Difinitive U joint/driveshaft thread


The old and reliable.

Golden Jubilee
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Post Fri Jun 09, 2023 9:57 am

Difinitive U joint/driveshaft thread

Or in other words, how I spent the last week or so "getting the shaft'!
The K and I assume D and may be later trucks use several versions of the "Mechanic's" style joint. The one most people are aware of are the "winged bearing lug type. Although these are still made and used, they never had the market share that the Spicer type joints had.
The Winged bearing lug came in many styles and sizes ( like 4-C, 5-C etc) the larger sizes are the ones that are common today, 6-C and up. They can have the lug threaded or drilled and the flange they mate to is threaded or drilled (which ever half is threaded, the mate is drilled). Styles with lugs that start with "D" have a drilled hole, and those that start with "T" have threaded holes. There are also three types of wings, low, high and "delta" which describe the bolt hole/thread portion. A high lug has bolt holes that are level with the top of the bearing, These are drilled hole for flanges that are threaded, the Low wing is threaded and bolted from the yoke side of the joint. Then there is the CSR, which is a low wing with a drilled hole but a cast trunnion strap that essentially makes it a high lug.
Next there is DR series that at 1st glance looks like a Spicer joint with attachment straps. The straps are welded to the round bearings.
Lastly there is a Mechanic's joint with four round bearing caps and internal snap rings.
The "C" joint with the winged lugs are made in two styles one uses four winged lugs, but they can be of mixed type (drilled or threaded, high, low or delta)
Next there are the DR and CR joints. The DR has two round bearings with the straps welded on and two with the internal snap rings. The CR has two winged lugs and two internal snap ring round bearings.
The K series used all except the one with four snap rings which came out in the 1960's for double cardan type CV joints.
Now the bad news:
The DR joint is obsolete and none seam to exist. I have found a picture of a new one in an old Neapco box but none seam to be available anywhere.
The DR series was used in the early K's and I imagine the D's. My K built in late 1941 has three of these joints. The yokes for these joints look similar to a modern Spicer strap mounted joint except there is no "Tit" in the bearing bore to keep the bearing from sliding out and the strap flange has a pilot to keep the strap located.
Later K's used C and CSR type joints, The yokes are not compatible with the DR type joint, to switch from one to the other, you have to change all the yokes. I haven't found any CSR joints for sale but I think you could replace with High drilled lug or reuse the trunnion strap on a low threaded wing and drill out the threads. Both the C and CSR joints use a pilot on the yoke that is similar to the DR yoke but there isn't a bearing bore on the C style yoke, rather a slot cut into the flat surface to transfer the torque to the lug. In both styles the torque is transmitted directly to the bearing and the bolts just retain the joint.
The Mechanic's style round joints use a 1.313" round bearing cap (in the 5 series) which no other mfg used, so no other mfg joint will fit a Mechanics yoke.
So, after a week of work, I am no closer to solving my drive shaft problem. Finding yokes to fit the rear axle, and carrier bearing in a Spicer size is not difficult but not cheap. The output yoke on the transmission is another story. It also holds the E brake on trucks without an Aux trans or powerdivider (on these trucks the E brake is on the output of these units).
It would seam that the C series was used up until the Loadstars with a T 34, 35 or ,36 transmission but no others. Other transmission use and internal expanding shoe E brake, the K's and T34 trans use an external brake band.
I did find a output flange that the E brake drum could be modified to fit, but it take a 6C joint and cost over a grand for the flange alone! The 6C joint is too large to mate with the K-7's driveshaft tube.
I could likely find and make/ modify enough yokes to have a new driveline made, but cost would exceed $2000 easly.
Now that only takes care of the joint portion of the driveline.
The K's use a double taper bearing mounted in a housing. The bearing is made of four pieces, two cones a single double cup and a spacer that is select fitted at the bearing mfg. The cones are off the shelf but when in the assembly they are a mated assembly and shouldn't be interchanged with other bearings of the same numbers.
Fortunately "Parts depot" has 6 left (I bought one).
Driveshafts have "critical speeds" based on tube length, diameter and thickness. The longer the shaft, the lower the critical the speed. Same for diameter, the larger the diameter the faster it can turn. While my shorter wheel base K has 2 1/2" shaft front to back, the longer wheel base with a 10" longer shaft, the shaft is wider in the middle (3 1/2") and tapers to 2 1/2" near the joints.
According to what I can find out the smaller tube is below critical speed for my shorter wheelbase truck but nearer the top end of what is acceptable.
This leads to a conundrum when considering a replacement shaft. My current shaft has too much run out and needs to be replaced. Do I replace the tube only and re-use non obtainable U joints and hope they last until I am dead? do I re joint with a obtainable joint when I get the shaft? Do I keep the same diameter shaft or increase the diameter? If I stick with the same diameter than I am limited to 1410 series joints (in Spicer) If I go with a larger shaft I can go 1480 or 1550 series.
Another option is to add another carrier bearing and jackshaft and make the driveshaft with the sliding yoke shorter.
I can easily spend four times what I paid for the truck in the driveshaft.
So, if you are looking for new joints for K, you first need to determine what kind of joint you have, that will likely determine what you can find. Mechanics joints aren't common or cheap even when they are available.
Attachments
DR joint.jpg
DR joint
Last edited by cornbinder89 on Thu Jun 15, 2023 2:55 pm, edited 2 times in total.

