1973 Dodge Dart sport speed related shimmy

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oneno

oneno

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Hey everyone, a follow up to a post I had in regards to a '73 Dart Sport shimmy. It starts after a sustained speed 45 up for around 3 miles, then you can slowly feel it shimmy and within a half mile you have to pull over due to shaking so much, It feels like it may be coming from the right side but it isn't steering related directly, however if you let it go you will feel it in the steering but nor more than you can feel it in the entire car/ it is a 318 w/a tf727. I've shimmed the pinion angle, all wheels tires, drive shaft drums have been balanced. Rubber shackle cushions are good. I can put it into neutral while it's shaking and it doesn't change, when I apply the brakes you can feel it in the pedal and the shaking slows when the car slows. The only way to get it to stop is to brake and come to a complete stop, then start going again for about another three miles then the whole thing repeats. New wheels and tires did not change anything either. All wheel bearings is fine and both u-joints have been freshly replaced. Any Ideas? Thanks in advance. It all just slowly happening out of the blue
 
oneno said:
Hey everyone, a follow up to a post I had in regards to a '73 Dart Sport shimmy. It starts after a sustained speed 45 up for around 3 miles, then you can slowly feel it shimmy and within a half mile you have to pull over due to shaking so much, It feels like it may be coming from the right side but it isn't steering related directly, however if you let it go you will feel it in the steering but nor more than you can feel it in the entire car/ it is a 318 w/a tf727. I've shimmed the pinion angle, all wheels tires, drive shaft drums have been balanced. Rubber shackle cushions are good. I can put it into neutral while it's shaking and it doesn't change, when I apply the brakes you can feel it in the pedal and the shaking slows when the car slows. The only way to get it to stop is to brake and come to a complete stop, then start going again for about another three miles then the whole thing repeats. New wheels and tires did not change anything either. All wheel bearings is fine and both u-joints have been freshly replaced. Any Ideas? Thanks in advance. It all just slowly happening out of the blue
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Have you double checked all your steering linkage?? When any part of your steering linkage is loose it can cause a shimmy that gets worse and worse until you come to a complete stop. Also, there are companies that can actually balance a tire/wheel while it's still on the car. This is done in cases where a brake drum slightly out of balance gets aligned perfectly with a tire/wheel out of balance and together they cause a problem at higher speeds. I guess you could also swap you tires around to check before you pay for an extra balance job.

Treblig
 
oneno said:
a follow up to a post I had
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I wish you guys would simply add on to your previous post, I'm assuming this is part of or is the same problem?

You said something about "new wheels and tires?

Are the wheels and or tires "new" since the last time around?

How have the wheels and tires been checked?

For balance?

For true

For true "on the car?" (Jack it up turn the wheels, use a home-made pointer on some scrap wood, etc)

Is there any play you can determine in the steering? What have you or anyone done about looking over things from front to rear?

Play in general in suspension, steering? Have a friend wiggle the steering wheel in various speeds and amounts while you look at movement underneath

Ditto the rear. Have a friend "jostle" the car left/ right at the rear while you look for movement underneath. Look CAREFULLY for movement between the wheels and rear brake drums (loose wheel)

Look CAREFULLY at the leaf mounts, the axle U bolts.

Shackle and leaf mounts?

Rear axle U bolts?

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At this point I would find a stretch of level road that is little use, "out" somewhere. Find a friend with a second car. Get two or three guys with you, two in the other car. A video camera AND I DON'T MEAN A PHONE might be of help

Have them follow you, drive near along side, maybe along BOTH sides and look for wobble in wheels / tires / suspension.

Have a friend ride with you. Hang his head out the window, front/ rear, and look at the tires / wheels going down the road.

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As bad as you describe this being, it should be easy to find. Crap, the only time I've had a shimmy that bad was on the beat - up old Landcruiser, and it had been down in the mud, stones, woods. "Things get bent." "Mud gets in the wheels"
 
Tie rods and ball joints have all been replaced. Tires and wheels have all been professionally balanced and this started before I bought and installed the new front and rear tires and cragar SS's. Shackle, leaf mounts and u-bolts have all been checked out. I take my car to well known reputable local shop shop since I can no longer work on it myself and have faith in them that they aren't misleading me as they don't ask for payment if what they do doesn't fix the problem.
 
Well according to that, "it should not be happening."

Like I said........get a couple of friends.........find a flat stretch of country road............

This is not difficult stuff. This is simple mechanics. You have to use your head. In addition to the many things I suggested, what me and others have intimated is that........

you might have a WHEEL FIT problem, that is, something causing the wheels to not seat flush on the hubs

How about answering some of the questions I asked you?

Saying that "you trust a shop" is not an answer.
 
67Dart273 I am disabled not stupid. Can you please refrain from being condescending "How about answering some of the questions I asked you?" Is there someone else on here that can help me? Please 67Dart273 do not respond to my posts any longer.
 
LCA tube in your K frame may have broken loose.
 
Have any of the front suspension bushings been replaced?
ie: Upper and Lower Control Arms, Strut Rod Bushings?
You said tie rods and ball joints have been replaced how about the Pitman and Idler Arms? If these weren't replaced with the rest they could be the issue because they are the basis of the steering set up of the car so any looseness could cause the problems you are experiencing.

Do you still have the old front wheels and tires that were not wobbling? Reinstal those and see if the shimmy goes away. Your new wheels may not be seating correct on the hub due to interference of the drum or caliper depending on which brake you have up front.

