Installing hold off valve in Disc brake conversion
#2107544
07/10/16 10:21 PM
07/10/16 10:21 PM
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Joined: Jan 2003
Posts: 8,198 New Mexico
UCUDANT
OP
Troll Hunter
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OP
Troll Hunter
Joined: Jan 2003
Posts: 8,198
New Mexico
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I have a 72 Cuda and I'm upgrading to 73 Cuda disc brakes and hoped someone can provide some guidance for installing this disc brake hold off valve. Basically which brake lines go where and how? It has 3 ports Thanks
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Re: Installing hold off valve in Disc brake conversion
[Re: UCUDANT]
#2107986
07/11/16 04:41 PM
07/11/16 04:41 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
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Didn't have ABS back then
that changes the equation.
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: Installing hold off valve in Disc brake conversion
[Re: UCUDANT]
#2108273
07/11/16 11:04 PM
07/11/16 11:04 PM
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Joined: May 2003
Posts: 96,666 On The Boat, On The Lake, Wa. ...
amxautox
Still Retired. Still Posting on Moparts. A Lot.
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Still Retired. Still Posting on Moparts. A Lot.
Joined: May 2003
Posts: 96,666
On The Boat, On The Lake, Wa. ...
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Yes you do, BUT!
are you changing from all drum? or did it already have disc fronts, just a smaller size?
if changing from drum to disc, then you have to change to a disc/drum prop. valve.
If changing from disc to disc then you should be able to use the original prop. valve.
I'd just eliminate the prop. valve and install a manual valve in the brake line to the rear brakes. Oh ya, that's what I DID do.
Tom
"Everyone should believe in something; I believe I'll go fishing."
-Henry David Thoreau
Men and fish are alike. They both get into trouble when they open their mouths
author unknown
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Re: Installing hold off valve in Disc brake conversion
[Re: Supercuda]
#2108296
07/11/16 11:20 PM
07/11/16 11:20 PM
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Joined: Dec 2003
Posts: 23,388 Here
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 23,388
Here
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Didn't have ABS back then
that changes the equation. Yes, it does, all the more reason for better tires on the front now, since rears aren't going to lock up.
Last edited by jcc; 07/11/16 11:21 PM.
"When one’s appeal is emotional, it does not matter if there is no substance."
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Re: Installing hold off valve in Disc brake conversion
[Re: jcc]
#2108825
07/12/16 04:50 PM
07/12/16 04:50 PM
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Joined: May 2003
Posts: 96,666 On The Boat, On The Lake, Wa. ...
amxautox
Still Retired. Still Posting on Moparts. A Lot.
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Still Retired. Still Posting on Moparts. A Lot.
Joined: May 2003
Posts: 96,666
On The Boat, On The Lake, Wa. ...
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Rears aren't gonna lock up? I'll leave that one alone. Please don't, by using the word "now" in my comment, I'm referring to today's cars with, I assume working "abs", and the rears shouldn't lock up, am I mistaken? BIG difference between 'aren't' and 'shouldn't'.
Tom
"Everyone should believe in something; I believe I'll go fishing."
-Henry David Thoreau
Men and fish are alike. They both get into trouble when they open their mouths
author unknown
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Re: Installing hold off valve in Disc brake conversion
[Re: amxautox]
#2108862
07/12/16 06:08 PM
07/12/16 06:08 PM
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Joined: Dec 2003
Posts: 23,388 Here
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 23,388
Here
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Rears aren't gonna lock up? I'll leave that one alone. Please don't, by using the word "now" in my comment, I'm referring to today's cars with, I assume working "abs", and the rears shouldn't lock up, am I mistaken? BIG difference between 'aren't' and 'shouldn't'. Then, which is it?
"When one’s appeal is emotional, it does not matter if there is no substance."
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Re: Installing hold off valve in Disc brake conversion
[Re: jcc]
#2108873
07/12/16 06:27 PM
07/12/16 06:27 PM
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Joined: May 2003
Posts: 96,666 On The Boat, On The Lake, Wa. ...
amxautox
Still Retired. Still Posting on Moparts. A Lot.
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Still Retired. Still Posting on Moparts. A Lot.
Joined: May 2003
Posts: 96,666
On The Boat, On The Lake, Wa. ...
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Rears aren't gonna lock up? I'll leave that one alone. Please don't, by using the word "now" in my comment, I'm referring to today's cars with, I assume working "abs", and the rears shouldn't lock up, am I mistaken? BIG difference between 'aren't' and 'shouldn't'. Then, which is it? 'shouldn't' If something is wrong, then they will lock up. Such as rusty drums after the truck hasn't been driven in weeks, but only on the gravel driveway. I've had them even get a SOLID pedal on the '92 Dakota that I bought new. Absolutely NO brakes at all. Only did it once, on a rainy day towing the boat, never found out why.
Tom
"Everyone should believe in something; I believe I'll go fishing."
-Henry David Thoreau
Men and fish are alike. They both get into trouble when they open their mouths
author unknown
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Re: Installing hold off valve in Disc brake conversion
[Re: Challenger 1]
#2110850
07/15/16 10:18 PM
07/15/16 10:18 PM
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Joined: Jan 2003
Posts: 8,198 New Mexico
UCUDANT
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Troll Hunter
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OP
Troll Hunter
Joined: Jan 2003
Posts: 8,198
New Mexico
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That is a early valve for the early disc brake cars, 73 uses a combo proportioning valve and does not use that valve. So with the 1972 Drum brake valve and the additional valve pictured adding the proportioning valve would complete the valving needed for even my 73 Disc brakes correct?
