Drive Shaft Vibration - After lift (8 Viewers)

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Azca

Azca

If there is a harder way - I will find it...
Joined
Oct 25, 2007
Threads
143
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1,922
Location
Surprise AZ.
Ladies and Gentlemen,

After lifting I had a drivline vibration on decel. So, went to Mr. Landtank and ordered a front DC shaft. Installed the shaft and now the growl is ever present and tad louder. So, below are the specs and what I am running into. For a short read, I have a 2.9 degree difference between the shaft and the face of the u-joint (see pics below).

Question: Will changing to 4L, 5 or 5L delta arms help to address this?

I have the installed a 3.5" Dobinsons lift with the following:
  • C97-144VT front coils - 3.5"
  • C97-145VT rear coils - 3.5"
  • MRA45-A912 front 4" length shocks for additional travel
  • MRA59-A687 rear 4" length shocks
Center of hub measurements to fender: Front 24, Rear: 24.5

I have not weighed this before starting all the work on her. The following is what I have added which would alter the vehicle's weight:

Dynamat sound deadening throughout the vehicle and additional insulation
New mass backed carpet
  • Front
    • 4xlabs bumper
    • 12k winch with synthetic rope
    • Front skid (25 lbs)
    • Dual batteries, the largest that will fit in the battery boxes.
    • Baja Designs LP9s
    • Hydro boost brake system with PSC steering reservoir.
  • Mid vehicle:
    • White Knuckle Sliders
    • Skid plate (cant remember who – also covers xfr case and replaces factory cross member)
  • Rear
    • 4xlabs rear, dual swing out bumper with 3 gas can carrier and tire carrier.
    • High lift jack
    • Puma compressor and mount
    • Tailgate storage (Delta)
    • Delta attic rack
    • WitsEnd quarter panel mount with Amplifier
    • No current plans for a drawer storage system but thinking of a Dometic Cooler.
    • Removed rear seats
    • Removed rear tire carrier from under the vehicle.
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To boil all that down>>> The front pinion needs to point staight at connecting (lower) shaft of DC shaft assembly. I image you do have quite the growl at 2.9* off. I was only 1.5* and I had a critical speed issue at 68-75. Under that was OK and over that was...better, but not what anyone would call good.

You need to figure out which way that 2.9* degrees is off. Does the pinion need to rotate up (closer to the engine) or down (away from the engine)?

If the pinion needs to move up you need to get closer to the stock radius arm offset. And conversly if the pinion needs to be lowered to bring it into alignment with the DC shaft you need taller lift arms.

Based on my expireance with this issue, I went from Delta 4 arms to Delta 2 arms to fix my miss-aligment.
 
landtank said:
My 4” caster plates aligns for a DC shaft within a 1/2 a degree. The plates rotate the axle 7 degrees.

I’d put the stock arms back in and take those measurements again.

If the reading is around 7 degrees the arms are the problem.

If the reading is greater than 7 and around 9 or less than 7 and around 5 you have an axle problem.
Click to expand...
Unfortunately, the arms are long gone. I sent an email into @Delta VS Friday, but they must be busy.
 
Rusty Marlin said:
To boil all that down>>> The front pinion needs to point staight at connecting (lower) shaft of DC shaft assembly. I image you do have quite the growl at 2.9* off. I was only 1.5* and I had a critical speed issue at 68-75. Under that was OK and over that was...better, but not what anyone would call good.

You need to figure out which way that 2.9* degrees is off. Does the pinion need to rotate up (closer to the engine) or down (away from the engine)?

If the pinion needs to move up you need to get closer to the stock radius arm offset. And conversly if the pinion needs to be lowered to bring it into alignment with the DC shaft you need taller lift arms.

Based on my expireance with this issue, I went from Delta 4 arms to Delta 2 arms to fix my miss-aligment.
Click to expand...
Pinon must rotate up. Wont going back closer to stock kill the caster?
 
Yes it will reduce your caster. But the caster angle isn't all that great, IIRC its only 1.5* and it's "measureable" off the top cap of the knuckle bearing if you are careful. The Drive line angle is also important and if not correct will cause premature failure of that expensive drive shaft you just bought.
 
efjayatee said:
@Azca
Click to expand...
4". I am thinking about going back to the factory shaft and going down to 3" springs. The old shaft only growled under deceleration as compared to the DC all the time. It is definitely unhappy which bothers me because it is beefy and oh so pretty! Go to love LT products. Anyway, the more I think about it, I believe the DC shaft actually is increasing the DS angle as the DC portion of the shaft extends the point of where the shaft connects to it forward. If I had been smart, I would have done a before and after check on the angles but, as my tag line states: If there is a harder way - I will find it...
 
