[Richard]

   

I couldn't wait till April 1 because of the outcome. 

My original concept was to post this as an install I did on the passenger side. I was going to explain how the co pilot was always helping me apply the brakes, so why not just make it easy for her. It would have been a simple process to tee into the supply and delivery brake lines to allow duplicate brake pedals. I was also going to observe how the coach now went into corners and exit ramps much slower than before. Go figure.

But, the outcome of this brake pedal change overrides the prank. 

As long as I have owned Newells, I have found the brakes hard to apply. Meaning it took a lot of leg force to apply the brakes. As a recovering engineer I did a lot of noodlin about that, and asked many of you if you had the same issue. Most said no. I finally figured out that it had a lot to do with the angle of my leg and the design of the brake pedal. I won't bore you with the vector diagrams and force calculations, but I sit high and close to the steering wheel, and that results in my brake foot pressing almost straight down on the brake pedal. A lot of the force from my foot is wasted because of the angle. If one sits further back or lower then the force is more in line with the direction of travel of the pedal. It's intuitive and the force vector analysis shows proves it. I wasn't going to have much more luck changing my short legs, short arms, long torso build than I will have growing hair. 

I also did the math for the standard floor mounted treadle, the math indicated that for my seating position I would gain almost a 30% mechanical advantage due to the angle of a floor mounted pedal. For the hardcore engineers, I did take measurements of the pivot points, angles, and moment arms for both the Newell horizontal mount pedal and a standard floor mount pedal in order to calculate force applied to pedal into force applied to the valve. The problem that stopped my pursuit was that the floor mount treadles mount the air valve underneath. That would have meant cutting a hole in the floor, rerouting all the brake lines, and wiring to install one. No go, with the first barrier being the floor is about six inches thick. That was the status for almost 7 years. 

Last fall I completely stumbled into a treadle valve assembly with horizontal mounting of the brake valve. I decided to take a chance on a $500 experiment. 

Holy Moly!!!!!!!

For me and me seating position it is the difference between driving an old car with drums without power brakes and a new car with power brakes and discs. I held my breath on the first drive after the install (Rhonda did too thinking it wouldn't stop) hoping I had not thrown the money away. I was blown away by the difference in reduction of force required to stop the coach. 

For the install I had to lengthen several of the air lines, and I left the air lines so that I could reinstall the original setup quickly in case my experiment didn't work. I have to rework the foot panel to fit the new pedal now. 

The math does not explain the difference completely. Brake pedal valves have different compensation ratios, in other words the amount of back pressure fed into the pedal compared to the pressure applied to the brakes. If there were no back pressure there would be no brake pedal feel. However I do not know the compensation ratio of the old unit or the new unit. 

I have a way of measuring the pressure in the brake line by plugging a gauge into the outlet for the toad brake. I wish that I had run a little trial with the old pedal before I removed it. Then I could have rerun the trial with the new pedal. I may enlist help from one with an M&G toad setup at Ruidoso to gather the data. 

If you get interested in this mod, the part number is Williams WM569A, and I sourced it from www.brakesystemsinc.com.  It is not in their catalog, so call and talk to an application engineer. They do show a horizontal treadle, but it is not dual circuit, show don't buy the wrong part. (Don't ask how I know this). I also could help with the air hose routing if you need it, since it took me a minute to understand how the ABS system was tied in. And in case you are wondering, the setup is FMVSS approved. 

I am one happy driver after the test drives.

[folivier]

Great job Richard. Probably most of us have the same problem. Newells don't seem to have enough fore/aft seat travel with either the cabinet, sofa, or slide wall behind the driver seat so you end up sitting like you said: high and close.
But now Rhonda will expect you to slow down quicker and stop shorter........

[Fulltiming]

That's great Richard.

[RussWhite]

Richard,

I had a treadle valve type on a previous coach. In concept I like the Newell's more familiar brake pedal, but not the EFFORT to takes to apply the brakes. If you had asked me, I would have said the effort is unusually and uncomfortably high.

