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Hey all, I have a 1990 F-150 302 EFI long bed supercab and i am experiencing vibration at about 60-70 mph. Its been doing this for awhile and has been getting worse. I noticed the other day when i take off from a light that there is a shuddering sound coming from behind me. I am assuming the U joints are either dry or need replaced. Anybody have any problem replacing them, i havent done this before so any help is appreciated. thanks
To properly replace a U-joint you will need to remove your drive shaft. Beat the old joint(s) out then have the new joints pressed in.
On almost sure fire way to tell if it is your U-joints is to listen when you take it out of park & put it into reverse or drive. If you here a CLUNCK then you probally have bad joints.
Here's a suggestion: In order to maintain the balance of the shaft, take a paint pen and mark the yokes with a line across the u-joint on each end. This is to make sure you align your marks and reassemble them the way they came apart and maintain the balance of the shaft, hopefully eliminating the possibility of new vibrations. I may have been misinformed, but that's how and why I was told to do it. Then beat em out and replace the u-joints.
Clunks can come from other places than just u-joints (but its the first place I'd look).
A vibration at speed is usually tire balancing or alignment.
U-joints can be checked by getting under the truck, and trying to move the joints back and forth looking for movement/sloppyness.
A haynes manual (good idea to get!) will give you all the instructions you need to complete the job. You can do it with a bench vise or c-clamps. An extra pair of hands makes the job a lot easier too.
Thanks all, i will try seeing if there is some play in it before i change them out. I dont remember hearing any clunks but i will listen for them. Could the vibration be coming from the ball joints? I have been told that it would be a good idea to replace them, since they never have and the truck is about to hit 200,000 miles.
if they're not worn, don't worry about it. At 200,000 miles, you're going to spend a lot of money on parts that 'might be worn out'.
To see if they're bad, jack up one front wheel, and pull at the top and bottom and sides. If there's any play at all, have someone looking at the front end and try to pinpoint where the play is coming from. It could be ball joints, tie rod ends, or bearings. If it's bearings, you won't really be able to tell where the movement is coming from, other than the wheel itself.