Golden Jubilee
Posts: 5177
Joined: Thu Nov 29, 2012 9:28 pm
Location: Lyman, IA
Difinitive U joint/driveshaft thread
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The DR joint is obsolete and none seam to exist.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.