Completely new brake system, no pedal

[CantPutTheSmokeBack]

Originally Posted by geezer#99

And here’s another read for you.


https://www.onallcylinders.com/2014/...der-bore-size/

So I went and did the math to calculate needed pedal ratio based on one of the links you sent me yesterday for master cylinder bore vs caliper bore. This morning I went and measured and I'm pretty close to where I should be as far as pedal ratio is concerned. I'm 2.5" center to center and the math says I need 2.32"

[geezer#99]

So you’re at 6 to 1.
You need a longer stroke so drill a new hole to get to 4 to 1.

What m/c bore number did you use in the calculation.

[CantPutTheSmokeBack]

Originally Posted by geezer#99

So you’re at 6 to 1.
You need a longer stroke so drill a new hole to get to 4 to 1.

What m/c bore number did you use in the calculation.

The math says I should be at 6.56 to 1

Caliper piston bore is 3.37 which gives an area of 8.91 and master cylinder is 1.315 which gives an area of 1.35 and that spits out 6.65:1 pedal ratio from one of the articles you sent yesterday.

https://www.speedwaymotors.com/the-t...e-system/30895

[geezer#99]

That may be true but how long does it take to drill a new hole in the pedal to get to 4 to 1 ratio.

[RichardJ]

>> I can feel the dead slack in the pedal now as well as feel when the rod makes contact.<<
If you can actually feel the booster rod gap, it is way too excessive.

Use a tool as shown by 71Blazer in post #23 or you can make actual measurements. It is hard to do on the vehicle, but if the brake lines are long enough, it is doable.
The depth of the hole, minus distance to the MC flange, equals the booster pin stick-out. This image shows the tool, but A,B,C is what you are measuring.

[CantPutTheSmokeBack]

Originally Posted by geezer#99

That may be true but how long does it take to drill a new hole in the pedal to get to 4 to 1 ratio.

I drilled a new hole at 4:1. The pedal feels just a bit more firm but the truck still doesn't stop well. I think all the pedal ratio change did was mask the poor brakes and make the pedal feel a bit better by reducing the amount of leverage the other hole gives. In any case, it still has poor braking performance.

[CantPutTheSmokeBack]

Originally Posted by RichardJ

>> I can feel the dead slack in the pedal now as well as feel when the rod makes contact.<<
If you can actually feel the booster rod gap, it is way too excessive.

Use a tool as shown by 71Blazer in post #23 or you can make actual measurements. It is hard to do on the vehicle, but if the brake lines are long enough, it is doable.
The depth of the hole, minus distance to the MC flange, equals the booster pin stick-out. This image shows the tool, but A,B,C is what you are measuring.

I only added that excessive space to see if there was any kind of difference. I wanted there to be a big gap so I knew absolutely there was no contact or preload. I removed the washers and clayed the rod-to-master area and there is still no preload.

[geezer#99]

Originally Posted by CantPutTheSmokeBack

I drilled a new hole at 4:1. The pedal feels just a bit more firm but the truck still doesn't stop well. I think all the pedal ratio change did was mask the poor brakes and make the pedal feel a bit better by reducing the amount of leverage the other hole gives. In any case, it still has poor braking performance.

Now try a smaller master.
The 1 1/8 or 1 inch one.

[CantPutTheSmokeBack]

Originally Posted by geezer#99

Now try a smaller master.
The 1 1/8 or 1 inch one.

I put the smaller master back on and there was no pronounced change. Still seems like I have much less braking power than I should.

[geezer#99]

You work fast.
Swap and bleed and test a smaller master in an hour.

Have you considered residual check valves?

[CantPutTheSmokeBack]

Originally Posted by geezer#99

You work fast.
Swap and bleed and test a smaller master in an hour.

Have you considered residual check valves?

I already had the master handy from putting it on just a few days ago, still had fluid in the reservoir. I plugged the ports when I pulled it and just set it aside. Tools have been sitting on the bench because I keep using them. All I had to do was bench bleed it again, put it on, and hook the vacuum bleeder up. The bleeder drains the reservoir down quick so I just hook it up and let it eat. All bleeders are easy access.

The proportioning valve I have has 10lb residual valves built into it for the rear. CPP PV-2
https://www.summitracing.com/parts/CLP-PV-2

Theres a special tool for that prop valve that keeps a safety valve open while bleeding brakes that I got and use whenever I've bled them.

[RichardJ]

>>The proportioning valve I have has 10lb residual valves built into it for the rear. CPP PV-2
https://www.summitracing.com/parts/CLP-PV-2<<

Combination Valves DO NOT include Residual Pressure Valves.

