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Do I Need a Proportioning Valve?
#174098
12/24/08 01:49 PM
12/24/08 01:49 PM
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Joined: Jun 2005
Posts: 1,534
Florida
CHRGR69
OP
pro stock
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OP
pro stock
Joined: Jun 2005
Posts: 1,534
Florida
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72 Cuda drums all around. Have a power booster with M/C laying around.
Grandma always said I had "hands of gold"!
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Re: Do I Need a Proportioning Valve?
[Re: CHRGR69]
#174102
12/24/08 08:30 PM
12/24/08 08:30 PM
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Joined: Jan 2003
Posts: 10,968
Hampton, Ga.
70dart360
Green Meister
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Green Meister
Joined: Jan 2003
Posts: 10,968
Hampton, Ga.
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Bosster just makes the pedal easier to push, dosent affect the actual hydraulics of the master cylinder.
70 Dart Swinger
72 D-100 440 shortbed
76 Pinto, 68k 21mpg!
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Re: Do I Need a Proportioning Valve?
[Re: Supercuda]
#174104
12/25/08 12:05 AM
12/25/08 12:05 AM
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Joined: Dec 2005
Posts: 1,233
Eastern North Carolina
cyphre666
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Joined: Dec 2005
Posts: 1,233
Eastern North Carolina
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I guess ALL the manufacturers are wrong. Why have a proportioning valve at all ? So it evens out the pressure from the front to the rear. Hydraulics, Closest to the first point of contact. Quote:
Quote:
Yes
If not it will always hit fronts first.
Since they are the closest to the M/C
What? Someone has no idea about hydraulics here.
No, in an all drum setup you do not need a proportioning valve.
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Re: Do I Need a Proportioning Valve?
[Re: 70dart360]
#174107
12/25/08 04:05 AM
12/25/08 04:05 AM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
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Here's a pic of the four wheel drum distribution block that I am using for my four wheel disc conversion. The car originally had front disc rear drum AND a factory proportioning valve, which had to be removed. Properly designed and balanced brake systems that have either four wheel drums or four wheel discs use distribution blocks.
The "proportioning" of the brake bias from front to rear is governed in general by the size of the caliper bores in relation to each other. Rotor and pad size and composision also plays a role.
A proportioning valve is typically used in an attempt to balance the proportion of front to rear brake power. In general, it is a bandaid for a less than ideal brake design such as matching front discs to rear drums. In certain cases it can be a useful tool to balance the proportioning of brake bias during races to compensate for changing fuel loads, track conditions, tire wear etc.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Do I Need a Proportioning Valve?
[Re: jbc426]
#174108
12/25/08 10:00 AM
12/25/08 10:00 AM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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Quote:
Here's a pic of the four wheel drum distribution block that I am using for my four wheel disc conversion. The car originally had front disc rear drum AND a factory proportioning valve, which had to be removed. Properly designed and balanced brake systems that have either four wheel drums or four wheel discs use distribution blocks.
The "proportioning" of the brake bias from front to rear is governed in general by the size of the caliper bores in relation to each other. Rotor and pad size and composision also plays a role.
A proportioning valve is typically used in an attempt to balance the proportion of front to rear brake power. In general, it is a bandaid for a less than ideal brake design such as matching front discs to rear drums. In certain cases it can be a useful tool to balance the proportioning of brake bias during races to compensate for changing fuel loads, track conditions, tire wear etc.
Yup, and that's why I'm going to be looking for one to put on my Dakota. originally power disc/drum, it's now manual disc/disc but my truck is a 98...in 03/04 they upgraded to bigger discs, and 4wheel discs. that's where I got the rear discs from...and thye are actually LARGER than the fronts, although brake pad contact looks to be about the same.
however, since it's a truck and all the weight is up front, I'm gonna need a prop valve until I can find a set of front discs to match my new rears, that way I'll have larger discs with a larger swept area up front, and will be able to dial down the front bias for more even hydraulic distribution on the brakes.
if you are having trouble with fronts locking up first, or rears locking up first, you can adjust the bias with a prop valve for even braking. if all 4 lock up at the same time, then you can maximize your braking by getting the most out of each corner before one locks up and either kills your steering or brings the back end around.
