Technical Hillbilly tech. Drive shaft shortening

Used a heavy wall piece of rectangle tubing as a jig.
Removed the yoke and precision ground with a grinder.
Cleaned yoke surfaces. Clamped square on jig.
Cut driveshaft.
Clamp pieces back on jig and align scribe lines.
Lots of measuring.
Tack weld. Measure, weld. Let cool naturally in jig.

 

I did it slightly similar ... shortened one end. Removed the original weld with grinder then tapped the end back into the tube (same as you). Here is where my method differs ... I then installed the driveshaft in the car and put a dial indicator on the tube and turned it. A few light taps with a hammer until it ran true then a single tack. Turned it again to check (again with the dial indicator) and if straight, another tack or more tapping if it needed it. Repeated this until I had four tacks ... a final check with the dial indicator then remove and weld. Never had a problem doing it this way.

I have never tapped the end in the tube, installed it in the car, and found it straight ... it has always needed adjustment (tap tap tap) before welding.

If I needed a longer driveshaft, I didn't bother trying to lengthen, I bought a used, longer shaft then shortened it.

 

Nice,
My buddy does a similar thing using a piece of 2" or 3" angle iron as his base jig.
Chappy

 

I've done them occasionally when I'm in a hurry and didn't want to wait for the local driveline shop. Actually have one in the Austin in my avatar I put together "temporarily" 11 years ago, and figured I'd have it redone later. But it's worked so well I never did.
I mark my driveline tube lengthwise with a piece of angle iron to make a witness line. Then file or cut a mark on the yoke end before removing the weld. Then once it's shortened I can simply realign the witness marks to ensure it's clocked exactly the same. If I have to remove a weight, I mark it's location also, and move it back to the same orientation on the shortened driveline tube.

 

I learned to do these the same way. The first driveshaft I actually had made at a shop was two years ago. All the others were done like this.

A couple of fun tricks my grandpa taught me;

1. after you carefully grind the factory weld down, but before you pull the yoke assembly, scribe a line down the shaft at a recognizable point on the yoke so you can keep the end clocked exactly the same.

2. If you have ground carefully you should be able to split the factory weld seam between the yoke and shaft and have the factory shaft end exposed, which will be very square. Take a measurement off of that end to get your shortened length and mark, and then use a big pipe cutter to run a scribe line around the shaft. The cutter should clock a square line and you can measure from the factory end to verify. Cut a fuzz long and carefully grind back to the scribe line. All of this assumes you don't have a fancy cold saw or something equally amazing to make the cut, and are using a handheld grinder/death wheels like we had.

3. Assemble, tack, and make 1" welds while jumping back and forth on sides to help keep the yoke straight.

We built a bunch of these on a flat spot on a concrete floor and never had to balance one. He was super good at it.

Edit: While I was typing, some of the same tips got dropped in above. Must. Type. Faster!

 

Heck yeah man! I've done it just like you and never had a problem.

 

I see you used a level with the saw. Good idea. Is the floor also level? Ha ha!

 

Several great threads over the years. Just pollinating this thread to help in future searches

https://www.jalopyjournal.com/forum/threads/shorten-your-driveshaft.447741/

https://www.jalopyjournal.com/forum/threads/how-to-shorten-my-own-drive-shaft.873177/

https://www.jalopyjournal.com/forum/threads/school-me-on-driveshaft-shortening.36923/

 

I make sure the Tube is very clean and wrap a piece of printer paper around the tube being very careful to keep the cut edge lined against itself. Then with a scribe mark along the edge on the tube. This will make an exact square line for the Guys without a large pipe cutter. I then cut just long of the line and file up to it. Works good for me.

 

I usually just use a cut off wheel and try to go just past the factory weld depth wise. If you cut in the right spot the yoke should pop off the shaft with a bit of light heating on the shaft and tapping on the yoke. The idea is to not touch the mating surface of the yoke with a grinder at all. There are quite a few thousands of interference (press fit) on a driveshaft yoke. Not sure on exact dimensions but if I remember right it is somewhere around .005". This press fit helps keep things lined up and concentric. Cut off the excess shaft with whatever you have handy and don't worry about making it perfect. Heat the shaft lightly and tap the yoke back in leaving a gap for weld penetration. Re- install in vehicle and use a dial indicator and a hammer to get it to run true. Tack it in and recheck. Then you can burn it in.