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Re: Installing hold off valve in Disc brake conversion
[Re: UCUDANT]
#2111295
07/16/16 07:39 PM
07/16/16 07:39 PM
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Joined: Jan 2003
Posts: 26,736 Rio Linda, CA
John_Kunkel
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Rio Linda, CA
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The problem with factory prop valves is they're just a guess. Check the parts book and you'll find the same prop/combo valve used in a plethora of models with different front/rear weight bias.
One-size-fit-all is good from a production standpoint but can't possibly prevent rear wheel lockup in all instances.
The INTERNET, the MISinformation superhighway
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Re: Installing hold off valve in Disc brake conversion
[Re: Supercuda]
#2118569
07/26/16 10:22 PM
07/26/16 10:22 PM
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Joined: Dec 2004
Posts: 10,625 Rittman Ohio
fourgearsavoy
I Live Here
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I Live Here
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Posts: 10,625
Rittman Ohio
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Didn't have ABS back then
that changes the equation. My 71 Imperial did Gus
64 Plymouth Savoy 493 Indy EZ's by Nick at Compu-Flow 5-Speed Richmond faceplate Liberty box Dana 60
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Re: Installing hold off valve in Disc brake conversion
[Re: UCUDANT]
#2124814
08/04/16 01:38 PM
08/04/16 01:38 PM
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Joined: Jul 2011
Posts: 819 Eugene, Oregon
Secret Chimp
super stock
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super stock
Joined: Jul 2011
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Eugene, Oregon
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Is any of this objectively necessary, or can you just run a tee off the front circuit and a single line with a prop valve for the rear circuit?
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Installing hold off valve in Disc brake conversion
[Re: Secret Chimp]
#2124931
08/04/16 03:53 PM
08/04/16 03:53 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
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Posts: 14,889
up yours
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Is any of this objectively necessary, or can you just run a tee off the front circuit and a single line with a prop valve for the rear circuit? This has been hashed out over and over. Rather than rehash it here, it's in the search function btw, I'll sum it up. All the manufacturers spent considerable time and money developing them. Does that answer the question?
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: Installing hold off valve in Disc brake conversion
[Re: John_Kunkel]
#2124934
08/04/16 03:55 PM
08/04/16 03:55 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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The problem with factory prop valves is they're just a guess. Check the parts book and you'll find the same prop/combo valve used in a plethora of models with different front/rear weight bias.
One-size-fit-all is good from a production standpoint but can't possibly prevent rear wheel lockup in all instances.
Not entirely true. Case in point, my 87 Diplomat could have had one of two combination valves. One for 10" rear drums, the other for 11" rear drums, both with the same front discs and M/C.
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: Installing hold off valve in Disc brake conversion
[Re: Supercuda]
#2124971
08/04/16 04:32 PM
08/04/16 04:32 PM
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Joined: Dec 2003
Posts: 23,388 Here
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 23,388
Here
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The problem with factory prop valves is they're just a guess. Check the parts book and you'll find the same prop/combo valve used in a plethora of models with different front/rear weight bias.
One-size-fit-all is good from a production standpoint but can't possibly prevent rear wheel lockup in all instances.
Not entirely true. Case in point, my 87 Diplomat could have had one of two combination valves. One for 10" rear drums, the other for 11" rear drums, both with the same front discs and M/C. That kinda proves Kunkel's point, if that difference in drum size requires a different spec valve, how the heck does, tire size, tire TW rating, tire pressure, passenger count, trunk loading, speed, weather, road surface, fuel load, etc factor in?
"When one’s appeal is emotional, it does not matter if there is no substance."
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Re: Installing hold off valve in Disc brake conversion
[Re: UCUDANT]
#2125096
08/04/16 06:35 PM
08/04/16 06:35 PM
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Joined: Feb 2005
Posts: 28,312 Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
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Posts: 28,312
Cincinnati, Ohio
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That is a early valve for the early disc brake cars, 73 uses a combo proportioning valve and does not use that valve. So with the 1972 Drum brake valve and the additional valve pictured adding the proportioning valve would complete the valving needed for even my 73 Disc brakes correct? No it won't be the same as using a later distribution/proportioning combo valve. I know what your wanting to do with minimal brake line work by using that valve but it's not a good idea unless you use the early proportioning valve with it. The best course of action is to use all 72-73 stuff or all 70-71 stuff...master cyl, brake lines, distribution/proportioning valves. I know it requires new brake lines and is a PIA. Call Fine lines and have a new fresh properly working disc brake system. It's worth it in the long run, the investment in proper factory parts that we know will work well together. Sure you may be able to do it with a adjustable valve, but we know factory stuff works and real good. Adjustable proportioning valves... I have them on both of my E body's. There in the rear lines to reduce even farther the rear brake pressure and makes a big difference on how the cars brake. They make the car brake very "flat" and all four will lock at about the same time. That's how you adjust JCC for varying amounts of weight and where it is placed in the car. One time I did a big burnout and then looked up and had to stop fast and the car did with all 4 skidding just a little. It was a awesome stop for a factory disc brake car and I could not have done it without the rear proportioning valve and the sticky goodyear eagles. (pretty much stopped doing burnouts on the street after that one ) I just can't see you getting that same performance using a drum brake distribution block and that metering valve. Edit: Since your car is a 72 and your using 73 disc brakes, then I would use use all late parts and not use the metering valve that was used on early cars. Don't mix brake parts because there not all the same IMO.
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