Brakes Not Releasing

[Toby Linder]

SHORT VERSION: Rear brakes are not fully releasing, any suggestions? DETAILS: Purchased used '04 CR31SP (new Rotax FR125) in April 05 from MRP Austin. Came with F / R brakes, disconnected the F brakes from day 1. Have ~5 hrs of total track time. Recently the rear brake discs would not fully release after a practice day. Went ahead and bleed the brakes (w/o bleeder) using the procedure from this forum, http://www.mrpmotorsport.com/mrp_bleed.htm, (did some research on eKartingNew's forums too). Brakes worked fine ~10min session and then wouldn't fully release (had to move the piston to get them to release). Disassembled the brake caliper and cleaned everything (it was fairly dirty), did not lubricate any parts of the caliper. Brakes worked great for practice, qual, pre-final and final. Took kart out of the enclosed trailer the next day and the brakes wouldn't release again. (Also noticed when the rear brakes are not releasing the front brakes have the same problem, even though they have been disconnected). Next step is bleed the brakes again??? (19 Master Cylinder, part # 10.6406.00). Also, my friend bought an identical CR31SP at the same time from MRP Austin and is having the exact same problem. So we're wondering what we are missing? Any help is appreciated. Thanks

[Andy Seesemann]

T-

Garry has spoken on this issue a few times. Some karts of that vintage were sent with master cylinder pistons that would grow as time went on and stick.

MRP and their dealers were sent some replacement pistons to rebuild the master cylinders with to solve the problem. Garry is at South Bend this weekend at the WKA race and probably won't see this for a few days.

Contact your dealer.

Andy

[Toby Linder]

Thanks! I believe that's the "missing piece to the puzzle" that we were looking for.
Toby Linder ('04 CR31SP, Rotax Inter, Dallas, TX)

[Garry Lobaugh]

Please get the karts or the brake systems down to Tim in Austin as soon as possible and we will replace the problem parts.

thanks Andy for filling in.

[Toby Linder]

MRP Austin is sending us two master cylinder pistons. If that doesn't resolve the problem we will contact Tim. Thanks, Toby Linder ('04 CR31SP, Rotax Inter, Dallas, TX)