hi all quick one please help

im getting a slight vibration at 50mph and then gets better untill it it hits 70mph and it gets worse. sounds weard i know. had the u joints checked and the rear one replaced. had all the tires rotated and re balanced. getting a little pulsation in the brake pedal when on the brakes. any idea what to check next?

thanks gabe (2002 f350 7.3 4by4)

 

You have a suspension lift installed?
Your description makes me think driveline or wheel bearing.

 

Tires are chopped. Classic symptoms. Do you have the General tires on it that it came with? For some reason they chop faster than others. I have had this problem until I got new ones. I now rotate my new ones on my dually every 6k miles ($5 per tire from where I got them at) and do a front-end alignment every 12k. I was rotating every year and doing a front-end alignment at the same time, but tires kept chopping on the front. Man at 75-80 mph I felt as if I were in the shuttle returning to earth. When I did finally get new ones I found out that one of the tires I had on the front had a plug in it, and when they took it off the rim you could see the tire was starting to separate. I found out then NOT to ever plug a tire, have them pull it and patch it. Some new tire warranties will void if you plug them. Plugging tires is now illegal in 13 states. Since the new tires it runs extremely smooth at ALL speeds.

Hope this has helped. Good Luck.

 

There is a good chance that your rotors are warped.(pedal pulsation) I had the same situation last year and the only symptoms where brake pedal pulsation. Had the rotors ground and the vibration went away. I would start there. Otherwise for free, you can lift the front/rear of the truck and pull and push on the tires to see if you have any play anywhere. That will diagnose a wheel bearing problem.(most of the time)

 

Kwik, where in the driveline would you look? I've got a vibration, but it's not very consistent. May be the tires though, they are reaching the end of their life.

 

You'll want to start here. http://www.vibratesoftware.com/html_...haft%20Phasing

 

Hey, this will be my 500th post!

 

What I would do is get the rear wheels off the ground and put it in gear, and examine the driveline as it rotates.

 

500 it is! Congrats.

 

If you feel it ONLY when you apply brakes then it probably is a warped rotor(s). If you feel it without brakes applied, it could be tread separation, a bubble, balance, flat spot (tire out of round), cupping. For a balance problem, sometimes rebalancing doesn't help (if the tire is shot), then it's time for replacement. Otherwise could be tire itself or worn suspension in some cases, ie. cupping can be caused by worn shocks. Go to a good tire/suspension shop for diagnosis if you can't find the problem.

 

Had similar problem, it was a bad brake caliper.

 

thanks for all the advice guys. i thought that if it was something in the brakes than you would have to be on the brakes right. i do get a palsation from the breaks but i also get another slight vibration in the stering first at 50 to 53mph then it goes away till i hit 70mph on the dot every time. from their up it stays constent.
thanks alot
gabe

 

oh ya i am runnig michelins about 1/4 tread left on them.
gabe

 

well, the deal with disc brakes is that they are always touching the pad, therefore any variance in the smoothness of the rotors can be felt if bad enough. Of course when you push on the brakes you will feel it more... You could remove the tires and spin the wheel and see if it rubs excessively, that might help in your diagnoses. I just had all new rotors put on yesterday, and it fixed my vibration issues.

 

With the problem happening at 50 then worst at 70, I would again like to direct you to the tires as being the source of your problem.

Good Luck.