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The Tail Moves Violently Side to Side Above 100 MPH

Shocks, Springs, Brakes, Frame, Body Work, etc

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LS14gezr
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The Tail Moves Violently Side to Side Above 100 MPH

Post by LS14gezr »

‘71 Nova, back half ladder bar, Koni single adjustable 12 bolt, 10.50 big tire car. Old race car I’m bringing back. Nicely done in it’s day but needs attention now. It just started recently to vigorously shake the tail side to side. Not up and down. Balanced the tires. Then I found the forward rod end of the diagonal bar to not have any torque on the thru bolt and the rear thru bolt to have about 30 ft/lbs. Tightened those two and checked the others. Figured that was it but no. No change.

It’s been suggested to me that I may have a shock going bad. That might explain the uncontrolled side to side motion at speed. Have any of you experienced a shock go bad and how did the car react?

I’m considering just replacing all the rod ends in the rear suspension but I’d like to know WHY. Besides old age that is. How do you properly inspect rod ends?

No vibration in the steering wheel. The car tracks straight until about 900’ and then the side to side sets in. As the speed continues to increase the more pronounced the side to side movement becomes until it becomes a question of safety for myself and my competitor.

I would welcome anyone opinions getting me started in the right direction.
Thanks in advance.
miniv8
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Re: The Tail Moves Violently Side to Side Above 100 MPH

Post by miniv8 »

How is the panhard bar set up?
I'd pull the shocks out and see if everything is moving freely and not binding because of some geometry error.
Check the welds on the axle tubes going into the 12Bolt.
Magnús Aðalvíkingur Finnbjörnsson
LS14gezr
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Re: The Tail Moves Violently Side to Side Above 100 MPH

Post by LS14gezr »

miniv8 wrote: Tue Sep 14, 2021 4:24 pm How is the panhard bar set up?
I'd pull the shocks out and see if everything is moving freely and not binding because of some geometry error.
Check the welds on the axle tubes going into the 12Bolt.
No panhard bar. Diagonal link.
That’s a good suggestion, checking the axle tube welds. Will do!

Question to anybody - What are the symptoms of a worn rod end? How to test for it?
lefty o
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Re: The Tail Moves Violently Side to Side Above 100 MPH

Post by lefty o »

radial tire in front, and bias ply in back?
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