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Re: Why do Mopars vibrate??
[Re: boydsdodge]
#529828
11/19/09 02:57 PM
11/19/09 02:57 PM
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Joined: Dec 2008
Posts: 210
Denmark, Helsingor
AAR70
enthusiast
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enthusiast
Joined: Dec 2008
Posts: 210
Denmark, Helsingor
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Quote:
I totally hear what your saying, it is an in and out droning vib felt thru the car after 3500 rpm starting at 70 and up.
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What does that mean: in and out droning vibration?
Lau
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Re: Why do Mopars vibrate??
[Re: AAR70]
#529829
11/19/09 03:22 PM
11/19/09 03:22 PM
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Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,443
Indiana
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I have a vibration that starts around 70-75mph and gradually gets worse. Mine is from the rear wheels. When I had the shop install my tires, I was watching the machine as they spun up the wheel/tire assemblies. The tire was walking left to right as it was spinning. The guy told me that there is too much runout in two of the four wheels, so he told me to put these on the rear. He then told me that it should be ok up to 65-70 but above that is will start vibrating. All I can say is that he was correct. In my future I will be buying two new Rallyes and setting these two aside.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: Why do Mopars vibrate??
[Re: GTX70sixpack]
#529831
11/19/09 04:45 PM
11/19/09 04:45 PM
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Joined: Nov 2004
Posts: 7,647
Houston Texas
PAINT IT BLACK
Got a CHIP on my shoulder
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Got a CHIP on my shoulder
Joined: Nov 2004
Posts: 7,647
Houston Texas
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Quote:
My trans mount resently failed in my GTX when I was out thrashing on it pretty hard and it had a bad vibration at different rpm ranges in nuetral and a drone at highway speed (sounded like a out of balance drive shaft) dropped in a new poly mount and it's quiet and smooth again.
Same thing happened to me a couple of years ago. Took me a while to piece it together, but sure enough... trans mount was bad. Much better now.
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Re: Why do Mopars vibrate??
[Re: boydsdodge]
#529835
11/20/09 06:29 AM
11/20/09 06:29 AM
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Joined: Jan 2003
Posts: 3,623
Millinocket, Maine
JonC
master
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master
Joined: Jan 2003
Posts: 3,623
Millinocket, Maine
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Quote:
Cruising down the highway about 3500 to 4000 usually, I will feel an all around vib that will come in and out , at that speed it will be like counting one thousand and one, one thousand and two, one thousand and three, etc...
If I pick up speed it will just get closer together. 85 and up I just back off after short blasts because it sucks to feel it.
If I am next to a Beemer or ricer I go for it not letting them know I am driving a cement mixer. lol.
Did that help?
I have been fighting this with my 72 340 904 Cuda for some time now. I can get to 90 and it smooths out a lot. I haven't tried changing the rear tranny bushing and slip yoke as was suggested on one of my ealier posts on this. Will do that this winter and see if it helps.
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Re: Why do Mopars vibrate??
[Re: kielbasa]
#529840
11/20/09 06:22 PM
11/20/09 06:22 PM
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Joined: Nov 2009
Posts: 48
Los Angeles
Hazwoy
member
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member
Joined: Nov 2009
Posts: 48
Los Angeles
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I have the exact same problem as you!!! Only my car ran super great and smooth and developed the vibration you are talking about. I have owned this car for 6 years, 1972 Dodge Charger with rebuilt 1990 360 motor. 9:1 stock or small upgrade cam. Davis HEI Ignition, Holley street avenger carb. B&M Flexplate, Mopar performance 145K torque converter with neutral balance (no weight(s)). When torque converter was installed 5 years ago the shop had to knock off the weight to make converter neutral balance as B&M Flexplate s already balanced. Car ran smooth and strong for many years. 1 year ago I noticed a little vibration upon acceleration. Got progressively worse over the last year. Sure enough, tranny mount was bad but that stopped clunking , not vibration. Rebuilt carb, new plugs, verified timing, verified spark plug wire order. Car runs really strong but vibration still there. 18" vacuum at idle and needle rock solid so I cannot believe it is a tuning issue. I replaced harmonic damper with Summit Racing damper #163318 for external balance 360. My old damper looks exactly like Mopar Performance P5007301. If anything vibration may be worse. Then replaced motor mounts. A little smoother but vibration still bad. So bad now I only drive car to take it to get opinions from expert mechanics. For sure it is engine/balancing/torquue converter. Exact same smyptoms as Kielbasa's orginal post only mine have developed over time. Dash, steering wheel, and floor pan shake at anything above idle. Help!!! Thinking of rebuilding original damper but now I am getting into replace my new replacement parts...
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Re: Why do Mopars vibrate??
[Re: kielbasa]
#529842
11/21/09 01:17 AM
11/21/09 01:17 AM
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Joined: Oct 2004
Posts: 214
moparmandc
enthusiast
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enthusiast
Joined: Oct 2004
Posts: 214
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Quote:
Seems like every old mopar I ride or drive in, they just vibrate (sort of like worn out U-joints).
My AAR does the same, and I hate the junker feeling it conveys when driving it...I replaced the u-joints, had the driveshaft balanced. Although better, it's still there. Just sitting (not moving) the steering wheel/column just resonates when running the engine through various speeds (i tried another factory harmonic damper)- still does it. Every time I talk about this with my friends, it seems like it's an accepted fact.
I can't stand it anymore - other than the obvious, what are some things I can do to smooth my car out? I haven't touched the rearend (8 3/4), but I wonder if changing pinion/axle bearings is necessary?
Thanks for any input!
look at accesorys on the engine (alt, waterpump, ect.) it is very often over lookedfor light (or heavy vibration in park). but many older cars just had some vibration, not as much isolation like newer cars they kind of evolved starting in the early 70's from being powerhouses to cruisers remember that it takes alot to have all the creature comfort in an old car that the newer ones have. 
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Re: Why do Mopars vibrate??
[Re: moparmandc]
#529843
11/21/09 01:51 AM
11/21/09 01:51 AM
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Joined: Nov 2009
Posts: 9
Ontario , Canada
Purpleheart
member
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member
Joined: Nov 2009
Posts: 9
Ontario , Canada
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I have a AMC 71 AMX with a bad vibration . It actually cracked the bell housing of my 904 tranny . The motor and driveshaft were balanced , all new mounts , I'm using a 8 3/4 rearend and that's the only possibility left . There seems to be a lot of play in the pinion . The symptoms your describing sound very much like my problem . Do the Mopars with Dana 60 rearends have the same problems with vibration ?
Paul
71 AMX best time 11.97 @ 113 mph 1.71 60ft
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Re: Why do Mopars vibrate??
[Re: DennisH ]
#529844
11/21/09 08:52 AM
11/21/09 08:52 AM
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Joined: Dec 2004
Posts: 5,278
San Jose, California
DennisH
Vacation
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Vacation
Joined: Dec 2004
Posts: 5,278
San Jose, California
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Quote:
69 Coronet R/T. Keisler. Smooth. Sweet.
Got the USCartool subframe connectors, and firm feel box too. After riding in a co-workers 78 Corvette, the Coronet is a Cadillac. Dyno-Max turbos, no drone.
The 500 mile drive to Vegas is smooth and comfortable.
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At the time, I attributed it to maybe being 4spd cars. Who knows?
