Couple issues with the lightning

[Root1022]

First issue is it is shakes pretty bad after about 50+ mph on smooth road, feels like its coming from the rear passenger side, im thinking possibly the driveshaft or a bent axle, but if it was that wouldnt you feel it at all speeds? I just had new wheels and had them balanced today hoping it would fix it, no luck

Also when cruising at around 45mph in town it shifts to 4th and it just rides like complete shit. If you touch the gas at all it shakes violently, ill knock it back down to second let it shift to third then try and keep it from shifting into 4th its so bad? Anyone expierence this or know what could be causing it? I just put new plugs in it today and fixed a vaccum leak thats plauged me since I bought it, I was hoping this would fix it.

It has a shift kit and a torque converter on it. No suspension work done to it.

 

[fruhdaddy]

Vibration you feel might be the ujoints going bad, I had that happen. What plugs did you use and whats the gap? You still on stock tranny? If so with alot of miles might be time for a rebuild or the computer is faulting out on you

 

[Root1022]

NGK TR6s gapped at 0.32, and stock tranny, truck only has 44k miles. I'll check the ujoints today

 

[Fade 2 Black]

The vibration would be tire balance I'd guess. Put the rear on jackstands and put it in D with it running and you can look the drive shaft and axles over while in motion.

As for the 4th gear issue, who tuned the truck? Your sig says it's fully built so there could be something wrong in there. If you have a wideband is it going lean, rich or staying the same when depressing the pedal in 4th?

 

[Root1022]

Tires just got balanced yesterday, and no wideband, I just bought the truck, I have a wideband on order so I can check a/f ratio

 

[Root1022]

Also no clue on the tune, I plan on getting it tuned asap.

 

[Jroc]

It sounds to me like your truck was rode hard and put away wet.

A L isn't a Terminator ridden with a bunch of common stupid, and annoying problems like stalling issues, and vibrations after 80 MPH, and creaks and clunks coming from the chassis, etc. A F150 is a much better built vehicle than a old Ford Fairmont Mustang. I while admit that that stupid clunk that comes from the left lower control arm is pretty annoying though.

Anyway when did you sell your Cobra and get a L?

 

[lightningmanny]

check your rear bearings.... 44k shouldnt be bad but if you or the 1st owner hit a ditch or side walk...that could be it...and the 4th gear has to be the tune...since u said spark plugs or fine and gap'd at 32...