Mentioned that to KD in another thread. Suggested to him increase air pressure in tires to there max allowable psi. Then try to lock them. Those big tires would make it hard to lock them. Wonder what a G meter measuring device costs?
Members with 4 wheel disc systems.....Can you get the tires to skid?
- Thread starter Kern Dog
- Start date
- Local time
- 3:56 AM
- Joined
- Apr 13, 2012
- Messages
- 38,993
- Reaction score
- 142,305
- Location
- Granite Bay CA
I'm not so sure that there is a lack of braking power, just that it seems like it could be better.
- Local time
- 6:56 AM
- Joined
- May 14, 2011
- Messages
- 18,194
- Reaction score
- 35,420
- Location
- On the Ridge, TN
That's what I said, yeah.
jag_mopar
Well-Known Member
- Local time
- 6:56 AM
- Joined
- Dec 17, 2010
- Messages
- 347
- Reaction score
- 54
- Location
- Now in East Orlando FL.
So the only way I see if it will stop in a reasonable distance is to setup a test in a parking or similar location. Mark 25foot increments and drive at 60 mph and see how far it takes to stop. What is a reasonable stop distance?
Modern vehicle 60-0 brake test results..
Just in case your feeling like a hotshot....
- Local time
- 3:56 AM
- Joined
- Apr 13, 2012
- Messages
- 38,993
- Reaction score
- 142,305
- Location
- Granite Bay CA
Well, I do have tires about as wide as many of those cars!
275-40-18 front 295-35-18 rear, 200 treadwear for excellent traction.
275-40-18 front 295-35-18 rear, 200 treadwear for excellent traction.
jag_mopar
Well-Known Member
- Local time
- 6:56 AM
- Joined
- Dec 17, 2010
- Messages
- 347
- Reaction score
- 54
- Location
- Now in East Orlando FL.
I figured it was about that distance. Thanks for digging up the comparisons. These are numbers all of us should strive to achieve. @Kern Dog , if you can get braking to around 100 feet I think you are doing great. When the weather warms up let us know your results. I am curious to find out what is achievable on our cars.
Last edited:
This Charger took considerably less distance to stop....
64fury74charger
Well-Known Member
This Charger will now be able to park in one of those spots marked “compact cars only “ at the mall…….lol
4406bbl
Well-Known Member
As an example only a scat pack challenger with standard 4 piston brembos and 245 tires does 60-0 in 117 ft, at 4200lbs or so. The 6 piston 275 or 305 tire cars are better but I don't have the specs. Hellcats with 6 piston do 70-0 in 155 ft. at 4655 lbs.
Last edited:
- Local time
- 3:56 AM
- Joined
- Apr 13, 2012
- Messages
- 38,993
- Reaction score
- 142,305
- Location
- Granite Bay CA
The hydroboost unit that I had didn't work out. I couldn't get it to provide any assist at all. I tried a few bleeding procedures but never could get it to build pressure. I had no leaks with it and it was plumbed properly. I don't blame the concept of hydroboost, just the unit that I had.
Thrashingcows
Well-Known Member
I have 4 wheel discs on my 68 Chrysler Town and Country wagon, 440 car with A/C so a big heavy beast, I can easily lock up my brakes on the wagon. I run a 1.125" bore aluminum master cylinder from an 80's RWD mopar (disc/drum) on a Cardone replacement disc brake booster. I'm running an OEM mopar 73 C-body disc brake set-up on the front of the car and the Scarebird rear conversion with Caddy rear calipers with integral E-brake, think the rear rotors are from a Crown Vic with just generic daily driver quality brake pads all the way around. Tires are 225/70/15 BFG's.
I plumbed the front calipers directly off the master cylinder, no junction block or proportioning valve, the rear circuit is straight off the master cylinder as well with just an adjustable proportioning valve to dial in the rear brakes. In fact the brakes are kind of a little too touchy...just barely have to apply pressure to get it to slow down, and only light to medium pressure to lock up all the brakes.
I plumbed the front calipers directly off the master cylinder, no junction block or proportioning valve, the rear circuit is straight off the master cylinder as well with just an adjustable proportioning valve to dial in the rear brakes. In fact the brakes are kind of a little too touchy...just barely have to apply pressure to get it to slow down, and only light to medium pressure to lock up all the brakes.
