Drag Link Bent again?

[pron022020]

I am back after a long hiatus. Putting my 27 back together from a hogshead overhaul, I noticed that my drag link is somehow bent again. I straightened it earlier this year while restoring the front end. Any reason why this happened again?

[Mark Gregush]

Did you use heat or bend cold last time? If heat, wonder if you got it too hot and was left too soft when cooled.

[jiminbartow]

You should heat it red hot and quench it in oil? Cooling in oil instead of water makes it hard, not brittle. Jim Patrick

[John iaccino]

I was always told to bend vanadium steel cold. Has this changed?

[pron022020]

It was bent cold.

[TWrenn]

Well they don't bend on their own so maybe you somehow hit something or forced the steering too far one way or the other?

[jiminbartow]

In years past, someone may have heated it and neglected to re-temper it. You will need to do that. Jim Patrick

[Original Smith]

I've always straightened them cold, and have never had one re-bend!

[speedytinc]

In years past, someone may have heated it and neglected to re-temper it. You will need to do that. Jim Patrick

When you straightened it & re straighten, does it bend easy This would confirm the theory. If you had another one, you would have a comparable reference. This does sound like the scenario with your part. Heck, it could have gotten too hot from a pan of burning corn cobbs meant to soften the oil in winter. A lot can happen over 100 years of existence.

[TXGOAT2]

If the ball ends are worn way out of round, they could bind enough when turning to stress the drag link.

[jiminbartow]

A hundred years ago, most amateur shade tree mechanics were unaware of how to straighten a tempered part, which means they were also unaware that, if they used heat to straighten a special alloyed part that never should have been heated, they needed to re-temper it, which, in this case, they obviously failed to do. At least they did not use water to quench it or the shaft would have probably broken during a turn, causing a wreck. If you have ever watched “Forged in Fire”, where 4 contestants (usually blacksmiths), compete to make the best historic weapons (swords, knives or axes), the part where they harden their blades with a long metal tube filled with oil will show you how tempering metal is done. Jim Patrick

[Original Smith]

A 26-7 drag link is shorter than earlier years. Your problem is probably because you have an earlier drag line.

[Ken Buhler]

I submitted a post on this subject on Dec 14. I think it is relevant to this discussion today. Also, there is a chart of drag links for different years on the forum. It was originally posted by Chris Brancaccio.

[John kuehn]

Heres a post about the different drag links and differences for 26-27. https://www.mtfca.com/discus/messages/4 ... 78761.html

Pictures are there for comparison of lengths.

[pron022020]

Thanks everybody for all the information. Tomorrow I will pull the drag link off and see if it is an earlier one.

[CudaMan]

Just a suggestion, before you pull the drag link it off, jack up the front wheels and have a helper turn the steering wheel from lock to lock to see if the drag link is fouling on another part which is causing it to bend.

[Jerry VanOoteghem]

In years past, someone may have heated it and neglected to re-temper it. You will need to do that. Jim Patrick

I do not believe this would not have been a part that was ever heat treated and tempered in the first place. To assume so, and to attempt any sort of heat treatment on it now, may have unforeseen and unwanted results.

[Jerry VanOoteghem]

A hundred years ago, most amateur shade tree mechanics were unaware of how to straighten a tempered part, which means they were also unaware that, if they used heat to straighten a special alloyed part that never should have been heated, they needed to re-temper it, which, in this case, they obviously failed to do. At least they did not use water to quench it or the shaft would have probably broken during a turn, causing a wreck. If you have ever watched “Forged in Fire”, where 4 contestants (usually blacksmiths), compete to make the best historic weapons (swords, knives or axes), the part where they harden their blades with a long metal tube filled with oil will show you how tempering metal is done. Jim Patrick


A6487642-7A92-4C03-953E-462112C2C63A.jpeg

This is nowhere near the same steel that knifesmiths use in Forged in Fire.

[Bill Robinson]

It's also possible that a non-Model T Ford drag link or pitman arm was installed at some time in the past. This might create some binding on a full turn. Length matters on a drag link (as well as orientation in a degree wheel), just like length matters on a pitman arm.
Look at your pitman arm. Is it pointed straight down when the front wheels are headed straight ahead?

[Allan]

I am a real novice as far as heat treatment goes. I oil quench the new tips I weld up on handbrake pawls, believing this will harden that tip. I had no idea that such quenching will harden stuff to the depth of a drag link. Knife edges yes, but at depth? Do I need to revise my thoughts?
I just straightened the draglink in my 1912 van, holding it in my bench vise and hauling on it where needed.

Allan from down under.

[speedytinc]

I like theo ot of round ball theory. In steering, the flat worn areas on the balls would be in play. If one tightened that wear out. the balls would bind @ some point in a turn. The test of getting the front end off the ground & turning the wheels lock to lock would show such bind. Whall up, look @ the pitman arm straight down,. The wheels should be straight ahead. As mentioned. Does the drag link seem easy to bend with one end in a vise?

[Allan]

John, mine was bent 8-9" from one end. It was easy to straighten in the vice. A bend near either of the yokes would be more difficult. I found that balancing the rod across the vice jaws made the rod rotate to find balance. I kept at the re-bending until the rod imbalance was far less noticeable.

Allan from down under.

[Jerry VanOoteghem]

I am a real novice as far as heat treatment goes. I oil quench the new tips I weld up on handbrake pawls, believing this will harden that tip. I had no idea that such quenching will harden stuff to the depth of a drag link. Knife edges yes, but at depth? Do I need to revise my thoughts?
I just straightened the draglink in my 1912 van, holding it in my bench vise and hauling on it where needed.

Allan from down under.

Most likely, the steel used for those pawls does not have enough carbon content for them to respond to heat treat. If they were made out of high carbon steel, then maybe they've already been hardened, in which case trying to harden them further may mess up the original heat treat. Test it before & after with a file to see if there's any change. I think you'd have to have the pawl carburized & hardened to get a meaningful result.

[Allan]

The pawls vary in construction. Early ones are cast/forged, later ones folded steel sheet. RHD items need to be rebuilt in the absence of reproductions. I have seen them brazed up, but you can imagine how long that lasts if the driver drags the lever back without holding the pawl off the quadrant. I guess I am heat treating the mig weld material on the tip of the pawl. It seems to work.

Allan from down under.

[Original Smith]

Does anyone know the difference in length between the pre-26 and the 26-7? My guess would be one inch.