Beating a dead horse

[MuddyXJ]

Vibrations.........been revisited over and over again but this one is puzzling me. I have about 5-6" of lift in the rear due to a faulty spring pack lame fix by supplier and about 4" in the front due to sagging springs. No time or money to replace lift now. I get a vibration that seems to be more of a binding nature at about 45 mph and seems to get lesser above 65 mph. Also seem to be getting more heat through the firewall and floor then before. What I have replaced so far to try to eliminate vibrations:

New rear drive shaft from Tom Woods
SYE (JB Conversions)
New transmission mount
Have about 6 degree shim on rear axle
Replaced axle shafts in D35


After doing all this I still have the vibration. Does anyone have any other suggestions on what to try next? I was going to replace motor mounts and maybe try replacing the rear brake parts.

[simonsxj]

A six degree shim does not sound like it is going to be enough. If your driveshaft is the cardan type cv shaft then the rear pinion needs to be pointed directly at the output of the transfer case. Unlike the regular driveshaft that is supposed to have equal angles of the input and output. Hope this helps you. I have had several customers come in with this problem and all you have to do is to cut the rear spring perches off realign the pinion and reweld them. Do not under any circumstances stack shims.

[MuddyXJ]

Well the shims are custom made to point right at the output of the tc. Anything lower or higher made the vibration worse. There is only one shim and I am guessing at the degree.

[marcusguy]

Muddy

Just wanted to say that my front driveshaft in my 99 vibrates since I lifted it. If I have more than 1-2 degrees of castor up front I feel it between about 50-60 MPH. Might not be your problem, but you never know. Taking the shaft off fixed the vibration, confirming my suspicion (although, it seems like I can hear gear noise from the front without the shaft on... kinda weird.)

Marcus

[MuddyXJ]

I have gone from the front to the rear and found that if the rear shaft is off the vibe is gone. I am hoping it's not the new drive shaft but I figure I will regear to see if that fixes it.