Front DC drive shaft vibration: (1 Viewer)

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JUST LIFTED...NO ADDED WEIGHT TO TRUCK EXCEPT SLIDERS...WON'T BE ADDING WEIGHT EITHER.

I've been doing searches for solutions and have some ideas (plus I've spoken with Ben at Slee). Here's the deal:

1. Truck very smooth
2. Installed J-s and L's with stabilizer, AND Slee caster plates (lift turned out about 4-inches). Corrected pan hards and got an alignment.
3. Vibration rumbly at most speeds. Higher speeds it grrr'd (the search word)
4. Slee sent me a DC front shaft
5. Grrr gone but vibration still all over the place at all speeds especially when speeding up a tad or slowing down some. But speeding up is worse.
6. Installed rear upper control arm adjusts today. Took the front shaft out and tuned the adjusters.
7. With ONLY the REAR shaft in the things is smooooth.
8. Threw the DC front shaft back in. Still have vibration. It's much better than before "fixing" the rear, though it rumbles at around 45-60MPH. You feel it in the wheel, the seat and see it in the side mirror (blurr).

We R&R's the front shaft and re-checked the grease. All looked OK. Same vibration.

IDEAS? Ben said on the phone and I read Landtank's remarks about there being a "spot" where vibration could occur with EITHER shaft? Both said it might help to lift the front a bit more to assist in the DC shaft in reducing vibration. ??? :confused: What things should I try first? THANKS!
 
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For a DC shaft to work correctly the pinion needs to point at the transfer flange. Is yours hi or low? How many degrees off?
 
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Tools R Us said:
For a DC shaft to work correctly the pinion needs to point at the transfer flange. Is yours hi or low? How many degrees off?

Just drove it again. It's home now.

It does vibrate a little at other speeds, though that 45-60 is irritable.

EYEBALLED the front shaft angle...It LOOKS as the though the pinion angle is just a TAD lower than the T-case.

I guess that another inch lift will raise that angle? So, trim packs might do it?

I also measured from the hub to the wheel well. 23-inches. That's the number LandTank said was a problem number in between a stock vs DC shaft.

???
 
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sleeoffroad said:
Normally the driveshaft vibrations does not manifest themselves in the seat and steering wheel.

I would try the packers first as Ben suggested, but I would also look at the front-end to make sure all is ok there.

Please check my updated post. Still think packers will help? 15 or 20mm? Will I need to re-adjust the rear arms after the packers?
 
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ShottsUZJ100 said:
Just drove it again. It's home now.

It does vibrate a little at other speeds, though that 45-60 is irritable.

Mine is between 50 and 65 mph.

ShottsUZJ100 said:
EYEBALLED the front shaft angle...It LOOKS as the though the pinion angle is just a TAD lower than the T-case.

Eyeball aint going to cut it!:D

ShottsUZJ100 said:
I guess that another inch lift will raise that angle? So, trim packs might do it?

I also measured from the hub to the wheel well. 23-inches. That's the number LandTank said was a problem number in between a stock vs DC shaft.

???

It depends on your caster correction method, as much as the lift. I haven't played with the plates, so no data base, grab the protractor and measure the driveshaft and pinion angles, they should be the same.
 
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Sure it's not wheel balance? I've never felt an out of balance driveshaft through the steering wheel.

I've never studied harmonics, but could it be that the wheel balance and driveshaft are both slightly off and combined they are creating what you are feeling? Just an idea.
 
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It vibrated before I added the new AT tires. Rig is all new. We're not using it...cuz it vibrates.

Did not try the front shaft only.

Got back from a freeway test. It vibrates little below 45 though when acc (mainly) there is some slight rumble. At 45 is comes on FAST and STRONG especially when acc-ing. Even keeping a steady speed the vibration is not acceptable.

It was smooth as could be before the lift.

We know the rear shaft is OK cuz it's smooth on it's own.

The vibration can be felt everywhere (floor, dash, wheel...see a blur in the mirror) because it's a lower-pitch (rumble).

It's supposed to go 2-hours each way to get gears and lockers Saturday.

:confused:
 

Romer

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take the rear shaft off and see what it does. If the problem goes away. Take it and have the U Joints checked and the shaft balanced.
 
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Romer said:
take the rear shaft off and see what it does. If the problem goes away. Take it and have the U Joints checked and the shaft balanced.

But it's smooth as silk with only the rear shaft? Rear shaft would be good then? No?
 
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Have you checked the wheel bearings? My truck started vibrating similarly after my new tires went on. I think the increased weight let the bearing problem show itself more. At first I chalked it up to big bias ply swampers, but one of them started wearing poorly so I went with a good alignment and and new TRE's it was still there. Both my wheel bearings are loose. I haven't adjusted them(I'm wating till I rebuild the axle and install a front locker), but I fully expect that to fix the problem.
 
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ShottsUZJ100 said:
But it's smooth as silk with only the rear shaft? Rear shaft would be good then? No?

It should be, when you pull one shaft the other axle carries twice the drive load, deflecting the bushings slightly more, slightly changing the angle. Yours sounds like more than slight!

How much stink bug do you have, what's your hub center to flare measurement front and rear?
 

Romer

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My front is 24.75" hub center to flare, with the caster where I want it the shaft and pinion are straight, perfect for a DC shaft. My caster mockup put the tie rod almost touching the arms, probably about the same as the Slee brackets. The easiest, cheapest test would be to hit a local speed shop or pep boys and get a set of 1" plastic spacers, slap them in and see if that changes it?

The DC joint is installed at the transfer end right?
 
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Romer said:
My problem went away when I pulled the front shaft after I had it rebuilt. Turned out to be the rear shaft

Do exactly what Romer says. I chased down a "front" driveshaft vibration for months that turned out to be the rear drive shaft. With the front driveshaft removed the vibrations went away so I assumed it was the front driveshaft. When I finally pulled the rear driveshaft and drove with just a front DC drive shaft the vibrations disappeared as well.

In the end I wound up with a DC rear shaft and all has been well. I think my stock rear shaft wasn't quite right from the factory since the yokes on both ends were not aligned perfectly to each other.
 

landtank

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On my truck that has a lift that is 4" higher on the front when comparing the hub center to fender measurement with a stock truck it took 7* of compensation to get the pinion aligned with the drive shaft. If you truck is similar to mine than the Slee plate is off by 3* which might be your problem. I don't have a solution for you but you might start by reading your pinion angle at the front diff.

there is a thread out there that I started that has a side shot of my pinion angle in it. It's pretty much spot on at close to 0*. I'm not at home otherwise I'd post here again for you.
 
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LandCruiserPhil said:
A eyeball tad low is to much. If you are out over 2 degrees you will get vibration even with a DC shaft.


Mines like that too and I get no vibrations. I really think it's the rear shaft.
 

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