One Lap Help needed..residual check valves

[GreenGSX]

guys, we spoke to a fellow One Lapper who suggested that we install a pair of residual pressure check valves inline with each front caliper. That would hold just a few pounds of pressure in the caliper and take care of our wheel bearing rotor run-out issues. I don't know to much about them so I am asking for help finding a set that will fit our car and finding a way to get them in our hands ASAP. We have no problem paying the overnight few as long as we know they will fit.

Tim

 

[toybreaker]

Was he in your class? /ubbthreads/images/graemlins/idea.gif

( /ubbthreads/images/graemlins/rofl.gif )

I would strongly recommend against using a residual pressure valve to "solve" your problem.

Pad knock back is caused by a rotor that is not spinning true.

It's primary symptom is increased pedal travell.

If you're having problems with increased pedal travell due to pad knock back, machine or replace the rotors, check the hub for run out and your wheel bearings for freeplay.

Problems in any of these areas will knock the pads back from the rotors and increase the pedal travel as the pads have to be moved a considerable distance before they contact the rotor and begin to do work.

Using a residual pressure valve to hold the pad against the rotor will allow the pad face to reach temperatures above it's design parameters, and may very well lead to outgassing... (you won't like that, to put it mildly.)

In addition, the body of the pad acts like a heat sink, and you will end up transferring a whole sh*t ton of heat into the caliper, potentially causing more serious issues like damaging the square cut o-rings, boiling the fluid and the like.

But, the number one reason I would recommend against this is that when you stop, the pad will be solidly up against the rotor.

This will cause the rotor will cool unevenly...

Best case is a warped rotor...

Worst case is a serious case of pad material transfer as the pad matrix breaks down, making the brakes all but unusable.

If you're running the 3kgtvr4 set-up, be sure to check your calipers for alignment, and the caliper pistons for freedom of movement.

The pads will tell that tale.

If they are tapered, investigate and repair the cause, fire in some fresh pads, machine/replace the rotors and you're good to go.

 

[GreenGSX]

We have wheel bearing issues. We changed on the passenger side and it got better and the plan is to replace the drivers side right after the afternoon session which is starting now.

 

The valves are on their way. Right now, machining the the rotors is not a viable solution. The center bore of the rotors should be the same as factory. I can double check that to confirm. The valves are 2 lb valves designed for use with disc brake systems. Another thing to check is the center bore of the wheels & as mentioned checking to make sure the caliper is properly aligned with the rotors.

I did supply the team with a back up set of pads & rotors. The valves should work & have been used in this application before with good results. Right now, anything to help the team survive the rest of the events & be able to drive home will be a big plus. The problem seems to be happening when the car is tossed around. In a straight line it's fantastic but they need a little help to perform @ their optimum in this environment.

Hopefully UPS will deliver them early tomorrow morning & the team can find the necessary flaring tools to get them installed. We are stil trying to figure out where the best place would be to put the valves. So far the suggestions have been in the wheelwel where there's approximately a 4" straight section in the line. Still trying to figure this out so any help would be great.

 

I agree with John, you are putting a band-aid on a serious problem, and you are going to make a big problem with your band-aid even bigger.

I hope you don't have brake fade going into a corner and end up like that Cadillac if you put these things on. /ubbthreads/images/graemlins/frown.gif