Moparts
Why do Mopars vibrate??
Posted By: kielbasa
Why do Mopars vibrate?? - 11/18/09 06:05 PM
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!
Posted By: Jim_Lusk
Re: Why do Mopars vibrate?? - 11/18/09 06:32 PM
Replace the trans mount......
Posted By: 62maxwgn
Re: Why do Mopars vibrate?? - 11/18/09 06:33 PM
Or the tail shaft bushing.
Posted By: StealthWedge67
Re: Why do Mopars vibrate?? - 11/18/09 07:32 PM
If it vibrates, something needs to be fixed. My '67 Satellite, even at 3100 RPM with 3.91's out back, is very solid at freeway speeds.
Posted By: dulcich
Re: Why do Mopars vibrate?? - 11/18/09 07:36 PM
Install an aluminum driveshaft and the drone/virbration coming from the drivetrain at speed will completely disappear.
-dulcich
Posted By: pro451bee
Re: Why do Mopars vibrate?? - 11/18/09 08:08 PM
Bad or incorect converter balance can cause it too
Posted By: Crizila
Re: Why do Mopars vibrate?? - 11/18/09 09:07 PM
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!
Well, if it vibrates just sitting there, you can eliminate anything past the flywheel / torque convertor on the back side and you have already eliminated the balancer on the front side. That leaves: engine ( rotating assembly), flywheel or flexplate & torque convertor, unhealthy motor - includes partial miss or one cylinder down on compression or flat cam. Since it is the easiest to trouble shoot, I would proceed with the last item first ( verifying that the motor is healthy and hitting on all 8 holes evenly. In that regard, you might want to start with an rpm drop test. Next you might want to physically look at the flexplate and torque convertor for loose bolts / missing weights.
Posted By: OLD318
Re: Why do Mopars vibrate?? - 11/19/09 12:01 AM
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...
Just sitting (not moving) the steering wheel/column just resonates when running the engine through various speeds...
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?
Depending on your model year, you are in a 35-40 year old car. That's what they feel like...
You are use to modern cars and there is no comparing them (fairly) to one another...
Regardless...
For mopars dated up until 1972 you have to remember that the steering gearbox bolts directly to a steel K frame which bolts directly to a steel frame. So there is NO isloation between tire vibration, engine vibration and the steering gearbox to steering column. The result is
you feel everything with your hands on the column.
And no set of tires/alignment/wheel balancing
or sound proofing can fix this... Its the basic design.... and it is antiquated...
So no matter what you do, you cannot smooth out this feel in the steering wheel.
In 1973 (Take a charger for example)...
The K frame gets isolated from the front sub frame, and the column gets isolated from the gearbox... this is a big improvement in terms of "feel" at the steering wheel. But it is still not on par with cars of today, where you feel almost nothing... in say a Camry or an Accord or
just about any sizeable new car.
If you want to change the "old junker" feeling.
I suggest you try a modern sound deadener.
My recommendation would be a combination of 2 products Damplifier Pro followed by a layer of
Luxury Liner Pro... This stuff installed inside your doors, your entire bare floor pan from backseat to front firewall AND the roof skin.
As well as the trunk floor.
This will kill 80-90% of the sound/vibrations you hear and feel. You will be amazed at how solid the car will feel. But it will not correct 2 things... wind noise off of the front pillars/vent windows- which went away in 71-73 I believe, and that vibration you feel at the steering wheel.
Most mopar guys don't like this sound proofing stuff because it does add weight to the car and
does not look factory especially in the trunk.
It is also expensive and a little time consuming to put it.
However ,having done it... I would strongly recommend it... I was pleasantly surprised....
I have a 70 Coronet btw...
Best of luck to you!
Posted By: Anonymous
Re: Why do Mopars vibrate?? - 11/19/09 12:03 AM
Pure POWER!!!
Posted By: minivan
Re: Why do Mopars vibrate?? - 11/19/09 12:05 AM
Quote:
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!
Well, if it vibrates just sitting there, you can eliminate anything past the flywheel / torque convertor on the back side and you have already eliminated the balancer on the front side. That leaves: engine ( rotating assembly), flywheel or flexplate & torque convertor, unhealthy motor - includes partial miss or one cylinder down on compression or flat cam. Since it is the easiest to trouble shoot, I would proceed with the last item first ( verifying that the motor is healthy and hitting on all 8 holes evenly. In that regard, you might want to start with an rpm drop test. Next you might want to physically look at the flexplate and torque convertor for loose bolts / missing weights.
