Vibration?

[#1pony]

When I get on my Cobra up to about 100 mph I get a very bad vibration that comes from under the centerconsole and makes my dash vibrate. Could this be a bad throw out bearing?

 

[sled]

A U-joint is probably starting to go bad. if you have gears you may need the fms driveshaft.

 

[LEE93COBRA]

A U-joint is probably starting to go bad. if you have gears you may need the fms driveshaft.

I 2nd that

 

[unibager]

Not saying anyone is wrong, but my 90 saleen had a nasty vib at 90+ mph. Same feeling, shook the dash and all. I had ford gears, ford driveshaft, and thought that the shaft was bad too - it wasnt, but it did cost me 200 to find out. It turned out to be the bearing in the tail section of the trans. I dont know alot about tranny stuff, but I had a tremec 3550. Good luck.

 

[#1pony]

I had 3:73's installed last summer. Should I get an aluminum drive shaft?

 

[sled]

i would start there. then see how it goes.

 

[BADBOYSPACK]

I had 3:73's installed last summer. Should I get an aluminum drive shaft?

There are 3 ways to do this!

1. Goto the local Ford dealer and ask them if they have an EVA, if they do they might charge you 1hr (about $80) to tell you exactly what the problem is.Then give you an estimate on what it will take to fix it.

2. Index the drive shaft 180 degrees, if the vibration changes then you know its the drive shaft. Then try moving it 90 degrees in either direction after the 180 degrees to try to fine tune it. In all honesty I will bet you lunch that its the drive shaft.

3. Try going to a local driveline shop and have them balance your drive shaft on the car.


Its that simple!

 

[LEE93COBRA]

2. Index the drive shaft 180 degrees, if the vibration changes then you know its the drive shaft. Then try moving it 90 degrees in either direction after the 180 degrees to try to fine tune it. In all honesty I will bet you lunch that its the drive shaft.

Yeah since a gear install has been added to the post I will strongly agree. What BADBOY mentioned above is correct but I have never had good luck with a stock driveshaft after doing gear installs for people.

I always recommend to install an aluminum driveshaft

 

[#1pony]

Thanks for the information.

 

[#1pony]

I had my drive shaft spun at a shop and they said it is fine but there is a vibration that comes on at about 85 mph. I know that it is not rpm dependent so what could be causing this? If it is part of the transmission how can I find out exactly?

 

[93cobra#3326]

I had my drive shaft spun at a shop and they said it is fine but there is a vibration that comes on at about 85 mph. I know that it is not rpm dependent so what could be causing this? If it is part of the transmission how can I find out exactly?

sounds like you need a lift so you can get under it safely while running it up to speed to isolate the cause/location of the vib.

ps. you sure its not tire balance related?
rear tires out of balance = seat of pants vib.
fronts = steering wheel shimmy

 

[BADBOYSPACK]

I had my drive shaft spun at a shop and they said it is fine but there is a vibration that comes on at about 85 mph. I know that it is not rpm dependent so what could be causing this? If it is part of the transmission how can I find out exactly?

You need to verify that it is a driveline vibration and not a tire vibration, or a bad strut.

You said the vibration was at 100 mph and now its at 85 mph. That tells me that when the driveshaft was indexed it changed the vibration speed.

 

[#1pony]

You said the vibration was at 100 mph and now its at 85 mph. That tells me that when the driveshaft was indexed it changed the vibration speed.

My fault, the vibration has always come on around 85mph. I am going to get my tires re balanced and then go from there.

 

[BADBOYSPACK]

Good thought, and its the cheapest thing to start with.