My SN 95 vibrates badly at speeds over 100MPH (done at the track, under controlled circumstances of course!). I can let off the throttle at the higher speed and the vibration remains untill around 80 MPH. Has anyone else had this problem? How do I fix it? My 1st inclanation is to balance the drive shaft, what do you guys think? Another gentleman in my office said that it may be the tail stock bearing in the tranny? It is a stock t5 transmission.
I don't see a sig so....are you running gears???? how bout an FMS Aluminum DS????
have you checked the u-joints??? any noises when doing slow turns or backing up??? those are some signs of bad u-joints...
i just got my Romac today..see that rubber coming out the back of the stocker...that'll give you a vibration....took it off one with 104k and a severe shake...
OK, After weekend update: I run a machine shop, mainly in pump repairs for the petrochemical industry. We have a balance machine here on site. I brought the drive shaft in and replaced the U-Joints and balaced the drive shaft. We balanced the drive shaft on a machine that is state of the art. In order to balance the DS we removed the ujoints and welded on weight to correct the imbalance. I still had the vibration even after the balance and new u-joints! Damn what is it? Since we are not DS balancers maybe we did it wrong?? As far as the harmonic balancer is concerned, wouldent I see the vibration @ high RPM's? I only see the vibration at high speeds and can disengage the transmission & shut the engine off and still have the vibration. My machinist did tell me that the shaft has a slight twist to it should I replace it?
You're right about the harmonic balancer, it would be rpm related, not mph. The DS is twisted? You need to fix what you know is wrong before you can find what you don't know. The obvious places to check are; tire balance, ds balance and straightness, and trans output bearing. BTW- an aluminum driveshaft is not that easy to "bend". I'd suspect tire balance or rim out of round if your DS was straight. A bad tranny output bearing should have more symptoms like oil leak due to DS wobble eating up your tranny seal and maybe hard acceleration vibration not just on top end. (but I'm not sure it's not the bearing)
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Have owned 10+ 'stangs from 65-95.
1st was '65 289 3 speed (bought from original owner for $300, body was straight-no rust), fastest was '86 coupe with 468 and aluminum CJ heads, current car is '95 Cobra with 18x9 and 18x10
.5 rims full length headers, SLP exhaust, K&N cool air.
I called a good freind of mine and asked the same question about the vibration. He said that it sounds like the transmission mount is sagging causing the drive shaft to pinion angle change. He reccomended supporting the axle housing with jackstands, removing the rear wheels and bringing the car up to the speed that the vibration started. Then he reccomended shimming the tranny mount to remove the vibration. Sounds kinda interesting and dangerous at the same time! I do not know what a syncro acts like when its crapping out, would the vibration still occur even with the transmission disengaged?
The car has 97K miles on it, the wheels & tires are new 2003 GT take offs from Ford, vibration is ONLY at high speeds - no abnormal vibrations at normal operation, the twist that I mentioned before was a maximum of .010 runout - I do not know what the maximum is - Any Ideas? We balanced the DS here in my pump shop AGAIN, dont know what a standard balance procedure is from a shop that does the DS balancing, maybe we missed something? My initial thougt was the DS out of balance. Maybe the problem resides in the tail bearing of the transmission- has anyone ever had this problem with a bearing going out in the tail stock of the transmissiion. This is about all I have, I wish I could just pop in another driveshaft to put that theory to bed!! Anyone in Houston Tx. that happens to have a DS in their garage that would be willing to send it out on loan?
Vibration @ High Speeds 
