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Re: 800psi enough for manual disc brakes ?
[Re: Supercuda]
#1290777
09/03/12 12:32 PM
09/03/12 12:32 PM
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Joined: Feb 2003
Posts: 1,646
Ontario,Canada
firefighter3931
OP
top fuel
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OP
top fuel
Joined: Feb 2003
Posts: 1,646
Ontario,Canada
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Do your lines still go through the factory distribution block?
No sir....the rear (large) chamber from the master is plumbed into the Hurst linelock and from there the left and right calipers are plumbed in. Using the Hurst unit as a "T" because it has multiple discharge ports. The factory distribution block was deleted.
Rear brakes go directly to an adjustable proportioning valve that has a residual pressure valve installed.
All brake lines, hardware, wheel cylinders are new.
Thanks, Ron
Can I ask why you plumbed it like that?
Sure ;
The stock distribution block was designed for 4 wheel drum setup and i was told it would not work with a disc/drum conversion with no residual pressure valve. I did install a residual pressure valve after the adjustable proportioning valve as recommended by Wilwood with their tandem 1in bore master cylinder.
The linelock is needed for racing so it was installed at the time the front brakes were converted over using the SSBC Force 10 Kit.
Thanks, Ron
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Re: 800psi enough for manual disc brakes ?
[Re: firefighter3931]
#1290778
09/03/12 02:13 PM
09/03/12 02:13 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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Quote:
Sure ;
The stock distribution block was designed for 4 wheel drum setup and i was told it would not work with a disc/drum conversion
That would be correct
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with no residual pressure valve.
There is no, and never has been, any residual pressure valve in any stock MoPar distribution or combination valve. Whomever told you this doesn't know MoPar braking systems. In a stock system, all drum or disc/drum, the residual pressure valve is located under the brass seat in the master cylinder exit port(s).
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I did install a residual pressure valve after the adjustable proportioning valve as recommended by Wilwood with their tandem 1in bore master cylinder.
I do not know how Wilwood builds their stuff, but if they gave you the advice on how to plumb this setup they are pointing you in the wrong direction. It would be ok if is were all disc, or all drum, but for a disc drum combo you need more than just an adjustable prop valve in the back.
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The linelock is needed for racing so it was installed at the time the front brakes were converted over using the SSBC Force 10 Kit.
Thanks, Ron
The problem with aftermarket brake kits is that the engineering is only as good as what they want. You mix and match manufacturers and both will point to the other as the fault. Sounds like you need a smaller bore M/C and a real combination valve in place of your current plumbing.
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: 800psi enough for manual disc brakes ?
[Re: firefighter3931]
#1290780
09/03/12 03:49 PM
09/03/12 03:49 PM
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Joined: Jan 2003
Posts: 31,050
Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,050
Oregon
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Quote:
Thanks for the feedback so far 
I've looked at the pedal ratio and taken some measurements ; the pedal ratio is 6:1 which seems OK from what i've been reading 
I was mistaken in my previous post about lowering the pin on the brake pedal when the conversion from power to disc was completed several years ago. I did have to enlarge the brake rod hole slightly for the adjustable pushrod hardware but the hole is still in the original location and the pedal ratio is intact.
Next step is going to to be installing the guage directly to the output port on the master and measure line pressure there. This will at least confirm that there are no issues downstream of the master. At this point there is a linelock between the master and calipers so it's possible that the issue lies there but it doesn't seem likely.
Ron
Checking with the pressure gauge is a good idea so you're on the right path. A 15/16 bore master cylinder might do the trick for you. If you have 15 inch wheels then you really should put a larger rotor on there.
An 11 inch rotor for a 4000 lb car is just asking for trouble. No one would design a system like that anymore. Go visit a car lot and look at 4000 lb cars with 300+ hp engines. They'll all have 13 inch or 14 inch rotors.
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Re: 800psi enough for manual disc brakes ?
[Re: feets]
#1290782
09/04/12 05:27 PM
09/04/12 05:27 PM
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Joined: May 2005
Posts: 6,446
NJ-USA
HPMike
master
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master
Joined: May 2005
Posts: 6,446
NJ-USA
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You can play with this as much as you like. The bottom line is manual brakes + multi piston calipers = no brakes.
