The roads were clear and it was sunny with the temperature around 40 degrees F, so I took my 1923 touring / pickup out for its first drive with its AC brakes today. On the first drive, I was somewhat underwhelmed with their braking power, but when I got home and felt the temperature of the brake bands it was obvious that the passenger side was doing all the work, so I tightened up the driver side a bit and went back out again. The second drive was better, but the passenger side was still hotter when I got home, so I tightened the driver side up some more and will take the car out again tomorrow if the weather cooperates.
So far I haven't noticed any sign of the brakes dragging, so apparently they are releasing properly when I release the brake pedal. I have the AC brakes adjusted to clamp firmly with the pedal about 1 inch above where it would stop with the transmission brake.
I need to find a quiet dirt road somewhere so that I can do the "skid mark" test to get them dialed in.
Any other adjustment tips from other members who are running or have run AC brakes?
I also have a '23 touring and added AC brakes and had the same initial experience - that is, "underwhelmed." It does take a while for the brake linings to "seat in" on the drum though, so give it time. The do work pretty well once they've been broken in a little.
And yes, do some skid tests on gravel to get the L/R adjustment correct. That's critical.
They're worth having, and I like mine.
I make sure and count the threads on the adjustment bolts so that I know they are even. Once you get them really right I can lock my wheels up no problem. You want very little travel from when the brakes are not engaged to when they are touching.
Thanks Rick and Seth, I'll keep taking drives and sneaking up on the adjustment, from what I'm hearing it will only get better.
If one side is "HOT" then you need to back off the adjustment on that side. They should be both warm to the touch. I would not rely on counting turns, if one side is hot and the other cold with the same number of turns then adjust as needed. Find a parking lot that you can let the car coast then check the band temp. If neither feels hot then they should be close.
Thanks, Mark. Neither side is hot, the passenger side was warm and the driver side was stone cold after the first drive. After the second drive, the passenger side was warm and the driver side was above stone cold, but not up to warm yet.
I'll keep sneaking up on it and I'll be sure to back off the adjustment if things get hot.
Mine didn't work up to expectations so I took them and the drums off and found that the shoes needed to be adjusted (bent) to match the curvature of the drums. Also, you really need to take out ALL the slop in the system to where the shoes are almost dragging. My peddle moves about 1/2", Don.
Update - I have driven the car several more times, with small tightening adjustments on the driver side between each drive. Based on the post-drive warmth (not hot) of the brakes after my latest drive (I have to descend a medium size hill at the end of my drives to get to my house), I think I have both sides pulling pretty close to evenly now.
Observations: There is more braking power with these AC brakes than I initially gave them credit for, it just takes enough pedal force. I wish I had spent more time trying to engineer in some self-energizing action into the brakes, but I didn't see an easy way to do it (sorry, Glenn Chaffin).
These are not power discs, so the standard Model T driving habits still apply (plan ahead, use engine braking as much as possible, don't ride the brakes for long periods).
Overall, I'm pleased with the brakes and if nothing else they are taking the load off of the transmission brake band, extending its life.
Thankyou everyone for your advice and assistance.
Hey Mark, just like with an oil filter wrench, the brakes by design are already self-energizing. The top half of the band does most of the braking when moving forward, the bottom half when moving in reverse. One way you can gain some leverage is by moving your linkage to the pedal further up, or as far as you can go without hitting the floor boards.
Also, the band design is why the ACs are anchored in the middle, versus the new repro Rockys that are exactly the same design as an oil filter wrench and anchored near the linkage. That's why they don't work well or at all if the car is moving backwards.
Thanks Seth, the pedal effort is fine - it's just different than before, I can get used to it.
Glenn Chaffin had told me that if I could find a way to allow the rear anchor bolt to move up and down about an inch, it would increase the amount of self-energizing action, but I didn't see an easy way to do it, so I stuck with the stock setup.
Looking under the car and working the brake arms by hand, I think I have the brakes adjusted about as tight as I dare for now, others have told me that as the linings and drums wear to a better fit the braking action will improve further.
Sounds like you are on track.
Yesterday I installed a set of Larry Sidmore's AC brakes and his AC brake pedal on my 25 T coupe. Rather than using cable, I installed a linkage mechanism atop the torque tube that includes an equalizer to which the 5/16 inch diameter brake rods are attached.
I'm also underwhelmed with the braking performance, and wonder if I have adjusted them correctly. In particular, the part of the lever linkage below the main casting that attaches to the bottom portion of the band.
Each brake came with two hex nuts on the threaded rod in that area. One is a jam nut to keep the threaded rod locked in the lower clevis. The other, which is larger, appears to be for positioning the lower part of the band relative to the drum. I removed the larger nut so the band would be closer to the drum in the hope that braking action would be improved, but I wonder if that was a mistake. What is the correct adjustment for the distance between the large nut and the jam nut?
Thanks for any suggestions!
I can't help you with Larry's particular design, but on my original design AC brakes I started out with the same length spring above and below the front anchor location. That put the lower band too far away from the drum, so I put a shorter spring on the bottom and a longer spring on the top, see attached pics:
I also ended up replacing the overkill arm return springs in the above pictures with weaker springs.
Thanks, Mark. I'll try reinstalling the large nut and adjusting the lower part of the band away from the drum.