Technical 1939 ? cluster - can a tooth be welded

Boy oh boy! A guy has to do a lot of reading to make what they will of this bunch of opinions. But I'm seeing some balance between the will and won't, the do's and don't, the have it to spend and the money don't grow on trees crowd.
If you indulge my wanting to offer a second opinion on the repair side after reading some of the negative responses... luck favors the brave.

 

Oh, it can be welded....the tricky part is getting the hardness back to what it was. I notice the old book doesn't say anything about that.

 

With all due respect (and I mean that) A guy has to read a lot more about metallurgy to understand the effects of welding on a heat treated part. It's really not about having money, luck, or being brave. It's about risk management.

It's the OP's gear box and if he chooses to take the risk that's his deal. He might get "Lucky" and it might last a while but, if he breaks anymore chunks off that cluster well...…….. his box might be total trash on the side of the road.

 

With all due respect, if he can not find replacement gears, the current trans is, according to many here, "trash".
If its junk to start with, there are several options to gain some use from it before he may have to pull it and s**** it, all of which will most likely be a result of how the trans gets abused from here on. Most logical people understand that if you have a transmission with weaker gears, and you want to use it for a long period of time, you don't abuse it. Any abuse will shorten its expected life. With that in mind, he can do a few things to get some use out of it until he finds better gears, or a replacement trans.
Filing and smoothing the chipped teeth is probably the most simple process. Sharp jagged edges are what you should be concerned with, and you want to keep the reduction of the tooth contact to a minimum, don't remove any more tooth contact area then is necessary for the smooth surface. With the condition of the gears pictured, that may by far be the best approach.
Building the chipped teeth up with weld complicates things pretty fast. Its not something I would give a lot of consideration to given the nature of the gear condition. If teethe were completely missing, or several in a row were damaged, that would be different (and yes, I have built up broken off teeth on gears successfully before). The process is slow, and heat control is important. The after welding reshaping of the teeth is critical and how well that was done probably has as much, maybe more effect of the long term life of the gear then the heat treat most are so concerned with. The teeth mesh with the other gear is of the upmost importance, it has to be correct, and it has to be smooth. Some people think they can do a quick grind on the teeth after the welding and all is good, then when the repair fails, they blame the welded area (or the "heat treatment" being wrong), not the ****py tooth engagement. When you get done, this is still probably not the transmission you want to go drag racing with, but that too has been done.

Or, you can just s**** the trans and go get a better one, since they are so cheap and easy to find.... Gene

 

It can be welded but do you think a decent tooth engagement can be done by hand?
As mentioned, smooth it off ...and hope the teeth are not fatigued with internal flaws and will break off and jam the ge****t

 

Welded up a cam lobe once.
Lasted until the car totaled about 75k miles later

 

I wonder what the stress is on a cam lobe, compared to a transmission gear?

 

Zero. I never stressed about it at all

 

It's been done many times. The main thing is grinding the tooth where it contacts the other gear. Many Farmall m's broke a tooth , we're welded in and "fitted", so the welded tooth was making correct contact. You will be able to hear it. Give it a try.

 

One USD equals 75 Rupeees in ****stan.The average salary in ****stan is 81,800 PKR (****stani Rupee) per month, or around USD 498 according to the exchange rates in August 2021. Considering this, ****stanis "do what they have to do". We are lucky to live in the USA.

 

I would think (or hope) that the guys in ****stan rebuilding engines, welding crankshafts etc. are making above average salary, but still it's a lot less than the first world rate.

 

Random thoughts: When I was in grade school I created a "high-lift high-duration" cam for the family lawn mower by adding giant globs of 6011 welding rod to the cam lobes then grinding the excess away until the desired profile was achieved. Amazingly, my rookie efforts at "Eyeball Engineering" won the day, that Briggs and Stratton running like a striped ape until the connecting rod let go.

Something every serious fabricator should own is a copy of "The Complete Modern Blacksmith", the writer discussing in great detail the process of heat-treating, to include "case hardening".

Automobile purchasers have always been used as "Beta testers", the flathead and it's ***ociated transmissions undergoing endless revisions and improvements throughout the years, if NoelC can't find parts for his earlier transmission, what is keeping him from swapping in the entire ge****t from a later (and improved) flathead transmission?

 

It would be a reasonable ***umption that the OP's gear is made from 8620, or some similar alloy that might have been available in the 1930s, and then carburized. A bit of research on forums focused on welding engineering will yield one common answer on the weldability of carburized low alloy steels. They are not capable of being successfully welded once they are carburized.

A gear needs the hard surface for wear resistance, but it also needs the softer core for toughness. Carburizing is a one way street. Once carbon is diffused into the surface, the part can't be "un-carburized". If you weld on the part, even using a filler that's a perfect match for the core material, the high carbon content at the boundaries will diffuse into the filler and change its properties. The weld heat softens the surrounding surface, so it loses its wear resistance in those areas. If you attempt to heat treat the welded gear, the varying carbon content in the core due to the carbon diffusion causes hard and soft spots in the core. Without going into a long explanation of why, the mix of hard and soft areas in the core create internal stresses that can put the repaired area on the verge of breaking with any externally applied load.

