Balancing your own driveshaft?

[mustangtoby]

Anyone here ever balanced their own driveshaft? I have heard of people doing it with hose clamps, just by trial and error I guess. I just extended mine to make up for 1.5" lift blocks, and get a pretty good vibration at about 45 mph. I am a long ways from a machine shop, and would really like to cure this myself.

 

[bronko69er]

Is your pinion angle correct?

 

[uncle ray]

how did you extend it? that is not a job for most do it yourselfers.

 

[mustangtoby]

Looks ok. It wasn't vibrating like this before. I had a spare driveshaft laying around that I extended, still have the old one. I had a bad u-joint in the old one, and it had a little vibration around 55-60. I think next step is to put a new u-joint in the old one and see if it goes away. I can live with it until I can get my homemade one balanced if I have to. The nearest shop that I know of is 2 hours away, and they aren't open on weekends. This means missing work to take it down, blah blah blah.

 

[Bronco717274]

When you slide your yoke back on make sure your u-joints are lined up. Same on one end as the other if they aren't you will be out of sink so to speak. It will vibrate like crazy. Also check your weld more on one side than the other grind off and recheck, Good luck!!!!

 

[Broncobowsher]

I watched my last driveshaft being made. It was trued up to .002" on a lathe befoe welding and came out at .001" after welding. I have also cut driveshafts down, cut of the yoke, trim the tube, line the yoke back up, square as much as possible, weld. Even my good ones are nowhere near as true as the proper one. And every one that I shortened was for a low speed application and shook like mad. They are either spares or very low speed farm equipment that never sees ofer 20 MPH.

The hose clamp trick is a fine tune. Unless you are exceptionally good or lucky the driveshaft you welded up is probably too far off to balance with hose clamps.

To do it, place the vehicle on a hoise and bring the shaft up to vibration speed. Hold chalk close to the shaft so it bearly grazes the chalk. Stop. Attach 2 hose clamps 180° from the chalk mark. retest. Keep seperating the hose clamps equeally until the vibration disappears. If you get to the clamps to be 180° apart, then try the other end of the shaft instead. Yes, it is a trial and error.

 

[mustangtoby]

Got the yokes lined up, welds are ground smooth. I may try the hose clamp idea with a little weight, trial and error. Can't hurt. I have built many driveshafts for the front axle, but never run fast enough in four wheel drive for it to matter. Last one I built started vibrating at about 45 mph. Not a problem. That truck was a trail rig, never went that fast in four wheel drive. It is still working fine. I may cut this one apart and try another shot at it. Nothing to loose, I reckon.

 

[mustangtoby]

Thanks, Boswsher. I have a hoist, but don't know if I want to be laying under it with the tires turning 45 mph. Maybe jackstands to take some of the weight off of the hoist. Pretty spooky!

 

[Apogee]

If I had to choose between driving 2 hours or dropping my shaft in a shipping tube and paying $15 to get it there...I wouldn't have to think about it that long. I can't drive half that without spending more in gas and that's just one way.

A front shaft is one thing, but for the rear I'd definitely let someone with the proper tools balance your shaft for you, but that's just me.

 

[blubuckaroo]

I heard of floating the driveshaft in a tub of water to find the balance point. I wouldn't run it on the road though. Good way to wipe out differential and tailshaft bearings.

 

[scsm76]

I have heard of people filling the tube (not full) with ATF or motor oil to balance home built shafts. They usually fill it before welding or drill a hole, fill, and weld up the hole. I have never done it so I can't speak as to how well or if it works.
If you just lifted the bronco you may also check that the rear pinion is pointed at the TC output. More than about 6° offset at the bottom u-joint will create some vibrations.

 

[bronko69er]

I bet that works just like the air soft pellets in the tires.....

 

[mustangtoby]

Hey, good Idea! I run anti-freeze in my tires instead of airsoft, same idea. This weekend, a drill, some atf, and a small spot weld! I'll let you know how it works!

 

[Bronchole]

I have heard of people filling the tube (not full) with ATF or motor oil to balance home built shafts. They usually fill it before welding or drill a hole, fill, and weld up the hole. I have never done it so I can't speak as to how well or if it works.
If you just lifted the bronco you may also check that the rear pinion is pointed at the TC output. More than about 6° offset at the bottom u-joint will create some vibrations.

Gotta love the inginuity, fluid damped driveshaft! I love it.

 

[uncle ray]

again, what did you do to "extend" it?

you don't extend a driveshaft that sees high speed, you retube it. if your spare was longer and you cut it down, fine, but if you cut it and welded in an extra chunk of tube or something that's a big no-no. if you don't have a lathe to cut the old tube from the yokes, etc. it probably isn't done right. the only place it should be welded is where the tube meets the yokes. it takes a little skill to properly build a shaft, you not only have to worry about balance, but phasing of the yokes, running true, and keeping unnecessary weight to a minimum. get any of this wrong and you will NEVER get it to balance out.

 

[mustangtoby]

I cut the ends off with a hacksaw, then ground it as carefully as I could. I had another driveshaft of the same diameter, cut the tube to the lenght I wanted, then welded it back together. I did line the yokes up.

 

[Broncobowsher]

I garantee that the shaft is not true. You can't balance it. Just like you can't true up a bent wheel by balancing it. You can make it not as bad, but it will never be able to run high speeds safely. Fine for the trail/low speeds.

 

[DirtDonk]

Also, did you lift it an additional 1.5"? Or just 1.5" total lift?
If it's just an inch and a half, you should not have had to lengthen the shaft at all. You probably know that, but I wanted to ask to make it clear.

Thanks

Paul

 

[mustangtoby]

The Bronco already had a 3.5" lift on it when I boughts it, but the back sagged a little bit. I put 1.5 lift blocks on it to level it out. Eventually I will get a better lift.

 

[old number 8]

To balance your driveshaft in the vehicle takes 2 people. Have it on jack stands with the tires off. Use the lug nuts to hold the drums on. Label the driveshaft on the u-joint yolks, 1-2-3-4. Have the driver run the vehicle up to the speed the vibration is most evident. Place your hand on the t-case extension and the diff. The one that vibrates the most is where you start with the weights. It may help to have the driver take notes as to the rate of vibration, as they will tell you how the vibration rate changes. . Start at #1, place one hose clamp, with its screw at #, run the vehicle up to speed. Check the vibration. Rotate the clamp screw at positions 2, 3, 4. The position it is smoothest is where you continue. Add a second clamp. Run it up and recheck the vibration. Now move the clamps ¼ turn one direction, then the other. You can also fine tune by moving each screw head an equal amount in opposite directions. You shouldn’t need a 3rd clamp, if you do, you have a gross error in the assembly of the d-shaft. This is an acceptable balance method, but if you are going to rub your shaft on the rocks, you may want to mark the location of the clamps, or weld on washers in the correct positions.


If you have the tubes welded, then I would suggest making a new shaft with one piece of tube welded to the yolks, like Broncobowsher recommended