proportional valve?
#1
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Car: grand prix/84 z28
Engine: 4.6 Northstar
Transmission: t-56
proportional valve?
I am converting a drum car to disk. Can I keep the master cylinder and just use a proportional valve?
I want to say no, just because it seems like you would need alot more pressure too fill a calipe then to fill a wheel cylinder. A proportional valve and just decrease the about of fuild.
Am I right or wrong?
thanks for you help
I want to say no, just because it seems like you would need alot more pressure too fill a calipe then to fill a wheel cylinder. A proportional valve and just decrease the about of fuild.
Am I right or wrong?
thanks for you help
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Car: 1989 GTA Nighthawk
Engine: 389 CID TPI
Transmission: TCI 700R4
Axle/Gears: 9 bolt 3.23
No, a drum brake uses a lot less fluid to engage the shoes compared to a disc that needs a lot more fluid to move the pad to engage the disc. You need a new master cylinder.
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#8
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Car: 91 Camaro Vert
Engine: 02 LS1, HX40
Transmission: 2002 LS1 M6
i had a 4 paragraph reply typed out, and i lost it.
in a nutshell, the stock one will work, but to get max effectiveness yuo need aftermarket.
even if you managed to plumb the LS1 one in, its intended for ABS systems, therefore the rear brakes would lockup too soon.
in a nutshell, the stock one will work, but to get max effectiveness yuo need aftermarket.
even if you managed to plumb the LS1 one in, its intended for ABS systems, therefore the rear brakes would lockup too soon.
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Car: 1991 Trans Am
Engine: LQ4
Transmission: T-56
Axle/Gears: 3.70
you can get an adjustable one from wilwood at summit for $39.99. I was going to run one, but I decided thats just another thing I dont want to mess with, so I shelled out 70 somethin for a 1LE for my LS1 conversion. Ill sell my wilwood for $40 to your door.
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Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
The guys that said to keep the current m/c are correct. Apeiron dug up a tech article from GM... but let me throw out some background info first:
Between 82 and 88, GM had two different master cylinders. J65 was for 4-wheel disc, with a 1 inch (25.4 mm) bore. J50 was for disk/drum, with only a 24mm bore. Doesn't sound like much, but the J65 m/c was meant to give the driver an increased road feel- which is what any performance driver would want.
Check out Apeiron's find here: https://www.thirdgen.org/techbb2/sho...threadid=58295
I went drum-to-disk and replaced the m/c, and went through hell. (Bled it like hell, wound up being a badly rebuilt m/c whose seal tore. After fighting it forever, I took it back, got another m/c, and all was good.) I say if you don't have to replace it, all the better!
But the prop valve, yeah, you gotta change it. Okay, well, you don't Have to change it... guys here have used the disk/drum prop valve and still have been able to stop their cars. But if you're going to go thru all the trouble of a swap, might as well grab the correct prop valve.
"Supposedly" I read that on a 4wheel disk car, there's no proportioning. 50% goes to front, 50% goes to rear- the prop valve on a J65 4-wheel-disk car is just there to (a) split one front line into two front lines, and (b) give a spot for the brake warning sensor to hang out.
Between 82 and 88, GM had two different master cylinders. J65 was for 4-wheel disc, with a 1 inch (25.4 mm) bore. J50 was for disk/drum, with only a 24mm bore. Doesn't sound like much, but the J65 m/c was meant to give the driver an increased road feel- which is what any performance driver would want.
Check out Apeiron's find here: https://www.thirdgen.org/techbb2/sho...threadid=58295
I went drum-to-disk and replaced the m/c, and went through hell. (Bled it like hell, wound up being a badly rebuilt m/c whose seal tore. After fighting it forever, I took it back, got another m/c, and all was good.) I say if you don't have to replace it, all the better!
But the prop valve, yeah, you gotta change it. Okay, well, you don't Have to change it... guys here have used the disk/drum prop valve and still have been able to stop their cars. But if you're going to go thru all the trouble of a swap, might as well grab the correct prop valve.
"Supposedly" I read that on a 4wheel disk car, there's no proportioning. 50% goes to front, 50% goes to rear- the prop valve on a J65 4-wheel-disk car is just there to (a) split one front line into two front lines, and (b) give a spot for the brake warning sensor to hang out.
#12
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Car: 91 Camaro Vert
Engine: 02 LS1, HX40
Transmission: 2002 LS1 M6
Originally posted by TomP
But the prop valve, yeah, you gotta change it. Okay, well, you don't Have to change it... guys here have used the disk/drum prop valve and still have been able to stop their cars. But if you're going to go thru all the trouble of a swap, might as well grab the correct prop valve.
But the prop valve, yeah, you gotta change it. Okay, well, you don't Have to change it... guys here have used the disk/drum prop valve and still have been able to stop their cars. But if you're going to go thru all the trouble of a swap, might as well grab the correct prop valve.
if you keep your disc/drum valve, its not ideal, however, it will still stop better then it did before.
there is no "delay"
there is no drag.
there is no problem.
and anyone wanting to debate it is welcome to take my car for a spin.
you dont get the full advantage of your new brakes, but you will never get that with a factory prop valve anyway.
even a stock disc/disc car will have a improvement with a properly setup aftermarket prop valve.
Originally posted by TomP
"Supposedly" I read that on a 4wheel disk car, there's no proportioning. 50% goes to front, 50% goes to rear- the prop valve on a J65 4-wheel-disk car is just there to (a) split one front line into two front lines, and (b) give a spot for the brake warning sensor to hang out.
"Supposedly" I read that on a 4wheel disk car, there's no proportioning. 50% goes to front, 50% goes to rear- the prop valve on a J65 4-wheel-disk car is just there to (a) split one front line into two front lines, and (b) give a spot for the brake warning sensor to hang out.
if it was split 50/50, then the rears would lockup first, everytime.
thats a big NO-NO from the factory... thats actually why 3rdgen rear brakes dont do squat... they are so front brake bias in the name of saftey that they bearly work at all. this is why a aftermarket prop valve is useful on even a stock car...
its also another reason why you cant out brake a ABS car.
ABS equipped cars have more rear pressure... without ABS theres the chance of the rears locking sooner, but because ABS is on there, it stops the rears from locking, so you get 100% rear brake useage, plus the full fronts.
#14
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Car: 91 Camaro Vert
Engine: 02 LS1, HX40
Transmission: 2002 LS1 M6
Originally posted by fyrechikyn
ok so i can use my old m/c and booster where do i put the prop valve?
ok so i can use my old m/c and booster where do i put the prop valve?
how:
https://www.thirdgen.org/newdesign/tech/propvalve.shtml
also, do a search on "wilwood prop* valve" you'll find more install tips and such.
the basic layout is like this:
#15
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Car: 1987 Black IROC-Z (SOLD)
My opinion, use the GM Proportioning Valve for a four wheel disc brakes and avoid the aftermarket Wildwood valve. I made that swap from 87drum rears to 89 disc brake using the stock parts and I have everything working great and that was three years ago.
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