The prior suggestions to polish up the broken areas so other small pieces don't break off is the only workable option. The damage was caused by jamming the trans into first gear, either from neutral or 2nd gear, and not from overloading. Don't abuse it and that gear should last as long as any of the rest of the trans.

 

Also, you're not going to clean it up with a file, you need to grind it....the surface is very hard.

 

IIRC according to Van Pelt, the gear set change was in '39 and just listed as early'39. The big difference was the " syncro hub" in the early trans was replaced by the design that used Br*** blocker rings to permit the 2-3 shift collar to move the blocker against the cone surface of either 2nd or 3rd gear and permit easy engagement (smooth shift). Your trans could easily have come from the factory with the early gear set.
Late 39 to 48 gear sets will work in your case except the 2-3 shift fork. You need that out of the late trans also.

 

Case hardening is easy and can be done at home. I have done it. Amazing what you can learn when you dive into the past.

 

For reference, this is the cluster that was in my '41 pickup and it was constantly jumping out of 2nd gear. It never jumped out of 1st.; the problem was a worn syncho hub and thrust washer on the cluster gear. I rebuilt the trans with the later ge****t and some other wear parts.

 

That book may be talking about very different gears, such as large cast iron gears used in low load, low speed machinery. There's a very big difference in the precision needed and the load a gear has to handle in an automotive gearbox, and, say, the huge, slow moving cast iron machinery that moves logs around in a sawmill.

 

Have you tried the "Early Ford V-8 Sales, Inc.", 1-800-417-3347, E-Mail, Earlyfordsouth@msn.com. They advertise in the V-8 Times every month and their ad shows, 68-7113 Cluster Gear for '36 to '48 p***enger car, they might have what you need.

 

I don't get these 3rd world videos, it's impressive what they can do with so little but if you can weld up gears why can't you weld up a welding table?

 

Its a societal thing. Why do some cultures sit on the floor and eat with their fingers? Just a thing. BUT, I get your comment, I always chuckle as well.

 

There's another thread about welding cracked cylinder heads and this video. Unbelievable but entertaining!

 

I believe it's in a functional state right now. It's first gear. First is not synchronized so for driving it should be fine.
If it was mine, I would run it. I feel that welding it would actually damage it more than it is now.
This is just what I would do.

 

I sincerely appreciate all the input regarding my original question.
Some secondary information than most are disregarding, but still answering to;
The cluster gear and it's related components are unique as a set, and I can't change one and not the others.
I currently have NOS input, out put,
2nd gear, rebuilt syncro, and other pieces - bought and donated to my trans.
1st and reverse are available, cluster is unobtainium , so it's either run what I have available as a set or replace them as a set. I have "Heard" that a later side shift cluster and parts will interchange, but don't know for sure and haven't seen one for sale lately. A T-5 would and should be myb1st choice, but I do have this and if it can be saved then I have money to spend on other things.
The T-5 being a great choice, also creates other problems both financially and also mechanically - it needs an adapter, different clutch and pressure plate, modify the floor and crossmember enough to accommodate the shifters location, shorten the drive shaft and torque tube to compensate for the added length of the T-5.... and so on.
I didn't wand to bother Mac with my little issues, even if it meant buying parts from him - and this being an open format I figured I could gather from others knowledge and experiences to get the problem resolved. When I read others questions and comments, I will offer anything I possibly can if I know it will help resolve their issues, as we all have a finite amount of time both here and on.our projects. In the end, there are far too many good & valuable parts involved in this 39 trans project to s**** it, and few if any of the readers of my post would s**** a project for the lack of a single missing item standing in their
way.

 

And everything gets thrown on the dirt floor.

 

Personally I would run it, as stated in other posts, grind down the Sharp edges, clean the case up good and glue a magnet into the drain plug. This is what I’ve done with my t 85 and it’s in far worse shape, just have to remember to make carefull shifts into 1 st and rev.

 

Since the other option to using the chipped cluster gear is to replace the entire set, you don't have much to lose if the whole shootin' match gets ******ed by reusing the chipped gear. So I don't see a downside to just putting it back together and giving it a try.

Regarding the third world repairs, I watched one where they welded up a holey crankcase really nicely, but dragged the block on its head gasket surface along the ground.

 

Hey thanks for that educational video! Now I know how to repair a pan rail crack on a flathead. Or perhaps send him fifty to repair and then sell them around the HAMB....

 

Of all the clusters you see only one is serviceable..the rest were ruined by folks jamming them into first or reverse..another issue is shift forks,people hung on the shifter for dear life..Ford made high quality steels,almost 50 different designs..weld a tooth? NO

 

That's quite a collection of clusters. Only one serviceable? That's what I call regular cluster F@#k !