- Local time
- 3:56 AM
- Joined
- Apr 13, 2012
- Messages
- 38,993
- Reaction score
- 142,305
- Location
- Granite Bay CA
This is something that I have considered doing....plumbing the system without a combination block of any kind.
The dual diaphragm booster is probably going to be my next move along with plumbing the lines directly.
The dual diaphragm booster is probably going to be my next move along with plumbing the lines directly.
- Local time
- 4:56 AM
- Joined
- Feb 22, 2021
- Messages
- 3,257
- Reaction score
- 6,689
- Location
- Roswell, New Mexico
"The adj prop valve is designed to restrict pressure to the rear brakes to keep them from locking up, he can't get them to lock up! So putting a restrictor in the system will do absolutely nothing but make it worse."
A proportioning valve can be adjusted
to the point where the rear brakes grab
first. It only restricts the flow if you
want it to.
The valve is needed to fine tune
the brake bias. It's purpose is to
restrict reaction time. The first hit
on the brakes during a panic stop
should, for a fraction of a second
restrict the transfer of vehicle weight
(bias) to the front. Holding the weight
transfer back. Tire contact and springs
play a major role here. Too little
contact and a soft front spring
will result in rear tire lock up when
trying to stop 3800 lbs of momentum.
The weight wants to nosedive into
the pavement.
The system on my build from a blank
slate is cobbled together from different
vehicle manufacturers. Ford Granada
front rotors and calipers, Jeep rear
rotors, Ford Explorer rear calipers,
Mopar master cylinder w/1.031 bore,
Chrysler Le Baron dual booster, 2lb
residual check valves in each line,
adjustable proportioning valve
to the rear, 1/8 ID steel brake lines,
Vehicle weight is 3100 lbs., brake
pedal ratio 4:1. First time in with
no components swapped out,
or trying to diagnose poor braking
conditions.
She stops on the proverbial dime,
and does lock up all four in the event
of an "oh sh*t" occurrence.
Bare in mind, this system never
existed before. All parts are new
and ordered as seperate components.
KD, hopefully you can gleen some info
from what is posted. Cars of old have
always had brake "lock up". And back
then, reading the skid marks on the
pavement gave a pretty good
indication as to each wheels braking
performance by the marks they left,
and most mechanics could "feel" the
bias of a properly functioning brake
system.
Which, evidently, makes you a pretty
good mechanic, as the brake bias
you are experiencing just isn't quite
right.
Me, 47 years as a mechanical Engineer...
My brakes work as required.
A proportioning valve can be adjusted
to the point where the rear brakes grab
first. It only restricts the flow if you
want it to.
The valve is needed to fine tune
the brake bias. It's purpose is to
restrict reaction time. The first hit
on the brakes during a panic stop
should, for a fraction of a second
restrict the transfer of vehicle weight
(bias) to the front. Holding the weight
transfer back. Tire contact and springs
play a major role here. Too little
contact and a soft front spring
will result in rear tire lock up when
trying to stop 3800 lbs of momentum.
The weight wants to nosedive into
the pavement.
The system on my build from a blank
slate is cobbled together from different
vehicle manufacturers. Ford Granada
front rotors and calipers, Jeep rear
rotors, Ford Explorer rear calipers,
Mopar master cylinder w/1.031 bore,
Chrysler Le Baron dual booster, 2lb
residual check valves in each line,
adjustable proportioning valve
to the rear, 1/8 ID steel brake lines,
Vehicle weight is 3100 lbs., brake
pedal ratio 4:1. First time in with
no components swapped out,
or trying to diagnose poor braking
conditions.
She stops on the proverbial dime,
and does lock up all four in the event
of an "oh sh*t" occurrence.
Bare in mind, this system never
existed before. All parts are new
and ordered as seperate components.
KD, hopefully you can gleen some info
from what is posted. Cars of old have
always had brake "lock up". And back
then, reading the skid marks on the
pavement gave a pretty good
indication as to each wheels braking
performance by the marks they left,
and most mechanics could "feel" the
bias of a properly functioning brake
system.
Which, evidently, makes you a pretty
good mechanic, as the brake bias
you are experiencing just isn't quite
right.
Me, 47 years as a mechanical Engineer...
My brakes work as required.
Last edited:
Do you have a thread somewhere where you go into detail on what all you did and how you did it?
Similar threads