Golden Jubilee
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Post Fri Jun 09, 2023 10:07 am

Re: Difinitive U joint/driveshaft thread

To add more to the above:
It seams my '48 used CR joints where the round bearings were in the driveshaft side with internal snap rings, but a a 7F (full tandem) truck I have parts from used 5C type joints (flanged) on the driveshafts. So it looks like either could have been used or the parts truck was re-shafted at some point. My '48 is all original.

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Post Sun Jun 11, 2023 1:28 am

Re: Difinitive U joint/driveshaft thread

Miscellaneous comments:
I knew I didn't like Mechanics u-joints for some reason . . .

Be sure to check Parts Depot for the brake drum too. And some of the IH vintage parts dealers. A drum is spinning and balanced and I myself would hesitate to modify one to fit a flange except as a last resort. With my modification skills I'm sure I would end up with something unbalanced.

A Spicer 1550 is the largest U-joint that can be put on a T35 transmission. I've tried to get matching 1610 U-Joints for all all my Loadstar 4x4 joints. And I can do it too for both front and rear axle, and input and output transfer case joints. But with off-the-shelf parts I'm limited to a 1550 trans output joint. So my 4x4 conversion has gone from 5 different joints to two, a 1550 and five 1610 u-joints.

And if you can stay at 1550 or smaller, Spicer joints, flanges etc are relatively inexpensive. But going above 1550 in size, prices quickly begin to soar.

And a note to any driveshaft company personnel who reads this in the future - save your old catalogs. I contacted every major driveshaft company I could find about trying to get custom driveshafts made for my 1969 IH truck 4x4 conversion so they would all use the same u-joints. Not one could do it. And most would not consider trying. The reason most often given is their catalogs don't go back that far. So I spent evenings going through a complete set of Spicer catalogs from the '60's I got from eBay until I found a joint, yoke and flange every axle and transfer case input/output had in common that's still available today.

Sorry for the hijack, but it is kind of u-joint/driveshaft related.
CB89 let us know what you finally do.
I wish you all a great day.

Golden Jubilee
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Post Sun Jun 11, 2023 9:35 am

Re: Difinitive U joint/driveshaft thread

There are Catalogs to help The Spicer J300-P4 "driveline components end yoke catalog" is on the .net in PDF form. I can't attach a .pdf file on this site. There is also a similar catalog for tube yokes and slip spline parts. To use the end yoke you are going to have to remove the end yokes you have now, and take all the measurements. there are a lot of variations. I have yet to find a similar catalog for Mechanics style yokes. It takes more time than looking by application but the info is there to fit old stuff if you know all the parameters. I had no problems find yokes to fit my 1941 2 spd axle. At least most older stuff uses course splines and imperial measurements on the shafts, so easy to get it right. Not like trying to make sure it was 32 spline and not 31 spline on some metric sized shaft!
Thankyou for the link to the transmission flange. I am having trouble finding a brake drum that will fit and match the brake I have. I do have (I think) the IHC part number but I draw a blank on a search for it. I may think twice about having my drum modified if they are so hard to find, one screw up and I'm done with something that spins that fast.
Changing joint sizes on one vehicle, isn't the end of the world. I have parts from a full tandem K-7 and they used a bigger joint from the trans to the powerdivider than from the power divider to each axle. tandem semis use a bigger joint from the trans to the front drive then they do from the front drive to the rear drive.
If at all possible you want the ends of a sliding spline shaft to be the same, but a jack shaft from the trans to a carrier bearing can be one size and the output from the carrier to the rear axle another.
You can go too big on joints, and have too much rotating mass for the speed the shaft turns.
I may keep the DR joint and brake drum I have now, and change to a common joint behind the carrier bearing, then save the two mechanics DR that are there now for replacements for the front should it ever need it. That way I can keep the drum and flange I have.
I'd love to find mechanic yokes for my driveline so it would match the other (1948) K I have and I could stock one joint for all trucks. So far I am drawing a blank on finding a source for end yokes in mechanics style.