**Photobucket sucks**
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Re: Do I Need a Proportioning Valve?
[Re: 68Bullit]
#174111
12/25/08 01:19 PM
12/25/08 01:19 PM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
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You can use the factory combination valve, which combines a fixed, one-size-fits-all proportioning valve along with some other features, and you can plumb an adjustable proportioning valve behind the combination valve for added adjustability of rear brakes.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Do I Need a Proportioning Valve?
[Re: jbc426]
#174112
12/25/08 03:21 PM
12/25/08 03:21 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Eberg suggested in his Mopar Action articles to iirc toss the factory one & add an adjustable one in the rear line & I went with that but a guy here said this would cause the fronts to wear excessively(which makes sense) because the fronts(discs) are going to hit before the drum linings are even in contact) & (for an A body) to use a M body proportioning valve(2 different M ones available). When it's right should a person jamb on the brakes & have 4 equal patches of rubber???
Last edited by RapidRobert; 12/26/08 11:23 AM.
live every 24 hour block of time like it's your last day on earth
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Re: Do I Need a Proportioning Valve?
[Re: farmington]
#174115
12/26/08 10:13 AM
12/26/08 10:13 AM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Quote:
The factory valve is just a distribution block. Period!!!! It has the valve inside but its only for the brake light in the dash.
Only in an all drum setup, which will NOT work when swapping discs up front.
Last edited by Supercuda; 12/26/08 10:14 AM.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Do I Need a Proportioning Valve?
[Re: dirtybee]
#174117
12/26/08 01:08 PM
12/26/08 01:08 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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My 65 dart(318/904/7&1/4) w 73 discs(76 2.70" calipers as opposed to 73-75 2.60" ones) & 10" drums on the 7&1/4, I didn't use a prop valve when I put it together & it stops fine(around town) though I have not had the displeasure of having to do a panic stop. I sold the car & I'm buying it back this weekend so I am going to check the pads/linings & see what I see
live every 24 hour block of time like it's your last day on earth
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Re: Do I Need a Proportioning Valve?
[Re: CHRGR69]
#174119
12/26/08 01:42 PM
12/26/08 01:42 PM
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Joined: Nov 2008
Posts: 1,565
tennessee
pushbutton
pro stock
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pro stock
Joined: Nov 2008
Posts: 1,565
tennessee
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Quote:
72 Cuda drums all around. Have a power booster with M/C laying around.
I thought the question was about a all drum set up 
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Re: Do I Need a Proportioning Valve?
[Re: pushbutton]
#174120
12/26/08 03:11 PM
12/26/08 03:11 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I believe it was. We got sidetracked a bit.
live every 24 hour block of time like it's your last day on earth
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Re: Do I Need a Proportioning Valve?
[Re: RapidRobert]
#174121
12/26/08 05:16 PM
12/26/08 05:16 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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True, we (me) got sidetracked, sorry.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Do I Need a Proportioning Valve?
[Re: farmington]
#174123
12/27/08 09:30 AM
12/27/08 09:30 AM
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Joined: Jun 2003
Posts: 3,325
Truckville, the capital of NY
85_Ram_4speed
master
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master
Joined: Jun 2003
Posts: 3,325
Truckville, the capital of NY
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Quote:
The factory valve is just a distribution block. Period!!!! It has the valve inside but its only for the brake light in the dash.
I can only speak from an '73 model perspective, but in the '73 factory service manual, you are indeed correct---only for an A-body. All the other models show an actual proportion valve.
Thus in replumbing my brakes in my '73 dartsport when i did a manual brakes, aluminum 2 bolt cylinder and line lock, i removed the distributon block and used theline lock to split the fronts. The rear was feed directly off the M/C. Car had discs fronts and drums rear (10"). I never had a problem with the few panic stops i encountered, but the rears would slightly lock first. And lets face it, in my application with 3.5" front wheels with 165r15 tires, the fronts werent going to do a whole lot.
Just my personal experience in modifying and doing a little research in factory systems---your experience may vary.
Outcast Dodge guy.
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been about 5 years now. are my drums maybe just pooched? i've been curious about it ever since. sorry to hijack.
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