shakes at highway speed

[73dartneedswork]

Hello,
I have a 73 Swinger that sometimes shakes real bad at highway speeds. If the road is smooth the ride feels fine, but if the road is a little rough the card shakes a lot. I mean I thought my tach was going to fall out of it's mounting. I drive this stretch of freeway almost everyday in another car and you can feel the roads a little rough, but it doesn't feel like the car is going to shake apart like my Dart.
All the suspension has been rebuilt except for the steering gear. The steering gear does have a fair amount of slop. Would the steering gear cause this? What else should I look at?
Thanks

 

[fanofpetty]

I had the same symptoms with a cuda I had years ago. The car had bias ply tires on it, so I put radials on it , and that cured it. cars that are sprung to stiff will feel this way too.

 

[FISHBREATH]

Hmmmm. Car feels fine on smooth roads, but vibrates all over the place on rougher roads. How are your shocks?

 

[BillGrissom]

Several possibilities. It could be that road has regular bumps that excite a natural frequency in your suspension. Honda paid to have a road in Lancaster, CA grooved so that certain models played a song when driven over it at a certain speed. As fanofpetty said, the tires could make a difference.

Another is that your suspension and/or steering is too lose from worn bushings or ball joints. It could be OK on smooth pavement, but jiggers around when excited by bumps. Jack it up by the frame and tug on all the wheels to look for play and look for severely cracked rubber in the bushings.

 

[73dartneedswork]

fanofpettyI had the same symptoms with a cuda I had years ago. The car had bias ply tires on it, so I put radials on it , and that cured it. cars that are sprung to stiff will feel this way too.

I have new radials. I do have new SS springs in the rear. The torsion bars are the stock ones.

FISHBREATHHmmmm. Car feels fine on smooth roads, but vibrates all over the place on rougher roads. How are your shocks?

They are new, but they are cheap Monroes. I should upgrade.

Another is that your suspension and/or steering is too lose from worn bushings or ball joints. It could be OK on smooth pavement, but jiggers around when excited by bumps. Jack it up by the frame and tug on all the wheels to look for play and look for severely cracked rubber in the bushings.

My suspension has all been rebuilt except for the the steering gear, but I'm going to crawl under the car and double check everything.

 

[jerry6]

When were the LCA bushing changed ?? UCA and LCA bushings are hard to inspect visually , everything in my front end looked good , but rubber in bushings were shot to hell . Put in energy bushings and it rides great on all roads

 

[RustyRatRod]

Sounds like sumffin loose. In Jeeps that's called "death wobble" and is almost always associated with the panhard bar. The closest thing you have to a panhard bar is the center link. I would double check ALL those connections.