Does Anyone Shorten Their Own Driveshafts?

I do, and I was wondering if anyone else does? It is a pretty easy project if you know how to cut, measure and weld. Obviously you will need a driveshaft that is longer than the one you will be needing. I won't get into measuring the length because I figure that most will know how to do that. You also want to do your cutting opposite of any weights that are welded on, and make sure you have a solid shaft to start with free from rust,dents or dings.

1. I cut through the center of the weld very carefully on one side of the shaft with a fine tooth hacksaw. You could also use a cutoff wheel on an angle grinder, but I have had the best luck with the hacksaw. You want to cut through the weld and through the thickness of the shaft tubing. It may take a few trips around the shaft to get down to the driveshaft end pilot material that is inside the tube. Once you feel that you have cut deep enough, you can give the end a few taps to free it from the tube. If it does not move you will need to cut a little more all the way around the shaft.

2.Once the end is free from the shaft you can see the pilot that slips tightly inside the tube about 1/2". You can tune up the edges of the end with a file.

3. You now will measure the piece to be cut off from the tube and cut it with a good quality large diameter tubing cutter. Mine is a Rigid PVC tubing cutter that works great for driveshaft tubing and leaves a nice square cut. The inside edge of the tubing will need to be cleaned up with a half round file, and the outside edge can be beveled slightly with a sanding disc on an angle grinder.

4. The driveshaft end can now be tapped back into the tube. I leave a small gap(1/16"-3/32") between the end of the tube and the edge of the old weld on the end for weld penetration. You will need to phase the ends of the driveshaft by placing the flat ends where the u-joint cups press in on a flat surace and adjusting until they are both lying nice and flat. I use a piece of 1/4" thick 2"x 2" angle iron.

5.The next step will require you to measure to make sure both sides of the driveshaft are the same length. I measure from the inside edge of the end where the U-joint cup presses in, to the same place on the opposite side of the driveshaft. Your measurements will have to be exactly the same on both sides of the driveshaft.

6. I place 4 small tack welds 90 degrees apart, re-check my measurements, and weld away. I have never paid to have a driveshaft shortened, and the best part is that 90% of them will be fine and will not need to be balanced. I have done dozens of driveshafts using this method with great results.

 

yeup ive done 1 or 2... S.R.I. showed me this trick

 

Yup I do them everyday! I use a lathe , shaft press and a 3000rpm balancer!

 

there's a driveshaft shop here that charges about $100 to adapt,shorten or legthen, thats balanced too.pretty cheap for good insurance

 

... no but I had an ex-wife that threatened to... oh wait, different driveshaft.

 

...thats not the point...to me its the little tricks like this that put the traditional back into hot rodding, not what ultra rare part your able to afford

 

yeah but when you rip the rear of your transmission out, because it wasn't done right you'll be spending more than $100.I understand you want to be traditional and be true to the culture,but being safe has to be put into the equasion too.

 

i've done them myself with no problems.my own cars have driveshafts i shortened . if i'm working on someone else's car i find it's more economical to just send them out.

 

I've probably done at least 40 or so . The only thing I do different is I put the driveshaft loosely in a vise and use a level on the fixed end to make sure it's perfect . Then I put the loose end on with the level and then both ends are in phase.
I have never tore the tranmission off a car or know anyone who has,maybe I'm just lucky.

 

A buddy showed me that same trick about 20 yrs. ago and neither of us had a problem with them.

 

Wow, I was expecting more naysayers. I've done several over the years without the benefit of a lathe. I've never had a problem. I thought there was a possibility that I would need it balanced afterward, but they was never a trace of a vibration. I cut the tube with a pipe cutter to get a square cut and then de-burr it with a file.

 

Good Topic!
I've done a couple my self as well. It can be a time consuming process since you're dealing with exact measurements here. One thing I like to do before I cut the shaft is to index the end I'm going to re-use with a straight edge and a long whitness mark from the end on down the tube. This helps save a lot of time remeasuring and phasing the ends when you put it back together for final welding. Never had a problem with the finished product.

BYC

 

ive done a couple and let me tell you ive done em a completetly different way and have never had vibrations or problems

used chop saw to make my cuts and large c channel as a jig for the re-weld

 

i did my own for the truck i`m running now, i just cut the shaft just behind where i thought the cast end was, then i cut what was left on the cast end off, cut the tube to length and tapped the end back in the tube, it was a snug fit and i made sure it was lined up from end to end, works great, took a 2 piece shaft to a big truck garage to have shorten and balanced and $300 later it vibrated so bad i had to take it out, took it back and another $50 and it still vibrated, i checked the center spline with a dial gauge and it was running out 1/8". you would think that would of shown up when it was being balanced.

