TRX250R.ORG
Workshop => Suspension and Chassis => Topic started by: rmw214 on April 19, 2021, 08:47:15 PM
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I'm in the process of troubleshooting the front brakes. Got them to where they will pump up and build pressure but once I let the lever out for 2-3 seconds, I lose all pressure. Not getting any air bubbles out of the bleeders and I also tried zip tieing the front brake lever over night with no luck either. I did replace all crush washers on the brake lines as well. I'm going to try re-building the master cylinder next. Anyone have any other suggestions or have this same problem? Thanks
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Do you still have the oem rubber brake lines?
Joe
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I have Galfer braided lines
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Did you recently rebuild the calipers? If you rebuilt the calipers & are able to build a little bit of pressure by pumping the brakes & than it goes away shortly after that sounds like there's still air trapped somewhere. Never personally tried it but I've read about pushing fluid in from the bleeder's up to the MC which is supposed to be a better way of bleeding brakes on bikes.
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Everything was disassembled as I'm doing a fresh build. Calipers have been rebuilt but not recently.
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Ive had good success with the bottom up method
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Ive had good success with the bottom up method
I agree. I blend the traditional top-down open/close method for 2 decades and it will work. I did buy a reverse bleeder for a stubborn caliper on the old drag bike - seemed like there was an air bubble/pocket tucked away that just would never come out. Had never had one that stubborn, but this worked and now it's all I use - wish I bought it 20 years ago!
https://www.amazon.com/gp/product/B00GRV800S/
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Some good suggestions....
https://www.forums.trx250r.org/index.php/topic,3204.msg31754.html#msg31754
Joe
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Zip tie a hose on to the bleeder. You want the hose the fit tight. Stick the other end into a container that has some brake fluid in it. Make sure the end of the tube is submerged in the fluid. This will keep air from entering the system. A plastic water bottle works well. Drill a hole thought the cap, run the tube through the hole and zip tie both sides so it is secure in the cap.
Open the valve and compress the pistons. I typically use a c clamp, or channel locks on an old brake pad. This will get any air out that might be trapped behind the piston. Close one valve. Install calipers on the spindle and bleed away. You can leave the valve open while bleeding. Bleed until you get clean fluid coming out. Close the valve on that brake and open on the other. Repeat bleeding. Make sure you don't run the master cylinder dry. As long as the hose is in the fluid and tight on the valve you don't have to worry about air getting
Close both valves and bleed normally. You should have good tight brakes.
f you still are not holding pressure you will want to look at rebuilding the master cylinder.