i have a shake/ vibration in my '96 f-250SC 4x4 powerstroke with 156,000 miles. tires have 3400 on them and are mounted on stock alum. rims. the tires were replaced because i thought the last set were bad because of the vibration. the vibration is worse in the 38 to 42 MPH range, but can be felt throughout the 32 to 60 range. after having the tires rebalanced twice i had a ford dealer put an electronic vibration analyzer (EVA) on the pickup and it was determined that the vibration was the frequency of tire rotation. i then had the front wheels/ tires balanced while on the pickup. they couldn't do the rear because of the limited slip carrier, but i once again had the rear tires balanced. after doing this the vibration got worse!!!!!!! the EVA mechanic was convinced that the vibration was coming from the rear axle. so this is where i am at this moment. i am considering options on what to do next. one option is to have a run-out done to eliminate the tires or wheels as a possible cause.

could a small problem in the rear end have this kind of effect?anybody have any question or help for me out there?

bryan

 

Sounds like u-joints if the tires are good. They are cheap, easy to replace and with that many miles probably need new ones anyway.

 

Maybe a warped rear drum, or a bent wheel?

 

i removed the rear drive shaft and drove it that way and i still have the vibration.

yes i could be a bent/ warped rear drum. wouldn't the shake increase with an increase of speed if the drum were warped? i don't know, but i will look at that possibility. the alum. wheels i believe are not bent. i jacked the rear up and put a pointer near the wheel and spun it with no noticable movement.

bryan

 

well gentlemen, i checked the rear end fluid level and behold it was full, but there was a high amount of fine filings on the magnetic plug. after calling my mechanic, he feels it is a carrier bearing going out. so i'll be taking the pickup to him on the 26th and he'll pull the rear cover off and have a look. i am sighing a breath of releif that we may have found the source, but i am also worried that other components are going to be bad in there as well. i will update you when it is all said and done or if something else arrises (sp?).
bryan

 

my mechanic pulled the rear cover and found the pinion bearings to be in rough shape. i didn't ask if he replaced the carrier bearings, i assumed he did. but, we still have the shake!!!!! i am leaving for a two week vacation tomorrow, so i left the pickup with him to try and resolve the problem. i will check in on the trip if possible, but i assume i won't be. so when i get back i'll surely check in again.
thanks guys.

bryan

 

 

well gentlemen, after a two week vacation/ honeymoon and having trouble signing in because of a password problem I AM BACK!

i finally took the pickup to a shop that has a runout/ vibration machine they call a "2700" or it may have been a "9700", and it found two of the tires had what they call "high road force". so back to the tire dealer again and they replaced the tires. i now have them (the new tires) in for the "road force" test as well. they also eliminated my wheels because they put the two bad tires on "true rims" and retested with the same results. we will now wait and see the results of that.

after the new tires were on i handed the tire shop a bill that showed the time and money i put into showing them that i indeed had bad tires. they basicly handed it back to me and said they couldn't help me. any legal minds out there have any comments?

bryan

 

the above "machine" was indeed a Hunter 9700.

bryan

 

What kind of tires are they?

 

goodyear wrangler at/s 235/ 85-16

can i expect goodyear slams now

 

No slams, here. Just wondering what "High Road Force" is? About the only defect I ever saw (Besides Firestones) is broken belts, usually from climbing curbs heavily loaded or hitting some deep chuckholes. Which is usually followed by a bulg in the rubber.

Chris

 

from what i understand is that road force is measured in pounds. the wheel is mounted to the Hunter 9700 and a roller of some sort is placed against the tire, this roller attached to an arm and then attached to the Hunter 9700 measures the "road force". it would be, i believe, the physical effect the wheel and tire combination transmit to the road. i assume that if the tire has a defect that a normal balancer cannot eliminate, then this Hunter 9700 will tell you if it is indeed the tire or a bent rim. if you would like more detail i can call them and ask.

bryan

 

I know its been a while since the last post, but I was curious if you found a solution to your problem. I have a 99 f150 4.6 with a violent vibration at 40mph(give or take a mph or 2) I have done everything to fix the problem and have not found the miracle. The only difference is that my truck does this only under braking.
I have changed all 4 rotors and had them dialed(all within spec) changed shocks, new tires-"balanced twice" Now Im tearing the rear apart to replace the seals and bearing.

Maybe there is something Im missing.
Thanks
GHayde

 

it was my new tires. i used a local shop with a hunter 9700. the hunter determined that the tires had anywhere between 25 and 54 pounds of roadforce. i have returned three with this problem and one with a buldge in the sidewall. so in disgust i returned them all and got my money back along with the mounting charges. i then bought a new set of a different name brand (can't remember which) and put them on the hunter 9700 and they showed 5 to 15 pounds of roadforce. end of problem!

my old truck will shake while braking, and i'm sure its the rotors. the shake will slow as the trucks slows and it will "throw" you back and forth in rhythm with the shake. is this what you expirencing?

bryan