If the welds are good, it will be as good or stronger than the original...assuming it will be used for the original weight/torque specifications. There's nothing wrong with what he did! This driveline is just basically a pipe! He alligned the corresponding marks, cut off the piece in between, the put them back together! I see so many people criticizing this video and even a 'wrong for so many reasons ' comment...yet why is this wrong? Some people are saying it needs to be reinforced...you could, but its not 'reinforced' anywhere else, so once again, if the welds are good, it will be as good as the rest. If adding a sleeve, you'll also have to make sure it's balanced. Anyways, if its slightly off, nothing terrible is going to happen, it will just cause the car to use more gas, and perhaps higher wear on the axle and transmission parts. You should of coarse keep it as far from the center as possible, because a slight misalignment at the center will cause a much larger misalignment of the shaft...basic math...the shaft will be shaped like a 'V'. Also, I recommend doing this on the end that goes into the axle NOT on the transmission...becuase if for whatever reason the joint comes to fail while driving (bad welds for example), the longer piece will simply slide on top of the road....but if it fails at the transmission end, it will be forced against the road and if it hits a hole, it will rip the entire rear end of the car, possibly cause the entire rear end of the car to jump up and/or cause the car to be suddenly stopped without direction....causing an accident! Let's keep it simple and not try to be smartasses here people.
If vibration shows up after shortening, the GM service manual has a simple procedure using two hose clamps of the worm clamp type. Start with two side by side opposite on any weights. Test drive or place on hoist/jack stands with front wheels blocked. Have a helper run the speed back to the problem area. If vibration felt in rear fender, move the clamps opposite directions 1/4" for a total of 1/2. Stop & re-try. Once smooth, the clamp head weighs about 1/4 oz. Tach weld a 3/8 flat washer a both locations. If fixed, with clamps off, retry again. It takes about 1/2hr but can save $40+. DK, ASE master, retired.
Not what i would do at all..The weld in yokes on the ends are machined to slip fit in the tubed after being "faced off" square,therefore the run out measured in this area will most always be within a few thousands even if the pipe is bent.You should support the tube at each end next to the yokes and dial the run out as close to the weld as possible tapping the tube and adjusting run out as you tack it..my two cents
The v-block at the indicator won't allow the droop to show. On a long driveshaft the weight itself will obscure your runout too. He's effectively measuring the surface runout and/or eccentricity on the shaft. Put the indicator at the weld and run the v-block just behind the new weld.
Everything about their technique was wrong. Should have been shortened at the yoke where the original weld but is pressed into the tube. You can't just weld two bits of tube together. Good luck getting that thing balanced!
Haha dial indicator over the v block, ofcourse your not going to get any run out, but as you can see at 2:30 they had cleaned an area around the center of the shaft were I bet they originally had the v block and most likely had a shit load of run out, so moved it to make it look like it was all sweet! Fail
instead of 2 minute tech, this should be "how to ruin a driveshaft in 2 minutes". Modified lots of driveshafts,narrowed rear ends,built race car chassis in my 40+ years building cars and have never seen a driveshaft shortened like that and be serviceable afterwards. it's fine for mockups but I'd never use it
I have been doing drive shafts this way for 45 years and never had any problems Drove a 1960 Ford 50 miles with a driveshaft that had been done in a machine shop (the right way) and it vibrated the starter and generator loose had to drive 15 miles any hour when I got to the farm shop of my dad's got 2 drive lines cut and welded them and never had any problems.It was my brother-in-laws car and did not tell him for several years until he sold it.
I've done 5 or 6 myself. Even lengthened 1 by joining pieces of 2. I've always measured and marked very carefully, cut with a hacksaw and mig'ed it together. If you're sloppy you'll end up with a sloppy shaft, but if you're careful and know how to measure, cut, and weld precisely, you'll be fine. You can balance your driveshaft if necessary with a little effort with the hose clamp balancing method ruodders and racers have been using for decades. I've seen pictures of racewinning Grand National Stockcars from the early 60s with hoseclamps tackwelded in place. The shaft in my 440 powered '66 Belvedere is a pickup shaft I shortened and balanced myself. No vibes, strong enough to take 5 years of abuse with no problems. Nothing wrong with paying people to solve your problems for you if you choose, but most of us can solve more of our own problems than the people who want us to pay them would like us to believe
I just lengthened a shaft kind of like that but slipped a piece of bigger shaft over it and eyeballed it. I plowed snow all winter with it and i wasnt nice to either and It held up just fine.
