ironmanLS1

iTrader: (9)

I know there are many topics on vibrations in third gear. I had my A4 originally rebuild with a beast sunshell and had the dreaded third gear vibration. It was fairly bad. The builder changed to a Sonnax sunshell (supposedly) and although better, the vibration is still there.

Does anyone have data to show a before and after how much et or power draw this vibration was consuming? My car is a little slower than I would expect and I am trying to narrow down the root cause. Thanks!

bbond105

There should be no vibration from the Sonnax sunshell.

performabuilt

iTrader: (25)

The power the vibration takes would be unmeasurable however a question are you running a poly mount ? If you are the vibration with any set up is pretty much inevitable. The drive train will always have some vibration and because its direct through 3rd will be the worse this is why GM installed that rather expensive to make liquid filled mount.

ironmanLS1

iTrader: (9)

I am running poly engine mounts and a stock replacement trans mount with the torque arm removed from the tailshaft.

performabuilt

iTrader: (25)

Have you changed the tail housing bushing and inspected the yoke on drive shaft. Also during the trans build was the bushing in the rear sun gear and the rear case bushing changed? Many times they are no and could certainly help create vibration. I change these in all my builds. However with non stock mounts engine or trans some vibration is probably inevitable .

ironmanLS1

iTrader: (9)

The driveshaft is new with a new yoke. If I recall, I think I checked the tail shaft bushing and it was replaced. The yoke fit nice and snug. I don't know about the rear sun gear and case bushing being changed. For what I paid it sure better have been but then again, I really don't know.

performabuilt

iTrader: (25)

I just know these get skipped a lot in a build but have no idea they should always be replaced IMO