69' RR 383/727 rattling noise...What is it?

[Bcamp69]

I was out for a drive and about 30 minutes into it I started hearing a rattle as I would decelerate coming to a stop. The rattle continued while idling at a stop but as soon as I began to accelerate the rattle would seem to go away. Almost sounded like exhaust rattling and started out very faint. I stopped and let the car cool for an hour or so before trying to locate the source of the noise. When I started it again the noise was gone, not even a whiff of it, so I started the 30 minute drive home. Well before I could make it home on a short highway stretch (55mph) it came back but this time was loud and sounded like some broken flex plate videos I've listened to on youtube. Anyways, I pulled it over and called for a tow.

Once at home I started it again and the noise was there sounded like it was coming from the bellhousing area....clank, clank...rattle rattle, clank, clank rattle rattle...so on in PRND (didn't matter which gear it was making the noise. I checked the tranny dust cover it was tight. I checked the flexplate to torque converter bolts and they were properly torqued and tight. A friend brought a scope over and we checked the flexplate for damage. He thought he saw damage near a bolt. I pulled the flexplate off and inspected it and could not find any damage. Bolt everything back up, all torqued to spec, fire the car up and the noise is gone. Go for a ride around the block and the rattling clanking sound returns. Sounds like it's underneath my feet???

I installed a roll control about 3 weeks before this problem started and did a couple burnouts. I may have done 1 burnout with the transmission in Drive. All fluid levels are good.

The day the noise began I was not getting on it at all, but I did hit a strange channel, almost like a French drain, in the middle of the road at about 30mph under acceleration and the rear end of the car kicked over to the right about a foot. It was very strange.

If I start the car cold and just leave it in park or do not drive it it will not make the noise. If I shift the gears then it will start and will not stop.

I'm kinda lost here. Have a cruise coming up tomorrow night I'd really like to make any ideas?

 

[Bcamp69]

It doesn't make any noise until I shift gears. Here's cold start video after inspecting the flexplate.

 

[Zeppelin264]

While doing the burn outs did the car get traction while in 1st gear? That's a big no no for 727's from what I've read. I always start in 1st and shift to 2nd immediately.

 

[Don Frelier]

You may have broken a fin on the torque converter.
I have no idea what zeppelin264 is talking about?

 

[khryslerkid]

I've heard having too long of a torque converter bolt will do this. Just a thought.

 

[Photon440]

You may have broken a fin on the torque converter.
I have no idea what zeppelin264 is talking about?

Zeppelin264 is talking about the possibility of a sprag clutch failure, a common upgrade part on competition torqueflites.

 

[khryslerkid]

Header flange bolts, exhaust pipe clearance, trans cooler lines. Get under the car, take your hand and bump on some of these items and see if you hear it. Maybe even put her up on four jackstands and run it to try and get it to do it. Think simple first!

 

[Don Frelier]

Zeppelin264 is talking about the possibility of a sprag clutch failure, a common upgrade part on competition torqueflites.

Sorry, if that sounded harsh I found it confusing that's all.
Another possibility: Check the motor mounts and rear trans mount. The engine sounds bone stock to me, I think spinning the overrun clutch would be unlikely but I suppose it can happen.

 

[Bcamp69]

While doing the burn outs did the car get traction while in 1st gear? That's a big no no for 727's from what I've read. I always start in 1st and shift to 2nd immediately.

No, but it did shift into 2nd gear.

 

[Bcamp69]

Header flange bolts, exhaust pipe clearance, trans cooler lines. Get under the car, take your hand and bump on some of these items and see if you hear it. Maybe even put her up on four jackstands and run it to try and get it to do it. Think simple first!

I think I’ve checked just about every externally accessible part I can think of.

 

[Johnpat]

Do you have a heat riser or are you running headers?
If you have a heat riser make sure it's not rattling

 

[Lefty71]

While doing the burn outs did the car get traction while in 1st gear? That's a big no no for 727's from what I've read. I always start in 1st and shift to 2nd immediately.

This depends on the manufacture of the valve body or transbrake valve body. He should do burnouts according to the manufacturers instructions. I would wonder if he fried the sprag as well (or if it already was). I just pulled a 727 apart with a fried sprag, and the rollers were split and scattered everywhere. I have no clue if the car could have been moving with that trans in it, but im betting it made a hell of a racket if it could still move the car.... hth, lefty71

 

[Cyty Slykers]

I was out for a drive and about 30 minutes into it I started hearing a rattle as I would decelerate coming to a stop. The rattle continued while idling at a stop but as soon as I began to accelerate the rattle would seem to go away. Almost sounded like exhaust rattling and started out very faint. I stopped and let the car cool for an hour or so before trying to locate the source of the noise. When I started it again the noise was gone, not even a whiff of it, so I started the 30 minute drive home. Well before I could make it home on a short highway stretch (55mph) it came back but this time was loud and sounded like some broken flex plate videos I've listened to on youtube. Anyways, I pulled it over and called for a tow.

Once at home I started it again and the noise was there sounded like it was coming from the bellhousing area....clank, clank...rattle rattle, clank, clank rattle rattle...so on in PRND (didn't matter which gear it was making the noise. I checked the tranny dust cover it was tight. I checked the flexplate to torque converter bolts and they were properly torqued and tight. A friend brought a scope over and we checked the flexplate for damage. He thought he saw damage near a bolt. I pulled the flexplate off and inspected it and could not find any damage. Bolt everything back up, all torqued to spec, fire the car up and the noise is gone. Go for a ride around the block and the rattling clanking sound returns. Sounds like it's underneath my feet???

I installed a roll control about 3 weeks before this problem started and did a couple burnouts. I may have done 1 burnout with the transmission in Drive. All fluid levels are good.

The day the noise began I was not getting on it at all, but I did hit a strange channel, almost like a French drain, in the middle of the road at about 30mph under acceleration and the rear end of the car kicked over to the right about a foot. It was very strange.

If I start the car cold and just leave it in park or do not drive it it will not make the noise. If I shift the gears then it will start and will not stop.

I'm kinda lost here. Have a cruise coming up tomorrow night I'd really like to make any ideas?

Several months ago I started experiencing the same exact thing with my 68 Charger. I was told that it could be that my torque converter is bad and need replacing so that’s up on my to do list because the metal rattling noise had me thinking that it was coming from the motor which I’m thankful it’s not that.

 

[Bcamp69]

Do you have a heat riser or are you running headers?
If you have a heat riser make sure it's not rattling

Headers

 

[Macdon221]

Bcamp69,

I know this post is old, but did you ever discover the source of the noise? I am having the exact same issue.

macdon221