Baggedf150

I have a 2006 f150 quad cab. It has been fully custom built. Air bags with a 4 link 6 valves . I am now having trouble with my drive shaft. The stock drive shaft broke at u joint, I replaced it. The truck has a vibration starting out in first gear and is worse when I turn.everyone keeps telling me the trucks are know for drive shaft problems but I think something is wrong maybe pinion angle. Any suggestions

Bhelton

Get your truck to ride height on level ground and use a angle finder to see what pinion is set at (should be close to 2*) also check your bushings and end links in your link setup. The reason it's worse in 1st gear is due to there being more torque applied and rear axle twists more and if bushings are wearing out it'll get a lot worse.

PerryB

Most likely the nose of the pinion is too high and needs to be shimmed down, thats the primary cause of a launch shudder. The pinion shaft and transmission output shaft should be parallel. If anything the pinion should be slightly low because it will rise under torque.

Baggedf150

I just found someone who will look at it. He said pinion angle should be a little negative at ride height and when I drive it will be where it should be. Does this sound right.

PerryB

Yes, thats what I meant by saying it should be a little low when the vehicle is not under power. I'm thinking along the lines of 1/2 degree negative. It sounds like you have someone who knows what he's doing. I think you'll get it handled, good luck. Post a couple pictures of your system, I'd like to see it.