You forgot motor or transmission mounts..
Posted By: 340dart4spd
Re: Why do Mopars vibrate?? - 11/19/09 12:05 AM
lousy stock engine balancing doesn't help...
Posted By: GTX70sixpack
Re: Why do Mopars vibrate?? - 11/19/09 12:57 AM
Vintage cars do not transfer drivetrain vibrations like many are describing above unless there is an issue.
You need to look at the engine mounts and the transmission mount. Sacked out mounts transfer a lot more vibration to the chassie. Another big culprit is the exhuast dead up agaist the frame, a torsion bar, the steering column etc; look for anything that is making solid contact.
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.
Posted By: Crizila
Re: Why do Mopars vibrate?? - 11/19/09 01:45 AM
Quote:
Quote:
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!
Well, if it vibrates just sitting there, you can eliminate anything past the flywheel / torque convertor on the back side and you have already eliminated the balancer on the front side. That leaves: engine ( rotating assembly), flywheel or flexplate & torque convertor, unhealthy motor - includes partial miss or one cylinder down on compression or flat cam. Since it is the easiest to trouble shoot, I would proceed with the last item first ( verifying that the motor is healthy and hitting on all 8 holes evenly. In that regard, you might want to start with an rpm drop test. Next you might want to physically look at the flexplate and torque convertor for loose bolts / missing weights.
You forgot motor or transmission mounts..
Did I mention checking motor and transmission mounts 
Posted By: boydsdodge
Re: Why do Mopars vibrate?? - 11/19/09 03:18 AM
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.
On long drives where the speed limit is in the seventies it gets to be a real drag.
I went thru my dart from front to rear all mounts complete front end rebuilt with bushings. Checked pinion angle, tires, new drive shaft after ballancing three.
On this next build I have had the engine ballanced at a different shop hoping that might be the thing this time.
I feel this same vib in lots of mopars from pick ups, vans, 4 speeds, autos, it seems to be small blocks from what I have noticed and cast cranks.
mmmm, maybe something there.
Posted By: DennisH
Re: Why do Mopars vibrate?? - 11/19/09 12:27 PM
69 Coronet R/T. Keisler. Smooth. Sweet.
Posted By: patrick
Re: Why do Mopars vibrate?? - 11/19/09 01:09 PM
if it comes and goes with road speed, usually at multiples of the first speed (say, 30mph smooths out, comes back at 60, etc) check pinion angle. excessive pinion angle (like the 5 degrees nose down recommended for drag racing) can cause vibrations at cruise.
Posted By: Triggerfish
Re: Why do Mopars vibrate?? - 11/19/09 01:36 PM
My Challenger rides smooth as can be. Only vibration is from my teeth when the elephant wakes up at a stop sign. But my car's totally redone. My bro's 69 Charger drives like a dream & the ride in his 68 GTX was perfect, too. But those cars were totally restored, too. Be sure to check your steering box/front suspension, bushings, spindles, brakes & tires old or out of balance. One wheel may be tweaked from hitting a curb? As was said, there's a lot that can cause vibration including tail shaft bushings, trans mounts, u joints, rear end/axles, drive shaft...
I'd start w/ the tires, wheels, ball joints & bushings first.
Good luck.
Posted By: GomangoCuda
Re: Why do Mopars vibrate?? - 11/19/09 01:59 PM
Quote:
Just sitting (not moving) the steering wheel/column just resonates when running the engine through various speeds
This is not a suspension or driveline problem. This is strictly engine and/or steering related.
1. Check motor and trans mounts.
2. make sure the dampener and flywheel or torque converter are correct for your engine. There are internal and external balanced versions of all of them.
3. Adjust the steering column so that the joint with the steering box is not in a bind or bottomed out.
If none of these solve the vibration then install a big cam and loud exhaust and tell everyone the steering column is supposed to vibrate. 
Posted By: Crizila
Re: Why do Mopars vibrate?? - 11/19/09 02:00 PM
Chryslers fix was to hang a big chunk of steel off the tailshaft on later automatic cars. Think I have one if you wanna try it.
Posted By: autoxcuda
Re: Why do Mopars vibrate?? - 11/19/09 04:06 PM
Quote:
Chryslers fix was to hang a big chunk of steel off the tailshaft on later automatic cars. Think I have one if you wanna try it.
I looked under a new mustang at the dealer and there's a bunch of chunks of steel under them. Also has a two piece driveshaft with CV type joints in it.
