Driveshaft shortening

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dartfreak75

dartfreak75

Restore it, Dont part it!
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Has anyone ever shortened there own driveshaft before? I have 2 driveshafts and have plans to get the one done professionally eventually but I thought about attempting to cut and weld the spare one myself just to see if I can. Anyone had luck doing it without it vibrating the bolts out of your car?
 
I've done it. You cut the welds near the U joint, and it slides out of the driveshaft which is just a tube. You cut it where you want it, on a chop saw is probably best to get a straight cut. Then slide the end back in, and weld it. I haven't had one vibrate, unless you totally warp the thing.
 
70DartMike said:
I've done it. You cut the welds near the U joint, and it slides out of the driveshaft which is just a tube. You cut it where you want it, on a chop saw is probably best to get a straight cut. Then slide the end back in, and weld it. I haven't had one vibrate, unless you totally warp the thing.
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Yea that's kinda what I was thinking too. I would most definitely do it on the rear side that way if something bad happened and it broke it would just drag the shaft instead of impailing in the ground and picking the back end of the car up lol
 
I've done a few. I prefer a large tubing cutter. The biggest things are, make sure your cut is straight and make sure the drive shaft is timed correctly when you put it back together. As long as those two things are done correctly, it's very doubtful it will need balancing.
 
RustyRatRod said:
I've done a few. I prefer a large tubing cutter. The biggest things are, make sure your cut is straight and make sure the drive shaft is timed correctly when you put it back together. As long as those two things are done correctly, it's very doubtful it will need balancing.
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Just like the rear end tubing when I narrowed the rear-end. Wth I may give it a try may wind up saving a couple hundred bucks lol
 
RustyRatRod said:
I've done a few. I prefer a large tubing cutter. The biggest things are, make sure your cut is straight and make sure the drive shaft is timed correctly when you put it back together. As long as those two things are done correctly, it's very doubtful it will need balancing.
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Timed Correctly? Please Explain.
 
eekvonzipper said:
Timed Correctly? Please Explain.
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Sure. Drive shaft timing refers to "where" the two u joint yokes are in relation to one another. They MUST be installed on the same plane and dead in line with each other, or there'll be some funky harmonics set up. Look at this picture. See how the u joint yokes are lined up perfectly on the same plane? That's drive shaft timing and that drive shaft is "in time".

DRIVE SHAFT.jpg
 
If I swap my A903 3-Speed to a A833 4-Speed (both with Flange Output) will I need to do this?
or will my 3-speed shaft work as-is?
 
eekvonzipper said:
If I swap my A903 3-Speed to a A833 4-Speed (both with Flange Output) will I need to do this?
or will my 3-speed shaft work as-is?
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Hard to say probably just have to wait till it's installed and measure it.
 
eekvonzipper said:
If I swap my A903 3-Speed to a A833 4-Speed (both with Flange Output) will I need to do this?
or will my 3-speed shaft work as-is?
Click to expand...

I believe the drive shaft is the same length. Depending on "which" four speed you use, you might need a new slip yoke. The earlier a body four speeds used the 904 size slip yoke, but the later ones switched over to the larger 727 style. So it depends on which four speed you have.
 
I have watched several driveshafts being shortened and built from scratch. Not just a cut and weld job. Most tubes require straightening and is done while still attached to the lathe used to cut the tubes. This is specialised, expensive equipment and if it wasn't needed they wouldn't have it. If you have 2 shafts at least if yours doesn't work out you can have the other one done professionally. My shop motto " Do what you do, don't do what you don't do" All people specialise in something but not everything.
 
Had a bad vibration in my shaft after a slip yoke replacement. Had to have shaft balanced. Damned Chinese yoke.
 
MoparLeo said:
I have watched several driveshafts being shortened and built from scratch. Not just a cut and weld job. Most tubes require straightening and is done while still attached to the lathe used to cut the tubes. This is specialised, expensive equipment and if it wasn't needed they wouldn't have it. If you have 2 shafts at least if yours doesn't work out you can have the other one done professionally. My shop motto " Do what you do, don't do what you don't do" All people specialise in something but not everything.
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I agree but not everything has to be exactly perfect everytime either. Your talking about custom lathed Driveshafts with a zero runout. Im talking about something do get the car moving as soon as possible. I'm not building a space shuttle haha
 
MoparLeo said:
I have watched several driveshafts being shortened and built from scratch. Not just a cut and weld job. Most tubes require straightening and is done while still attached to the lathe used to cut the tubes. This is specialised, expensive equipment and if it wasn't needed they wouldn't have it. If you have 2 shafts at least if yours doesn't work out you can have the other one done professionally. My shop motto " Do what you do, don't do what you don't do" All people specialise in something but not everything.
Click to expand...

While certainly if they are bent they require straightening, but it's just not true that you cannot do it yourself and very successfully. I've done a lot of them and other people have too. It's not difficult to get them dead straight and true.
 
x2 on the tubing cutter, and phasing the u-joints. Only thing I would add is to tack weld the yoke in about 4 places around the circumference of the tube to keep the yoke square as you do the continuous weld.
 
Have you priced out a shortening job at a local driveline shop? Mine charged me $75 to shorten/balance the driveshaft in my '68 when I swapped rearends. At that price, it's not worth the time IMO.
 
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