Got a vibration...at 55MPH
 

LS swapped 62, 4L60E one piece driveshaft, 2-1/2 drop spindles with 1 coil cut, 4 or 5" drop springs in the rear can't remember...I get a vibration at 55mph that goes away at 60mph...Truck is smooth (for a 54 year old truck) other than at this speed. All u-joints are new. Tranny shifts good. Could it be my driveshaft? Why would it not vibrate at other speeds? Thanks

Re: Got a vibration...at 55MPH
 

Pinion angles are the first thing I generally look at with vibrations. 5mph is a pretty narrow window, so its completely fine at 1-54 and then like 60-80?

If its the driveshaft, you can find an empty space of road and get up to 55, pop the truck in neutral and see if the vibration goes away. If its a wheel/tire/brake issue, it will persist. Might be a bit tricky if you only have a 5mph window, so just use caution.

Re: Got a vibration...at 55MPH
 

Ok been busy these last few weeks:
Tried to pop it in neutral at 55 and shake is still there...

Found a kinked brake line for passenger side disc that was not allowing passenger side calliper to open.-changed it.
New front shocks as old ones were toast
New rear shocks


Front end seems to jump around right around 50-60 now. Smooths out a bit but not completely... Alignment? Truck has a 78 disc front end...

Re: Got a vibration...at 55MPH
 

Front end jumps around? Sounds like tire balance to me. If they are the same size, swap them with the rears and see if front end gets better.

If you suspect alignment, that wouldn't hurt either, get it done. I'd also look for play in steering system, ball joints, etc.

There could still be a driveshaft issue lurking here too. Been there, done that many times.

Re: Got a vibration...at 55MPH
 

Dropped off the front tires at the tire shop today to see if that's the issue.

Re: Got a vibration...at 55MPH
 

Rally wheels are balanced but bent...apparently this is the cause of the vibration...they came with the truck so I don't know origin.