If I got the same reduction in effort that you describe it would justify the change for me. I'm a bit nervous about splicing the lines.

If you have some time a more detailed explanation with pictures of the install would be very welcome. Russ

[Richard]

The install was relatively straight forward once I figured out what fittings I needed and ordered them.

All the fittings on the old valve are 1/4 NPT to push on. The two supply lines are 1/2 DOT tubing, one of the delivery lines is 1/2 DOT, one is 3/8, the ABS line is 3/8, and the two lines to the gauges on the dash are 1/4. Yeah, that's why I had to draw a picture and detail the needed fittings.

I simply used push on butt connectors to splice the lines. Now that I know the pedal is a permanent addition, I will replace with compression fittings. I didn't have any qualms about splicing or using push on connections since the air lines were originally connected at both ends with push ons. Yes I added one more place to potentially leak, but in my mind I didn't alter the safety element by adding a splice.

I will take some pics later today of the install, and post.

Because the treadle sits higher than the accelerator, the place where my foot finds it is VERY close to the contact point of the old pedal.

Russ, you and I are of similar builds, so I can see why we have had the same impression of the force required. Play with the trig and force vectors for an A Ha ! moment.

[77newell]

I've thought of trying this on my 93 coach for force and geometry reasons (long legs, short torso). I don't see any ABS indications on this coach so the install would be similar. Interestingly the 77 coach I had came from the factory with ABS though it was disabled when an engine transplant was done.

Good job Richard.

[Richard]

The install was relatively straight forward once I figured out what fittings I needed and ordered them.

All the fittings on the old valve are 1/4 NPT to push on. The two supply lines are 1/2 DOT tubing, one of the delivery lines is 1/2 DOT, one is 3/8, the ABS line is 3/8, and the two lines to the gauges on the dash are 1/4. Yeah, that's why I had to draw a picture and detail the needed fittings.

I simply used push on butt connectors to splice the lines. Now that I know the pedal is a permanent addition, I will replace with compression fittings. I didn't have any qualms about splicing or using push on connections since the air lines were originally connected at both ends with push ons. Yes I added one more place to potentially leak, but in my mind I didn't alter the safety element by adding a splice.

I will take some pics later today of the install, and post.

Because the treadle sits higher than the accelerator, the place where my foot finds it is VERY close to the contact point of the old pedal.

Russ, you and I are of similar builds, so I can see why we have had the same impression of the force required. Play with the trig and force vectors for an A Ha ! moment.

Here are the pics.

   
In this pic, the two lines on the lower left are the supply lines from primary and secondary circuits. On the top, the rear brass Christmas tree feeds the primary delivery, the ABS circuit (red), and the brake switch light. The two lines on the right side are connected to the dash brake pressure gauge. There are two additional ports on the bottom of the valve plugged with hex pipe plugs.

I did have the Christmas tree standing straight up from the valve, but it slightly interfered with the pedal when fully depressed. 

   

There are different ways that you could plumb this since there are two supply openings and two delivery openings in both the primary and secondary circuits. To connect to the Newell setup, the primary and secondary supply is easy. I used the other supply ports for the gauge. The delivery ports are a little more work. The primary delivery has to feed the primary delivery, the brake light switch, and the ABS circuit so you have to go from one outlet to three in some fashion. The valve can be rotated in the assembly, to allow access to the two ports underneath, BUT it you screw fittings in the ports with the valve rotated it will not lie flat on the floor. 

   

[MrE]

Richard,

Thank you for this post, one of my back issues is called 'foot drop', where I can't lift my right toes off the ground. This tends to make using the brake and throttle pedals uncomfortable when driving and I would never admit to using my left foot on occasions. I will definitely look into this!

[Richard]

There is no reason that both the accelerator and brake pedal could not be mounted on the left side.

[valento]

Looking forward to seeing your brake mod at Ruidoso!