'92 F150 vibrations/drive train problems

[fishdog4449]

Hey guys,
question about my truck here..1992 F150 manual 5spd 4.9L I6. Driving at 35-50 mph there the whole truck begins to vibrate...almost sounds like that helicopter sound you get with one window halfway down, except you feel it in the floor and seats as well.
Once you get above 50 it goes away. Doesn't matter what gear it's in or if the clutch is in or not. I thought it might be a ujoint going bad (my dad concurred and had same problem in his blazer) so we took it into the shop and the joints were fine. Mechanic thought it might be wheel weights out of balance, adjusted those and it's still there.
I just want to know if it's something to be very concerned about. Any ideas?
Thanks guys!!

 

[woosterken]

Re: '92 F150 vibrations/drive train problems

did you loose the balance weight off the drive shaft?

woosterken

 

[Bob_VT]

Re: '92 F150 vibrations/drive train problems

CHeck you universal joints...they are notorious for going

 

[gibletts]

Re: '92 F150 vibrations/drive train problems

You could have a close look at your tyres, I had a very similiar thing happen to me, thought i had damaged the drive shaft but turned out one of my rear tyres had delaminated slightly causing it to go all asymetrical and bulge, it would set up with a nice resonant vibration at about the same speed you describe.

 

[fishdog4449]

Re: '92 F150 vibrations/drive train problems

Bob,
I thought it may have been one too, but they checked out fine.

Gibletts I will check thats sounds like it could be the problem!

Thanks guys'!

 

[i386]

Re: '92 F150 vibrations/drive train problems

Keep at it until you track it down. I had a 98 Explorer that vibrated like hell at a certain speed. I tried a lot of things including new wheel bearings. It turned out to be uneven tread wear on those Goodyear Wranglers.

 

[SeaKaye12]

Re: '92 F150 vibrations/drive train problems

As odd as it may seem, I once had a pair of roof racks do that on a '63 Chevy Belair Wagon.

I had racks up there for carrying an aluminum boat. The racks had a wooden block mounted on each end to keep the boat from sliding off.

It took a while for me to establish the connection. With the racks on; the car vibrated at appx the speeds you describe. Took the racks off...and the vibration stopped!

Must have been the way the air turbulence worked around the racks; odd, but certainly true.

Chuck