I have a 2005 FX4 Off-Road Ford Ranger 4.0L, I bought the truck with 84,473 miles on it last march and was told the trans was rebuild when previous owner traded it in. Ever since I drove off the lot Ive had a number of concerns but my main concern was the 40-45 MPH shake that I had, When I first had the vehicle it had 31 BFG AT tires and 16 Dick Cepek Rims on it never had the stock rims. It bounced bad on the way home after purchasing it so I thought maybe tires are not balanced so the next day I had them road forced balanced and rotated and the bouncing did not go away, I had to make a trip to the city and going 70 mph down the interstate it felt like the passenger rear tire was bouncing up into the air, I pulled off and looked and everything seemed fine so I continued driving and it proceeded to do it shaking the drinks out of the cup holders so when I got home called Ford and told them I have a issue with the truck and they said bring it in and the next day I went to ford and they took it in and looked at and not even 10 mins later they were done ( I work at a dealership shop ) and I know they didn't look at it, takes longer then that just to get the vehicle back into the shop and they said the cause was me having " off road tires and rims " so they wouldn't ride smooth, last time I checked "all terrains" can be used on all terrains I know it wont be as smooth as a road tire but still and Dick Cepek rims are far from off road rims they are some cheap $450 set of rims. Well I battled and battled with them and nothing got done they said its a truck and its a ranger so it not gonna ride good, have not been back since. I then proceeded to get new tires Nitto Terra Graps and the bouncing was still present but not as bad so I looked into other idea and jacked the rear of my truck up to check and see if the rims could be bent, the driver side tire was straight but the passenger tire was wobbling ever so slightly so i rotated the tires and rims to see if it was the rim or the rear end and it still did the wobble when i rotated the tires so I figured it was the rear axle I proceeded to get that replaced buddy of mine ( was a ford mechanic now has his own shop ) replaced it for me didn't have the correct tools for the job, When the truck was done went and picked it up and it drove like heaven then the next day it came right back so I gave up on it was gonna trade it in but they would only give me 5.7k for it trade in with 91k miles on it and I still owed 6.2k on it at the time ( purchased truck for 12.5K ) so that was no go so I figured well its mine so I continued putting money into it and making it the way I wanted it and eventually got 33 MTs and 20x10 Rims ( yes i know mts dont ride good but bare with me ) after I got these I still had the shake its not from the tires theses MTs I purchased actually ride good and smooth. I then had the U joints replaced with moog 270s and had them check the driveshaft if it needed to be balanced, it did not( Solid One Piece Aluminium Drive Shaft ) still have the shake, rode behind it with my girlfriend driving it and it looks like the bed is shaking side to side and up and down and you can see the bed shaking in the mirror also when your driving. Im back on trying to get this shake/vibration fixed its bothered me for so long just ready for it to go away and Ive asked many other ranger owners if they had any kind of shake and all of them said no, also I got a hold of the previous owner and asked him if he experienced it and he said no it just didn't take bumps well so Im lost on what it could be thinking on getting brakes redone and purchasing new shocks, but im thinking something happened between when ford had this owned vehicle and when i purchased t cause this shake if the previous owner did not experience it, So any ideas ?

Also here is my service history since I've had the truck :

84,473
Truck was Purchased
Drive Belt was Replaced

87,000
5W30 Motorcraft Synthetic Blend Oil Change with Motorcraft Filter

88,500
New Tires 265/75r16 Nitto Terra Graps
4-Wheel Alignment
Road Force Balanced Tires
New Motorcraft Thermostat
New Motorcraft Fuel Filter

90,000
5W30 Motorcraft Synthetic Blend Oil Change with Motorcraft Filter
Rotated Tires

93,000
Dorman Right Rear Axle Replaced
New Motorcraft Belt Tensioner
New Fel Pro Lower Oil Pan Gasket
New Motorcraft PCV Valve
New Motorcraft Fuel Filter
5W30 Motorcraft Synthetic Blend Oil Change with Motorcraft Filter
Brake System Flush
Rear Differential Drain & Fill
Rotated Tires
Road Force Balanced Tires

95,000
New K&N Engine Air Filter

96,000
5W30 Motorcraft Synthetic Blend Oil Change with Motorcraft Filter
Motorcraft Oil Drain Plug Replaced

96,100
New 33x12.5x20 Federal MT's
New 20x10 -12 Offset Black Fuel Mavericks

96,200
4-Wheel Alignment

97,800
Air Conditioning System Service ( Vacuumed,Oiled,Refiled )
U-Joints Replaced with Moog 270s

 

The only thing I can think of is maybe the rear axle shaft is bent. You could check the runout if you have the tools to do so.

 

by shaft do you mean drive shaft or do you mean the shaft inside the rear end housing ? I just had the rear axle replaced and the drive shaft is not bent, had the guy at my local power train shop check

 

Yeah I ment the axle shaft. Didnt see you mention that.

Have you checked the U-bolts for the leaf springs? Checked the condition of the shocks?

 

I have new u bolts since removed my 3in factory blocks and put 2in blocks so it would level out the truck I had to get shorter u bolts so I would have thread and the shocks Ive been planning on replacing them, they are the factory motor craft shocks that came on the vehicle back in 05 they have never been replaced,but shocks are still pretty stiff can barley push them up when i took them off to see if they were bad or not.