65mph + = bad..why

[DMAN302]

I have been bombing around in my 88 since I had the 3.73's put in a couple months ago and not noticed much in terms of bad vibes untill tonight. I had her up on the highway for the first time since the install and got to say once I crossed passed 63-65 mph+ the ride became kind of ignorant. The shifter was shaking (but it does that pro-5.0) but there was some serious noise coming from the shifter and vibes from what seemed like the drive line. With gas pressed the car shimmied but it did not transfer up the wheel you could just feel the shake, and when the clutch was engaged off the gas there was still some serious noise and vibe untill I droped below 60 mph again and all was well. What causes should I be looking for..here is what I'm thinking.
1. Bad wheel bearing
2.bad motor/tranny mount
3.drive shaft
4. rear end..but runs fine at lower speeds fairly quiet for having gears
5.crappy tires..but didn't notice vib prior to gear install
6. help me figure this out.

 

[ECU5.0]

drive shaft more than likely...common problem after gear install. get an aluminum one and you should be fine

 

[90mustangGT]

drive shaft more than likely...common problem after gear install. get an aluminum one and you should be fine

Agreed

 

[281pony]

id say its somewhere in your rear or with the driveshaft. ocassionally my car with vibrate if i get into the upper rpm's in fourth. has the dogbone been removed?

were the gears installed properly by a shop? seems like they might be getting a bad mesh at speeds over 60. like my gears howl at speeds over 40 from a bad mesh.

just throwing out some idea's. good luck

 

[2000xp8]

Did you work on your driveshaft recently? I always go and retighten the bolts, they don't like to stay in for me.

If not, just get an aluminum driveshaft, they are well worth the money.

 

[89MustangGX]

Sorry, still trying to figure out how the ride got ignorant...?

 

[HISSIN50]

Sorry, still trying to figure out how the ride got ignorant...?

the ride was ignorant about being vibration free.

 

[89MustangGX]

the ride was ignorant about being vibration free.

Oh...the car didn't know it had vibrations until the driver showed it that it did...?

 

[HISSIN50]

Oh...the car didn't know it had vibrations until the driver showed it that it did...?

Adam, i was trying to think of something cute, but that original statement was so weird (i cant even think of a word he was trying to think of), that i could not do any better.

 

[DMAN302]

Oh I see how it is now...the thread stealing eh....that's fine you two just keep making little smiley faces at each other and I'll be over here with my car vibrating and not knowing it......LOL

 

[5oh4fun]

It's probably the drive shaft. Hurry up and order one from Summit before July 1, heard the price is going up on the by about $100 after that. Had the same problem on a previous stang and the drive shaft made it drive like a whole different car. It was great! Good luck.

 

[89CopCoupe]

It could've been the fat chick in the passenger seat throwing the tires out-of-round

 

[DMAN302]

I think my wife will enjoy that..I will tell her when she get home tonight.

 

[5ive.oh]

I ordered my FMS aluminum one over a week ago, the dealer called me like 5mins ago, said they have not ordered it yet, and now the price is doubled! The ass's wouldn't even honor the quoted price! So now my car sits with a busted driveshaft and I have to go to a junkyard and get a used one for 150 bucks. I am pissed.

 

[89CopCoupe]

I think my wife will enjoy that..I will tell her when she get home tonight.

Keep my name outta it :worship:

 

[DMAN302]

Just purchased from Summit 20minutes ago...168 out the door shipped today..paid done.

 

[dastang2]

a wheel weight could have came off or a tire could have gotten a bad spot in it. i am not sure about the gears/driveshaft change since i have not done that yet, but i know my car started to viberate very badly for a day and then the back tire blew. i got new back tires and the viberation was gone. all of this started after i gave a very heavy friend a ride. over 300 pounds

 

[HISSIN50]

all of this started after i gave a very heavy friend a ride. over 300 pounds

LMAO. ok, the solution is to let him drive the same distance on the same road, and it will get the car back to 'equilibrium.' LOL.

 

[battyice]

For future reference, it is always a good idea to check the driveshaft bolts to make sure they're tight. Also a good idea to check the u-joints and make sure they aren't loose.

 

[gt90stang]

Also read these:

http://home.hiwaay.net/~ctfrench/Driveline Vibration.htm

http://www.tccoa.com/articles/tranny/transmission/page17.shtml

Good Luck, Don