soulbounder

Looked at an 89 TTA today. Not a collectors car, but a pretty good driver. Has 77k miles. Engine has an upgraded or refreshed valve train, turbo, new motor mounts, etc. The car looks sorted out but the engine shakes more side to side than I've ever seen before. Under load, it seems to smooth out. He was saying it was very common on the Buick GN for this to happen. He even had a strap inside the engine bay he can use to put tension on the motor through some bracket attached to the top of the alternator.

Anyone have any knowledge on this topic? I want to make sure this isn't some issue trying to be passed along as normal.

LiquidBlue

seems odd. happy you are verifying for the truth.

RBob

iTrader: (1)

It is normal for the even-fire Buick V6 engines to rock at idle. The crank rod pins are offset which doesn't help in this regard. How the engine is balanced also affects this rocking. A 36.6% balance puts the vibration in the horizontal plane. IIRC this is what GM used on these engines.

Balancing at 50% puts the vibration in both the horizontal plane and the vertical plane.

RBob.

instro84

mine doesn't shake could be motor or trans mounts

soulbounder

I did some more searching and reading and it does appear this is pretty normal. The two most common solutions I've seen are to use HR Mounts poly motor mounts (this helps with the shake, but does transmit more vibration throughout the rest of the body), or use a torque strap or motor brace of some kind. I supposed you could also use some combination of the two. Thanks.

soulbounder

Just as a final update, the alternator wasn't charging which could have been contributing to a miss in the ignition causing extra shaking. After replacing the alternator there is what I would consider a normal amount of engine shake.

instro84

i'll shoot a vid for you when i get home this weekend, don't think mine shakes much, but it did when had a miss from bad plug wire

TTOP350

iTrader: (8)

A turbo tweak chip with larger injs really helped the last one I had.

Bob88GTA

iTrader: (2)

^^^^What TTOP350 said^^^^^ Also check your 3 torque converter bolts. Mine were very loose and it shook like a bast@#d!!!

82tarecaro

iTrader: (4)

The 3.8 turbo had vibration issues which is why the torque arm is mounted differently. The later fwd versions added a balance shaft to fix the vibration. Mine has a pronounced vibration at idle as well and it runs strong. If you go with poly mounts the vibration will become more pronounced throughout the car.

soulbounder

It is running pretty well and I think what I'm now seeing is normal.

The car has modifications already. Among the ideas listed above, it already has a turbotweak chip, 80lb injectors, and powerlogger with scanmaster. Kurtz Stage 2 transmission, and a Husek 2800 stall convertor.

Thanks!

instro84

sounds like a good car with good parts on it.

soulbounder

The last owner put some good parts on it. I have a list somewhere. I have a ton to learn for sure.