Posted By: b54406barrel
Re: Why do Mopars vibrate?? - 11/19/09 06:29 PM
I have 2 good friends who both bought new a '70 383/4spd cuda and a '71 340/4spd challenger. Back in the day, I clearly remember riding in both & they were both 'buzy' even in the passenger seat, especially Gary's 340 car. They both rode in my rr and commented on how smooth it felt.
At the time, I attributed it to maybe being 4spd cars. Who knows?
Posted By: AAR70
Re: Why do Mopars vibrate?? - 11/19/09 06:57 PM
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.
.
What does that mean: in and out droning vibration?
Lau
Posted By: YO7_A66
Re: Why do Mopars vibrate?? - 11/19/09 07:22 PM
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.
Posted By: minivan
Re: Why do Mopars vibrate?? - 11/19/09 08:19 PM
I worked on my 67 coronet vert for 18 years before being able to drive it ( for the 1st time ) this last spring... I tried to do everything correct so I would never have to go back and redo it....
I had many "friends" tell me I would not like driving the car as it would be an "old tank" with soft steering etc...
If I could afford the gas and not care about weather ( it will not see the rain) I would drive my car everyday.. It is a pleasure to cruise it anywhere.. I do have 2.94 gears in it, but no drone or vibration, except when the foot presses on the gas pedal too far....
beginning to wonder if exhaust is your drone problem??
Just my experience.....
Posted By: PAINT IT BLACK
Re: Why do Mopars vibrate?? - 11/19/09 08:45 PM
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.
Posted By: camdog440
Re: Why do Mopars vibrate?? - 11/19/09 10:03 PM
My '73 Cuda had substantial vibration because the top of the cowl was broken where the front subframe connects under the top of the front fenders. You can't see that area unless you take the fenders off. It causes the whole front sub to vibrate.
Hotchkiss makes some bars to strengthen/stiffen that area.
Posted By: Jim_Lusk
Re: Why do Mopars vibrate?? - 11/19/09 11:00 PM
I'll add another description of the vibration that I felt in both my GTS and my folks Fury. It felt like it would start at the rear and go forward and then back at the rear again, like an oscillation.
Posted By: boydsdodge
Re: Why do Mopars vibrate?? - 11/20/09 03:53 AM
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?
Posted By: JonC
Re: Why do Mopars vibrate?? - 11/20/09 10:29 AM
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.
Posted By: kielbasa
Re: Why do Mopars vibrate?? - 11/20/09 12:37 PM
ok, I see I am not alone! Yes, good descriptions on the oscillations, in and out, especially when driving at higher speeds on the highway. I guess I'm starting to think it may be a combination of everything (since it vibes while sitting in place AND driving) - I guess I'll end up going thru the entire car. But it just seems like every mopar i ride in, they all have these orgasmic quakes and rhythms.....I'm probably just jealous, because the few GM's of that era I've driven in just seemed buttery smooth and had a more refined feel.
Posted By: buildanother
Re: Why do Mopars vibrate?? - 11/20/09 01:04 PM
I know of a duster that developed the on and off drone while at cruise AFTER installation of a heavy duty direct drive flex fan. No other changes were made supposedly. Just a thought.
Posted By: boydsdodge
Re: Why do Mopars vibrate?? - 11/20/09 08:44 PM
I tried the fan and water pump thinking it was one of those but no diff. Installed new drive shaft after balancing the first one twice to make sure and checking pinion angle, no diff. Swapped trans and engine mounts, no diff.
New tires and rims, no diff. New torque converter, no diff. The only thing I haven't done is balance the bottom end and change the trans output shaft bushing.
My Challenger is getting a balanced bottom end and a new 5/speed so I hope that helps.
Posted By: GTXKen
Re: Why do Mopars vibrate?? - 11/20/09 08:52 PM
I have either not noticed or it dosen't bother me. Maybe I just expect a muscle car to vibrate
Posted By: Hazwoy
Re: Why do Mopars vibrate?? - 11/20/09 10:22 PM
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...
Posted By: boydsdodge
Re: Why do Mopars vibrate?? - 11/21/09 05:03 AM
I am glad I am not going thru that kind of prob.
Posted By: moparmandc
Re: Why do Mopars vibrate?? - 11/21/09 05:17 AM
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.
Posted By: Purpleheart
Re: Why do Mopars vibrate?? - 11/21/09 05:51 AM
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
Posted By: DennisH
Re: Why do Mopars vibrate?? - 11/21/09 12:52 PM
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.