Does Anyone Shorten Their Own Driveshafts?

I did one similar to the original poster for a '51 F1 I build years ago. After tack welding it, I put it in some wooden V-blocks & had my dad very slowly turn the shaft while I welded it.

A couple years later, I was going through the thing & sent the driveshaft to a friend's shop who did 4x4 rigs to have him balance it - he actually removed part of the original balance weight. When I told him I did it myself on my bench instead of a lathe, he just smiled...

 

when we put the 4 inch blocks on the chevy we had to chop about 3 inches outta the driveshaft..that worried me
creepy

 

Yeah, I've done a few over the years, and the pilot piece is a snug fit, so it kinda squares itself. The gap for welding don't have to be exact. Just eyeball it. By gosh and by golly. You should have a small gap and bevel for a real nice proper weld . There are probably a lot of good balancing methods, everybody has a favorite. It's also real important to line up the universals. About the easiest is to use the angle iron method, and scribe or soapstone a line from one end to the other. Good luck....Ole Pork

 

If the car has highway gears, you'd be suprised at what you can get away with due to low shaft rpm. Somebody with a highway geared cruiser that drives it gently could have 1/2" of bend and not even know.

However, a key part of this process has been neglected.
Inspect the inside of the shaft while it's open!

Driveshafts can have large amounts of internal rust and appear fine on the outside. And you won't know til they twist apart.

 

Shifty, Is this REALLY a problem?? Every driveshaft I have cut apart was PERFECT inside. Which is what I'd expect since they are welded "shut". Now granted I'm only talking about a handful of driveshafts for my experience, but your statement makes me wonder how they are getting moisture INSIDE of them. I live in the salt belt - so rust is a familiar thing - just never seen it inside of a driveshaft. Do certain manufactures make them "non air tight"??

Hey since we're on the subject - I always wondered why they stuck that hard carboard tube inside of the old driveshafts. ANyone know why??? I always guessed it was because they were using small diameter tubing and they did this to increase the critical speed. Later shafts I noticed don't have the cardboard, but are also typically bigger in diameter. Just curious.


Edit: Not sure about that 1/2 inch of bend!!! :0 But I know what you mean. On my old non hamb friendly truck the driveshaft under went some near disaster at sometime in it's life. It is smashed, crinkled, dented - in one spot and looks horrible - and yet it works perfectly - doesn't even eat u-joints. However it does have freeway gears.

 

Groucho, you can always put a few temporary shims the thickness needed in between the shaft end and the U-joint housing shoulder to maintain that gap while the tack welds are done. After the tack welds are in place, pull the shims out and finish welding the U-joint cap in place.

 

I live in the rust belt (Man DO I!) and I've never seen a shaft rusty inside...although you would think that condensation would be a factor. Still didn't see any water or rust worth talking about though!

I wonder was the cardboard to dampen harmonic vibrations on longer, thin wall shafts? Only saw that once and I can't remember what the shaft was from...

I've noticed that certain shafts have a tapered index that makes realignment to the tube a real *****. You need to slightly bell the tube end as you install the index back into the tube and its hit or miss. You can spot the type by a close examination of the uncut shaft...look for a minute taper just before the weld.
You can do it home but your working a little harder than normal!

RANT:
I take my chances on doing just about everything myself as the local machine shops think car guys are only a step up the ladder from Gronk the caveman. Just about everything I ever had machined or fabbed at a "shop" was screwed simply because the guy doing it thought it unusual so therefore it wouldn't work anyway!

"It's goin' in the garbage anyway so **** the alignment etc...grab the money and run!"

Housings narrowed (MAN!...you should have seen that!!!), shafts shortened, metal bent for unitized frame reinforcement...you name it...nothing was right due to inattention from lazy nimrods masquerading as professionals.
Now this ol' HACK does it himself and it works or else it needs no more "fixing" than something the "Pro's" would have hammered and charged me for anyway.
It's a pain sometimes to do something that might have been cheaper to farm out, but I'm simply afraid of the usual resulting mess I'm left with from going that route.
Once bitten, twice shy.
Rant off...LoL

 

Hackerbill, I've been told I am an "arguementative type" (except most simply shorten that term to "a$$hole" ) and given that I'd very much like to argue with your "RANT" - but god dammit - you're RIGHT ON THE MONEY. And it's not the REAL PRO's it's those "lazy nimrods masquerading as professionals" as you say. They are the ones giving the real Pro's a bad name.