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Post Tue Jun 13, 2023 9:14 am

Re: Difinitive U joint/driveshaft thread

I've decided to update the U joints from Mechanics to Spicer 1480. I would stay with Mechanics if yokes and assorted parts were readily available like they are for Spicer. Tube yokes seam no problem, but end yokes are. I could find Spicer end yokes is a number of sizes to fit the differential pinion and front carrier bearing shaft in Spicer but none in Mechanics.
I chose 1480 series Spicer as they are close in size to the 5C Mechanics in all aspects. They are also a common joint, and had the most choices in yokes.
The original spec shaft for the wheel base I have from the IHC service manual lists it at 2 1/2" on a 55" length. With the BLD max recommended speed of 3000 RPM and the O/D ratio in the trans, puts the max driveshaft speed at around 3650 RPM. Some charts online show a 3" shaft at 54" has a critical speed of 5400rpm. At first blush it would look like I am nowhere near critical speed. BUT put the numbers into Spicers online calculator and the picture changes dramatically. For the 2 1/2" shaft at 55" they show a critical speed of 3050 rpm and a half true critical speed of just 2714 rpm both are well below the operating speeds of the shaft.
I had not come across the "half true critical speed" term before and had to do some reading on it. It turns out at exactly half true critical speed there is a harmonic set up that can cause a vibration, not as bad as at true critical but bad enough you don't want the shaft turning at that rpm all day. SO the idea is to make sure at say 65-70 MPH you are not turning the shaft at half critical. Interesting when I mentioned to my driveline shop, he didn't know anything about it either.
The only way I can square the difference between the "charts" and Spicer's calculator is: the calculator is meant for shafts used daily on road or in industry and the advised shaft max speeds are kept to a conservative value of some percent below actual critical speed. The charts are more for racers, who will not be turning those speed all day every day. For them, keeping the weight of the shaft to a minimum, but still keeping away from critical is the important thing. Spicer's "half true critical" rpm works out to almost exactly 1/2 of what the chart show.
Getting back to my K's, I have designed a shaft with Spicer's calculator that is below both their recommendations for critical and 1/2 critical for my 1942. It means I am upping the shaft diameter a full inch (to 3 1/2 inches) and because the yokes are slightly longer reducing the length by an inch. This will allow the engine to be driven at rated speed with the transmission in O/D, with the tire size I have giving a top speed of just over 60 MPH. To do the same on my 1948 with a longer wheel base and longer drive shaft of 65 inches, would require a 2nd hanger bearing and jackshaft to reduce the overall length of the driveshaft. It currently has a 2 1/2 shaft at the joints that flares to 3 1/2 for most of the run, but it, like the shaft in the 1942, exceed critical speed recommendations from Spicer.
This begs the question: Did they not know of critical speeds, or not fully understand them back in the day? Did they expect the truck would never see speed above say 45 mph and at that speed they would be ok?
Most times when replacing a driveshaft, you just copy what was there before. I am glad I took the time to research the current info on shafts. If you are going to replace a shaft on an early truck I would suggest going to Spicers calculator and plugging in your numbers 1st. A bigger or mulit piece shaft to replace a long single piece shaft may cost more, but may save you in the long run. I was amazed by how far from current thinking the OEM shafts were in these trucks.

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Post Wed Jun 14, 2023 7:58 pm

Re: Difinitive U joint/driveshaft thread

Today the yoke for the pinion shaft came. I was pleased to find that I measured correctly and it fit! Not a given at my age. I knocked the slinger off the old yoke and installed on the new one, then installed the yoke on the pinion and torqued it. I am waiting until the other yoke arrives and I can fit it up and take a measurement for the new shaft. I should be able to figure it out on paper, but don't trust myself to get it right, and getting wrong is a costly mistake.
Started on replacing the tie rod ends, first time the rims have been off in about 20 years. Had trouble getting the left one off, found the rim had fractured under the spoke because of internal rust. Rim is junk, tire is near junk, only thing worth saving is the lock ring, which I cleaned and painted and moved to another rim of the same type. Mounted a tire with 50% tread on the reconditioned rim.
The rear driveshaft is going to cost more than I paid for the truck, I hope the end results are worth the cost.

