Bad Vibration and "whir"
07-18-2011, 09:12 PM
#1
Thread Starter
Join Date: Jul 2011
Location: Indiana
Posts: 11
Bad Vibration and "whir"
2007 Roush Mustang. I bought it used for a great deal. Can't really go wrong finding a Roush right? From the get go it has had a vibration over 70 mph after I let off the accelerator. It goes away when I give a little gas, but gets way worse whenever I'm anywhere over that speed, and feels like it's going to shake apart if I hit 130. I've installed a Steeda adjustable upper control arm, and that didn't change anything. The drive shaft is a Roush Performance steel 4" drive shaft, and the rear end has 4.10 gears that seem to get louder the faster I go. I have noticed tons of posts in regards to the S197s having this problem. Any suggestions? What about an aluminum drive shaft vs. the steel I have?
07-18-2011, 10:14 PM
#3
Thread Starter
Join Date: Jul 2011
Location: Indiana
Posts: 11
Not yet, but I'm compiling a list of the lower end things that I can do before forking out almost $1G for this issue. That and having the drive shaft balanced. Previous owner put 4.10 gears and a line lock system in it...so I know it's been run hard. Took out the line lock.
07-19-2011, 10:17 PM
#6
Thread Starter
Join Date: Jul 2011
Location: Indiana
Posts: 11
Ok, so I get why you guys might think it would be the tires, but it just seems really strange that it really only vibrates as I let off the accelerator. I would think if it was a bad tire, it would get worse the faster I got no matter what I was doing. I definitely will have the tires looked at though, and thank you. Still wondering what the overall opinion is on the steel vs. aluminum solid one piece drive shafts.
07-19-2011, 10:24 PM
#7
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
is the vibration in the butt or the steering wheel?
Rotate the tires see if the shake moves. If it does the you know it's either a bent rim or bad tire/unbalanced tire.
If it doesn't move and its in the butt it's a drivetrain issue like the drivehshaft.
If it doesn't move and its in the steering wheel a brake rotor with out of spec lateral runout could cause it. Could also be a bad ball joint or strut mount.
Tires general have a natural wobble at 60-65 mph which is why most off-the-car tire balancers will balance tires at that speed.
Rotate the tires see if the shake moves. If it does the you know it's either a bent rim or bad tire/unbalanced tire.
If it doesn't move and its in the butt it's a drivetrain issue like the drivehshaft.
If it doesn't move and its in the steering wheel a brake rotor with out of spec lateral runout could cause it. Could also be a bad ball joint or strut mount.
Tires general have a natural wobble at 60-65 mph which is why most off-the-car tire balancers will balance tires at that speed.
07-19-2011, 10:30 PM
#8
Thread Starter
Join Date: Jul 2011
Location: Indiana
Posts: 11
It's in the butt, and all through out the bottom of the chassis...I can literally feel it through the whole car. The drive shaft that is there now, is a Roush steel 4" solid shaft, and I'm hoping it's just out of balance. The guy at the driveline shop is trying to sell me a whole new rear end AND drive shaft...so I'm just getting some opinions. These S197s are new to me, but I'm die hard and want this one to be my baby.
07-19-2011, 10:45 PM
#9
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
so the steering wheel is solid? I'd rotate the tires first. If the butt doesn't feel it anymore but the suddenly the wheel wants to jump out of your hands then you have a bent rim or really messed up tire. Do that before you go any further.
07-19-2011, 10:57 PM
#10
Thread Starter
Join Date: Jul 2011
Location: Indiana
Posts: 11
Thank you. I will update as I go along. Also, if I need to get a new DS at some point, Shaftmasters is just 6 miles from where the Ford plant it located. I have heard nothing but good things about their aluminum shafts, and for the cost they say you can't beat it.