I would swap the front wheels to your old ones first and go from there
 
oneno said:
67Dart273 I am disabled not stupid. Can you please refrain from being condescending "How about answering some of the questions I asked you?" Is there someone else on here that can help me? Please 67Dart273 do not respond to my posts any longer.
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I'm not being condescending, I'm expecting some answers so the rest of us know what in heck you have done, what you are up to.

This is a simple problem. These cars go down the road at high speeds all the time. If you expect to kick me off here just because you don't like the answers, then you are terribly mistaken.
 
These drums have balancing weights welded on that interfere with aftermarket wheel and/or wheel adapter to hub mounting.
 
oneno said:
But I do not want you to answer any of my questions 67Dart273.
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Del is one of the most helpful people on this board.
there is no way in hell we can give you answers if you can not provide specifics.
he and (we) are asking you questions for a reason, if you cannot answer them , then do not expect any kind of remedy for your issues.

there is a reason Del has been thanked 1,041 times

we are not there riding in YOUR car, we have no clue on what you or any body else has really done to it outside of what you tell us. you need to answer questions about your car relating to the issue you are having if you want suggestions and answers, or , you can just keep paying a shop to take more of your money.
 
my hunch is torque converter/transmission

it's probably after you get in 3rd gear / trans warmed up

i especially lean toward the trans because your symptom does not affect the steering at all

if it was wheels/suspension related it would affect the steering unless it's in the back. my guess is your trans is cooked
 
I am leaning towards the tranny/TC as well. I think with the help of the group I'm ready for the next step in getting this fixed. Thanks everyone and I'll keep this thread updated as I find out more.
 
oneno said:
I am leaning towards the tranny/TC as well. I think with the help of the group I'm ready for the next step in getting this fixed. Thanks everyone and I'll keep this thread updated as I find out more.
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Instead of just throwing money at the issue......Swap the old wheels back on like I previously stated..... Especially since the issue started after you swapped everything



74DartSwinger360 said:
Do you still have the old front wheels and tires that were not wobbling? Reinstal those and see if the shimmy goes away. Your new wheels may not be seating correct on the hub due to interference of the drum or caliper depending on which brake you have up front.
I would swap the front wheels to your old ones first and go from there
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RedFish said:
These drums have balancing weights welded on that interfere with aftermarket wheel and/or wheel adapter to hub mounting.
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This and what 74Dart said. I didn't read the whole thing.
 
Wheels with other than OEM offsets,specifically neg.offset,can initiate a shimmy due to the magnification of the scrub-radius. Worn control-arm bushings can allow it to continue.I have also seen it happen with structurally unsound front unibody weldments and control arm mounting points, or mismatched parts. Non-factory alignments may be able to compensate for the wheels but not the other problems.My experience also shows that A-bodies like as much caster as you can find.At 3 deg. they start to drive nice. At 4 to 4.5 they become very stable at speed. If you go for the caster, you will also have to fix the bump-steer.I have also cured shimmies with a change of tires.Tires worn on the edges actually making them cones are sure to cause problems,esp. on cars with worn parts. Hope this helps.
 
...I have been told that 55 MPH is the hardest speed for tires to run balanced....could be a myth..anyway, does this also happen at 45, 60 and 65 mph or is it specific 55 mph ?
 
I no longer have nor have ever had the original wheels and tires. It seems just recently if I even run a sustained speed starting anywhere from 45 miles on up it starts to occur now. The steering is not effected until the shaking becomes more pronounced, then you can feel it pretty much throughout the whole car. Drums still have their weights on them too. Tires and wheels are all new and this started before the new wheels and tires were installed. The wheels and tires I replaced have since been sold but they were centerline wheels and not oem.
 
no pull what so ever. Just a slowly building metered shake that eventually builds and then you can feel it throughout the entire car, and will not stop until you come to a complete stop. Then starts up within a mile or two.
 
I believe there are 4 places that your problem can originate; the front end, the rear, the powertrain and the body itself. You have already eliminated the engine and most of the tranny by putting it into neutral at speed. So heres what I would do; get the rear wheels up off the ground, run the speedo up into the vibration zone for several minutes. Make sure not to have anything of value behind the tires in case they throw stones. Watch the wheels for wobbles or excessive runouts. Now,if the problem fails to show, it probably originates elsewhere, or in the wheels. If however, it does show we are on the right track. First eliminate the wheel assys by removing them, and securing the drums appropriately, and retest.Still vibrating? Check the driveshaft for runout or odd behaviour at the ends.Next remove the drums and retest.All good? Well theres nothing left but the rear end itself and the trans outputshaft which has only a few rotating parts on it (when in neutral). I suspect that if the problem originates in the rear, that when the wheels came off the problem went away. If so; it could be axleflange runout,rimhole to pilot runout or wheel runout. If however no vibration occured at all then we have eliminated the rear as a source. Next I would put the front wheel assys onto the rear and retest, again looking for runouts.If good then only the body and the front end are left. The body is usually not a problem but can be excited by problems in the wheels, the shocks or various suspension mounting points. And that takes us back to my previous post, which details the most common issues, esp mtg points. Also note that wheels can be fully balanced on the machine yet have enough runout(vertical hop) to excite the body through the suspension parts. Hope this is of some help. And finally I think it bears repeating;I have seen front wheel shimmies caused by incorrect allignments and loose mounting points, often. I would also check/adjust the sectorshaft end play.
 
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