>>Theres a special tool for that prop valve that keeps a safety valve open while bleeding brakes that I got and use whenever I've bled them.<<

There is NO safety valve. There is a Pressure Differential Switch and if you are using a plastic piece of crap tool in place of the switch while bleeding, it will not stop or aid the bleeding process.

There is a tool used to hold The Metering Valve OPEN while bleeding the the front calipers.

[RichardJ]

On the CPP web site ;

When upgrading your stock drum brake system to a disc brake system a proportioning valve is needed to ensure that the proper amount of brake fluid pressure is going to the front and rear wheels. Residual check valves are needed when using an adjustable valve (sold separately).

#PV-2.....Disc/Drum Prop Valve, Brass.

The PV-2 is a Combination Valve with a FIXED Proportioning Valve section, so why are they mentioning an adjustable Valve. They do sell adjustable proportioning Valve, but the PV-2 is not

[CantPutTheSmokeBack]

Originally Posted by RichardJ

>>The proportioning valve I have has 10lb residual valves built into it for the rear. CPP PV-2
https://www.summitracing.com/parts/CLP-PV-2<<

Combination Valves DO NOT include Residual Pressure Valves.

>>Theres a special tool for that prop valve that keeps a safety valve open while bleeding brakes that I got and use whenever I've bled them.<<

There is NO safety valve. There is a Pressure Differential Switch and if you are using a plastic piece of crap tool in place of the switch while bleeding, it will not stop or aid the bleeding process.

There is a tool used to hold The Metering Valve OPEN while bleeding the the front calipers.

In the Summit link I posted someone explicitly asked if there was a residual pressure valve and a CPP rep responded with yes there was, 10lbs. Their site doesn't list either way, so I'll see if I can get ahold of them monday and double check.

If I can't get a straight answer from them, what happens if there are two in the same line? Putting one in is an easy way to make sure there is one in the system.

The cutaway I saw of this prop valve has an isolation valve that, in the case of an open/broken line, will slam that open line side shut and cut off fluid supply to the open side or isolate one side as its name implies. Before I ever got the thing I saw the tool and did some looking to see if I actually need it and saw guys saying yes you need the tool because that valve will slam shut and not flow fluid out while you're trying to bleed.

[CantPutTheSmokeBack]

Originally Posted by RichardJ

On the CPP web site ;

When upgrading your stock drum brake system to a disc brake system a proportioning valve is needed to ensure that the proper amount of brake fluid pressure is going to the front and rear wheels. Residual check valves are needed when using an adjustable valve (sold separately).

#PV-2.....Disc/Drum Prop Valve, Brass.

The PV-2 is a Combination Valve with a FIXED Proportioning Valve section, so why are they mentioning an adjustable Valve. They do sell adjustable proportioning Valve, but the PV-2 is not

Yeah the adjustable valve part got me for the same reason. I'll see if I can get some answers monday. I kind of questioned if there was one in there from the start because the prop valve seems awful small to have that as well and I didn't see one on the cutaway I looked at.

[CantPutTheSmokeBack]

Even if it fixes my rear brakes, my fronts have just the same problem. Full brake to the floor it never locks up. Not that I'm trying for that all the time but if I could I would know I have enough brakes and I simply don't right now.

Also, I read in several places that most master cylinders have residual pressure valves built in them already. Been an OE thing for quite a while. I have a hard time believing I bought two that didn't have them when they're OE parts.

[RichardJ]

>>did some looking to see if I actually need it and saw guys saying yes you need the tool because that valve will slam shut and not flow fluid out while you're trying to bleed.<<

What's going to slam it shut, as you put it? You're using a air powered vacuum pump. Never used one, but I'm guessing it can produce maybe 28"hg.
I generally use a hand vacuum pump and pump it to 15-20"Hg, then go check and make sure I haven't sucked the reservoir dry. Your air powered unit would need the reservoir checked almost continually.
At any rate, 15 or 28"Hg will not close the Differential pressure switch.

What is it that makes you think a 10lb residual pressure valve is going to do that will effect any brake problem you have? Any affect a residual pressure valve has on a brake system occurs when you take your foot OFF the brake pedal. Residual pressure in a system is used to prevent air from entering the system, past the wheel cylinder cups. When your foot is OFF the pedal.

post#9
>>Pumping the brakes doesn't give me a harder pedal. I cannot lock up the brakes.<<

Is that with the engine OFF? After pumping the brakes about three times, that should relieve the booster of all vacuum and you should then have a very hard pedal.

