Brake metering valve

[Fannydunk]

I hope someone out there can help. My 89 VR rear brake didn't let all the way off after an emergency stop. It heated up to the point it pulled the bike to a stop about 3 miles later. I have I have rebuilt the caliber and it looks good, no rust or pits. Next I took the master cyclinder off and thought I had found it stuck. I freed it up and worked it off and on all day by hand. it had good return every time. I put it back on bike and used it to fill the left front caliber. When I went to fill the rear caliber the peddle would not go down at all, even with the rear caliber line unhooked.

Question? Does the metering valve under the fairing have a slider valve that isolates the front caliber from the rear, like cars used to have, or is it a proportioning?

I have read all the post I can find, and I don't see any mention of the metering valve

I appreciate any info, Thanks

[Squeeze]

The Valve is a proportiong Valve.

 

 

You may take a Look at the Linkage, being stuck or binding or wrong adjusted or the Relief

Hole in the Master may be clogged.

[Fannydunk]

The manual calls the valve under the steering head a metering valve. It calls the one attached to the master cyclinder a proportioning valve. I'm wondering if the metering valve has a slider in it that isolates the front from the back if one or the other fail.

[greg_in_london]

My understanding is that the gubbins near theheadstock is basically a restriction so that the front brake acts less effectively than the back brake.

 

The proportioning valve between the rear brake banjo and the master cylinder has a ball bearing that slides as the bike slows (ie during heavy braking) to make the back brake less effective.

 

The sole purpose is to make sure that even an idiot can't brake to heavily, by making both brakes less effective (although not affecting the other front disc controlled bythe handlebar, but taking away all feel) according to the manual.

 

If the pedal won't move, then either both have simultaneously jammed (unlikely) or you have a mechanical problem with the master cylinder and/or its linkages.

 

You won't be surprised to hear that I junked the proportioning valve with no ill effects to the back brake and then fitted a larger bore front master cylinder to operate both front discs so the other disc could function properly.

[Fannydunk]

Thanks Greg. My 89 does not have a ball bearing in the proportioning valve. It has a little copper or brass piece about an inch and a quarter long with a rubber piece on the end. This is forced into the bottom of the valve and held in place by a spring that surrounds it.

Am I to understand I could take this out and put the cap back on and have brakes like an older moto?

[greg_in_london]

Mine is an '83, so check on the parts fiche that they are the same. On mine it was a five (ten with bleeding the brakes) minute job when I finally did it - unbolt the banjo, unbolt the valve, replace the banjo without the valve and bleed the brake lines.

 

Do it quickly so you don't have air somehow getting into the front brake line.