Shaking around 50 mph.
 

For some reason my 04 SVTF shakes bad around 55 and up when im accelerating.. Just had new tires and balance and alignment.. What im reading is it could be a motor mount. So im wondering how you can tell what mount is bad or which one might it be.. The car just turned 90k so i know im going to be replacing stuff ...

Did it shake before the new tires/balance/alignment?

no it started about 3 months after.. I took the car to Ga on a trip and it started about half why through the trip.

I had both issues. I replaced my tires first cuz I could visibly see they needed it, and the problem went away. Then it sort of started up again... while repairing an exhaust weld I noticed I also have a broken motor mount. Hopefully that'll fix me up. I ordered a new (better than stock) one from newedgeperformance.com

Thats what im thinking i have also.. guess its time to jack her up...

Sounds like you threw a wheel weight to me. Have them rebalanced using a roadforce tire balancer if it still does at higher speeds like then then maybe a motor mount.

^^ That's a good suggestion.

If it only happened on a trip, it could just be the balance is thrown off again.

If you had a motor mount issue, it would do more than vibrate it would also make a metal to metal sound of the engine bouncing on the mount with a bad rubber.

Ray

You would be surprised how many ppl throw weights after they get new tires or the tires have excessive road force and have to be rebalanced.

Just recently happened to me on my Pathfinder. The days of the stick-on wheel weights...

a Roadforce balance will tell you if you have a bent wheel too.

I had a wheel on the Miata get bent such that the face of the wheel was no longer parallel with the flat part of the wheel that mounts to the hub. Basically it looked round to the naked eye, but threw up like 50 lbs of road force! A rim shop was able to pull it straight/true for me, now only reads a 4 lb road force.