[1983Rampage]

I was sitting around the other day and was looking through the trusty ole service manual and was looking at the specifications of the proportion vavles from the 1987 year of cars, which I would expect to be the same for the following years. And I was looking at the split and slope of the different valves and noticed that the All Disc Brake and the L-Body differential-proportioning had the same split which is 500. But the slope on the on the L-body was .27 and the slope on the All-Disc was at .43. My question is what does this mean. I was wondering, couldn't you just use the L-Body proportion valve with the SLH3 setup and not have to worry about changing anything on the front of the brake system except for the master cylinder. And all that would do is that with heavier breaking, there would be more of a response to the pedal movement? Just a thought to ponder. Let me know what everybody else is thinking.

 

[1983Rampage]

Alright, I started to look at the manual again, and noticed that later on it shows a table which looks as follows:

Split Point (PSI)/Slope Inlet Pressure Outlet Pressure to Rear Brakes
500/.27 1000 575-700
500/.43 1000 675-750

This makes me kinda wonder would this mean that it would take more pedal movement to be able to get the same response in the rear end, or would it mean with a full press, there would be less pressure at the rear end which would mean there would be less of a chance to have the rear end lock up with a vehicle that has less weight in the rear end. This is just a little bit more food for thought.

 

[1983Rampage]

ok, the graph did not work quite right, but the 500/.27 split and slope, inlet pressure is 1000 and the outlet pressure to the rear brakes is from 575-700, and for the 500/.43 split and slope, the inlet is also 1000 and the outlet is 675-750. I wish I could have gotten it to look good.

 

[NAJ]

Here is all the info from a 1990 Chrysler Service Manual.Do not know if it is the same as an 87.
The control valve assembly contains a warning switch with a dual proportioning valve.
Proportioning valves balance front to rear braking by controlling at a given ratio,the increase in rear system hydaulic pressure above a preset level. Under light pedal application the valve allows full hydraulic pressure to the rear brakes.
The hydraulic system on non-abs vehicle is split diagonally.The L/F and R/R are part of 1 system and the R/F and L/R are part of another.Both systems are routed through, but hydraulically seperated by a pressure differential switch. the function of the pressure differential switch is to alert the driver of a malfunction in the brake system.
If hydraulic pressure is lost in 1 system the warning light switch will activate a red light on the instument panel,when the brake pedal is depressed.However since the brake systems are split diagonally the vehicle will retain 50% of its stopping capability in the event of a failure in either half.
Valve Application Chart
Body, Function, Proportioing(Split and Slope) Indent Tag
AL, Differential/Proportioning, 500/.27, Gray
AG, 14" Disc, Diff/Pro, 600/.43, Tan
AG, 15" Disc Diff/Pro, 400/.43, Yellow
AA, Diff/Pro, 600/.43, Tan
AJ, 14" Disc, Diff/Pro, 600/.43 Gray
AJ, 15" Disc, Diff/Pro, 400/.43 Yellow
AP, L24/H24 Diff/Pro, 600/.43 Tan
AP, H24/H44 Diff/Pro, 500/.27 Gray
AC (Except ABS) Diff/Pro, 800/.59 Gray
AC (W/ABS) Screw in Proportioning, 800/.45 None
Diagnostics,
Split Point(PSI)/Slope, Inlet Pressure From M/C , Outlet Pressure to Rear Brakes
400/.43. 1000, 600-700
500/.27, 1000, 575-700
500/.43, 1000, 675-750
600/.43, 1000, 725-825
750/.43, 1000, 800-900
800/.45, 1000, 850-950
800/.59, 1000, 875-950

 

[1983Rampage]

AG, 14" Disc, Diff/Pro, 600/.43, Tan
AG, 15" Disc Diff/Pro, 400/.43, Yellow

AJ, 14" Disc, Diff/Pro, 600/.43 Gray
AJ, 15" Disc, Diff/Pro, 400/.43 Yellow

From these, I noticed that they are for the Daytonas and Lebarons, but what does it mean by 14" and 15" discs. What is difference between these, such as which is the vented brake and the solid. Because from the way that it is looking one is close to the in terms of the comparative pressures on the diagnostics, the 14" proportion valve is about the same as the 500/.27 or the one from the earlier L-bodies. But I also noticed that they changed the proportion valves from 87 to 90 in the all wheel disc brakes. The rear discs in 87 had a proportioning of 500/.43. The information that you gave really helped but what is the ID tag on the solid disc brakes and the vented? That is the question now.

 

[NAJ]

The only other info I could find is that the 14" Rear Brakes are Solid Rotors with a 34mm Piston and the 15" Rear Brakes are Vented with a 36mm Piston.

 

[crazymadbastard]

My guess on the 14" and 15" is referring to wheel size.

 

[NAJ]

No that is not true. My Daytona Shelby is 4 wheel disc with vented rear rotors and has
16" wheels.

 

[1983Rampage]

Alright, from there the, here is a thought. From the numbers above, and with some of the issues that have been found with the higher SLH packages and that there is too much power in the back. Would it not be doable with the use of an L-Body proportion valve and use the larger master cylinder. That way you would not have as much pressure in the rear, and would have less of a problem with the rear end locking up. Just thinking about it, yah, there will be less pressure to the rear end, but with a vehicle like the Rampage and Scamps where there is a lot less weight in the rear. Plus on the same not, with the larger master cylinder, there would be more flow to the rear, so that would solve the amount of fluid to go to the rear.

 

[1983Rampage]

People have called me crazy before. But I decided to start thinking outside of the box. And make a car that could more than likely kill me. And besides, who really needs brakes when you can always find that tree or pole. LOL.