lowered 2004 lightning, 1 leaf removed and 3" shackle and NO SHIMS

i was having lots of trouble with vibration, I had 4 degree( bought them after market because i thought thast what id need) shim in there, and vibrated lots, so i think my pinion was far to negative

Now i have removed shims altogether, and took it for a test run, no vibration on the highway or city driving at all

But on a hard launch i get vibration, could that be wheel hop? the shackles, the fact that its kinda snowy out?

any ideas??

 

43 views no reponses? anyone

 

Anything is possible. It's not to hard to check your pinion angles. Get a carpenters protractor, and with the truck on the ground or a ramp type lift, I used a big socket or something like it about the diameter of the the u-joint cap and then set the protractor on that. It's a little tight at the transmission end. Obviously this it one of the u-joint caps secured to the differential and to the slip yoke at the transmission. Those secured to the driveshaft won't tell you anything. They should be pretty much equal at ride height if you are set up right. Some strip cars are set up with the differential pointed down slightly so that under acceleration it straightens out (trying to climb the ring gear) to avoid vibration. Usually this isn't necessary in a street car. If you took out a leaf I would suspect some wheel hop. Have someone watch the axle movement while you nail it and see what's going on. You may need some traction bars. Any way BTT.

By the way I have 3 inch shackles on my 03 and I just did the flip of the factory shim as recommended. It worked out just right and I have no vibration. I haven't played around with nailing mine from a standing start much so I don't know about under that condition.