So guys, i've noticed that when i drive my 7, that for the longest time it would vibrate when i hit 40 miles an hour in 4th gear. Sometimes it does it and sometimes it doesnt. It sounds kinda like a really really deep bass sound.

The thing is, in 3rd gear at 40 mph no vibration, no other gear does it and if i shift to 4th gear before 40 mph it wont do it. It only happens when i shift to 4th and when i hit 40 mph. It also stops when i hit 50.

So in 4th gear at 40mph its just vibrating like a really deep bass sound then at 50 it stops.

Any ideas? i'm stumped, my engine is bolted down, my plugs are new, my plug wires are new. so i have no clue as to what the hell is going on, it really sucks for long streets.

 

Your driveshaft's u-joints could be going out.... I mean.... usually that would be in any gear... but under certain loads it can happen too... In my Wrangler, I would get vibes in 2nd gear between 2000-3000rpm, but not in any other gear.... replacing my u-joints fixed it.

Definitely not wheel balancing. Maybe diff mounts?

 

you know, i didnt think of that (usually cuz i dont think of little things like that) but i'm not so sure it could be my u joints.

Of course i'll look to be sure but i need more input too.

thanks buddy

 

id jack up the car and see if u can move the driveshaft in weird ways.
i drover around on effed up u-joints for about 3 months. it got so bad that if u first startred it up cold and drove down the road it felt like the car was gonna fall apart.
got a used driveshaft and it worked good for about 3 weeks now im started to wear them into.
get a used driveshaft int he forsale section that is in good condition and see if it helps any.

 

I apologize OP if this is a thread hijack...I honestly dont mean to, but I have a somewhat similar issue and didnt think it good to start a new thread for something similar. OK

In every gear, at about 2500 RPM and again at about 4500 PM I get a shake. Its very very subtle and unless you drove it everyday you probably wouldnt notice, but I do. It's not making any noise that I can tell, and like I said very subtle.

Ideas?

Oh...91NA standard tranny

 

you should both be looking at your U joints soon. If the Driveshaft breaks you'll need a new tranny also.