Excellent! You know it fits. You can now take it to a driveshaft company and ask them to make you a new one using yours as a pattern, better that bits of paper with measurements and photos.
I`ve done many of them with a framing square and a level only 2 that I remember where out of balance which was corrected with a hose clamp.... Never cut out of the center... Talk about balance problems...
I must agree with the criticism about this video. I would like to add that just drawing a line the length of the shaft will not be accurate. Laying angle iron the length of the shaft will give you a straight line.
I agree. First thing I noticed, is the way he measured runout is all wrong. Both Vees need to be on the same side of the weld. The short piece sitting in it's own Vee, is not going to indicate runout, because that side is going to run concentric with the Vee. What he is measuring, is not runout, but out of roundness!
I never knew you could cut a drive shaft there I always thought you had to cut at a certain end and then re weld the u joint knuckle. Maybe it’s cause it’s a temp solution till he gets a new one maybe?
the only part of a driveshaft that is balanced is the ends where the weights are. you can lengthen or shorten it anywhere in between. the secret is to have the welds the same thickness all the way around. good if you have someone to slowly spin or turn the driveshaft between the angle iron parallels while the welder does his magic.been there done that
If you can weld it in one pass 360, then it will not warp. Or you can do one half, flip it and continue on the other half but doing so within 2-4 sec so the pipe temperature doesn’t drop significantly.
If you’re going tho do it this way use a pipe cutter to keep the cuts straight and perpendicular to the tubing. The bevel in the cut will make welding easier. Clamp it in angle iron to make the tack welds and then check runout before welding and then again after.
can anyone help me i have a question. i recently bought a foxbody drive shaft that was shortened anyone know why that is? or is it something you do for racing? please help
@@robwells5753 he should have used "nonfunctional". That is a mod suitable for mock-up, NOT actual use. A butt weld joint is the equivalent strength of notching the original material to 50% of it's thickness. He declared that tubing to be 1/16 inch wall, so that butt has the strength of 1/32 inch wall. Because he used perpendicular to axis straight cuts, that is all the strength that joint can have. Read that "guaranteed failure under actual use, almost immediately". You CAN weld up a functional shortened driveshaft. You either have to sleeve it, or your butt joint needs to be cut into doll heads, so the weld is holding alignment but not actually subject to torsional stress (a VERY complicated cut).
Cutting it down with a chop saw and welding it is great for getting it to move under its own power. Sure you don’t want to go drag racing with it. But it’s perfect for making it capable of moving.
Done this dozens of times with zero failures but they were only temporary or for off-road applications only where speeds are very low like 10-15 mph out in the woods...I would never do highway speed or any kind of hard launching
Hey dude! This video was awesome, i wanna do an rx7 drift build but i also have an idea for a lighter drift car i build myself, is it possible to cut a big section out of a drive shaft so i can have semi rear end drift on a nissan diff, nissan drive shaft and pretty much nissan rear end with a 1jz
So I need to shorten a frame 50 mm on a RWD Chevy LUV, which involves taking 50mm out of the driveshaft. Everyone says not to do it this way, so can someone please explain to me WHY you shouldn't do it this way?
I have a driveshaft that has a slip built into it with flanges on each end. Can someone tell me the math on shortening it if need be? I e swapped in a new transmission and transfer case into my runner. So I have the measurement distance from output flange on case too flange on rear diff. Then I should measure the driveshaft and have a certain amount of play in the splines. I know you don't want it to bottom out. So you also need to measure the distance from flange to flange at full droop of rear suspension? Is this correct? I've always wondered the calculation on this but every website just tells you to measure the distance between flanges then send it to driveshaft shoop. That teaches me nothing....
i'm sure that works although a sleeve might be nice. still it seems way easier and safer to cut the welds that hold the yoke then shorten the driveshaft and weld the yoke back in like the factory did. i'm just a dopey shade tree mechanic with a very small fraction of the $ worth of tools and i have successfully cut down several so obviously it's not rocket science.