Azca said:
4". I am thinking about going back to the factory shaft and going down to 3" springs. The old shaft only growled under deceleration as compared to the DC all the time. It is definitely unhappy which bothers me because it is beefy and oh so pretty! Go to love LT products. Anyway, the more I think about it, I believe the DC shaft actually is increasing the DS angle as the DC portion of the shaft extends the point of where the shaft connects to it forward. If I had been smart, I would have done a before and after check on the angles but, as my tag line states: If there is a harder way - I will find it...
Click to expand...
Any vibrations can’t be tolerated. It’s a recipe for disaster
 
I run the same dobinson springs:
  • C97-144VT front coils - 3.5"
  • C97-145VT rear coils - 3.5"
I went with DVS 3 arms to resolve caster. I had a growl on deaccel and then went with a Slee double cardan shaft. First shaft had some issues at the double cardan end (manufacturing issue), that was remedied asap by the vendor. On installing the repaired double cardan, all is good, no growls accel or deacel and none at various cruising speeds. A happy camper.

So, can be made to work, but as many know, each 80 is somewhat different in how the suspension stuff interacts. With my previous lift, probably closer to a 2.5" my OEM arms were fine from a caster perspective and I ran that way for many many years. Then I got fed up with the harshness of the OME coils and cheapo shocks. Found a wonderful rabbit hole that I spent a whole bunch of $$$ renovating and expanding :)

The other thing is that I run custom aftermarket lower control arms on the rear, length was chosen to put the rear pinion in the sweet spot for the lifted rear. Many folk deal with this by using adjustable upper arms. Not sure this is any issue with your setup, but it is something different from 'stock'.

cheers & good luck,
george.
 
landtank said:
Any vibrations can’t be tolerated. It’s a recipe for disaster
Click to expand...
She is parked until I get a full battle plan on how to deal with it. One these days I will get to enjoy it again. The good part (ahem) is that I am so busy, even if I had the parts, I could not wrench on her. I am hoping to do it over Thanksgiving.
 
george_tlc said:
I run the same dobinson springs:
  • C97-144VT front coils - 3.5"
  • C97-145VT rear coils - 3.5"
I went with DVS 3 arms to resolve caster. I had a growl on deaccel and then went with a Slee double cardan shaft. First shaft had some issues at the double cardan end (manufacturing issue), that was remedied asap by the vendor. On installing the repaired double cardan, all is good, no growls accel or deacel and none at various cruising speeds. A happy camper.

So, can be made to work, but as many know, each 80 is somewhat different in how the suspension stuff interacts. With my previous lift, probably closer to a 2.5" my OEM arms were fine from a caster perspective and I ran that way for many many years. Then I got fed up with the harshness of the OME coils and cheapo shocks. Found a wonderful rabbit hole that I spent a whole bunch of $$$ renovating and expanding :)

The other thing is that I run custom aftermarket lower control arms on the rear, length was chosen to put the rear pinion in the sweet spot for the lifted rear. Many folk deal with this by using adjustable upper arms. Not sure this is any issue with your setup, but it is something different from 'stock'.

cheers & good luck,
george.
Click to expand...
The Dobinsons set up is so much nicer to ride on than the OMEs! When you went to the 3" arms, how was caster and handling after?

I was thinking about getting adjustable control arms as well. Hate to give up the Landtank lowers, especially since I know I have less that a couple thousand miles on them, if I can just swap out the uppers, that would be awesome.
 
Sorry I’m a little late to the party but I’m on the 2.5” VT’s (1st Gen) and sit right about 24.25” (flare less). I’ve got the DVS 4” arms and Landtank’s DC and it’s working for me, I’m within one degree on my flanges and my old growl is gone. Im lighter so I’m about the same height as you.
 
Azca said:
The Dobinsons set up is so much nicer to ride on than the OMEs! When you went to the 3" arms, how was caster and handling after?

I was thinking about getting adjustable control arms as well. Hate to give up the Landtank lowers, especially since I know I have less that a couple thousand miles on them, if I can just swap out the uppers, that would be awesome.
Click to expand...
Handling has been fine with the 3" arms. Doesn't wander and heads where pointed.

But it was handling decently (from my point of view) with stock arms and about 2.5" of OME lift. A friend with the same setup had awful handling withe the same setup. So, there's definitely a variance from 80 to 80 when it comes to caster/handling/noises.

I have about 24.5" front and 25.5" rear for center of hub to flare bottom. My vehicle description is in my sig.

cheers,
george.
 
Also just for reference as well I have a shy of 2.5" dobs lift (w/pucs) and the 3R delta arms and their panhard bracket on 315s. No issue with casters nor vibrations on stock drive shafts and stock rear control arms
 
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