Still vibrating after 4.09 install
Thread Starter
Burning Brakes
Joined: Jun 2000
Posts: 1,148
Likes: 47
Still vibrating after 4.09 install
Well, I had the gears put in a 6-7 weeks ago and I had some bad vibrations at 55mph and up. I since then have rotated the driveshaft 180degrees and have replaced all 4 rotors which did help a lot however now at 75 mph and up I'm getting vibrations. Prior to the gears being put in, the car was as smooth as silk at 110mph+.
Now, I am not blaming this on the gears themselves I just think that perhaps the extra RPM coming from the output shaft of the tranny is magnifying a prblem I may have already had but couldn't tell as much with 3.45:1 ratio.
My driveshaft was fund to be in balance but has .040" of runout.
Anyone have any ideas as to where to look next or has anyone else come across this problem with their install?
U-Joints are good, new hub bearings all around this year, Firehawks are balanced but are almost bald, however it doesn't feel like a tire/wheel vibration because I can feel it a lot in the shifter.
My first guess would be a new driveshaft but I'm still not %100 sure on that.
Now, I am not blaming this on the gears themselves I just think that perhaps the extra RPM coming from the output shaft of the tranny is magnifying a prblem I may have already had but couldn't tell as much with 3.45:1 ratio.
My driveshaft was fund to be in balance but has .040" of runout.
Anyone have any ideas as to where to look next or has anyone else come across this problem with their install?
U-Joints are good, new hub bearings all around this year, Firehawks are balanced but are almost bald, however it doesn't feel like a tire/wheel vibration because I can feel it a lot in the shifter.
My first guess would be a new driveshaft but I'm still not %100 sure on that.
Burning Brakes
Joined: Dec 2000
Posts: 1,161
Likes: 0
From: Orangeburg, NY
Re: Still vibrating after 4.09 install (Vette Threat)
Did you remove the shafts to the wheels? If so, retighten the bolts in th emiddle of the rims. This happened to me and once the bolts were retightened, no more vibration.
Instructor
Joined: May 2002
Posts: 105
Likes: 1
From: Garland TX
Re: Still vibrating after 4.09 install (Vette Threat)
I know this one! Driveshaft phasing. You did not install the driveshaft in the same position as it came out. Either at the transmission yoke or at the differential. It has to do with balance and wear patterns. Try re-installing the driveshaft 180 degrees out on the yoke then the differential. Do NOT drive the car for an extended period of time without correcting the problem. Otherwise you will be replacing bearings, bushings, seals, yokes, etc. In the future mark the "phase" of the drive shaft relative to the yoke and the diff. Use paint! Driveshafts do NOT like dings, dents or scratches. Let me know how it turns out. Yes, the same scenario plays out on the half shafts. Just to a smaller degree.
Glassman89
Glassman89
Racer
Joined: Jul 2000
Posts: 421
Likes: 0
From: Glen Burnie Md
Re: Still vibrating after 4.09 install (Vette Threat)
Jim,
I'd be willing to bet a dollar to a dough-nut, it's your tires.
If they're almost 'bald' as you say...then there are two things happening that are causing your vibration problems.
#1...Picture this...you are running down the road at whatever MPH, and you are feeling every 'tread height indicator', while doing so. (it must feel like you're running over cobblestones?)
#2...In addition the 'steel' in the tires (now that they're almost bald) that are imbedded in the rubber...are now 'wavering' as you drive along (if you let go of the steering wheel...it should feel as if the car is trying to go every which way, but straight?).
If all 4 tires are nearly bald as you say...then you can multiply by 4 and see that the tires are actually magnifying your problem.
Before you do anything more to cost you money, and time...get a new set of tires,...that way you would be eliminating potential problems, that is probably your main problem all along.
Good Luck!!
John
I'd be willing to bet a dollar to a dough-nut, it's your tires.
If they're almost 'bald' as you say...then there are two things happening that are causing your vibration problems.
#1...Picture this...you are running down the road at whatever MPH, and you are feeling every 'tread height indicator', while doing so. (it must feel like you're running over cobblestones?)
#2...In addition the 'steel' in the tires (now that they're almost bald) that are imbedded in the rubber...are now 'wavering' as you drive along (if you let go of the steering wheel...it should feel as if the car is trying to go every which way, but straight?).
If all 4 tires are nearly bald as you say...then you can multiply by 4 and see that the tires are actually magnifying your problem.
Before you do anything more to cost you money, and time...get a new set of tires,...that way you would be eliminating potential problems, that is probably your main problem all along.
Good Luck!!
John
Thread Starter
Burning Brakes
Joined: Jun 2000
Posts: 1,148
Likes: 47
Re: Still vibrating after 4.09 install (Glassman89)
Thanks for the input Glassman89 but I already tried that and even though it did improve, there is still vibration present that was never there before.
