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Vibration

Started by xx88man, December 15, 2023, 06:39:19 AM

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xx88man

I have a 1974 Challenger 360 auto. When running I can feel a very noticeable vibration... stopped in park or neutral. I know it needs a transmission mount so my question is this. Can a bad transmission mount cause this vibration when the car isn't even moving? It seems to be a vibration that comes in waves.. rough for half a second then smooths out for half a second when I'm bringing up the RPM.
Keep yer foot in it

MoparLeo

Is this something that just popped up or has any recent work or changes been made ?
moparleo@hotmail.com  For professionally rebuilt door hinges...

xx88man

I have only owned it a couple of months. Bought it from someone that wanted to get rid of it and it wasn't running when I brought it home.
Keep yer foot in it


73_Cuda_4_Me

My 340 had a similar issue when I first got it (oscillation every 3 seconds that you could feel right up through the seats), and after much trial and error, ended up finding the TC to be the culprit. PO had replaced original with like a generic off the shelf one (when they installed a truck 727 from 73), supposedly for external balance. I replaced it with a better quality torque converter, and everything smoothed right out.

 :alan2cents:
73 340 `Cuda 727 Auto on Column

BS23H3B

xx88man

Quote from: 73_Cuda_4_Me on December 15, 2023, 02:09:03 PMMy 340 had a similar issue when I first got it (oscillation every 3 seconds that you could feel right up through the seats), and after much trial and error, ended up finding the TC to be the culprit. PO had replaced original with like a generic off the shelf one (when they installed a truck 727 from 73), supposedly for external balance. I replaced it with a better quality torque converter, and everything smoothed right out.

 :alan2cents:

Thanks for your input!
Keep yer foot in it

bdschnei

Since you're talking about a 360 with a vibration and you're new to the car, make sure to check that it has a properly weighted balancer and torque converter (or flex plate). You'll find lots of discussion about that problem on this forum as well as others, but the short version is the 360 is the only mopar small block crank that's eternally balanced via the balance and torque converter. 
Bret

xx88man

I can't figure out how to post a picture here. The balancer has a thin metal collar in front of it that appears like it could be a weight. I assume there's no way to get a good look at the tc without pulling the transmission?
Keep yer foot in it


bdschnei

#7
I've attached a picture of both a stock balancer and torque converter. As you can see the additional weight is cast right into the body of the balancer. If you remove the converter bolt access plate and rotate the engine you'll be able to check for the converter weight.
Bret

xx88man

bdschnei thank you for that picture! I'll definitely check for that weight. My balancer looks right
Keep yer foot in it

xx88man

Does anyone know how much the weight on the torque converter should weigh? 1974 Challenger 360/727
Keep yer foot in it

Mr Cuda

19.79 in. oz.  A number that the balancer people can use. Not a static weight
A number straight from the mopar  performance book.


xx88man

Quote from: Mr Cuda on December 17, 2023, 03:13:51 PM19.79 in. oz.  A number that the balancer people can use. Not a static weight
A number straight from the mopar  performance book.

Thank you this helps. Has anyone here ever tried using a magnet in place of the weight to try to fix a vibration?
Keep yer foot in it

Mr Cuda

That would be one hell of a magnet.
Centrifugal force would fling it.
 I once clipped a wheel weight onto my clutch cover to prove imbalance.
 Then pulled the motor apart and balanced everything.

xx88man

Okay so I finally had the chance to check. My torque converter has the weight on it. I'm back to square one with this vibration
Keep yer foot in it

MoparLeo

Just to eliminate it, try putting a timing light to it and check for timing fluctuation. Also check vacuum for fluctuations. this will eliminate tuning issues.
moparleo@hotmail.com  For professionally rebuilt door hinges...