Powerglide makes loud bang when put in reverse

Hey everyone, kind of scratching my head over this one. I have a 327 in my 64 impala with the powerglide transmission. When I start the car up and shift into reverse the motor jumps several inches and makes a terrible loud banging sound. If i put it in neutral and start it it goes through the gears just fine. Any help would be greatly appreciated. Thanks

 

I would think it would be a motor mount or something wrong with the drive shaft. You should make a introduction post first.

Jim

 

You have a broken motor mount!

 

Should I change the transmission mount too while I'm at it?

 

You mean while you're doing your introduction? No...after.

 

Haha alright alright. I'll do an introduction

 

If one mount is broken it could be an indicator of the condition of the other mounts. If the car is something you would rather drive than work on every day, just take one full day and do all of them at once, transmission mount included. Especially since you'll already have all the tools out that you will need. That way you don't need to worry about having to screw with them another day when you would rather be out cruising.

 

Glad you took it well, Weston...lol. Welcome to the Hamb.

Don't hit the gas too hard with that broken motor-mount...she'll take off on ya!

 

Thanks for the advice. Would the loud banging sound just be the motor slamming against the frame? It only does it into reverse and not through the other gears

 

the motor is lifting up and then slamming back down.

it is because of the rotational torque of the motor, just as with a non-posi rear-end only one tires spins when you do a burn out.

Later

 

Awesome. Thanks man. Makes sense

 

Thanks man

 

How is your neighborhood? I could be a drive by...

 

Replace both motor mounts and the transmission mount. Don't drive it with a broken mount, if the engine lifts it can jam the gas pedal linkage wide open. Put a square of plywood or short 2 x 6 under the oil pan and lift the motor slightly with a floor jack to install the new motor mounts. You must use something on top of the jack to spread out the weight or you will crush the oil pan. Then move the jack under the transmission to lift it to do the transmount.

 

Check the bearing in the middle of the driveshaft, and the support. I'm not sure if it's called the 'propeller shaft bearing' or 'midshaft bearing and support'. I may be totally el-wrongo on both names... It's been a while-

If I member right, a bad motor mount will make that stuff waller around in the tunnel and make a noise like a bunch of stuff banging around. (cause that's what it is)
Good luck.

 

I appreciate the advice. Gonna tear into it tomorrow. I'll post an update soon

 

It's Boise Idaho haha. The only drive bys are hipsters on there bikes heading to the co-op

 

Carrier Bearing

 

Carrier bearing.

 

I wonder what it was?