Bad vibes at 60mph on load 79' (1 Viewer)

[rghouse]

I get vibrations, not wobbles, pretty bad at around 60 mph when accelerating, not when I let off the gas and not as bad below 50 or above 65. The truck has OME 2.5" lift and 33x9.50 kendas and OEM steelies, otherwise stock.

I currently have the front driveshaft out, and replaced the u-joints in the rear. It got better after this but still drives me mad, especially since 60mph is my favorite speed on the highway. Wheels have been re-balanced.

I do not know if I have the drive shaft bolt pattern matched right at the flange(s), it sat for 15 years with them removed. Is there a reference for that? There are washers welded on the shaft where it has been balanced before also. Advice appreciated.

 

[charliemeyer007]

Yep I be checking that the drive line is clocked correctly. I think its even in the Haynes but I'd look in the free download manuals.

Land Cruiser Factory Service Manuals (FSMs)

Factory service manuals (FSMs) for your Toyota Land Cruiser ! From the 1950s to the present!

www.cruisercult.com

 

[Grayscale]

Once the U-joints get angled like that, there is a speed-up and speed-down because some of the rotation is translated into changing the angle at the yoke. So, the next time you see a U-joint-type front axle, you can appreciate Toyota's constant velocity birfields on the front axle.
Video explanation.
Also - for driveshaft phasing.
The answer, have someone build a double-cardan driveshaft, and, rotate the rear pinon to relieve some of that angle (aware that the shock pins will sit a bit incorrect in the bushings). Or, find stock-size springs and shackles, and forget about 'rubber-overdrive.' Or, stay off the highway, leave it as is, and continue hammering your pinon and transfercase in a subclinical manner. As you can tell, I'm quite critical of 'lift-kits,' because it usually boils down to incomplete, or custom. Perhaps someone has greater success than I did, trying to run 33s?

 

[Grayscale]

Using an angle gauge from the Harbor Freight or whatever, you can measure the flange at the transfercase and at the differential pinon. Perhaps you can shim the spring side so that the geometry is closer to parallel, that way only the driveshaft itself is being spun at varying velocities, see the video for driveshaft phasing, above. I recall trying to make that happen with a 2-inch used lift kit, and I probably didn't quite dial it in with the shims that I ordered, but, it might work with your springs, which are different than the ones I used? Try Man-A-Fre

Also, look for u-joint wear, and other simple stuff that needs fixing.