 

Just proves its not rocket science!

 

I like the “precision ground with a grinder “

I may need to make that a sig line

 

I did my first couple like that with a piece of channel iron and guidance from my Dad, then I had good old Drag Machine do some, then I bought my old lathe and did them myself in that. But once I discovered our local Drive Line Service, their great prices (including balancing) and their 1 day turn around, I just let them do it. Unfortunately, as always, the place changed hands, prices climbed and service plummeted. I'm pretty much back to doing my own again.

 

@bchctybob ya know, prices around here haven’t really changed much in 40+ years, I had one shorten at a shop in the late 70’s and it was 65 bucks.
A few years ago I had a shop put one together (my ends and tube) for 100 bucks.
I’d probably go back to making my own if I had a precision hand grinder though

 

WE, 50 yrs ago used a plumbers pipe cutter. Welded with torch worked smooth, car was not sold with this. had good one done at driveline shop. FYI, I raced my 67 chevelle 396/auto 12 sec with a 63 olds rubber mount driveshaft and had no problems for half a season. Must have been a good one.. Pete.

 

I have heard of using a big worm gear clamp to make your scribe line square with the world.

 

Budget36, I've only had to do one driveshaft since I retired and moved to NorCal and I did it myself. I hadn't looked into local driveline services since I moved out here to cattle country. I'm gonna need two in the near future, one pretty soon for my roadster and later, one for my '33 pickup. I may just look into local shops.

 

id one on an emergency basis when we needed a new one for the modified back in the 70s. Used 2 transmission slip yolks, cut most of the spline end off, and used a piece of DOM tube. Used the top of the welding bench for alignment and Jim stick welded it together. Tack, tack, cool. Do again. took a while but on a Friday night, and no chance to get to the machine shop that made us driveshafts normally it worked just fine for a couple of weeks.

Oh and it was only 20 some inches long. We never balanced any shafts assuming they were so short it didn't matter.

Why did we need one? Forgot to check the u-bolt nuts on the QC and the old shaft dropped out on the track...

 

In my youth before I could afford a precision grinder I used precision hack saw cutting.

 

As mentioned above, "not rocket science". Just make sure you don't lose the phasing. and if there are balance weights, preserve them.

 

...and it ain't really Hillbilly Tech unless there's banjos and "shine" involved

 

Rubber mount driveshaft? Please educate me as I'm not familiar with this. Thanks!

 

I don’t know what’s around Grass Valley, but still a lot of old school shops in the valley, Stockton, Modesto, etc. the last one I had done was in Ceres.

 

In not familiar with the Olds mentioned, but lots of newer cars especially independent rear ones have rubber drive shaft couplings.
Like a heavy duty rag joint.

 

I love seeing this kind of tech. I shortened my own driveshaft when I built my car. I was attacked on a couple “other” websites for being “irresponsible” and endangering my life as well as everyone else’s on the road! It works great, and has zero vibration.

 

I'll be darned. I've shortened driveshafts similarity. Good to know others do it. Good tips for the next one.

Sent from my SM-N950U using The H.A.M.B. mobile app

 

I have a couple of 2 foot long hose clamps I use for stuff like this. Cut down a 36" water tanks by screwing 2 together

 

Well I guess the fusion process at the pro shops are different than the fusion process at home.
I read comments like that a lot. If you dont trust your welds then don’t do it. Or add a drive shaft loop.
That’s a good safety item even for the store bought/pro shop driveshafts.
I’ve got one cut and welded by a high school student I’d put against any I’ve seen from a pro shop as far as strength.

 

Yeah... This is a project for a competent weldor. It was inferred above, but is probably worth noting in this day and age.

 

Back in the Mid 70's JD Fikes in Waco showed me how to cut right next to the weld with a hack saw just going though the tube all the way around the tube and then pop the yoke out of the tube. He would use a ring compressor as a guide to cut the tube straight. I've had some come out pretty good and a couple that didn't do so well balance wise.