[CantPutTheSmokeBack]

Originally Posted by RichardJ

>>did some looking to see if I actually need it and saw guys saying yes you need the tool because that valve will slam shut and not flow fluid out while you're trying to bleed.<<

What's going to slam it shut, as you put it? You're using a air powered vacuum pump. Never used one, but I'm guessing it can produce maybe 28"hg.
I generally use a hand vacuum pump and pump it to 15-20"Hg, then go check and make sure I haven't sucked the reservoir dry. Your air powered unit would need the reservoir checked almost continually.
At any rate, 15 or 28"Hg will not close the Differential pressure switch.

What is it that makes you think a 10lb residual pressure valve is going to do that will effect any brake problem you have? Any affect a residual pressure valve has on a brake system occurs when you take your foot OFF the brake pedal. Residual pressure in a system is used to prevent air from entering the system, past the wheel cylinder cups. When your foot is OFF the pedal.

post#9
>>Pumping the brakes doesn't give me a harder pedal. I cannot lock up the brakes.<<

Is that with the engine OFF? After pumping the brakes about three times, that should relieve the booster of all vacuum and you should then have a very hard pedal.

There is equal fluid flow on either side of the valve, keeping the valve centered. If one side sees a loss of pressure the valve is able to slide to the low pressure side and shut off flow to that low pressure side and prevent loss of fluid.

I wouldn't have the slightest clue as to what kind of pressure causes the valve to move. All I know is what I read from other users experiences and what the manufacturer suggests. The vacuum bleeder I have comes with a bottle to fill with more brake fluid and put upside down in the reservoir. As fluid flows out of the reservoir the bottle is able to refill the lost brake fluid so it doesn't need monitored so close.

I never said a residual pressure valve would have any effect on anything, just that I have read many times over that drum systems need them and your typical drum master cylinder has them. I'm fine with adding one I just don't see how that would also fix my front brakes. I asked if there would be some kind of effect with having multiple, not implied there would be.

Pumping my brakes with the engine ON doesn't give me a more firm pedal, which was mentioned as a check against having any air left in the lines. Pumping with the engine off does produce a more firm pedal, but not nearly as firm as I've seen in every other vehicle I've pumped with the engine off.
Engine off feels like it what my brakes should be with the engine on.

[RichardJ]

>>most master cylinders have residual pressure valves built in them already.<<

That was true in general up until about 1970.

Up until about 1960 most cars and trucks had the MC under the floorboards. The MC was lower than the wheel cylinders and gravity pressure would move the fluid from the wheel cylinder, down into the MC. As the fluid left the wheel cylinder, air would enter past the fluid cups. By using residual pressure, the cups would seal against the wheel cylinder bore and air could not enter.
By the '70s most MC were mounted on the firewall, well above the wheel cylinders.
By then, the cup expanders have been improved, negating the need for the residual valves.
Few rebuilders replace the original residual valve when rebuilding the MC.

[RichardJ]

>>Pumping with the engine off does produce a more firm pedal, but not nearly as firm as I've seen in every other vehicle I've pumped with the engine off.<<

You have air in the lines. You can debate that, but you have air in the lines.

[CantPutTheSmokeBack]

Originally Posted by RichardJ

>>Pumping with the engine off does produce a more firm pedal, but not nearly as firm as I've seen in every other vehicle I've pumped with the engine off.<<

You have air in the lines. You can debate that, but you have air in the lines.

I've had air in the lines on other vehicles I've bled, and every time the issue would momentarily dissipate whenever I pumped the pedal. Why would that be any different in this case? Pumping the brakes with the engine on does not make the issue any better.

[geezer#99]

Do you have a pic or a link to the ‘air powered vacuum bleeder’ you’re using?

[CantPutTheSmokeBack]

Originally Posted by geezer#99

Do you have a pic or a link to the ‘air powered vacuum bleeder’ you’re using?

Harbor Freight special
https://www.harborfreight.com/brake-...der-92924.html

[geezer#99]

Have you always used that bleeder or have done the regular type bleeding?
Like pump the brakes up, hold firm, open bleed, pedal goes to floor, close bleed, let pedal come up slowly. Done repeatedly until all air is out then on to the other cylinders.

[CantPutTheSmokeBack]

Originally Posted by geezer#99

Have you always used that bleeder or have done the regular type bleeding?
Like pump the brakes up, hold firm, open bleed, pedal goes to floor, close bleed, let pedal come up slowly. Done repeatedly until all air is out then on to the other cylinders.

I did the regular 2 man type bleeding at first. I got ahold of this tool probably 4 hours into 2 man bleeding because I felt bad continually asking people to come help with this.