has been doing this for a while, not sure if it's getting worse but it's not getting any better. At about 75-80mph in OD, at light throttle loads the car vibrates/shudders like a manual trans, when in to high a gear, then goes away around 90. If I give the near/full throttle and bring the car up to the same speed there is no shudder? I don't beleive it does it when in D but not sure. Could this be a converter/trans problem, or something els? Thanx.

 

just wondering sorry if a dumb question but have you check the balance yet?

 

no, but I did get the car up to 120 last night racing(and beating) a 99 stang GT on a desrted highway last night and yes it was shaking alot. Tires could be out of balance but if they were that shouldn't have anything to do with the car shuddering around 80 in OD and not D. I need to make sure it doesn't vibrate/shudder in D at that speed, but I don't think it does.

 

probabl;y tires out of balance or the driveshaft

 

You're an idiot. Sooner or later you're going to hurt someone. Save the racing for the drag strip. While I'm up on my high horse I'll point out that the speed limit in most states is 65, 70 in some states, so a vibration at 80 should be no concern of yours.

 

I had the exact same problem, shuddering at 73-79 mph! above or below it was smooth as glass. It wound up being the driveshaft. have it checked before it does damage.
Out in Colorado the speed limit is 75 Coach Hawk and if your doing less than 80 your in the way!

 

I set cruise to 80 when I go back and forth to the shore. This is in NJ, where the lmit is 65. There usually isn't people passing me at 80, but there is a lot of people passing me if I drive at 70.

As for the vibration, probably driveshaft, get a 4th gen alum. driveshaft.

 

speed limit is 70 out there on I-4 and your getting passed if your not doing atleast 80, regardless, it shouldn't shudder, and I said "deserted highway" and if a car, especially a Mustang is going to get on my a$$ and try and pass me late at night, with no other cars around, I'm not going to go down without a fight, thats one of the reasons why I like having a gas guzzling fast car instead of a Honda. I was thinking it was driveshaft or converter, but need to see if the vibration is there with car in D, if it's not, it could,'t still be the driveshaft right?

 

It doesn't matter what "gear" you are in! A bent or out of balance drive shaft doesn't care.

 

have you checked your transmission mount??

 

I don't beleive he asked for an opinion on how he should drive the car. I don't condone street racing either, but this isn't the place for that debate. Half of us are emmisions "IL"legal too. You may want to consider another site if mere mention of these activites bothers you. Again, it doesn't make it right, and I don't condone it either, but that's not the point of the thread.

Sorry for the offtopic.

Driveshaft? Wheels/tires? An old worn out trans mount could do it too.

.....maybe something to do with the converter lock-up???

 

 

thats why I'm thinking it's transmission related if it only happens when the car is in OD, still havent had the chance to make sure. The transmission mount was just changed and there is no "banging" if I step on it at low or any rpms, and thanx 4 the backup Abubaca I'm very careful with driving my car, and that was actually the first time since I had it I got it up to that speed.

 

West Texas just raised the speed limit from 75 mph to 80 mph a couple months ago.

 

Sweeet.