Re: [FWDLK] L-FORWARDLOOK Digest - 2 Jul 2003 to 3 Jul 2003 (#2003-183)

[Nathan Nuttall <nnuttall@xxxxxxxxxxx>]

Title: Message

I would like to add my two cents about proportioning valves. The use of a combination valve is much better than the use of a single adjustable proportioning valve in the rear for all the reasons listed below by Dave - the inclusion of metering and residual pressures. Additionally, I am under the impression that combination valves are actual proportioning valves, giving typically a 65/35 split (I believe) of the total pressure to the front and back. The adjustable valve in the rear does not proportion the pressure. It just cuts pressure to the rear to prevent lockup. What this amounts to is more pressure required by the driver to get the car to stop when a combination valve is not used. The best way to set it up in my opinion, is to use a combination valve as well as an adjustable valve in the rear if your car still locks up the rears during an emergency stop.

 

Additionally, be sure to use a manual master cylinder if you are not using power brakes. The manual master has a smaller bore size to generate more pressure with the same amount of pedal force. It is also not a bad idea to alter the lever arm (torque) on the pedal if you are converting from power to manual or vice-versa. I am not sure about FWDLK cars, but GM typically had two holes in the pedal arm. The lower one was for use with power brakes, and the upper one was for use with manual brakes to improve the pedal feel.

 

Nathan Nuttall

56 Savoy

-----Original Message-----
From: Forward Look Mopar Discussion List [mailto:L-FORWARDLOOK@xxxxxxxxxxxxx]On Behalf Of Dave Stragand
Sent: Sunday, July 06, 2003 7:25 AM
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Subject: Re: [FWDLK] L-FORWARDLOOK Digest - 2 Jul 2003 to 3 Jul 2003 (#2003-183)

I also just finished installing the AAJ kit on my 1958 Plymouth.

 

I found it to be a great kit, and very easy to install.

 

I grabbed a combination (proportioning) valve out of a 1981 Chrysler Imperial, which mounted right to the same hole as the factory T block.  The '68 Roadrunner M/C uses some funky fittings, but I got them off of "adapter lines" from Pep Boys and just flared them onto new lines.  I did have to turn down the last 1/2" of the adjustable pushrod.  I turned it down on a grinder to better fit in the hole on the m/c pushrod rather than just cutting it shorter.

 

A combination valve is preferable to the adjustable proportioning valve, as proper disc operation involves several factors.  First, the valve allows the drums to start braking slightly before the discs, then cuts down the pressure slightly after the discs kick in.  The valve also maintains a slight residual pressure which stops the caliper pistons from retracting all the way back into the calipers (this becomes more important after the pads begin to wear... you would have to pump twice to move the pistons enough for the shoes to contact the disc).

 

The car stops on a dime now; truly amazing braking considering the original setup.  I'm still fighting with the rear wheel cylinders, which started leaking after I installed the new shoes (it pushed the pistons back into an area where there was some corrosion.) I honed them out on the car, and installed cylinder rebuild kits, but plan to replace the cylinders after Carlisle if they show any signs of leakage.

 

I'm putting in a mechanical stop light switch later this afternoon, and that should complete this year's projects... Discs, new rear shoes, new front suspension, and new shocks.  It feels like a different car now.

 

Kudos to AAJ!!!

 

-Dave

-----Original Message-----
From: Forward Look Mopar Discussion List [mailto:L-FORWARDLOOK@xxxxxxxxxxxxx] On Behalf Of Richard Whelan
Sent: Friday, July 04, 2003 1:12 PM
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Subject: Re: [FWDLK] L-FORWARDLOOK Digest - 2 Jul 2003 to 3 Jul 2003 (#2003-183)

HI, In regard to Gary's questions about the AAJ brakes on my 57 Plymouth, I found the kit to be well engineered and easy to install. All of the parts needed were easily available locally at reasonable prices (I ordered the basic kit). The only mods necessary were a little filing on the right side bracket to clear the steering knuckle and even the adjustable M/C pushrod I had needed to be shortened 5/16" or so. The car stops straight and true and fairly fast, but pedal effort is rather high without the power assist. I have most of the power brake parts and probably will install next winter. The dual master cylinder brings a lot of peace of mind, and I used a wilwood proportioning valve to balance the system. All in all very pleased. Hope to see many of you at Carlisle. Dick