When I narrowed my last rear end (pictured above) thsi fella I know stopped over and was giving it the once over. He says something to the effect of "dude - your weld is pretty lame". Knowing how much care I took I laughed and told him - "sorry THAT ain't my weld - THAT weld is HENRY'S - I think it'll be alright" My welds was similar to the one above in the origional thread. I cut the housing, beveled the edges, machined a sleeve, pressed it in, fit the end piece leaving a 1/8" gap between the origional tubes, welded the first p*** burning into the sleeve, second p*** to level it off - actually welded it so the bead was a wee bit "proud", then ground it flush. Finished it off with 3 or 4 rosettes on each side of the splice - also flush when I was done. All said and done I was happy with my work and have seen "pro" work not nearly as nice. The again I've got a friend who's basically an amateur like me - his weld beads blow mine away! Dude's unbelieveable.

 

Dunno how big of a problem it is, don't do this for a living. But my involvement with 4x4s and twisted driveshafts shows that when you look close at tubing failures, there's often a giant rust bloom on the backside, and the rest of the tubing is OK. Perhaps it's more of an issue on mulit-piece shafts like 4x4s use? Or related to submerging the shaft? Also had a shop reject one I wanted to get shortened based on internal rust. Whatever the cause, when helping my 4x4 buddies, we look close while they're open.

However I can attest to the half inch bend. O/T car with 2.41 gears and a hundred horsepower 305 that did about 80mph WOT. Ran that way for many many miles. Would never believe it if I hadn't watched the runout gauge.

 

I just had one shortened and balanced for $40. Not worth my time to do it for that price.
Sadly, I mis-measured and had to have it done twice.

 

did one in my drag car last week .went from a 400 to a 350 long tail .grind the weld off the end of the shaft. tap the cast end out .cut the driveshaft tube off with a big ridged tube cutter. tapped the end back in .make sure the round ends line up with the other end. mesure .tack weld. mesure again .weld it up .go do hole shots ..nothing to it .

 

I've done a bunch almost the same way. Usually take mine to a shop to make sure it's in balance. So far they've all been fine. Costs about $10 to have em check before I install it after i've whacked it.

 

That's there to keep the tube from ringing like a wind chime. It's a damper.

 

Just checked the one I cut for the roadster over yesterday..has it been 3 years already?...Anyway it was one of the easier things to do on my build, no vibrations and no weld issues...

 

I saw an ad on the TV about how Extenze will lengthen your drive shaft......but nothing about shortening it.

 

I've done a couple for myself... but it takes me more time than my money is worth so I just send them out...

never had problems with vibration or eating parts...

 

I had a factory driveshaft that vibrated the bushing out of the rear of my trans. It pushed the seal out and........made a mess, while I was supposed to be on vacation enjoying myself. If it had been an automatic trans, it would have been an expensive day. The shaft did not have visible runout or any dings. Maybe the weights fell off?

I had Inland Empire do one for me and it was 100%. I have also had Oceanside driveline do a couple for me. I was tempted to low buck my current project, but at the cost of a 700R-4 rebuild.......I will spend the money having the shaft balanced with the correct equipment.

Sure folks also weld up 9" fords without a jig in their sleep. My last one was so far off....and the shop said most are bent. No way I could have done it without a press and a jig.

 

I solved my driveshaft issue a completely different way on several engine/******/car builds.

I got the engine/trans/read end combo setup as it would be driving down the road. Then I simply measured the u-joint center to center, wrote the length on my gritty hand and hit the local boneyard. I measured all those hanging driveshafts for a one with the center to center length that came within 1/2" and had the same type joints my cars used, wasn't beat to **** and paid my $10. Only once did I need to buy a special u-joint with different cross bearings.

Never had a balance issue at all.