Hey-

got another question as long as I'm here. This is actually a problem that the truck has had for a while, but I had almost learned to ignore it until someone pointed it out the other day. The truck has a tendency to jerk REALLY hard if I go from no throttle to pretty heavy. It also makes a little jerk and thud noise if I go from partial cruising throttle to something heavier fairly quickly. The truck will also makes these same jerky feeling when I let off the gas, regardless of the RPM range. At first I was thinking U-Joints, but I had heard that U-Joints make more of general shaking motion while going down the street more than anything else. Any ideas? Could this be the sign of a slowly fading clutch?

Mike


1990 F150 Custom
4.9L I6 w/ Mazda 5spd
K&N FIPK, Magnaflow exhaust

 

93 F150 5.0 165K mi.

Ive got the same symptom. Sure would love to hear what the possibilites are. Ujoint were suggested to me. Test I was told to try was to put truck in neutral with parking brake on. get under truch and see if you can move it back and forth with your hands. If not, then its ok. Mine passed this test...but I really dont know what else to check.. If you find the culprit...pls post...>Hey-

 

My 94 F150 does the same. I can be coasting then when I hit the pedal it does this. I was thinking it was U-joints and I will replace them regardless.

 

u joints cost very little, so just replace them. while the driveshaft is out, check the play in the rear. i had an 85 150 4x4 once that had this problem, and i traced it to the rear, but the u joints were a contributing factor. if its the rear, look around in local salvage yards for a whole rear with the same gear ratio as yours. it will be a whole lot cheaper than to replace the guts inside the rear

 

I had a simular problem with my 88 F150. Mine was a combo of a roasted spider gear shaft and worn splines on my axels. I was told this is a comon problem on a 8.8.
An easy way to check u-joints is to soak them in wd-40 then go for a drive. Bad u-joints will normaly bleed rust.