need help with 93 SE KC, no one can fix.

I've never worked on your type of truck, but I wonder if it could be transmission related?

You didn't mention if it was an auto or manual, but what happens to the vibration when you put it in neutral? (Obviously don't slam it back in gear if this is an automatic at that speed, so be careful) If the vibration goes away, it clearly isn't anything related to the wheels or axel.

On cars I've seen a bad motor or transmission mount cause vibration and resonance like this as well.

Remco

Remco, its a AT. I also wondered about the tranny. The tech did not think there was a tranny problem, but was not 100% sure. When you get above 39 and put it in neutral the noise/vibration is still there. I forgot to add I have pulled a trailor withit for the past 5 years with my lawn equipment on it. Has 181k miles. Thanks

Weird - that driveline bearing would have been a likely suspect but that's been changed already.

This may be totally offbeat, but are you sure it isn't tire related? They do develop soft spots over time and maybe this is what unbalances it all. It could be easily checked, swapping the tires to the back to see if that helps or changes things.

Remco. I rotated the tires few weeks back, made no difference. The dealer I took it to has a tech that is the best at tire problems. He quickly told me that it was not a tire noise. Wished it were that easy!

That's a weird one. Have they checked the suspension? And it is always 39 mph on any road? If you go uphill/downhill does that speed where it makes noise change?

I remember reading a while ago on one of these groups that if you see the vibration in your rear view mirror, it tends to be tire related. If it is a low frequency noise or hum, it tends to be driveshaft related -- I am not sure if that is a true statement or an old wife's tale, but perhaps others here could confirm that. (if anything, it will keep this thread on top of the pile, so eventually someone might know what's going on)

My exposure to trucks is fairly limited (F-250) but they can't be that different from cars, right :)

Remco, it does not matter what type of pavement your on or going up hill either. When you hit 39 it feels sorta like the truck has electrical current going thru the floorboard and the noise is constant right up on up to any speed above 39. I have the truck for sale and I hate to sale it like this. It is not an unbearable noise but is noticable. Now someone might test drive it and not even notice it but I would.

A friend of mine had the same issue. On his it turned out to be the drive shaft. One of the balancing weights had fallen off, and once he had it re-balanced it was fine.

Well, that sounds very plausible since you started hearing that noise suddenly, right Danny? If that's it, goes to show you that one learns something new every day.

I got some additional info that may be more helpful. I talked to a tech today who used to be one of the best nissan techs around and had just got out of military. He told me he had a nissan identical to ine down to the color with the same problem that he had spent 3 weeks working on and off. Changed rear end (new) new driveshaft, center bearing and u-joints and did not fix it. Finally found out was the At tranny. Customer told him not to fix would drive till it quit. I took mine out today and ran it up to 65 and pushed it up in neutral. When I did the truck started surging intermittingly like you were smashing the brakes on and off. The tach also moved up and down between 1500 and 1800 rpm. When I got down to below 40 it smoothed out. Im not sure this is the tranny? I have a

2000 Tundra that goes thru brakes and cant keep the tires balanced on. I have both these babies for sale and there will be a NEW under WARRANTY vehicle sitting in my yard within the next 2 weeks!! Enough of this crap. When I get a vehicle or a woman that aggravates or dolllars me to death they are history!

wow -- weird how even the tech couldn't for sure tell what the problem is.. One would expect that to be an exact science. That you and me shady tree mechanics are stumped, is one thing.

Well, let me know when you find one that doesn't aggrivate you.. ( a woman, that is :)

Remco

Exactly Remco. If he cant guarantee me the fix Im not spending another cent on it. A rebulit tranny is 2000 and a junk yard is a 1000 and the truck is only worth about 3 grand. If these 2 vehicle are not sold by the end of the week they will be traded (give away) on a new one. I will say my nissan looks and runs brand new other thean the driveline noise. Im waiting to see if someone makes me a decent offer for it.

Oh BTW Remco, there is no such woman : )

Oh, man!?!?! Now you tell me!!!!! :)

Good luck with your new truck, once you get it.