Rattle rattle and rattle

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RaysGTS

RaysGTS

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This is a tough one, my 1969 Dart Gts has a rattle, yes a rattle, not a clunk or a knock, not even a tick. It occurs only at normal operating temp and it only occurs when trans is in 1,2,3, or neutral. I have narrowed it to the area between the engine and trans. Some have said it is a broken flex plate, others think it is the front bearing on the 727 trans, some say it is thrust bearing in the 318 bottom end. I have removed the inspection plate cover and there is no sign of shavings nor are the heads of the torque converter bolts loose and hence hitting anything. I think, after another diagnosis run today that it is possible that the flex plate is growing and lessening the clearance between the ring gear and the starter motor because this only happens at 2400 to 2600 RPM and doesn't happen with load or when decelerating, plus that is what it sounds like.. Is this possible ?? Anyone. I don't want to crack this apart until I am sure what I am fixing. Help..

P.S. The trans was freshened completely 1400 miles ago, and the starter is a high performance after market not sure what brand.
 
Have you had it on a rack while it was running and have someone put it in gear and out of gear?

Don't overlook your engine mounts and your transmission mount. I had a tranny mount that rattled in gear.
 
rob_robinson87 said:
Have you had it on a rack while it was running and have someone put it in gear and out of gear?

Don't overlook your engine mounts and your transmission mount. I had a tranny mount that rattled in gear.
Click to expand...

Negative on the rack, I can check the mounts. Thanks
 
Torqueflite's do not have a front bearing so you can rule that out. Rattles can be tough to find. I always do what Rob suggested which is put it on a rack and have someone run it while you inspect below. You can usually find it then. Just be extra super careful of the drive wheels spinning.
 
find a inch or so longish hose n put it up to your ear n then the other end of the hose to the tranny or whatever sorta can hear whats goin on inside idk my dad does that trick so maybe it will work to find where its comin from
 
Had the flex plate bolts loose on my belvedere gave a nasty rattle, looked under there and we're hanging on by a couple threads tightened em up and was good to go
 
Sometimes loose torq ue conv' bolts will offer one addition "Tink" when the engine stops.
If those bolts woller the holes out egg shaped the bolts wont tighten properly of stay tight. Common course of evebts is strip the threads out trying to get them tight, then replace the flax plate and the bolts, helicoil the threads.
 
Thanks alot for the replies and info, we are in storage now but the next and simplest move is to just replace the starter. I was talking to and old timer who used to race in the sixties and seventies. He gave a very complete description of what I have been talking about, he claims the bendix spring is weak and when up to not it creeps toward the flex plate and rattles since it hits the ring gear--- I will try this when it comes out of storage, at worst I will have an extra starter on hand. Thanks again everyone
 
how about the little bushings in the kickdown. i remember reading here you can get the whole set for $20 bucks somewhere.
 
Thanks Mopar lover that will get investigated as well, the starter will be quickest and easiest. This fella told me that between a weak spring and the possibilty that a C clip could have come off would be my saving grace. However it is so disturbing that it does not come on with load, and only shows up between 2400 and 2600 rpm, if you stab the throttle and give er it goes away until you level off at cruise speed around 45 to 48 mph. At that point if I drop to 2 or 2nd it will go away, odd. Also this rattle/growl only occurs in N D 2 or 1, and not in park. I am dying for the weather to warm up so I can get at this and see where to go next. Peace
 
As far as I can tell every mount is new-- exhaust is nos Chrysler factory w/ factory hangers. I have the MSD ignition set up and the timing seems great, but I can give that a look as well , Thanks
 
Well Gentlemen,

Problem solved, rattle was a thrust bearing that was bad. A whole motor rebuild, bored .03 and cam and crank and heads all is good again some $$$'s later. Thanks for all the suggestions unfortunately it was the worst case scenario.
 
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