Brake problem

[jimmish]

132278 Had a problem with the brakes this weekend. Did a line lock burnout and after releasing the button the car wouldn't move, front wheels locked, brake pedal stuck halfway down. Thought the line lock was stuck so pulled the fuse, Nope, actually had to bleed the brakes and heard and felt the caliper "pop". Rolled (but no brakes). Ended finding this, the front master cylinder pushrod into the balance bar bent down and got jammed against the pedal box. Tech from Wilwood replied he had never seen that happen before. At least it was the starting line, not the finish at 130mph. Waiting for a solution from Wilwood.

[RoadRacer]

Holy cow! How on earth?

[NAZ]

Wow, that must have been a lot of force applied through the pedal or a quality issue with the push rod. Never even heard of that happening. Would be interesting to send that part back to Wilwood and have them check the hardness against a standard or at least against others to see if the heat treatment was off. A simple Rockwell test would be useful.

Thanks for sharing.

[michael everson]

Wow. That's new one. Glad you weren't moving.
Mike

[cob427sc]

Can't imagine it would be humanly possible to do that unless the rod itself was defective.

[David Ferguson]

Just like engine builders, there's only two responses to most problems. "They all do that", and "I've never seen that before!".

How much pressure does the line lock apply do the hydraulic system? I have to assume it pushed the piston against the stopped pedal. Thinking about this, with a dual master cylinder setup, if the line lock only applied pressure to one cylinder, it would push back on the balance bar, and could actually activate the other brake slightly. Perhaps that see-saw action, let the clevis bind-up and the force bent the rod.

Certainly an unusual failure.

[NAZ]

David, a line lock is simply an electric solenoid valve that blocks the front brake system from returning to the M/C when energized. You apply the brakes (F&R) and once you have sufficient front brake pressure you hold down a momentary contact switch and let go of the brake pedal. The pressure in the front calipers is held until the switch is released. The M/C is under no pressure when the line lock is applied. There is no way a line lock would cause damage to the push rod.

[jimmish]

Talked to Wilwood today, even the bosses replied they had never seen that happen before. Never was a fan of the balance bar arrangement, especially being up under the dash. Going with a floor mount pedal to a single, tandem outlet, remote reservoir system. Of course that puts me under the gun to install and test that it works before the rescheduled Land Speed Event in Maine in 5 weeks.

[michael everson]

Sorry Just saw that this is a Hotrod. No other pedal box option.
Mike

[JimLev]

Of course that puts me under the gun to install and test that it works before the rescheduled Land Speed Event in Maine in 5 weeks.

Loring AFB?

[jimmish]

Yes. 5 years in the making and as its ready they cancelled the July meet. rescheduled for Labor day weekend, if it happens at all. Hoping for the best.

[NAZ]

Good luck, you have my second favorite hot rod so I'll keep my fingers crossed.