the cyl. "normal" pedal adjustment is with a small amount of freeplay which assures this orifice inside m/c is exposed to the refill fluid from the resevoir. If you tighten it up until you get a sufficiently hard pedal, it may not bleed properly, hence my previous statement. Once the pedal is sufficiently firm, wash off the rear disc and pads with the garden hose, then ride the bike around, dragging the rear brake until it is hot, the douse it with the hose rinsing it thouroughly. Repeat this four or five times and that should do the trick.It is very common for fluid to get spilled on the disc, but these steps normally provide a cure. If after all this it still is not sufficient, it may be time to start replacing parts, such as the caliper and master cyls. Jay Quote Link to comment Share on other sites More sharing options...
davybull Posted April 3, 2005 Report Share Posted April 3, 2005 I ride a 2001 TXT 249. I've had my rear caliper pistons seize twice now in 18 months. I've still not managed to sort it out and get a half decent pedal. Just drop it into Birketts and leave em to it! Is there an easy way of lubricating the pistons in the caliper without getting anything on the disk? May save it happening in the future. Cheers. Quote Link to comment Share on other sites More sharing options...
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