Drive Shaft: shortening & balancing

[Noxnabaker]

I've been shortening my driveshaft 4 inches & came to think that since it's much nicer welded now compared with the original weld (had a mighty good & serious welder doing the job, it took some time...) + the fact that it's 4 inches shorter, then is it really needed to balance it?

Also; is it possible to see if it needs balancing by jacking up the rear & let the wheels spin fast?

The car is going to be a family var & daily driver & sometimes hours of quite high speed.

(Everything from radiator to rear brake-drums is from a -77 Plymouth Volare stationwagon & sits in/under my -55 sedan.)

[DEEPNHOCK]

You should have it balanced.
You can't spin it fast enough on the car.
Balancing shops do it all the time and it does not cost much.

But, you could drive it once and see if there is a vibration, just for the fun of it.

I've been shortening my driveshaft 4 inches & came to think that since it's much nicer welded now compared with the original weld (had a mighty good & serious welder doing the job, it took some time...) + the fact that it's 4 inches shorter, then is it really needed to balance it?

Also; is it possible to see if it needs balancing by jacking up the rear & let the wheels spin fast?

The car is going to be a family var & daily driver & sometimes hours of quite high speed.

(Everything from radiator to rear brake-drums is from a -77 Plymouth Volare stationwagon & sits in/under my -55 sedan.)

[Noxnabaker]

Hey Jeff!
I just managed to post a shorter version on the Racing Studebakres site, yesterday I tried 3 times; shorter & shorter... & todays was super-short.


But I still wonder when the car is on the bridge & it's in highest gear & high rev...?
Well I guess I just have to find out for myself...

[Neal in NM]

I have a lathe that is long enough for most driveshafts. What I do is mount the driveline in the lathe and make sure that it is running as true as possible before I weld it. I have not had any returns. If I were in your position I would take it down to the nearest driveshaft maker and have it balanced but, I would try it first just in case you got lucky. Neal

[Noxnabaker]

Thanx for a good explanation Neal!
I was wondering about the "anyi-roundnes" when I fitted the endpiece in the slightly oval tube... + the fact that it actually was a welded tube with seam, but the stuff that amazed me the most was the clumsy welding at the ends, splatters (welding-fleas as we say in swedish) al over & I thought that "it's probably because it's from the 70's", the age when the real cheating began.

& anyway; the shaft is now mounted but it'll take a while before I can test it.
I was speaking to a guy who welded his shaft & then it broke when he was down in Portugal (that's pretty far) & I asked him if he didn't feel vibrations before it broke of & he said it vibrated all the time...