I'm looking at a 78' 2x4 for sale, and everything checks out, except on the interstate above about 60 mph the truck gets this vibration to it. It's not coming from the steering or wheels, I've felt that plenty of times before, and this is different. And its not like it's bouncing around, but just sorta really vibrating, like it's not bolted together right. (That's about the best I can describe it as.) Any ideas where it might be coming from? I was thinking the rear differential or drive shaft, but I'm new to this and I don't know whether this is normal for a truck that old, or if it's about to poop out on me. The speedo only goes up to 80 or around there, so maybe it's just not made for it, plus the owner says he drove across the country like that twice and it faired fine. Any ideas where it's coming from, or if it's normal?

 

Could be any number of things. Some things that come to mind that you might want to check are: wheel balance, tires, driveshaft balance, and u-joints.

 

If it just gets louder and stronger with speed, could be carrier bearing (or uni joint). Pretty minor repair, except stuff in your eyes while you are under there looking up.

It will be there at lower speeds, but get more and more obvious with speed. Doe this one actually have a carrier bearing?

 

A 78' long truck is bound to have some issues. I mean it has to have at least a 5 piece d-shaft or more.

Didn't know Toyota made one of those.

edit: Oh wait did you mean '78?

 

Ha! Yeah, it's a 1978, not a 78 foot. And in fact, the guy I got it from had the year wrong, it's a '79 instead.

Pingpong, you're right, it gets progressively worse with speed. I can start to feel it on a very smooth road at 2nd, more obviously at 3rd, which is sorta lower rumble vibration, then 4th just gets worse and worse. I crawled under there just now and the drive shaft definitely has a bit of play where it connects to the rear diff. I'm just gonna go ahead and change the u-joint this weekend, and post back the results.

 

Well, I just finished installing new u-joints and no more vibration! I will say though, that was the biggest pain the butt job I've ever had the displeasure of dealing with. I literally banged on the old u-joints with a hammer for an entire day. But, in the end saved $200 for not going to a garage. I suppose it's one way to spend your time off.

 

Its a great way to spend off some time. I saved $300-$400 by putting my lift on myself. Money I can use for other parts!

 

Not only did you save the money, but you KNOW the bolts weren't overtightened (or left too loose). Yup, they really get stuck on there though. I think I used a hydraulic jack to push them off after removing the nuts and bolts last time I did it!