'01 Lifted F-350 Having Problems at Higher Speeds

[SJB]

Hi, I'm new to this forum. I was searching for answers to my truck's problem and I ran across this. I have the v-10 and not the diesel, but I figured you could still help me in this situation. I'm sorry because this is going to be long and detailed, but I need help.

I have an '01 F-350 Crew Cab 4x4 with roughly a 4 inch lift and 35 in BFG AT's. At roughly 70 mph I get a feel through the floorboard and gas pedal of the truck. I don't know how to really describe it (not sure if its really a vibration, shudder, harmonic noise). I had the tires rotated and balanced with no help. I noticed after driving with my atv in the back it seemed to help eliminate it or at least lessen it. I was sure it was the carrier bearing shims based off of this. I took it to the lift shop and they played with adding more shims. So much in fact that they had to build an angled bracket to compensate for the increased driveline angle. All it did was seem to push out the speed to about 75 mph when I would feel it. The shop really didn't want to deal with me and basically said I was going to have to deal with it. I didn't like the extreme angle they put my driveline in so I took matters into my own hands. I purchased a new carrier bearing and shim kit, and all new u-joints. I took the whole 2 piece driveshaft to a shop to have them install the new parts and balance it. Two problems happened. Initially I forgot to leave some of the mounting hardware, so they balanced each driveshaft separate (rather than calling me) rather than a whole unit. Second, they installed the end mounts backwards on one shaft so it wouldn't mount to transmission. They corrected that, but told me it wouldn't affect the balance and that it would still be ok. This pissed me off because it still left doubt. So I installed everything and it had NO AFFECT. The problem may be there at lower speeds, but is a lot more evident at 70 mph and above. I NEED HELP!! Could it be wheel bearings, rear end, still something in the driveshaft? Anybody have any ideas where I need to go from here? Please post a reply, or better yet send me an email. Again sorry for the lenth of this. I just wanted to give details of everything I've done up to this point.

Thank you,

SJB

 

[hugeredford]

I 'd check the track bar for any movement and make shure your steering stabilizer is good. just have somebody move the wheel and you can look for anything moving in front. my truck had some of the same problems at first

 

[nevrnf]

Is it possible the front hubs are locked??? I know mine has a vibration at highway speed when locked.

 

[SJB]

F350 problem at higher speeds

I will try and check these things out. Thanks for the feedback. Please keep them coming. I need as much help as possible. I'm pretty mechanically inclined and try to do most of my own repairs to save money. However, I'm running out of ideas short of throwing all new parts into it hoping I finally get lucky. At this point I'm not sure which is going to be cheaper, taking it to a shop or replacing parts one by one. This is why your ideas would be greatly appreciated. Thanks!!!!

 

[SJB]

v-10 shudder

OK, I talked to my brother-in-law (who was the original owner of the truck and had the lift installed). He said that the truck didn't start having the problem until after the lift was installed. Initially, it had problems at about 55 mph. He said he took it to the shop, they adjusted carrier bearing shims and it pushed it out to about 70 mph when it would have problems. Unfortunately, he didn't pursue the issue any further and nothing is under warranty anymore. He also said that it helped when he loaded his dirtbikes in the back of the truck. So based off of this, it definitely seems related to the lift (drive angle or problem with wheels and tires). Is there something else that may need shimmed related to the lift (transmission, rear lift blocks)? If added weight in the back of the bed seems to help, which way would that indicate as far as shims (add more or take away)? A number of shims were added at one time (way too many in my opinion) but that did not eliminate the problem. Is driveline angle that critical or touchy to where I can't eliminate this problem? I have a friend who has the same truck, except with a lot larger lift and tires (8" lift and 37" tires) and he never complains of any problems. Again I'm sorry for this long post, but I'm getting frustrated that I can't eliminate this problem. So any info would be great!!!

 

[DaveBen]

Look at the angles of the output shaft on the tranny and the pinion shaft. These two shafts should be approximately the same (that is parallel shafts). They should be approximately level, not going up hill or down hill. If you have these correct, you may get rid of your vibration.

Dave

 

[hugeredford]

are the u joints in line with each other after the shafts haveing been slid apart

 

[SJB]

v-10 shudder

If you are talking about the two piece shafts in comparison to one another, they are mostly straight. They were pretty much straight from the start, but still had problems. I took it to the lift shop and they shimmed it so much that they had to fabricate a new angled bracket to compensate for the extreme angle. It just didn't look right, and all it did was push the speed out about 5mph that I would start to feel it again. The only difference this time, is it had the noise (feel) whether I had a load in the bed of the truck or not. It was putting stress on the rubber carrier bearing support, so I replaced the bracket with a new shim pack, carrier bearing, u-joints, and supposedly had driveline balanced (see comments above). I haven't tested it with a load in the back yet, but it still has the shudder even after doing all of this. I'm thinking of taking shims out since I've already added some with no luck (even with it mostly being straight). It just seems like something else is wrong. I know the angle would be important, but not this critical to where I would need to have it within a millimeter. Does the axle angle usually need to be adjusted (lift is only 4-5 inches)?

 

[SJB]

U-joints

are the u joints in line with each other after the shafts haveing been slid apart

As far as I know they are. Unfortunately, I'm away from home on business and will not be able to check it right away.

 

[DaveBen]

A 4 to 5 inch lift will not change things that much to cause your problems. You said you have a two piece drive shaft. Someone here made a one piece drive shaft and that stopped the vibration, they said.

Dave