 

Ive done a couple.

 

I'm concerned HERE. 1/16 to 3/32 gap? Doesn't this jeopardize it being square with the tube? It seems if you didn't botch the end on cutting it off, it would index to the tube if tapped in flush. I know you say you measure both ends, but how do you read .050(?) on a tape measure accurately? I'd want the undamaged(?) end flush, clamped in place somehow, then welded?

 

i know on my shaft the cast end was around an inch long where it went inside the tube, i dont think you could make it untrue with out hitting it with a really big hammer and bending the tube.

 

That was my observation, it really pretty much squares itself when you tap it in the tube, I just made mine but havent run it yet. It is only 36" long so hopefully I wont have issues with vibration, will know soon though.

 

I've done a bunch of shafts over the years, no problem. I think the point about leaving a small gap for additional weld integrity is a good idea but it just requires a little precision and double checking before the tack welds and during the tack weld process. I suppose if you crank up the heat you can burn in some penetration if you really have to **** the thing up.

 

The method described works so good because its basically the way a professional shop does it. The only difference is they use a lathe so the process is a little quicker but like many things, don't get in a hurry, double/tripple check everything and 90+ % of the time there is no need to rebalance. I've been doing this for over 40 years and have saved a small fortune in time and $$$'s

Frank

 

Not the way to do it, but the first time I ever saw it done was on a 4x4 and after cutting it he slipped the end back on and put it back on the truck. With the rear jacked up he ran it in place, then used a floor jack with a 2x4 on it and jacked it against the shaft till the wobble was gone (at least visually) and welded it&#8230; Serious redneck style, but it worked and didn&#8217;t wobble. For sure not the way I&#8217;d have done it but the guy is still probably one of the best mechanics I know, maybe he just couldn&#8217;t find his tape measure that day?<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

 

very easy to do- mark the weight location--then drill out weight spotwelds---(after im done i plugweld weight back on & grind plug weld smooth-i use a single wheel pipecutter (Always cuts accurate) then put piece cut off in a lathe then turn weld off---i have an I beam i ues to line up the universals--when you bottom the end out -remeasure then tack weld on 4 opposite sides --then do short welds till finished still going to opposite sides--grind weld as even as you can If you dont it will vibrate)---ive done hundreds this way & never had one vibrate

 

watched a guy do one with one of those laser level he had modified. took 2 magnets he bought from radio shack hot glued a laser pointer off one of those picture levelers on one of the magnets then glued a small piece of sheet metal with a mark "actually a round bullseye"that was same height as center of laser pointer. set them on each end and when laser hit the bullseye it was phased.

 

Theres this guy at work that wears a Rolex. I asked him what time it was, he said 2:15 then I looked at my Indaglow and said Ive got the same time as you. Point is your talkin about the thickness of a human hair. We all cant afford Rolex on a Timex budget. Mine was shortened the same way as well as the 9 inch rearend they both work flawlessly on a daily basis.

 

I learned to do this 40 years ago and many driveshafts ago Never had a problem except with ones I paid an expert to do and balance. I grind the old weld flush and cut thru the weld. The trick is to clean the end up to bACK TO the original shoulder so the end will fit square with tube, cut the tube with a Ridgid tube cutter it is designed to cut the tubing square ,when end is ready to install just tap it in intil it is flush. I also slightly V the area to be welded and lightly grind the welded area to remove high spots. iNSTALL AND ENJOY.

 

now what if you need to shorten one furether than the belled ends that the cast yoke slips in to?

 

Me too for me its more about, adapting a cheap, good part than actual ''period correctness''. Don't get me wrong I build to the period but I also use alot, alot of things from whatever I can find. just me though

 

YA done lots of em i used the lathe to cut off,pres on used old 85 rod to weld with no pull with it some times a torch to pull or twek with no prob.ever

 

I wish this had been around about 30 years ago, it made me smile!

I shortened a driveshaft myself, cut the welds with a hacksaw, popped out the end plug, just as you guys do it, then cut the driveshaft BY HAND with the same hacksaw, stuck the end plug back in, got it welded at the local gas station and threw it back in the car....

Vibrated the Hell out of the whole car at anything above 40mph, and ripped the back universal to shreds within 50 miles!

I can laugh about it now, but back then the 50 miles was AWAY from home!

Cheers, Glen.

 

Drivetrain Specialties in OKC did mine. My Driveshaft has a tapered end, so they cut the big end. Cost a little over $100 and balanced too. I took it to them and ask when I should come back (thinking about a week or so since they had so many Semis in there already)...the guy said, Oh, just come back around Lunch time and we should have it done. I went to the store, got a bite, picked up the drive shaft, and was home before time to pick up my daughter from Day Care.