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Post Thu Jun 15, 2023 12:37 am

Re: Difinitive U joint/driveshaft thread

cornbinder89 wrote: . . .
The rear driveshaft is going to cost more than I paid for the truck, I hope the end results are worth the cost.

I'm glad everything is working out so far. And knowing the quality of the work you do, I'm sure the end results will be more than worth it - lots to be said for a job well done.

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Post Fri Jun 23, 2023 4:54 pm

Re: Difinitive U joint/driveshaft thread

Well the last of the "small" parts arrived, now just waiting on the shaft itself. I hope I have it sometime next week. I put the new carrier bearing in, doesn't feel any different than the old one, which I saved. I may have a spacer ring made that is a few thousandths thicker for the old bearing and see how it feels when clamped together.
Truck got new tie rod ends and the king pins wouldn't take grease. Replaced the nipples with new, the lowers are "special" being on a long 1 1/2" 1/8" pipe tube that passes through the arm. A little heat and a lot of swearing got them to take grease.
One "new" rim and tire and 4 new rim bolts.
I hope it will be ready and up to being "in service" so I can down my car for a transmission change and new rods, mains, and timing chain. I had planned to do over the winter but never got to it.
There is a lot I am not getting too these days.

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Post Wed Jun 28, 2023 3:31 am

Re: Difinitive U joint/driveshaft thread

Pictures are always appreciated of the work in progress. It kind of makes us feel we're along for the journey.

Golden Jubilee
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Post Wed Jun 28, 2023 10:58 am

Re: Difinitive U joint/driveshaft thread

Not much to show, but I'll try and get some picture.
The truck was missing the underseat fuel tank and had a frame mounted tank behind the drivers door. Although It had '56 IHC written in paint marker, I question if it was for a truck. It had no provision for fuel gauge, and the venting was through the cap. I twas a 35 gal tank, but was poorly mounted, facing off level.
I am replacing with more modern "step tanks" from my junk Fleetstars. It doesn't seam that long ago, that you could pick these up for $1.00/gal cap in steel and $2/gal cap for aluminum (used). Looked on line and they are going for several hundred used steel!
All the tanks I have, need work. Mostly rust holes under the supports/ bands. The older tanks have diamond plate "tread" in the step spot welded to the tank. This is a problem area as they rust between the tread plate and tank. The drivers side tank on my '73 Fleetstar had been replaced with a later tank (date code 10-86) and on that one the tread is a raised open piece of metal to allow mud and moisture to drain away. Unfortunately they didn't "pad" the mounts with anything. There should be something between the mounts/straps and the tank. either inner tube, rim flap, belting material of some sort so it doesn't wear the tank, and none of my Fleetstars had any. Hence I have a bunch of tanks that need repair.
I got luck on the newest tank. all the screw on cover bolts came out without breaking a single one. Must have something to do with the fact it held diesel (a lubricant) not gasoline (a solvent) like my other truck. This allowed complete cleaning inside and out (no baffles in a 50 gal step tank) and left me confident welding new steel in the weak areas.
I have repaired tanks with epoxy, which works well on round tanks, where flexing is minimal. A rectangular steel tank is more likely to flex a bit. I didn't want the epoxy to de laminate and leak. I will seal my welds inside and out with a coat of epoxy as I have had trouble with porous welds in the past leaking.
I have one more to repair after the one I am working on now, but it held gasoline, and I am very cognoscente of the dangers of working on tanks that have had gas in them. It is also why I seal my welds, I don't want to find a pin hole once gasoline has been put in the tank, you can never get it completely out.
The '42 will have two 50 gal step tanks, one on the right for farm diesel and one on the left for gasoline. 50 gal of gas will give the truck about 500 mile range if I can afford to fill it. The new tank also has provisions for a fuel sender.
Still waiting to hear on the driveshaft, but without the fuel tank on the truck there is little point rushing the shop building the shaft.
I have another day of welding (I am using gas to weld, as I find it less susceptible to pin holes, don't have Mig) and that is slow going. Then epoxy inside and out, paint and mount, run new fuel line.
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