Stang Myster Posted August 25, 2007 Report Share Posted August 25, 2007 Hey guys, I've been toying around for the last 6 weeks in finding a vibration that only occurs at 100mph and more. The Ford dealer put one new parts (i.e. Driveshaft, Limited Split Clutch, Pinion Set, 4:10 gear and driveshaft hanger). I still have the problem. Then, I took the car to a specrapt and he went by detuction. Removed the wheels, then the Shelby brakes and so on. He measured the offset of the driveshaft for vibration, nothing. All of these test were performed at 100mph + on a special lift. We've concluded that the vibration comes from the connection point of the driveshaft to the differential. Has anyone experienced this before? Will a one piece aluminum driveshaft fix the problem? Link to comment Share on other sites More sharing options...
DeLa1Rob Posted August 26, 2007 Report Share Posted August 26, 2007 What is a specrapt? Link to comment Share on other sites More sharing options...
Stang Myster Posted August 26, 2007 Author Report Share Posted August 26, 2007 What is a specrapt? Oups! Special-ist! For some reason, everytime I type the right word in whole, I get "specrapt". A glitch or something. Link to comment Share on other sites More sharing options...
GPStang06_merged Posted August 26, 2007 Report Share Posted August 26, 2007 One piece drive shafts are recommended with these cars, especially V6's due to the factory ones not holding up under heavy load. Other members here have had there shafts break completely. I am currently having a vibration as well that I believe is related to the drive train all though it feels just like the one I had when the tires fell out of balance. Link to comment Share on other sites More sharing options...
Stang Myster Posted August 26, 2007 Author Report Share Posted August 26, 2007 I've had the wheels balanced also. That was the first thing we did. Also, we change the wheels and tires from front to back. Still the problem persist. Link to comment Share on other sites More sharing options...
stump_breaker Posted October 26, 2007 Report Share Posted October 26, 2007 I've had the wheels balanced also. That was the first thing we did. Also, we change the wheels and tires from front to back. Still the problem persist. Do V-6 Mustangs come with one piece shafts stock? If so, I'm willing to bet your approaching the critical speed of the shaft especially with 4:56's. This happened to my Dodge truck when I changed out the gears to 4:56's. Stock the truck had 3.92 and would not accelerate over ~100mph but with the 4:56's it increased the rotational speed of the shaft allowing it to get to it's critical speed quicker but never exceeding the truck shut off limit. Critical speed is the speed the driveshaft blows apart and you can do nothing to change the critical speed of a shaft except replacement. To make a long story short, my shaft did blow apart right in the middle at ~85mph. I had my shaft tested extensively for balance and so on - everything except determining it's critical speed since it's hard to do after it's been built - so it was within specs. It too was vibrating starting at 78mph and I tried to "push" through it. Bad idea and a lesson in stupidity learned on my part. If you want to know your shaft RPM's the formula is simple - engine RPM's / current gear of transmission (example: 3000rpm's/.65od = 4615 shaft RPM's). On the Dodge truck I had a drive shaft shop determine the critical speed to be ~4200 rpm's, after it exploded of course. That meant I could not exceed 3000 rpm's in OD (.72) without hitting critical speed. At 70mph I was at 2500 RPM's. Link to comment Share on other sites More sharing options...
Paleoc Posted October 26, 2007 Report Share Posted October 26, 2007 Do V-6 Mustangs come with one piece shafts stock? No they are 2 piece soft steel driveshafts (rust quite readily) which makes the situation worse. Link to comment Share on other sites More sharing options...
ilmor Posted October 26, 2007 Report Share Posted October 26, 2007 I'd like to know where you are going 100 mpg, because I want to be there! I may have your issue also, but I apparently won't know about it until SAAC 33! Link to comment Share on other sites More sharing options...
Stang Myster Posted October 27, 2007 Author Report Share Posted October 27, 2007 I'd like to know where you are going 100 mpg, because I want to be there! I may have your issue also, but I apparently won't know about it until SAAC 33! Gents, the car is V8, and you are correct, it's a two piece driveshaft. I actually had the problem fixed somewhat. I had them change the "joint" (sorry for not knowing the correct word) between the driveshaft and the differential. My vibration now starts at 148-150 mph. Above that, the vibration remains. Still, I'm quite happy with the additional speed without the headache. Link to comment Share on other sites More sharing options...
PhoenixCS8 Posted October 27, 2007 Report Share Posted October 27, 2007 Hey guys, I've been toying around for the last 6 weeks in finding a vibration that only occurs at 100mph and more. The Ford dealer put one new parts (i.e. Driveshaft, Limited Split Clutch, Pinion Set, 4:10 gear and driveshaft hanger). I still have the problem. Then, I took the car to a specrapt and he went by detuction. Removed the wheels, then the Shelby brakes and so on. He measured the offset of the driveshaft for vibration, nothing. All of these test were performed at 100mph + on a special lift. We've concluded that the vibration comes from the connection point of the driveshaft to the differential. Has anyone experienced this before? Will a one piece aluminum driveshaft fix the problem? I would have your driveshaft balanced... Link to comment Share on other sites More sharing options...
xyaada Posted October 30, 2007 Report Share Posted October 30, 2007 one piece aluminum is the way to go :angry: B) Link to comment Share on other sites More sharing options...
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