View Full Version : Driveline vibration
Ever since completing my Roadster it's had some drive line vibration. I measured the runout on the driveshaft with a dial indicator and got around .040. Not terrible but more than I thought it should be, and maybe the phasing was out a few thousandths. This was a Mustang driveshaft I had shortened. A new FFR driveshaft came up for sale from a forum member so I thought I'd buy it and see if it helped, if not I could resell it. It helped! A lot. It feels like a whole different car.
Bob
Geoff H
03-13-2017, 07:24 PM
That's great you were able to track it down. What were the symptoms?
Thanks,
Geoff
GFX2043mtu
03-13-2017, 07:30 PM
Drive shaft run out should be around .005". .040" is way to much glad you found the problem so quickly.
GoDadGo
03-13-2017, 07:50 PM
1. What is your pinion angle and your transmission output shaft angle?
2. They need to be within 2 degrees of each other you will have a vibration.
3. If the ends of the shaft are not in alignment, meaning the ends of the driveshaft itself, then this too will cause a vibration.
4. Please see the video shown below because it may help you diagnose where the vibration is coming from:
https://youtu.be/gmV4qwLfOMY
Good Luck!
There was a very distinct vibration that would come in about 70 and diminish at higher speeds. You could push in the clutch and still feel it. I put it on jack stands and you could still feel it even with the transmission in neutral and the clutch in. You could see some movement looking at the driveshaft turning slowly, which is why I put a dial indicator on it. I messed with the pinion angle while on jack stands and it definitely got worse if you lowered the pinion more than 2 degrees. I ended up setting it around 1 degree down. I was also able to improve the vibration slightly by spacing the transmission up a bit higher. I had a 1/2 spacer but ended up around 3/4 inch, then resetting pinion angle. But ultimately the driveshaft was about 90% of the vibration.
Bob
I watched that video you shared. I had never heard of phasing before so it definitely got me looking at the driveshaft closely.
1. What is your pinion angle and your transmission output shaft angle?
2. They need to be within 2 degrees of each other you will have a vibration.
3. If the ends of the shaft are not in alignment, meaning the ends of the driveshaft itself, then this too will cause a vibration.
4. Please see the video shown below because it may help you diagnose where the vibration is coming from:
https://youtu.be/gmV4qwLfOMY
Good Luck!