68 camaro proportioning valve (combination valve)HELP?

[Vince@Meanstreets]

depends on the type of bleeder system you have. What did you use to bleed the master cylinder?

[GregWeld]

To bleed a Master Cylinder -- it is best to be removed from the car --- mounted in a bench vise by one "ear"... I use SOFT JAWS to do this so I don't mar the ear with the vise -- Then you hook up short lines from the ports that go back into the fluid reservoir - and make sure they are fully covered with fluid so when you back stroke they can't suck air -- Then I use a large philips screw driver to drive the piston ALL the way forward many times until no air bubbles come out your lines... You'd be able to see any air as it bubbles out of the short lines you created that are down into the fluid reservoir.

The reason you don't do a MC bleed ON CAR is because you can't drive the piston forward enough with the brake pedal ---- and you can't see into the reservoir while sitting in the car pumping the brake pedal.

Typically this job is done when the MC is first installed --- but I've found lots of people that SAY they did this -- only to discover they actually had no clue what "bench bleeding" is.

Wilwood ships bench bleeding hoses with their master cylinder -- if you still have those they're handy -- although I made my own up out of old brake line and fittings.


Once you get done with that job -- you can then continue on to bleeding your brakes. Bleed them by cracking the furthest brake from the MC -- which would be the passenger REAR -- have someone push on the brake pedal as you crack the bleeder... and have them HOLD the pedal down as you then just snug the bleeder tight - have them push and hold again as you repeat the cracking of the bleeder and tighten and so forth. Making sure you check the MC fluid levels as you do this -- don't let it get to far down! When you get some fluid -- move to the driver rear -- repeat the process - then to the passenger front -- then the driver front........ when you're pedal starts to "firm up" -- repeat the bleeding process once again with the passenger rear and so on.


The pedal should come up quite firm and be able to be pushed on with all your might and it should not go down one iota! And NO air should come out the bleeders at all.

NEVER use old or opened brake fluid! Use brand new just opened fluid for all this process. Don't try to save the fluid that is being bled - it's a CONSUMABLE -- toss it.

Some times I tap (that's gently!) the calipers with a small dead blow hammer as I'm doing all of this in an effort to "shake" any air in the piston area out (bubbles SHOULD float to the top where the bleeder is - in theory anyway).

[GregWeld]

Now -- here's the problem with buying a "one size fits all" proportioning valve...


Those valves are usually specific for a car - as it left the factory. Well ---- as it left the factory it had bias ply skinny tires.... Now days we have staggered tire sizes... with big fat ones out back and fat nice ones in front...and or we also have different rotors and calipers on than came from the factory.... so now the brake bias is all wrong for what we currently have on the car.

Thus -- most people around here (performance enthusiasts for lack of a better term) will put on an ADJUSTABLE PROPORTIONING VALVE -- which, obviously, can be adjusted so that the bias will be proper for the car it's installed in.

The last thing you want to have happen is for you to need to panic stop, god forbid it's wet out -- and you lock up your rear brakes and have the ass end swap with you. Thus the need for the proper ratio of front braking power to rear braking power AKA a brake proportioning valve.

Wilwood will be happy to sell one to you -- along with a mount (if you want to use theirs) and instructions... The proportioning valve ONLY goes to the rear brakes since they're the ones we're trying to tune to get them to match what we have up front - whatever those are and the grip we have there.




http://www.wilwood.com/TechTip/TechFaqs.aspx

[dhutton]

I've always bench bled the way Greg described above but apparently there is a new better way to do it with the ports plugged. Tobin from Kore3 and Paul from Hydratech were both talking about it:

http://hydratechbraking.com/braketech1.html

I'm going to give it a shot the next time. A lot of master cylinders are coming with plugs for bench bleeding.

Don

[Vince@Meanstreets]

Originally Posted by dhutton

I've always bench bled the way Greg described above but apparently there is a new better way to do it with the ports plugged. Tobin from Kore3 and Paul from Hydratech were both talking about it:

http://hydratechbraking.com/braketech1.html

I'm going to give it a shot the next time. A lot of master cylinders are coming with plugs for bench bleeding.

Don

I started using that method too since the Wilwood masters come with plugs. Its nice cause can do it on car.

[GregWeld]

Hey! I'm all for learning new tricks! Now I'll research this 'tubeless' bleeding technique too!

[72Z/28]

Originally Posted by GregWeld

Now -- here's the problem with buying a "one size fits all" proportioning valve...


Those valves are usually specific for a car - as it left the factory. Well ---- as it left the factory it had bias ply skinny tires.... Now days we have staggered tire sizes... with big fat ones out back and fat nice ones in front...and or we also have different rotors and calipers on than came from the factory.... so now the brake bias is all wrong for what we currently have on the car.

Thus -- most people around here (performance enthusiasts for lack of a better term) will put on an ADJUSTABLE PROPORTIONING VALVE -- which, obviously, can be adjusted so that the bias will be proper for the car it's installed in.

The last thing you want to have happen is for you to need to panic stop, god forbid it's wet out -- and you lock up your rear brakes and have the ass end swap with you. Thus the need for the proper ratio of front braking power to rear braking power AKA a brake proportioning valve.

Wilwood will be happy to sell one to you -- along with a mount (if you want to use theirs) and instructions... The proportioning valve ONLY goes to the rear brakes since they're the ones we're trying to tune to get them to match what we have up front - whatever those are and the grip we have there.




http://www.wilwood.com/TechTip/TechFaqs.aspx

Thanks Greg for the write up. Actually the Wilwood MC was installed by the previous owner and I don't have the bleeding kit. I guess I am going to order the plugs to bleed the MC on the car.

As for the new stock proportioning valve, does that mean that it will not work properly with the wilwood MC and calipers? I wonder if wilwood sells a valve that does not require any adjustments because the car will not be used for autocrossing or at a track.

One more point, I recently replaced the rear brake line from right stuff detailing. It is a 1/4" line, which is basically a stock replacement. However, wilwood recommends a 3/16" line.

[72Z/28]

Originally Posted by Vince@MSperfab

depends on the type of bleeder system you have. What did you use to bleed the master cylinder?

I have not done yet, but I guess I am going to get the plugs and bleed the MC on the car

[408sbfmustang]

Possible that the metering valve is stuck in it.

[GregWeld]

Originally Posted by 72Z/28

Thanks Greg for the write up. Actually the Wilwood MC was installed by the previous owner and I don't have the bleeding kit. I guess I am going to order the plugs to bleed the MC on the car.

As for the new stock proportioning valve, does that mean that it will not work properly with the wilwood MC and calipers? I wonder if wilwood sells a valve that does not require any adjustments because the car will not be used for autocrossing or at a track.

One more point, I recently replaced the rear brake line from right stuff detailing. It is a 1/4" line, which is basically a stock replacement. However, wilwood recommends a 3/16" line.

You might have misunderstood why I posted what I did.... In a nutshell -- the stock type prop valves are designed to work with pretty much stock tire and brake sizes... I didn't say it wouldn't work with the master cylinder... I was giving you some information you could use so that you might question the use of a stock prop valve over a adjustable prop valve if you're NOT running stock or nearly stock tires etc. This is a safety issue.... you're brakes and understanding them should be your most important concern. Spinning at freeway speeds is nobodies idea of a good time. The brake bias of your system is critical to work properly when you'll need it the most... a panic stop.