race brake educators please step inside
#2410404
11/28/17 11:28 PM
11/28/17 11:28 PM
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Joined: May 2003
Posts: 13,185 aZLiViN
J_BODY
OP
I Live Here
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OP
I Live Here
Joined: May 2003
Posts: 13,185
aZLiViN
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I pulled the trigger on the Strange Pro/Race rear disc brake kit and proportioning valve for the Duster. I have Wilwood four piston calipers in the front and have killed two sets of rotors and recently after hitting them hard at Famoso a few weeks in the final things got a bit hairy. It's been obvious to me that the fronts have been doing most of the work the last few years (to much imho). I know that the front should be biased more, but I find about every track I go to I'm using the last turnoff. Keep in mind we're only trapping at 140 + or - a couple mph. The car currently has a 15/16 master and only what I believe is a distribution block after that before the calipers/wheel cylinders. Any tips on where to set the proportioning valve, or test tools to aid in the adjustment would be appreciated.
forgot to add.. currently running stock 70 drum set up.
Last edited by J_BODY; 11/28/17 11:29 PM.
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Re: race brake educators please step inside
[Re: J_BODY]
#2410500
11/29/17 01:52 AM
11/29/17 01:52 AM
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Joined: Dec 2005
Posts: 11,521 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,521
Fulton County, PA
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Tire sizes? What master cylinder?
Get any factory blocks, valves, or whatever off of it while you're doing the work.
Compare the piston sizes of the Wilwood vs. the Strange calipers. Not all 4 piston units are made the same.
That 15/16 MC may work depending on the bore size of the Wilwood calipers. But I would expect it to have to go up in size a bit. How was the pedal with the drums? Expect the pedal travel to increase with those Strange calipers using the same MC.
If the results don't match the theory, change the theory.
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Re: race brake educators please step inside
[Re: J_BODY]
#2410513
11/29/17 02:08 AM
11/29/17 02:08 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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What kind of prop valve... also.. the bigger the master cyl.. the less travel you get( the pedal gets real hard)you might need a smaller master so it travels more and brakes harder... anything.. if your running large tires on the rear you need more braking in the rear so the rear tires are working harder.. just dont let the tires skid at all.. I'm going to reduce the master on my Rampage 1 size to get a better pedal.. it stops fine but I have to press the pedal to hard.... tell me your total package that you have
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Re: race brake educators please step inside
[Re: J_BODY]
#2410522
11/29/17 02:25 AM
11/29/17 02:25 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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Car doesn't appear to have a proportioning valve on it. IIRC it was a 4 corner drum set up originally, but we swapped it over to a 73 front disc set up long ago before finally going to the wilwoods when we did the tube K. Got the feeling it's going to be "all new" by the time I get this done. Just another things that got added to and changed over the years. Sounds like you need 2 things... 1 size smaller master(it will allow a bit more travel and apply the brakes harder.. but put on a adjustable prop valve.. that will let you balance the front to rear better
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Re: race brake educators please step inside
[Re: J_BODY]
#2410534
11/29/17 02:53 AM
11/29/17 02:53 AM
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Joined: Feb 2011
Posts: 1,454 Glendora Ca.
Just-a-dart
pro stock
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pro stock
Joined: Feb 2011
Posts: 1,454
Glendora Ca.
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Hi Jay. I had the same problem. I changed to 4 piston Wilwoods on the rear with no prop valve. I also have a 15/16 master cyl. Calipers have the same bore size front and rear now. Things are much happier now, but I'm not fast like you and never play stripe games.
"Just a Bracket car dressed up like a streetcar"
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Re: race brake educators please step inside
[Re: J_BODY]
#2410749
11/29/17 04:06 PM
11/29/17 04:06 PM
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Joined: Dec 2005
Posts: 11,521 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,521
Fulton County, PA
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I would expect that if you take 2 1" wheel cylinders off and replace them with 2 calipers with 4 1.75 pistons each, there would need to be an increase in volume (larger bore MC) needed, especially if you had a soft/long travel pedal with the drums.
On a Strange Mopar style MC, the port nearest the pushrod is the higher volume outlet and is typically used for the rear calipers on a typical - big rear tire, small front tire - drag car. A larger bore MC will make the pedal "tighter" or have less travel. It will also reduce pressure at the wheels, causing you to have to use more pressure on the pedal. Bore size and getting the tubing hooked up to the correct port, determines how the brake pedal feels. Safety and personal preference are the issues.
I've never had to use a valve to reduce pressure to one end or the other on a properly set up system. Yes, sometimes you don't get the perfect MC on it the first time.
Valves, switches and any other OE "stuff" in the brake plumbing should be removed when going to the race/aftermarket stuff.
Last edited by CMcAllister; 11/29/17 04:19 PM.
If the results don't match the theory, change the theory.
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Re: race brake educators please step inside
[Re: CMcAllister]
#2411103
11/30/17 02:06 AM
11/30/17 02:06 AM
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Joined: Jan 2003
Posts: 5,484 SoCal
Brian Hafliger
master
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master
Joined: Jan 2003
Posts: 5,484
SoCal
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I just put the Street Wilwood front brakes on my duster, but have Drums in the rear...I'm using the stock P.valve right now, have not drove it yet (maybe someday!) so is this going to work correctly you guys think? Brian
Brian Hafliger
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Re: race brake educators please step inside
[Re: MR_P_BODY]
#2411539
11/30/17 11:30 PM
11/30/17 11:30 PM
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Joined: Jan 2003
Posts: 9,826 las vegas
70AARcuda
master
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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I just put the Street Wilwood front brakes on my duster, but have Drums in the rear...I'm using the stock P.valve right now, have not drove it yet (maybe someday!) so is this going to work correctly you guys think? Brian How big are your rear tires front tires are 26", slicks are 29x10.5.
Tony
70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: race brake educators please step inside
[Re: 70AARcuda]
#2411555
11/30/17 11:45 PM
11/30/17 11:45 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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I just put the Street Wilwood front brakes on my duster, but have Drums in the rear...I'm using the stock P.valve right now, have not drove it yet (maybe someday!) so is this going to work correctly you guys think? Brian How big are your rear tires front tires are 26", slicks are 29x10.5. I assume you mean front runners and a bias slick or drag radial
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