I had the same problem. IT went away after I got new shocks, coilovers, CV Axles, Front Hubs and an alignment. If I were you I would go wiht the obviouse first.

1. Tires need balanced ( not likly since it only happens underload )

2. I would go with checking and listening for bad bearings in your hub. Check them by seeing if there is play in the wheel while the car is jacked up. I belive a hand at 6 and 12 is the bearing check and 3 and 9 is for tierod ends.

3. CV Axles ( God, may his axles not be siezed in the hubs ) I know if these are bad, you can check by turning the wheel fully and going in circles and listening for unwanted noises and knocking paird with a slight bump bump bump feeling. Another way I knew my CV axles were bad is when I would cruise at like 75-80 ( wiht slight vibration like yours ) when ever I hit a dip in the road my car would shake reallybad. Like when the car hits the dip and compresses the suspension, just for a couple seconds. Know what I mean?

Start there and if its not those then I have no clue. Good Luck man.

Also see if you need aligned.

Is it possible your rear driveshaft is bent or damaged?

I see by your avatar that the car got hit from behind at one time. How long has it been since the car was repaired? Did it do it before the accident? Was it alright after the repair, and just now starting?

I would give the driveshaft a thorough visual examination for dents, deformation and other visible damage. Look carefully at the U-joints for rust/red dust around the cups. If the driveshaft was repaired, was it rebalanced?

Check the carrier bearings, and their mounting bushings. Make sure the driveshaft hardware at the rear diff pinion is still tight.

Good luck, and let us know what you find.

Also don't rule out engine and tranny mounts. Especially if it vibrates in lower gears at the same engine rpm that it did at 80mph.

I would definitely check your wheel bearings, as stated above check for play in the wheel. I had the same symtoms when one of my wheel bearings was bad. Does the vibration feel like its coming from one side of the car?

The car in the picture was my 97 Talon....it's no longer with us.

The vibration feels like it's the entire car, but mostly from the center of the car, which I thought might have something to do with driveshafts?? But it was weird that it came on only at a high speed.

I'll check the rpm's at 80mph and see if I can get it to do it at the same rpm but lower speed.

I'll check for any wheel play after work today.

I don't know if this relates....but I just had my 50trim with the GT manifold and a tublar o2 housing installed. The o2 housing didn't meet the downpipe 100% so the exhuast had to be stretched forward a little to meet the o2 housing. This caused 3 different spots to rattle or squeek becuase it was rubbing either a heat shield or a mount in the rear.

Well I trimmed off one heatsheild, I put a rubber cap on the rear most hanger by the muffler/can to keep it from rubbing/squeeking against a suspension mount on the right rear side....the 3rd spot the cat back pipe was rubbing against the heatsheild that sheilds the drivetrain mount....I know it's might be a cheep fix but I put duct tape between the heatshield and downpipe, which just muffled the noise, didn't fix it....it didn't seem to be rubbing on the driveshaft just the heat shield.

Anyway it's been like that a while before the 80mph vibration started so I wasn't sure if the exhuast had anything to do with it or not.

I'll check for the other things.


My motor mounts are origional with 115k miles, I'm sure they are ready to be replaced.

Shocks and springs are less than a year old...no major jolts or noise when I hit pot holes or bumps in the road....and these roads are bad here in MO.

So It is only doing it in 5th gear and starts around 3500rpm / 80mph.

Any other gear around 3500rpm I just get a loud humming vibration sound from the exhaust rubbing the heatsheild as mentioned above, but no actuall vibration in the car...runs smooth.

But in 5th gear at 3500, its funny how much it feels exactly like driving on the rumble strips, or whatever they are called.. the things that keep you from falling asleep, on the highway shoulder.

Wonder if it has to do with transmission.... but wouldn't you feel it all the time if there was a problem with the gear?

I have exactly the same problem. I think is something major like the axles or something because once i pass 80 the vibration also transmits to the steering wheel. The vibration is mostly in the front in my case. any additional help.

Thanks

I was getting 2 different vibrations.

The first one was in any gear around 3k rpm. Either cruising or that's when I would shift at normall driving I would get it to. It felt like the motor and transmission vibrating and I could feel it through the shifter. No so much in the wheel.

The second one would feel like vibration/rumble when I was going 70 - 80 mph either going up hill and somtimes down hill. On a flat highway it was smooth. I took a 3 1/2 trip out of town and about a 1/2 hour into it that vibration/rumble just went away. The trip was to a awd dyno. We did around 15 or so pulls and I went back home. I got on the highway and the first incline I hit it started doing the same thing. Than a couple minuets into the drive it went away, again. Then, a couple days later I did a couple 3rd gear pulls on the highway and it started coming and going again.

Now that vibration at 3k rpm now only does it at 2k. It's totally wierd.

All of this started after doing a lot of 3rd gear pulls on the highway.

I've check the axels, wheels and suspension and everything looks good. So I now suspect the motor mounts like mentioned earlier. They are origional mounts with 115k miles on them. I'm thinking too this is why it would do it on an incline at high speeds, maybe the motor is shifting too much.

I've bought oem replacements from Mitsu, I didn't want a stiffer ride than I allready have from my suspension, and just need a couple days to get them replaced. I'm hoping that this sould take care of the issues and will let everyone know.

Ok. I think it might be something different them because I can boost at 7k RPm and is fine.
But once the needle hits 80 mph the shaking starts.

Im having the same issue with my car ATM. Starts vibrating around 3k rpms only when under load, and not when sitting and revving in neutral/in gear. Started happening after i hit a bump pretty hard. Ive changed my wheels and tires just to rule out that is was a blanacing/bent rim/tire broke a blet issue.

I was thinking it was the motor mounts like you have suggested, but then the vibrations would be noticable whenevr the motor is being revved, wouldn't it?

Anyways if you figure anything else out please share your informantion

96TalonAWD,

sounds like you have a balancing/alignment issue because it is related to a certain speed IMO

Willicuddy said:

96TalonAWD,

sounds like you have a balancing/alignment issue because it is related to a certain speed IMO

Click to expand...

Mine "rummble strip" vibration was like that. Only over 70mph but also only on an incline while under load......then poof it doesn't do it anymore.......soooo strange.

I going to try alignment see what happens, even though the car dont steer to the side while driven. But that doesnt explain the steering wheel vibration.

While I was under my car I checked out my motor/transmission mount. It had a hole in it big enough to get my finger through.

I'm sure the mounts are why I'm getting vibration at low rpm's in all gears.

I might not get to change them out until my clutch gets replaced, now that it's slipping.

I was just going through some old stuff and figured I would update this.

I did replace all the motor mounts (oem) and put in a new clutch.

No more vibration I think it was more to due with the new mounts rather than the clutch, although..........
as I was taking out the clutch I noitced that I was missing the bolt in the back by the starter that holds the transmission to the motor. There was a slight gap between the two.
When I put everyting back together I replaced the bolt and made sure everything was snug.

I don't know how long this bolt had been missing....since the last clutch job done by another shop or if it worked it self out (highly doubt it)....either way I don't know if this might have caused some of the vibration, since there was a gap maybe things were moving around too much.

All in all I'm happy with my ACT2600 and everything runs smooth.