Re: Proportioning valve question
[Re: Otherlane]
#421454
07/28/09 07:44 AM
07/28/09 07:44 AM
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Joined: Aug 2005
Posts: 760 Southington Ct.
turbobitt
super stock
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super stock
Joined: Aug 2005
Posts: 760
Southington Ct.
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If you call Wilwood they will tell you to use there adjustable valve in the line going to the rear brakes.
1970 Challenger w/572 Hemi street car and my pride and joy.
1986 T-Type with 272 Stage 2 Buick V6 engine - True 8 second street car. Just updated the engine and put down 928 HP @ 35# boost to the ground on chasis dyno.
1976 Cee Bee Avenger Jet Boat - 460 Ford powered.
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Re: Proportioning valve question
[Re: turbobitt]
#421455
07/28/09 09:06 AM
07/28/09 09:06 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
If you call Wilwood they will tell you to use there adjustable valve in the line going to the rear brakes.
On a race car with big slicks on the rear and skinnies on the front.... I wouldnt put the adjustable valve on the rears... front yes... reason why... a adjustable prop valve is nothing more than a delay, all the pressures will equalize after a period of time depending on how the valve is set, so with skinnies up front and you put the valve in the rear you are slowing the fluid to the rears and giving full fluid to the front giving the front all/most of the load on the tires... they just arent big enough to carry that load If this was a street car with equal size tires then yes I would put it on the rears to slow the tires from locking up as the frontend dives on braking and the rear gets light
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Re: Proportioning valve question
[Re: Otherlane]
#421457
07/28/09 09:30 AM
07/28/09 09:30 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Pbody,in your opinion with a car with 3.5 wheels up front and 10 in tires out back would you use one or not?
Yes I would... I'd put it on the front lines to slow the fronts from locking up under hard braking. The prop valve is nothing more than a adjustable orifice and the more you close the valve(less braking on the initial hit) but after a short period of time the pressure will equalize (dependent how its set)
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Post deleted by Defbob
[Re: turbobitt]
#421460
07/28/09 11:31 AM
07/28/09 11:31 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Re: Proportioning valve question
[Re: Locomotion]
#421464
07/28/09 11:53 AM
07/28/09 11:53 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
It was brought up once before but I don't recall what was said:
Does a typical Mopar master cylinder have a certain amount of natural "proportion" built into it? In other words, would there be any difference in front-to-rear pressure without a proportioning valve......and would swapping the lines at the MC change it front-to-rear, if needed?
I have seen some that did have different prop in the master but from what I was told the 60/40 is the volume difference in the reservoir... unknow for fact
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Re: Proportioning valve question
[Re: Locomotion]
#421465
07/28/09 12:01 PM
07/28/09 12:01 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
It was brought up once before but I don't recall what was said:
Does a typical Mopar master cylinder have a certain amount of natural "proportion" built into it? In other words, would there be any difference in front-to-rear pressure without a proportioning valve......and would swapping the lines at the MC change it front-to-rear, if needed?
A quick test while bench bleeding would be, once you get it bled put the 2 lines(that you have going back into the res) bend them over so you can have them squirt into 2 measuring beakers... if its a different volume its a build in prop valve
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Re: Proportioning valve question
[Re: B G Racing]
#421467
07/28/09 03:03 PM
07/28/09 03:03 PM
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Joined: Aug 2004
Posts: 2,128 sweden
sshemi
top fuel
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top fuel
Joined: Aug 2004
Posts: 2,128
sweden
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Quote:
The proportioning in most mopar style master cylinders are a rated volume usually aprox,65%fr-35%r.This is volume only,not pressure.They were set this way for the disc/drum combos since large single piston or daul 4 piston calipers required more fluid volume than the small brake shoe wheel cylinder. Most race proportional valves are adjustable from 0 to 1000psi. most common manual brake systems working range is 400 to 600psi.
How can not the preassure differ if the volume does with the same stroke front and rear. I belive the the mopar MC has different piston sizes front and rear and that would differ the preasure also. Aldough most aaftermarket MCs like Wilwwod, strange etc have the same piston size front and rear therefore the same preasure.
P-body are you positive with the function of a prop valve? I thought that a prop valve had two pistons with different sizes to reduce preasure.
Im not very experienced so correct me if im wrong.
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Re: Proportioning valve question
[Re: sshemi]
#421468
07/28/09 03:21 PM
07/28/09 03:21 PM
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Joined: Apr 2005
Posts: 1,880 USA
Ron Silva
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Right in the mopar parts catalog when they are describing the MC % they are saying volume or displacement, not pressure.
Think about this. On a mopar MC the front port usually goes to the rear brakes. The only way to have 2 different piston or bore sizes would be for the front piston to be smaller which would generate a higher pressure to the rear brakes. So that would negate your theory, I think.
SRT DEMON ONE SEAT
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Re: Proportioning valve question
[Re: Ron Silva]
#421469
07/28/09 03:29 PM
07/28/09 03:29 PM
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Joined: Aug 2004
Posts: 2,128 sweden
sshemi
top fuel
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top fuel
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sweden
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Quote:
Right in the mopar parts catalog when they are describing the MC % they are saying volume or displacement, not pressure.
Think about this. On a mopar MC the front port usually goes to the rear brakes. The only way to have 2 different piston or bore sizes would be for the front piston to be smaller which would generate a higher pressure to the rear brakes. So that would negate your theory, I think.
Ok i only slept 3 and ahalf hour last night. But im really working my brain here trying to figure out how a smaller piston can give you higher pressure.
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Re: Proportioning valve question
[Re: Ron Silva]
#421470
07/28/09 03:29 PM
07/28/09 03:29 PM
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Joined: Apr 2005
Posts: 1,880 USA
Ron Silva
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top fuel
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Here is a picture of a Mopar MC rebuild kit.
SRT DEMON ONE SEAT
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Re: Proportioning valve question
[Re: Ron Silva]
#421472
07/28/09 03:36 PM
07/28/09 03:36 PM
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Joined: Oct 2003
Posts: 11,684 W. Kentucky
justinp61
I Live Here
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I Live Here
Joined: Oct 2003
Posts: 11,684
W. Kentucky
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Quote:
Right in the mopar parts catalog when they are describing the MC % they are saying volume or displacement, not pressure.
Think about this. On a mopar MC the front port usually goes to the rear brakes. The only way to have 2 different piston or bore sizes would be for the front piston to be smaller which would generate a higher pressure to the rear brakes. So that would negate your theory, I think.
There are two pistons of the same diameter on a common rod moving the same distance. They move the same amount of fluid per stroke and have the same pressure potential. It doesn't matter if the front of the reservoir or master cylinder bore holds five gallons and the rear only holds six ounces. They both move the same distance.
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