Vibration at 65mph after rearend rebuild
08-31-2009, 05:48 PM
#1
Thread Starter
Join Date: Jan 2009
Location: Wisconsin
Posts: 15
Vibration at 65mph after rearend rebuild
Hello everyone, really need some help on this one...
I just rebuilt my rearend on my 95 GT, 3:73s with a Ford Racing Limited Slip differential, new axles and all brand new bearings. I have .013 backlash and the ring is making full contact with the pinion gear.
The car drives perfect from 0-50 mph no shaking no grinding or slipping.
However, when I hit 65 or above the car starts vibrating through the shifter and I hear some humming throughout the car.
I heard that it could be that my Driveshaft is out of balance, but I don't know how to fix it, if that is even the problem.
The car did not vibrate at all at higher speeds before the upgrade.
Anyhelp would be greatly appreciated!
I just rebuilt my rearend on my 95 GT, 3:73s with a Ford Racing Limited Slip differential, new axles and all brand new bearings. I have .013 backlash and the ring is making full contact with the pinion gear.
The car drives perfect from 0-50 mph no shaking no grinding or slipping.
However, when I hit 65 or above the car starts vibrating through the shifter and I hear some humming throughout the car.
I heard that it could be that my Driveshaft is out of balance, but I don't know how to fix it, if that is even the problem.
The car did not vibrate at all at higher speeds before the upgrade.
Anyhelp would be greatly appreciated!
08-31-2009, 05:52 PM
#2
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
It could be driveshaft issue. You'd have to go to a shop that specializes in it and they would counterweight the driveshaft. Also driveshafts generally need to be put back the same way they are removed. Did you mark the tranny output shaft, driveshaft, rear pinion so everything was aligned the same whay when you put it back?
Have you had the tires/wheels checked? 60-70mph is generally tire vibration territory. Check there first.
Have you had the tires/wheels checked? 60-70mph is generally tire vibration territory. Check there first.
08-31-2009, 06:24 PM
#3
5th Gear Member
Join Date: Dec 2006
Location: louisiana
Posts: 2,763
Nope, its not driveshaft.
You have a driveline vibration and since you have humming, its probably the rear end.
What brand are the gears?
Do you have pictures of the gear paint pattern?
I am willing to bed your carrier shims are off and that is causing the noise (incorrect gear mesh) with the backlash still within spec.
I believe the spec was something like .008 to .015, so if that is right, you are still in spec there. If you change the side shims (carrier shims) the backlash will also change.
You have a driveline vibration and since you have humming, its probably the rear end.
What brand are the gears?
Do you have pictures of the gear paint pattern?
I am willing to bed your carrier shims are off and that is causing the noise (incorrect gear mesh) with the backlash still within spec.
I believe the spec was something like .008 to .015, so if that is right, you are still in spec there. If you change the side shims (carrier shims) the backlash will also change.
09-01-2009, 05:18 PM
#4
Thread Starter
Join Date: Jan 2009
Location: Wisconsin
Posts: 15
Sadly, I did not take any pics of the mesh between the pinion gear and ring, but I used the stock shims of the diff which were in great shape. I have a Ford Racing Pinion, ring and diff. there was full contact on both gears when I used the marking compound.
Again, sadly, did not mark the companion flange b/c I used all new parts on the rear end and I did not think that it would have mattered.
Thanks for the help...
Again, sadly, did not mark the companion flange b/c I used all new parts on the rear end and I did not think that it would have mattered.
Thanks for the help...
09-01-2009, 06:53 PM
#5
5th Gear Member
Join Date: Dec 2006
Location: louisiana
Posts: 2,763
Well heres the problem, if you REALLY know what your looking at, you can read the contact pattern and tell if its too far heel or toe, and high or low and if the pattern is too thin.
Another thing that came to mind is the pinion crush sleeve, what did you tighten it to and what tool did you use to do it with?
Another thing that came to mind is the pinion crush sleeve, what did you tighten it to and what tool did you use to do it with?
09-01-2009, 09:10 PM
#6
Thread Starter
Join Date: Jan 2009
Location: Wisconsin
Posts: 15
Okay, I tried putzing with my driveshaft tonight rotating it 90 and 180 to no avail, however, the car is not humming it is definitely vibrating at higher speeds, the vibration feels as if it is coming straigt up from the center counsel and shifter boot. I also inspected the driveshaft and there is one dent it in near the pinion gear. the u joints also felt tight.
Admittedly, this is the first time that I have put in a pinion gear and ring, the sleeve took approximately 250lbs to crush and preload read out to 12 in/lbs. I used a 1/2in socket wrench with a breaker bar to crush the sleeve. The ring meshed about 1/4 in down from the top of the pinion, and I had full tooth contact. The Diff spun true in the housing and it seemed as if the compound was the same thickness across the tooth. It could have been too light but i'm not exactly sure what it should have looked like. Anyway, let me know what you think, that's about the best I can explain it.
Admittedly, this is the first time that I have put in a pinion gear and ring, the sleeve took approximately 250lbs to crush and preload read out to 12 in/lbs. I used a 1/2in socket wrench with a breaker bar to crush the sleeve. The ring meshed about 1/4 in down from the top of the pinion, and I had full tooth contact. The Diff spun true in the housing and it seemed as if the compound was the same thickness across the tooth. It could have been too light but i'm not exactly sure what it should have looked like. Anyway, let me know what you think, that's about the best I can explain it.
09-03-2009, 08:09 AM
#8
4th Gear Member
Join Date: Jan 2007
Location:
Posts: 1,999
If you had a taller gear before. Switching to steep drag racing gears can easily amplify a driveshaft problem.
It may have vibrated before but with the driveshaft running at a lower speed, it may have not been noticeable. Now that it's running at warp 9, nothing short of perfect is required.
The easiest and a relatively cheap upgrade is a FRP aluminum driveshaft.
Not because al is balanced better, just easier to balance a lighter shaft and it's brand new vs 15 years old.
It may have vibrated before but with the driveshaft running at a lower speed, it may have not been noticeable. Now that it's running at warp 9, nothing short of perfect is required.
The easiest and a relatively cheap upgrade is a FRP aluminum driveshaft.
Not because al is balanced better, just easier to balance a lighter shaft and it's brand new vs 15 years old.
09-03-2009, 01:53 PM
#9
The stock driveshaft is only balanced to a certain RPM with the stock gear ratio. After I installed 3.73s, I have the same vibration that you have described. I plan on getting an aluminum driveshaft sooner or later.
09-05-2009, 05:26 PM
#10
Thread Starter
Join Date: Jan 2009
Location: Wisconsin
Posts: 15
Thanks for all the suggestions, I'm probably going to have the Driveshaft balanced, and if that does not solve the vibration, I'll tear it all apart and re-shim the Diff with the tool from Jegs. Thanks eveyone for the imput, much appreciated.
-Randy
-Randy