I don't know what you've been smoking but it's time to put it down.
The hot rod has manual brakes with 8 piston calipers up front and 4 piston calipers out back. The master cylinder is a manual unit off a 1981 D150.
Judging by your statement with 24 total pistons in the system you'd think I'd accelerate when I hit the brakes.
Rest assured that my brakes are the best they've ever been and are on par with any good non-electrically assisted/manipulated brakes on Moparts.
A manual master cylinder works great with fixed or sliding calipers. The type of caliper makes no difference. It's simple physics. You're making hydraulic pressure. As long as the master is properly sized and has the proper pressure applied you are going to get the correct line pressure.
Really shouldnt have any bearing on whether or not the car can effectively be stopped. Ive built many cars with manual discs and have no problem..
MB
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Re: 800psi enough for manual disc brakes ?
[Re: AndyF]
#1290784
09/04/12 07:51 PM
09/04/12 07:51 PM
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Joined: Jan 2003
Posts: 28,068
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,068
Irving, TX
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The master I use is the modern style aluminum piece straight off the truck in the junkyard years ago.
I do have a twiddly knob style valve in the rear lines but it didn't need any twiddling when I upgraded to the larger brakes.
I can roll on the brakes and increase pressure until they lock. The rears lock just after the fronts. It takes a little pressure to get to that point but you don't have to stomp on them.
It's a really nice setup.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: 800psi enough for manual disc brakes ?
[Re: feets]
#1290785
09/06/12 08:07 PM
09/06/12 08:07 PM
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Joined: Feb 2003
Posts: 1,646
Ontario,Canada
firefighter3931
OP
top fuel
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OP
top fuel
Joined: Feb 2003
Posts: 1,646
Ontario,Canada
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Well, some progress was made Spoke with several people bouncing ideas, theories and such to see if we could figure out what is happening. Dwayne Porter my engine guy suggested that something was limiting piston travel in the master cylinder. He theorized that if the rear brakes were hydrolocked somehow that it would not allow the front brakes to develop enough pressure. That got me thinking HP Mike spent some time on the phone with me and outlined what has worked well for him. One thing Mike stated about proportioning valve adjustment provided another clue. Thanks Mike The tech at Wilwood's only comment was that 800psi was plenty ; "what's the problem"  The freakin car won't stop with me putting 300lbs of pressure on the pedal...that's the problem ! So i asked about adjusting the proportioning valve and whether or not that would have any effect on front brake pressure. His reply ; Absolutely not...they are independant systems.  So, on a hunch....i backed the prop valve off completely and Bingo....1200 psi to the front caliper !  So for anybody who thinks that the prop valve has no bearing on front brake line pressure....i'm here to tell you otherwise.  I have to thank Dwayne and Mike for steering me in the right direction.  New pads are installed and i have to rebleed the sytem and will use the gauge to adjust the prop valve for 600psi rear brake pressure and see what happens. While pulling the back wheels i found a broken Strange 3in wheel stud and need to get that fixed as well.  A further update will be forthcoming once i can test it out but it's looking much better...i'm cautiously optimistic  Ron
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Re: 800psi enough for manual disc brakes ?
[Re: 70Cuda383]
#1290787
09/06/12 10:10 PM
09/06/12 10:10 PM
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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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My Dakota brakes! Stock baseline and follow up tests After one stop on stock size tires my brakes were cooked and useless. And my truck is one of the lightest out there, being a factory nonAC, no cruise, manual everything, 2wd, stick shift A fully loaded 4wd Durango will easily weigh 800-1000 lbs more than mine. And I'm tipping the scales at 3900 with a full tank of gas and a 220lb driver... Yet the much heavier truck will have the same brakes http://www.youtube.com/watch?v=rw0O7Hknzhg&feature=youtube_gdata_player
**Photobucket sucks**
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Re: 800psi enough for manual disc brakes ?
[Re: 70Cuda383]
#1290789
09/07/12 02:50 AM
09/07/12 02:50 AM
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Joined: Jan 2003
Posts: 27,471
So Cal
autoxcuda
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,471
So Cal
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Quote:
My Dakota brakes!
Stock baseline and follow up tests
After one stop on stock size tires my brakes were cooked and useless.
