lift question

[dangeruss78]

just put a 6 inch bds lift on my 78 and took it for a test ride and it has a bad vibration now, especially around 30- 35 mph. the drive shaft looks to have more angle, the rear lift was done with new leafs, i'm not sure but i think i may have installed them backwards, any help would be appreciated

 

[Broncoholics]

Usually there are markings on the leafs like FRONT so you know which way to go. Are they used? You can always take it apart and reverse them but that takes time. Is the 9" yoke pointing close to the t-case yoke?

If the yoke is sitting flat it could be that they are in reverse. Some lifts require a $25 6* shim under the leafs to help rotate the pinion (yoke) back up where it needs to be. What lift did you have on it before? The driveline might be over extended on the slip shaft causing a vibration and could fall out. Get under there and see if there is any side to side or up/down movement in the center slip shaft. The splines could be worn.

Second, you need to pull the driveline and inspect the u-joints. They are probably toast and now that the driveline is set at a new angle you can feel it. Most likely the needle bearings are dust.

 

[Ziggy]

Did you put the factory shims back in the rear axle? If not, you need to dig them up and reinstall them, this may help your vib problem.

 

[dangeruss78]

kit is brand new, i checked leafs, they are on the right way, the drive line has no slop in it, i have not had it aligned yet though, could that make it vibrate. I did have the whole front end off. All new bushings springs, shocks etc. This is the first lift the truck has ever had.

 

[jgvabronco]

FYI, you cannot put the rear springs on backwards. the front eye is 5/8" and the rear eye and shackle are 9/16".

 

[Broncoholics]

I still think its the u-joint thats bolted to the axle end of the driveline.

 

[dangeruss78]

i put a locker in the rear this week and before the install i put it up on jackstands and put it in drive and let it go through the gears and there was no vibrations, i think it needs to be aligned

 

[89Bronco58]

i highly doubt youd get a vibration with it up on jackstands and the wheels off the ground...since the truck isnt doing any work to spin the tires..try changing the u joints or at least checking them and go from there

 

[dangeruss78]

got it aligned today, no more vibration