89 F250, 302, M5ODR2, 4X4
Just replaced engine with Jasper with 40K on it. New clutch, master cylinder, and slave cylinder. I also replaced the bent rims aluminum rims with good, straight steel rims. The tires only have 10k on them. I've also replaced the upper and lower ball joints, front brakes and rotors, as well as all steering components from the pitman arm out to the wheels. It has a good computerized alignment as well.

When driving at highway speeds, from about 45 mph and up, I'm getting a fast vibration that you can't feel in the steering wheel, but you can in the gear shift and clutch pedal. If I take it out of gear, the vibration doesn't change, so I'm ruling the transmission out of the equation.

This vibration has always been there, and has been a pain in my backside since I bought the truck 3 years ago.

The PO said he replaced the u-joints before I bought the truck...is it possible that the joints are wrong/bad?

Just about everything he did when he owned it, I've had to make it right...

Also, is it possible that the drive shafts could be bent?

I'm looking for good ideas to fix this...

Thanks

 

I'd definantly give the U-Joints a shakedown....Just to be sure...

Also...if the DL was JUST a hair out of round, or bent....It'll do that also....Well...Untill the DL stops turning...

When he did the U joints, if the DL had a defect and he didn't put it back in, in EXACTLY the same position...It will show up as vibration...

 

Forgive my ignorance...what's a DL? LOL

 

Driveline....



























......J/K....lol

 

Nah...that was just a term I was unsure about. LOL

Just to further explain the vibration, it feels as if it could vibrate the truck apart. I've already had to repair cracks in the bell housing when we had the engine out. I'm hesitant to drive this any faster than 35-40 until I get the vibe taken care of.

Any other things to look for before i get under it??

 

Check for shiny metal......Denotes movement of parts....

 

Good point...

I've designed and built more complicated machines than these...I need to stop looking at them as automobiles and start looking at them as machines. LOL

 

I believe it has something to do with the DL as well. With the truck on jackstands, mark the relationship of the driveshaft yoke and axle pinion flange. Rotate the driveshaft 180 degrees and reassemble. Also, try spinning the wheels as fast as you can wth the driveshaft disconnected and see if you have any vibration. You could try this first before disconnecting the driveshaft and see if the results are the same or not.

I believe the P.O. did something to cause an imbalance. If rotating the driveshaft doesn't help, I would take the driveshaft to a machine shop or other shop that can check for a balance problem.

 

I posed this question on another site, and was told by a member there that his 89 Bronco did the same thing, and it was the double cardan on the drive shaft.

Does that sound like a possibility??

If it is, wold it be better to rebuild the shaft or buy a new one for around $300?

I want to be armed with as much information and possibilities as I can before I tear into it. I don't want to throw parts at it and hope that it will work, I want to make it right as inexpensively as possible. basically, I don't want to spend a ton of money and not fix it when i could use that money to improve other areas.

 

if a driveshaft is bent, it will vibrate. try going to a junkyard and getting each driveshaft and then test out the truck after each replacement. if it doesnt work, then return the driveshaft that you removed back to the junkard (if your junkie accepts returns). just an idea. did you check for play in the u joints?

 

I haven't gotten under it yet...I'm just trying to get all possibles out first so I know what to look at if I find nothing to start.

I plan on taking an indicator and a magnetic base under with me when I get under it...while it's on stands, of course

 

If your driveshaft lost a balancing weight then it will shake bad. If the drive shaft isnt bent you can take it to a shop and have it balanced. I just had both shafts balanced on my 94 for under $60 and it is smooth as silk now.