J clark Asbolutely a better idea than what is shown in the video! I've always used lathes to get them straight before heading to the balancer but you'd probably also be able to get a decent runout with the shaft temporarily mounted in the vehicle to check with a magnetic base dial indicator and then removing it to weld once you got good runout.
I hear JB Weld makes a product they claim to be as good as steel once cured. Lol. Throw some aluminum tape over it and as long as noone can tell, its strong as factory...
I'm going to tack it put it in the truck and use the trans and rear axle as v blocks then get the dial indicator then hold the mig gun and slowly rotate one tire to rotate the shaft to weld it in 1 run
And use the v-blocks to cut the section out. Rotate the shaft, at low speed, with a motor and belt. Just hold a cutting tool where the cuts will be. This way, both cuts will be perfectly square. Put one v-block at one end, and the other v-block inside where the cuts will be. About a foot from the end. This way, each cut will be outside the v-block. Should be almost a true shaft.
This might be ok on a low speed deal, but id be pissed if i found that on my car. Why not true it in a lathe and use the correct end to put back on it?
As someone who has dropped a driveshaft twice, and twisted another in two, I learned to pay the right place to make the one I twisted...l think it was around $130 about 20 years ago.
You are checking the run-out in EXACTLY the wrong place. You should have the v-block set-up just behind the cut/tack-welded area. The way you have this set-up, you are ONLY checking to see how round that section of the drive-shaft is.
Looks like to me to accurately determine run out the entire shaft needs to be between centers. Measuring tube run out is inaccurate to the entire shaft. V blocks are ok for measuring on single components
That is practical for off road 4x4 stuff that has no real danger of hurting anyone. I've butt welded drive shafts clamped in angle iron and never had one fail - actually killed a D70 R&P and a 35 spline axle shaft without damaging the ghetto out of balance "ticking time bomb." The video is crap advice for a street car but good enough for a weekend trailer queen.
Looks like plenty of material to shorten at the end and insert it inside the tube it's only 2 inches if you need to remove the balance tabs reinstall same location only further down the driveshaft.
You do not have to do increment welding on this pipe and in fact I wouldn't recommend it. If you weld it all in one shot, it will cool at the same rate all the way around. No chance of warping. It's called "welding sequence."
a new weld joint and take the length off the front or back... but that's where the weights go and we don't want to have it balanced. so nah do it the pole vault way LOL
You should have used a aluminium piece of angle to set your 2 pieces back together. Not everyone is using a "true" saw. They way your showing is the "true" cut way. Maybe both pieces should have been spun on the lathe, another tool most people don't have. For a DIY video, more thought should have been planned out. For a cut and splice method.
Previous owner did this shit to my truck had to deal with 2 companies 3 drive shafts then they tell me some dumb ass put a different transmission in and shortened the shaft now I have to pay to rebuild it will be in shop for 3 fucking days if I’m lucky
Zaq341 It is the amount of out of true it is. Ideally it'll be 0.000, indicating it is perfectly round(within tollerances of your machine :P), but a small amount can be tolerated by unis and CV joints.
+Rob F In this case they're are measuring how straight it is. If he welded that thing crooked, the runout would be greater indicating the shaft was no longer straight.
I am probably the laziest person you'll ever meet. I've hot glued holes in radiator hoses, I've ziptied broken hood latches, hell for a month and a half I used hay twine to keep my broken muffler in the right spot and even I can tell you powernation is trying to kill you. This is the definition of I have a welder so I can do anything whatsoever.
Alex Reed I've got a spark plugs jb welded in. Works good until it blows out. Then I jb well it back in. I have got 500 miles on the best and 20 feet on the worst. Helps to have plug and head clean and let set up good.
this setup is all wrong, especially the runout checking... all he was measuring there was the runout of the tube, and possobly any "wobble" introduced by the welded section. I would have rather put a sleeve in if possible, and the v blocks should have been on one side of the weld with the dial indicator on the other.. if a sleeve was cut at 90* and only a 2 to 4 inch piece needed it wouldnt affect the balance much, as well as it would provide some strength to the weld joint, and allow better control of the runout alignment. come on guys this is basic machining....
Got your indicator on the v block buddy your not going to get accurate run out your mag base indicator needs to be somewhere else maybe in the middle three different spots
