Hi, I couldn't find this problem searching but when I first start the car there is a very loud knocking coming from the tranny (the noise location has been verified). As soon as I put the car into R or D (not quite sure yet about N), the noise stops and it shifts great. Also seems to get better when it warms up.

HELP! Has this come up before?

Thanks.

Are you sure it isn't you're supercharger coupler? That sounds just like it.

Hi, why would that make the noise in park and come from the transmission? Where is the coupler?

Thanks.

P.*. The supercharger is only 3 years old and doesn't make any noise.

Maybe a flywheel problem? One thing for sure, I'm not replacing the transmission. The unibody is gone on this car and if I get into an accident, I think the car will actually wrap around the airbag!

Motor or Trans mounts are suspect....

I had a similar problem with a 4.0 L Jeep with auto. It turned-out to be that the bolts that secure the flex-plate to the engine crank were loose. When the transmission was put into gear, enough torque was supplied to eliminate, or at least noticably reduce the noise of the loose flex plate....

I'll bet it also does it in neutral.... ?

Everything old is new again.

Back in '66, I had a '49 Plymouth flathead 6 with the same knock at idle and when shifting gears. Bolts holding the pressure plate to the flywheel were loose.

Is either of these a big production or ? Also, if I let it go for any length of time can it cause worse problems?

Thanks much

Not a big deal. If loose bolts are the problem it will be fairly easy to fix, and if so, I would not drive it 'til the bolts were tight. Just put the car up on ramps or safely on stands, get under and remove the flywheel cover. Turn the engine 'til you see one of the 3 bolts that attach the flex plate to the torque converter. Get the right size wrench on 'em and see if they are tight. You can hold the flex plate from turning by slipping a large phillips head screwdriver through one of the holes in the plate and then turning one of the bolts, which will turn the plate 'til the screwdriver jams against the block.

Check the torque specs for your car. http://www.bonnevilleclub.com/forum/...e=article&k=18

If the bolts are loose and have been banging around for a while, the threads are probably damaged. If so, get some new bolts at the dealer and reinstall them with a drop of blue loctite.

Well, if the bolts are loose and you don't fix 'em, they will either shear or fall out.

If they shear, you will be trying to drill out a broken bolt from the torque converter from underneath the car, through a bolt hole in the flex plate. Possible, maybe, but not much fun. You may end up pulling the engine or the trans to redo the holes. It is worth 15 minutes of your time to check them out.

If they fall out, your car will stop where the last one fell. Maybe that would happen as you are pulling into your driveway.

Check to see if mounts are the problem by observing the mounts when a helper reproduces the noise. Changing the mounts will be more work than the flex plate bolts.