[drtbik111]

I have an 84' Ramcharger with 50k original miles. Just installed Rough Country 4" lift and found take off vibration and hard vibration at 50 mpr. The take off vibration was solved with 4-degree shims in rear but the high-speed vibration is still present even after the following mods:.

- new u-joints
- balanced shaft
- balanced tires
- 6-degree shims

Any help??

 

[phoenix827]

only thing I can think of off the top of my head is what I got with mine. Check the slip joint on the drive shaft, mine is near the limit and loose, that might be all you have too.
chris

 

[Desert_Dog]

50 MPH is the limit of driveshaft angle induced vibration... i.e., 30-50 MPH is where an excessive driveline angle issue will resonate.

Slip joint may also be a problem...

Are those 50K mile original U-joints?

Mike

 

[drtbik111]

The new u-joints replaced the original 50k u-joints. The slip joint is out 1” from original location and the driveline shop thought it acceptable.

They did suggest dropping the transfer case. I used 2 ¾ “ grade 8 bolts and ¾ “ spacers. The high-speed vibration is significantly reduced but not completely gone.

I was thinking about more drop on the transfer case but the distributor is almost into the firewall.

Any other suggestions??

 

[RAMMAN4]

Get yourself an angle finder and make sure that you driveline angles are within 3 degrees of each other. If you overshot the angle by dropping the t case too much that just made the problem worse.

 

[robo51]

if you are worried about the distributor hitting the fire wall, you can allways cut a access hole around it , saw a cheby with that set up worked great for him, im going to be doing the same.

 

[drtbik111]

Get yourself an angle finder and make sure that you driveline angles are within 3 degrees of each other. If you overshot the angle by dropping the t case too much that just made the problem worse.

Thanks for the advice; I am headed back to the driveline shop.

 

[drtbik111]

if you are worried about the distributor hitting the fire wall, you can allways cut a access hole around it , saw a cheby with that set up worked great for him, im going to be doing the same.

Truck is still pretty clean under the hood; don't want to start hacking into the sheet metal at this point.

 

[drtbik111]

You should also check the shock absorbers. They should be in good shape and long enough (4" lift will require, 4" longer shock's than stock).

Lift came with new shocks. With the transfer case drop i think the 6 degree shim may be too much. I have 4 degree shims on order.