building a 34 drive shaft

[cas3]

i have 5 drive shafts, only one has a good front bearing surface. i need two. so, i'm gonna make em. i know folks have been putting the 6 spline coupler in the rear, i need one of those, and the other will stay a ten spline but the front will be made by me. never done it, never heard of it, but i am determined to make use of an otherwise junk and hard to find shaft. i will use the REAR of a 42ish shaft for the front of one, and the 6 spline coupler modified for the rear of the other. crazy? maybe, tell me your thoughts. first let me talk about hardness. i always thought the front bearing surface was some special hardened and ground surface. not true. on two later solid shafts i have here i went all up and down with a triangle file and was able to easily make a cut. next i went on the bearing surface of a couple bad 34 shafts, same thing-easy cut. then i look at the REAR of the late shaft, it is machined to the bearing size, and has a nice finish, not ground perfect like i expect the front would have been when new, but nice. i cut it off and polished in the lathe with 600 wet, and it looks good, and is not wore out like all my other ford parts!!. now the 6 spline coupler, gotta be hard right?, no. and not true either. i had to take a light cut to get a consistent measure for boring the hole its going into. now the 34 ends. i got a long old lathe recently that will fit the whole shaft, so i cut the ends off with a cutoff tool. funny, the front went thru the tube and kept cutting into the male end, and the rear was a dead stop when i got thru the tube. very hard at the 10 spline end. side note here, a few years back this topic of bad drive shaft bearing surface came up, and at the time i stated that in model T's we weld em up and turn it back to size. done all the time. but the general concensus was at that time this would not work in a v8 shaft as the shaft is hard etc etc, and now i disagree, i think the shaft is the same all its length, and perhaps the weld would even be harder. nice machining, and polished would be my thoughts on that. more on hardness, the rear end of the 34 was chucked up to be bored out to fit the late coupler, and it was too hard to cut! i wrecked a nice big drill bit trying to rough it to size, sharpe bit too, but no cut. you can see it in the photo. so i decided to just make a bushing from scratch. two photos, you can see the cut off rear is slightly shorter in the spline, and the pointy nose that goes in the u joint is flat. i will loose about 1/8" of contact area on the u joint spline, and have to cut the snap ring groove in with a wiz wheel, but i'm goin for it. first photo is parts, second photo is after i froze the internals outside (its -5) and slipped the outer parts into place. (you southern folks must be jalouse you cant freeze parts just out the door!) welding is next. with the long lathe i know i can make it all true, but i may take this to a friend who is a real welder as my eyes are not what they used to be, i only have a wire feed, and i want this to be strong. i have talked to him already, and he has concerns that my front may want to crack at the weld. lots of sharp folks here, looking forward to you input, thanks, skip....wheoo, is he done yet?

[Pete]

All standard procedure. Done every day. Will work fine.
TIG weld is best.

[cas3]

thanks for the positive input pete, you are one of the respected opinions around here, always glad to hear your thoughts, skip

[Lawrie]

One thing to do AFTER welding is to clock the shaft up by the front bearing area and then check the shaft at the pinion end,.easy to straighten it in the lathe,have the coolant pump going,and use the oxy welding tip and with a dial gauge on the pinion coupling end,heat a small spot at the front u/joint end ,cool it using the coolant and after a few times you can get it spot on.
on the other end ,I machine up a mandrel to fit inside the 6 spline and do the same
Some where I have a good explanation of making a shaft and what steel to use.Let me know if you want me to find it.
Lawrie

[Bored&Stroked]

Originally Posted by Lawrie

One thing to do AFTER welding is to clock the shaft up by the front bearing area and then check the shaft at the pinion end,.easy to straighten it in the lathe,have the coolant pump going,and use the oxy welding tip and with a dial gauge on the pinion coupling end,heat a small spot at the front u/joint end ,cool it using the coolant and after a few times you can get it spot on.
on the other end ,I machine up a mandrel to fit inside the 6 spline and do the same
Some where I have a good explanation of making a shaft and what steel to use.Let me know if you want me to find it.
Lawrie

Hey Lawrie - if you have a good explanation, I'd love to see it and see what they're using for shaft material. THANKS!

[cas3]

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thanks lawrie, good info. yes it certainly needs to be checked after welding. i cut my new rear bushing to size, but at the front i left the od unfinished, so i can cut it down after welding in case the shaft has moved out of line. i'll take it all to the welder today. lawrie you must have a good boring bar to cut that rear 10 spline!

[rotorwrench]

I've purchased a good front spline section that was salvaged from one the old hollow shaft types from a fellow barner but I commend you on the decision to make your own. The splines can be cut on a horizontal mill with a good index to hold the shaft. It can be done other ways too depending on the machines at your disposal.

The late great Dick Spadaro used to make them or have them made. He had a hollow drive shaft kit a person could purchase and weld it up to what ever dimensions they needed. It was great for the guys building AV8 cars that wanted a later rear axle.

[Lawrie]

I run one of dicks shafts in my 33,it does a lot of miles.
Lawrie

[cas3]

me too, and another thing is you cant buy this tube size. its 1 3/4 od, and .100 wall. i have an agricultural mfgr near me that makes pto shafts, and another big company that makes drive shafts, and both looked up the size, and its not there to buy. you can get dom tube in 1 3/4, but not that wall thickness. to get that, the tube gets bigger, and that wont fit in the torque tube. the male end of a 35 shaft is 2", so changing to a later torque tube would probably make a larger size dom tubing usable

[Pete]

Originally Posted by cas3

me too, and another thing is you cant buy this tube size. its 1 3/4 od, and .100 wall. i have an agricultural mfgr near me that makes pto shafts, and another big company that makes drive shafts, and both looked up the size, and its not there to buy. you can get dom tube in 1 3/4, but not that wall thickness. to get that, the tube gets bigger, and that wont fit in the torque tube. the male end of a 35 shaft is 2", so changing to a later torque tube would probably make a larger size dom tubing usable

The problem with using DOM tubing for driveshafts is the wall thickness varies.
Not very much but it does. Using it for driveshafts can cause balance problems sometimes which requires more money to balance the shaft.
Driveshaft tubing is rolled and welded.