And my truck is one of the lightest out there, being a factory nonAC, no cruise, manual everything, 2wd, stick shift
A fully loaded 4wd Durango will easily weigh 800-1000 lbs more than mine. And I'm tipping the scales at 3900 with a full tank of gas and a 220lb driver... Yet the much heavier truck will have the same brakes
http://www.youtube.com/watch?v=rw0O7Hknzhg&feature=youtube_gdata_player
Very cool test! 
I see different rims in each test group. Did the tires change between test too? If so, what was the specific before and after tire model/size.
Did anything else change between the tests like shocks, springs, etc?
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Re: 800psi enough for manual disc brakes ?
[Re: autoxcuda]
#1290790
09/07/12 01:05 PM
09/07/12 01:05 PM
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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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Yes, the 2nd test was done with viper sized sticky tires.
315/35/17 fronts and 335/35/17 rears.
(baseline test was stock sized Dakota R/T tires, which were 255/55/17 all around)
One could argue that changing more than one thing at a time voids the test as a true brake test, but considering that I could not lock up the front brakes with stock brakes and stock tires, (only one rear locked up after they were heat soaked and not working properly) I could have done the same baseline test with the sticky tires and probably had the same results for the stock brakes.
now, if I was locking up and skidding through the stock tires, then I could see how a duplicate test with stock wheels/tires would be beneficial. but, like I said, even on the very first test with cold brakes, I didn't lock up the fronts.
**Photobucket sucks**
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Re: 800psi enough for manual disc brakes ?
[Re: jcc]
#1290792
09/07/12 02:39 PM
09/07/12 02:39 PM
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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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One could argue that changing more than one thing at a time voids the test as a true brake test.
Well yes one could, and I would. If one wants to be certain, one has to follow the rules, if one is going to guess at the reason for the favored results, why not bypass the test and just guess?
And the risk to the cameraman at the roads edge for 9? full bore stops is right up there with the kid and the red fuel can strapped in the car seat.
Different pad compound on the stock set-up might have given the same results as the second "test". interesting, sorry but that's all. 
You can tell making friends is not my priority here. 
You're absolutely correct, I COULD have bought drilled/slotted/dimpled rotors and aggressive race oriented pads, and MAYBE achieved similar results, but I didn't. Why? because that's not what I wanted to do. If YOU want to buy the parts for me I'll be glad to test them for you on a different truck, repeating baseline and follow up tests, using the stock wheels/tires.
Last edited by 70Cuda383; 09/13/12 07:52 AM.
**Photobucket sucks**
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Re: 800psi enough for manual disc brakes ?
[Re: 70Cuda383]
#1290793
09/07/12 05:16 PM
09/07/12 05:16 PM
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Joined: Dec 2003
Posts: 22,696
Bitopia
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: 22,696
Bitopia
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Last edited by 70Cuda383; 09/13/12 07:53 AM.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: 800psi enough for manual disc brakes ?
[Re: jcc]
#1290794
09/07/12 07:23 PM
09/07/12 07:23 PM
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Joined: Jan 2003
Posts: 28,068
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,068
Irving, TX
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You have questioned my input concerning brakes as well.
I agree with Tom. I'd like to know what your experience with brake packages really is.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: 800psi enough for manual disc brakes ?
[Re: AndyF]
#1290795
09/08/12 12:03 PM
09/08/12 12:03 PM
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Joined: Jan 2003
Posts: 525
Shannonville, Ont
Blown 68 R/T
mopar
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mopar
Joined: Jan 2003
Posts: 525
Shannonville, Ont
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Quote:
I agree. I run manual brakes with 13 inch rotors and Viper calipers on my B-body car and I can launch a passenger thru the windshield if I stomp on the brakes. It is a simple late model aluminum master cylinder. My setup is plumbed just like the OP description. Line lock up front and a prop valve to the rear drums. Nothing else in the system.
Andy, Aren't you running a residual valve after the prop valve as well?I'm in the process of finishing my set up which is same as Ron's but was wondering if i should install residual valve or not, My master is not below the calipers so do i have to plumb one in.Does it act kinda like the same theory as a relay valve does on an air brake system at the rear axle?
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