Vibration after gear install..?

[Blown2004Stang]

I had the dealer install a set of FRPP 4.10 gears into my '11 GT last week. There was a bit of vibration, which I figured was the driveshaft not being properly bolted back in it's indexed location. Well, sure enough, we put it on the lift, and it's off 2 bolt holes. So, we line it back up, and go for a spin. The vibration is just about gone, but, still just a tad bit between 50-55mph. It's more noticeable during deceleration, but, it will vibrate if you hold steady speed at around 55mph. There's also some vibration over 80mph or so..

What do you guys think? Is there anything else that could be causing this?

Travis

 

[Blown2004Stang]

I thinking that it might just be the stock drive shaft.. We went from 3.31's to 4.10's, so it's a pretty drastic jump. Maybe switching to a 3.5" aluminum shaft will help?

 

[69gt4speed]

I know this 03 cobras had some issues w alum driveshaft. We would try all positions. You could also find somebody to rebalance it. But the alum could get you .2 sec gain. Yea you are right gears show any imbalance esp that much change.

 

[Jimmysidecarr]

I would re-balance the rear wheels and then mark the tires at the valve stems with something subtle but something that won't wash off right away.

It is very common lately for modern high grip tires to rotate on the wheel, both braking(mostly up front) and acceleration(rears).

Then see what you end up with and watch those marks.

The Toyo tire link(PDF)
http://marktg.toyotires.com/file/rimslip.pdf

 

[Blown2004Stang]

lol.. bead locking OEM wheels would be funny..

 

[argetni]

Now you have a vibration and a shimmy?

 

[kingnut]

i like how the dealer f'd up the install to begin with. :face:

 

[2013Boss302]

i had my 3:73 replaced under warranty, and after the install i noticed a vibration but mine was at 100 - 120. i took it back and they said it was a wheel weight that was off. they said they fixed it. i took it on the freeway late at night and the same thing was still happening. my car pulls fine, its just that vibration at 100 then i let off the gas and it gets worse till i slow down. its bad enough that i cant even use my mirrors. if anyone has info on this please let us know.

 

[stang1971]

i had 4.10's put in a couple weeks ago and i didnt have a single vibration. i have been using the same guy since 92' and havent heard a single complaint about the guys work.

 

[Blown2004Stang]

Took the car for a 2 hour road trip yesterday.. I noticed at 80+ it just barely vibrates. You can only feel it on a smooth road, but it's there. Also, there's a ton of whine past 80...

Travis