Some trivial info. Ford used a proprietery formula steel closely approximating SAE3140 for his solid driveshafts.

[cas3]

well i'll be danged, i thought dom is what they use for drive shafts. one of my buddys is an aircraft guy, and he says to use aircraft tube which is available in more sizes. perhaps he is right!

[rich b]

1.75 x .095 wall tube won't work?

[HIGHTOWER611]

Originally Posted by rich b

1.75 x .095 wall tube won't work?

.095 will work but remember the thicker the wall, the more rotating mass you have. It is imperative that all items are in complete alignment. This will help to eliminate vibrations and potential failures due to stresses over time due to a whipping action because of misalignment. It would be best to use a dial gauge when setting up and be within 8 thou or less before welding and check after as well. This is why some of Dick Spadaros' driveshaft kits failed in the past. They need to be assembled precisely. I have his remaining stock of kits and they have .060 wall welded seam x 1 3/4. All driveshaft builders have assured me that this is sufficient when built properly.
Does anybody have the original wall thicknesses of 33-34 shafts as well as 35-36 shafts? I would assume that they were built fairly precise as well or they would have failed.

[Lawrie]

I fouind the info,its a bit hard to read but they used AISI 1020 steel with.125 wall.
Lawrie

[alan_d]

Originally Posted by Lawrie

I fouind the info,its a bit hard to read but they used AISI 1020 steel with.125 wall.
Lawrie

That's interesting, but I have to ponder if there's anything to loose by going to a much tougher material like 4140 or even Chrome Moly? would some HT material be better for a drive shaft? I don't know is why I'm asking, but 1020 is nothing special, IMO, it would seem there's room for improvement by using better material.

Speaking for myself, the real cost in duplicating parts is the time spent, so I tend to want to use the best material that I can. After all, it usually takes about the same amount of time no matter what type of material I use...

Alan

[ctaulbert]

Originally Posted by Lawrie

I fouind the info,its a bit hard to read but they used AISI 1020 steel with.125 wall.
Lawrie

Since I shared that message with Lawrie, I've made another handful of '33-34 type driveshafts. This setup has worked well behind a sbc (spiritedly driven too) for 10,000 miles.

I start with an original '33-34 Ford front coupler, or have used '35-36 front couplers as well. The back end gets turned down for a 0.002" interference fit into a new tube.



For the rear coupler, I start with a new 6-10 spline coupler from VanPelt. The diameter gets turned down to 1.750", which allows the use of a torque tube seal from Danny Burroughs at Bruce's Rod Shop (a great piece for lowered cars). The tube end of the coupler gets turned down for a 0.002" interference fit into a new tube as well. Another thing I do is "cap" the tube end of the coupler. This prevents any oil from migrating through the splines (again, on a lowered car) and entering the hollow tube.



Now for the tube....In my message to Lawrie, I had used some plain DOM mild steel for that project. It has served well with no issue. Since then, I've moved over to using 4130 chromoly seamless tubing only because I can more readily get the material (often times from Aircraft Spruce).

I've found most original tubes are 0.095", but I've occasionally seen slightly heavier wall thickness. I've been using 0.120" wall, only to increase the bending stiffness of the driveshaft.





I use my lathe, when the length permits, to weld the shafts in an effort to keep them as true as possible. I have a local machine shop that has the capability of balancing these shafts, so I take every one I make to them. I'm sure it's overkill, but for $70, it's worth the added peace of mind.

[cas3]

33-34 tubes are .100 wall thickness. rich, .095 would certainly be close enough for me, what did you find, dom, or aircraft 4130? this was two years ago when the two companys near me said that size was not made. at that time i only had one shaft, and it had a bad front. about that time i also found out speedway, and spadero shafts were no longer made. i now have enough bad shafts that i dont need any tube, just have to make the ends. thanks, skip

[rich b]

Originally Posted by cas3

33-34 tubes are .100 wall thickness. rich, .095 would certainly be close enough for me, what did you find, dom, or aircraft 4130? this was two years ago when the two companys near me said that size was not made. at that time i only had one shaft, and it had a bad front. about that time i also found out speedway, and spadero shafts were no longer made. i now have enough bad shafts that i dont need any tube, just have to make the ends. thanks, skip

Spicer driveshaft tube

http://www.northerndrivetrain.com/pr...0-62-7400.html

Interesting that Dick's tube kits were only .060 wall. Seems thin compared to
my experience with PTO driveshafts on equipment. Maybe that's why people have told me they twist up, always equated that to confusion with Speedway's kits.

[cas3]

thanks for the article lawrie, good read. they confirmed my thoughts that a 35 end wont fit in a 34 torque tube. should get my parts back this week so we'll see what next from there. thanks, skip

[rotorwrench]

The ones built after 1934 went to a divergent/convergent double conical shaped tube type shaft for a number of years before changing to the solid steel type shaft. I assume it was to insure strength but it was likely to reduce the possibility of whipping that can happen on a smaller diameter straight tube shaft. The smaller diameter tube used for those early shafts was thicker for the same reason. The larger the diameter of the tube, the smaller the wall thickness can be to a point.