Thanks in advance for any and all help.

My Brother in Law has a 95 F150, std cab, stock truck with about 85,000 on the truck, its a standard tranny, and an inline 6.

The truck when about doing about 45mph and above begins to vibrate through the steering wheel, but not in the same fashion as one would expect from a wheel balance concern. There is no whinning and I noticed a little clicking today for the first time when driving it slowly (rear end?) into a parking spot. I did the ever so spohisticated hand rub on the tires to see if there was any chop, but only one tire on the right front seemed to indicate anything of concern, the outer tread only seemed to rub fine in one direction (as if the truck was in reverse) and the forward direction seemed to stick a little. But it seemed rather minor for that one tread bar in comparison to the whole truck vibrating.

So Im looking for advice on what to check out and look for on his truck, Im no pro by and means, and I know just enough about rear-ends and trannys to cause a bit of damage. I doubt Ill have time to help fix it (im here in Austin for a few days more) but atleast I could help him get pointed in the right direction.

Anyways, thanks again

 

Welcome to the boards!

I just went through this with a GMC I had. Hopefully you will have better luck than I did because I am driving a Ford now

Here is what I learned. The first step in diagnosing any vibration is figuring out roughly what the frequency is. This will help nail down a tire or driveline problem. For example, a driveline vibration would be about 3 or so times faster than a tire vibration because of the gearing of the rearend. The next thing to do is start trouble shooting. When does it do it? At accelleration, under braking, while coasting, in a particular gear etc. Is it engine RPM sensitive or speed sensitive? To test, put the truck in different gears and run it up to the speed it does it at. If it does it in all gears at the same speed it is probably a driveline component behind the transmission. Honestly I would start out looking at the u joints (funny how often that comes up!). When they start going bad they will squeak and maybe click at first then start to vibrate at which point you are really on borrowed time. If they are bad enough to vibrate it shouldn't be hard to tell if they are bad.

That should give some things to try and narrow it down.

 

Thanks for the speedy reply!

The truck has squeaky brakes, I think the rears are in order for a change, I was chatting with the owner, and we took it out for a drive, it definately seems to be a function of load. When accellerating the vibration is more pronounced than say when you engage the clutch. Im also pretty ignorant about the workings of drum brakes, but I doubt it would be related as it should be more pronounced when braking and not disappear when the clutch is engaged?

I took a look at the U-joint, and again Im somewhat ignornant here too, but it externally looks ok, and there doesnt seem to be any slop when attempting to rotate the driveshaft by hand...

I guess I should also check the fluids of the diff, tranny just to isolate them from the equation.

Kevin

 

You might have a weak pressure plate or worn out clutch disc if it is starting to slip you might feel something like that. You say it does it during acceleration or it always does it and its worse under acceleration? Keep us posted as to what you try and what results. Hopefully we can help you figure it out.

 

Well, it is under load only, even when accellerating downhill say with the clutch depressed, the truck wont vibrate. I checked out the fluids to isolate that....

 

I re-read your earlier posts and that with what you have told me would lead me to believe that it may be engine related. I still think clutch is a possibility but when was the last time it had a tune-up? (plugs, cap, rotor, wires etc.) The 300 I6 my dad had was real finicky about the tuneup. If it wasn't tuned up once a year or so it would start to act funny. It could easily be a bad plug wire that is causing a horific mis at speed under load. One way to check is to pull the truck into a dark garage or outside at night and start the truck and have someone load the engine (hold the brake and load it with a little gas pedal and out on the clutch) and watch for sparks around the wires. If the wires are really bad it will look like a light show under there.