MTFCA Forum

What is the remedy when the teeth on the steering quadrant are worn and the throttle slips down while driving? Leery about using a file form new teeth.

If you don't mind a wooden block under the hood, there's an accessory clamp that holds tension on the control rods - available at Lang's.

https://www.modeltford.com/item/3524-25T.aspx

I have had a couple of the repro quadrants. They work fine, and look okay, if you don't know what the originals look like. If you know how they should look? They just aren't right.
Some people use silver solder to build up the teeth. I have never tried that myself. Although I have used silver solder to repair headlamp rims. I just don't know I would be comfortable using it to repair the quadrant teeth. On the plus for it however, if the silver solder doesn't hold up due to lacking strength? It shouldn't be a serious problem. Just back to no teeth to hold the lever where you wanted it.

Brass is tricky stuff to weld. It conducts heat far and wide fast. To make matters worse, unlike steel which progresses from solid to liquid slowly, the temperature difference for brass between solid and liquid is only a few degrees. With the fast spread of the heat, small items can have a couple inches go from too-cold-to-weld into a big puddle in a fraction of a second!
What I did to repair an early gear case was cast it into plaster. I tried sand first, but the acetylene torch blew the sand around too much. I surrounded the area to be repaired, and supported it underneath. Then shaped dams up around the area to be worked. The plaster allowed the brass to get hot enough to collapse, but held it in place. I Added the material needed to effect the repair, that held in place by the dams. I allowed it to cool overnight, then chiseled the plaster away. I had built the area up enough that some cutting and a lot of filing was involved. But I was very pleased with the results!
I just used standard brazing rod with the flux coating. It flowed together and blended very nicely. The color even matched well.

Thanks for the helpful info! As my welding/brazing skills are limited I ordered the tensioner from Texas T Parts.

What Rajo said about the wooden block clamp. It does help and it also could be the springs that are on each control rod that help put some downward tension on the rods. I noticed the ones on my 24 Coupe were compressed to much from being on the control rods nearly 90+ years. When I reassembled the column I had the steering box renickeled and the new springs made a noticeable difference in holding the spark and gas rods in place. They had more tension on them when you adjusted the levers.

Thanks John, if I don't have luck with the tensioner, I'll rethink. Replacing the spring is a good first step.

New springs may help with the early brass era quadrants? However, often they only make matters worse. The brass quadrants are bigger and thicker, and heavier, -- and softer than the flat steel quadrants most model Ts had. Of course, most of the wear is in the area where the throttle gets moved the most, and they eventually wear deep. They often develop a short dish where the teeth are completely gone, surrounded by high spots with most of the original teeth intact. New springs will pull the levers into the dish, and resist adjustments above it. They can make throttle control very difficult. Some people try to cut the good teeth down to match the low areas. However, the original quadrants aren't as thick or beefy as the repros are. They become very thin and fragile if cut down much. One of the original ones I have is worn so deep and so thin it broke through! I have it earmarked for my late 1912 project pile. I already looked it over and think I can weld it and build it up in an hour or two (not counting the two days to allow the plaster to dry enough!).

Interesting points I hadn't considered. Thanks Wayne

Wayne, a thought on your plaster technique; amendments to plaster for investment casting (talc, silica, etc.) may make it easier to remove. Of course investment flasks are calcined in a lost wax process, perhaps that makes it more fragile too ?

When I restored the 1909 Touring, the teeth on the quadrant eere very worn. Also it appeared to be a 1914 style column at 56” long. So I made the decision to cut it down to the correct 50” and replace the quadrant. There were no very difficult problems though installing the two brass rivets to hold the quadrant, outer column and inner section was a challenge.