SVTBill

Okay I know this is not about a Mustang but I ask you 5.0 guys because most of you are pretty intelligent. My dad's 1992 F-150 (5.0[8D]) extended cab with a shell on the back has a vibration from take off. I know it's not the balance of the tires because I balanced them myself plus it's not that kind of vibration. It happens at about 3mph to 7mph or so, my dad swears he cannot feel it and my mom says she can't feel anything either but, I know for a solid fact it's there. I think they're just used to the vibration and that's why they cannot feel it. Anyhow it feels like it's coming from the middle of the truck so that's why I am asking if it might be the driveshaft. I know its kind of hard for you guys to diagnose the problem with the amount of information I've given you but, thats all that I can think of for now. If you have any questions I'll be happy to give you more information and please help me.
Oh my question is what can it be and how can we fix it?

Can the shell have something to do with it, its weighs about 500lbs or so but, it's been on there since we've had it and I just started noticing the vibration about 3 weeks ago, it's not a slight vib. either its pretty noticable. The truck has 140,*** miles on it.

r.barn

clutch?

SVTBill

auto

capnacee

What RPMS If any Does the Viration start? Does it do it at any other speed/RPM?

SVTBill

just when starting donno the rpms sorry

capnacee

Only in drive though,Right? Mine vibrated around 45-55 mph, before I changed it, but it was definately noticeable

gspfunk

U-joints usually cause more of a clunk, but if they were really worn or damaged they could throw the drivetrain off....

showco77

I am sure that driveshafts like any other rotating assembly were balanced at one point, most likely right after they were manufactured. Also, it wont be vibration free unless it is also straight. Thus, if your u joints are worn, that could do it also. If you plan on keeping it for a while still, start by checking the u-joints, then replacing if needed, then look at a new driveshaft, or re-balance (don't know whats cheaper). Hope this helps.

Paul

MEM 302 5.0L

My car did this awhile back, after i changed the rear end. The problem ended up being where the driveshaft connects to the rear end. There are 8 holes that the driveshaft can connect to, but it only uses 4 of them, I just rotated the driveshaft clockwise one hole.

nmerrill

Yeah, if you have recently had the driveshaft out i would check the holes and make sure they are right. Is it a longbed/shortbed extended cab/regular??? I know some of those trucks had a split shaft with a carrier bearing in the middle bolted to a crossmember, and the bushings sometimes go out in that unit. Check that thing, it would cause vibration