In 1989 I did this very thing for my bracket car. While the car never ran faster than a 7.60 1/8 mile, I raced it from 89 to 07 with the same ujoints! peace
Hi guys, sorry for resurrecting an old, but good thread. I am looking for information on how to do something similar, to make a driveshaft for an RV that has had it's chassis lengthened. I am thinking, depending on cost, that paying a machine shop to remove the yokes (One end is a slip yoke) will ensure their squareness. Then, all I have to do is buy the DOM tubing, and weld in place, properly phased. Because the yokes will have perfectly square seats on the already squared tubing. What do you think? I was quoted $250 to start, to have it lengthened. That's... a bit rich for me. Especially if I can do it myself.
Yes, you can do what you are describing, but I would still use the dial indicator on each end of the shaft to get the least amount of run out possible. Placing each flat end of the weld yokes on a flat surface like an I-beam or a piece of channel while tapping them into the tubing like I described above is also suggested to get the weld yokes in phase.
Thanks for a btt. I paid $200 for a new ds on the sedan, need on for the coupester and just found out the old machinist who use to make ds for a living has retired. Since I'm doing everything else myself, think I'll give this a try. Great timing! RB
I also do my own driveshafts, and only use one scribed line. But I've found using a piece of angle iron as a straight edge keeps the line from wandering over the length, as it sits solid against the tube and makes a perfectly straight line. I always keep the yoke indexed this way, and have never had balance issues. The last driveline I shortened on my Austin gasser had weights on both ends, so I drilled out the spot welds and moved them back to where they'd be behind the cut prior to shortening, and welded them back on. This way I could get them perfectly lined up before the cut, and not have any chance of possibly getting them off a little.
Ah. I was hoping by having a straight cut, "Everything would be automatically perfect" but I see that's not necessarily the case, now. When you are cutting with your cutoff wheel, what signs do you see that tell you you are through the driveshaft? How do you know when you are cutting the right area?
You actually don't unless you are really good at checking which I'm not. If you have a stationary disk sander and a guide to hold the tube square to the disk you could square it up fairly easily. Outside of cutoff wheel and tube cutter the OP did it the exact same way JD Fikes (Bondo John) of Waco showed me in the mid 50's when I helped him put a couple of cars together. I've done a number of them over the past 30 something years and only had one that turned out bad. I could never get it to quit vibrating and think it ended up being hauled off to the scrap yard. My son just did the one I put behind my Cad 500 in my 71 GMC but I haven't driven it yet to know how it comes out. He did it the same way the OP did with a cut disk but he cuts and welds tubing every day of the week at work.
thanks drive em...i loved the detailed pics...i always thought special tools was needed for this....i will be using this method in the future
Done a bunch of drive shafts over the years similar to this on street cars, and race cars. I've even used shims to adapt a wrong sized end. Just make sure your tacks are right at the shims. Tack it, let it cool, and weld it up. One tip I learned is, even when using turning fixture, mig will distort the tubing much more than just rolling it on the bench and tig welding it. I never rebalanced one, and never (knock on wood) had a vibration problem.
Lots of good info here. I've shortened quite a few of my own driveshafts, and with no noticable vibration. However I had an old guy (younger than me) tell me that sometines he drills a small hole in the shaft and adds a small amount of auto trans oil then welds it up. I've never had to do this but he swears by it. Just throwin' this out there.
I had a M- 37 Dodge that I modified. The stock rear differential was offset to match the front. We had some vibration. To dynamically balance the shaft I drilled a small hole and poured in a couple cups of round steel shot that is used for giving dynamic balance to washing machines. I carried spare U-joints for ten years and only replaced them once. No catastrophic failure, just wore out.
Another good day on the HAMB.Found some more tricks to use.I have shorted driveshafts before and just took them to the driveshaft shop and had them balanced,but you guys added some great tips.Thanks for the tech.
Someone mentioned using DOM tubing for drivelines. This is NOT recommended. The wall thickness is not uniform and the inside diameter is not made to standard yoke and slip joint diameters. Driveline tubing is made from flat rolled sheet, rolled into tubing and auto seam welded. It has constant uniform wall thickness and it is ROUND. (much closer runout tolerance than DOM) The diameters and gauge of the tubing is designed to match standard available yokes without machining the ID of the tube or the mating surface of the yoke. There is only one method of doing a driveline right and most shops that specialize in it do it this way. Done right a driveline will have no more than plus or minus .002 runout over it's whole length. Even at these tolerances, some will be out of balance due to irregularities in the forged yokes. These can usually be used on the street without balancing though. One more thing, welding washers on a tube to balance is NOT the way to do it. Every time you touch the tube with welding heat, it bends.
The other problem with DOM tubing is it moves your week link to the rest of your drive train. This is something you want to think about.
I've done them like this for 40 years,somebody was always tellin' me I couldn't do that !! Never had a problem with any of them, and I raced an A coupe a few times with a homemade shaft.
Every since the drive shaft shop screwed one of mine up and charged me again to build a second one, I've done my own.
Thanks for the article. I had done shorter shafts on my lathe, but we have to shorten the driveshaft on my son's International because we are installing a B&M 700R4. Because of the tips in this posting, I have decided that, following the techniques provided, it is quite reasonable to expect a perfect job. As for putting foam or grease in the driveshaft, the theory is the same as is used for the viscus harmonic balancers. During rotation, the fluid will be tossed to the heavy side of the shaft to balance out the vibration. So the theory is reasonable, but because the foam might set in the shaft, the vehicle would need to be taken out for a long drive for the material inside the shat that is going to set, will do so in the proper place and not aggravate the balance problem.
The Jalopy Journal
