brake proportioning valve

[Richard McDonel]

Further to my self-congratulatory post of May 8, I must advise that I'm back again to Square 1.  I installed the rebuilt valve, and now brake fluid is getting to it, but not beyond it.

Anyone have an operable one to sell?

I appreciate your interest and support.    

[Captain Obvious]

Arrrrrgggh!!!

[240260280]

Sent a pm

[EuroDat]

15 hours ago, Richard McDonel said:

Further to my self-congratulatory post of May 8, I must advise that I'm back again to Square 1.  I installed the rebuilt valve, and now brake fluid is getting to it, but not beyond it.

Anyone have an operable one to sell?

I appreciate your interest and support.    

That sucks. I thought you had it beat. I wonder what is wrong inside. Probably the order of assembly. Another good reason for a simple piece of paper with instructions.....

Good luck with finding a suitable replacement.

[Namerow]

20 hours ago, Richard McDonel said:

Further to my self-congratulatory post of May 8, I must advise that I'm back again to Square 1.  I installed the rebuilt valve, and now brake fluid is getting to it, but not beyond it.

Anyone have an operable one to sell?

I appreciate your interest and support.    

Silly question, but it needs to be asked:

Is there any chance that you plumbed the valve back into the system backwards?

[Richard McDonel]

Namerow,

Thanks for the suggestion, but I don't believe so.  I put it back together as per the blow-up photo I attached earlier, and with the FSM at hand.  I'll give it a few days, then remove and have another run at it once my head clears. In the meantime I still have a hundred little things on the car to keep me busy

 

ps

Are you, or are you related to Canadian Motorsport Hall of Fame member Norm Namerow? 

[Richard McDonel]

The saga continues.  

Z-car veteran DKW and I worked on the rear brakes for a couple of hours yesterday. Work included dismantling and re-assembling the back-brake proportioning valve.  Same thing.  Brake fluid to the valve, but only the occasional drip gets through to the T and the wheel cylinders.

Someone advised me of a used valve for sale on E-bay.  Price was right, but somehow the seller couldn't figure out how to get it from the U.S. into Canada.

Questions:  Is this much trouble endemic to the early Zs, or is mine  a rare case?  If it is rare, I'm open to hear from anyone who might have one to sell.  If it is common, I'd like to know of peoples' experience with the Willwood adjustable prop valve.  I notice that it is recommended for use with disc brake conversion, which is not the case here.  My only previous experience with Willwood stuff is in-cockpit  adjusters on oval-track racers.

Thanks All

 

 

[grannyknot]

Richard, I have one that I removed from the Z I'm working on right now, yours for the price of shipping.

Send me your address in a PM and I'll get it in the mail to you. I'll do a little bench testing first to make sure working before I send it.

[Chickenman]

Richard. Regarding the WilWood proportioning valve. It will work fine on drum brakes as well as Rear discs. I've used them on many Autocross and Road Race cars to adjust corner Turn-in. 

You could gut the insides of the rear Datsun proportioning valve to turn it into a simple Tee fitting. That would be the easiest. Or buy a Metric Tee fitting. Then plumb the WilWood valve into the rear brake line that comes off the Master cylinder.

You didn't mention if the WilWood in cockpit adjustment on your Roundy Round cars was a Hydraulic valve or a balance bar system. Doesn't really matter. On a street car it's not something your are often changing. The hydraulic adjuster will be fine in the engine bay. Make a few braking runs on a deserted back Road and adjust the balance to where you want. You can get a LOT more rear brake than what the factory system uses as a default. 

[sweatybetty]

2 hours ago, Chickenman said:

Richard. Regarding the WilWood proportioning valve. It will work fine on drum brakes as well as Rear discs. I've used them on many Autocross and Road Race cars to adjust corner Turn-in. 

You could gut the insides of the rear Datsun proportioning valve to turn it into a simple Tee fitting. That would be the easiest. Or buy a Metric Tee fitting. Then plumb the WilWood valve into the rear brake line that comes off the Master cylinder.

You didn't mention if the WilWood in cockpit adjustment on your Roundy Round cars was a Hydraulic valve or a balance bar system. Doesn't really matter. On a street car it's not something your are often changing. The hydraulic adjuster will be fine in the engine bay. Make a few braking runs on a deserted back Road and adjust the balance to where you want. You can get a LOT more rear brake than what the factory system uses as a default. 

from what i have read, you want to do the adjusting on wet pavement

[Richard McDonel]

Chickenman,

Thanks for the information.  Interesting to learn that there is more back-brake power available than is stock.  I would hazard to guess that the factory designed it that way to be absolutely sure that there was no inadvertent rear-wheel lock up.

I'm not clear on gutting the prop. valve.  With only two connections ( M and R), I don't see how we would achieve a "T."  Would it not make more sense to simply remove the factory valve and install the Wilwwod in its place?  

In any case, I'm hoping it is all academic.  "Grannyknot" is mailing me a cleaned up old unit, and we'll hope that takes care of the problem.   

I really do appreciate all the replies I've had on this one.  With respect to my reply to Namerow a week or so ago, I believe I misunderstood his post.  The question he posed was not whether I had the guts of the valve installed bass-ackwards, but whether I had the lines connected to the wrong openings.   The answer to that is no; I've checked and double checked that "M" goes to the Master, and "R" goes to the rear T.  My apologies for the confusion.  

Best regards All

 

[Chickenman]

5 hours ago, sweatybetty said:

from what i have read, you want to do the adjusting on wet pavement

Not really.  That can create problems in the Dry. You get more weight transfer to the front under dry Road conditions.  That requires less braking force from the rear brakes. From us PNW Road Racers who always race in the Wet, you actually crank in more rear brake bias  ( Wet ) because you don't get as much weight transfer to the front..

Setting the brake bias up for maximum braking in the wet, can cause the rears to lock before the fronts when it's dry.  That's a good way to spin out.  An in-Cockpit knob for Race cars alleviates the problem somewhat.  But for a street car with the proportioning valve in the engine bay, it's best to set up Brake bias in the dry. 

Hill climbs also allow more rear brake bias as you're going uphill and the rear wheels have more weight on them under braking than when on a flat road.. or a downhill. I'd typically have to add a full turn of rear brake to my Camaro when I ran Hillclimbs as compared to Autocross or track days. And I liked a LOT of rear brake. 

Modern race cars such as F1, Indy Car and WEC have brake bias controls on the steering wheel. and the drivers will adjust them constantly for different types of corners ( Road racing ). You can often see the driver twiddling with knobs or buttons before a corner and see the Dash flash up numbers like 63.2,  63.0 etc. That's the brake Bias percentage.