Thud and jaring from start

[Phantom]

I never noticed it before I had the shift kit but I never drove the car hard and i have only owned it since January. But I added the shift kit and changed the filter and fluid to Dexron VI. After filling it starting it and checking the fluid I took it for a little spirited drive.

First time from a 2-3mph roll and getting on it there is a slight hesitation followed by a bang and the tires breaking loose.

Next I drive it for a bit after rechecking the fluid and its fine, this time I stomp on the gas and have the same issue.

Now if normally drive the car it does not happen it only happens when it use a lot of throttle.

I also noticed when doing this if I have the car in drive and brake torque it at about 2000RPM it feels like something lets go then the car bangs and feels like it was a harsh shift in to gear.


What could this be and what can I check the car has almost 100K and is mostly stock. I'm hoping that it is just motor mounts.

[LeSabre in Buffalo]

I'm thinking it's my rear drivers side transmission mount, but am not positive. Mine does the exact same thing, and has 102k miles on it. It's either that, or it's an early 4T65 issue. New fluid/shift kit/filter didn't help me, either.

The mount's cheap enough, so one of these weekends when I'm ambitious I'll replace it.

[Phantom]

Thats good to hear I guess now time to find some pics to show me what the motor mounts should look like on the car.

I had felt the issue one other time when brake torquing but thought that it was due to the hard shift issue I had when the trans was hot. I was assuming that it was not the trans as when I dropped the pan other than having very dirty oil there was no metal and only a little gray sludge in the pan.

[Phantom]

Update:
Today the Torque axis mount arrived and I promptly replaced it. The old one was not destroyed but it was close I could wiggle the rubber in the mount easily and it was deformed in a few places like it was being side loaded.

After taking it for a spin the delayed/double shift feeling from 1-2 WOT is gone. When brake torquing it at about 2000RPM it feels like the TQ converter is just sending power to the wheels no harsh banging there.

The one issue it still has is from a 2-3mph roll and getting on it, it shutters a bit and still has a bang/slam to it but not as bad. Does any one have a picture of the drivers rear side trans mount as I have not located that hidden one?

[willwren]

Tough to get a pic of it. You'll need to get under there. Rear crossmember of the subframe on the driver's side to the rear of the trans. Sandwiched between the subframe and trans.