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Discussion Starter · #1 ·
‘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.
 

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How old are the tires? Tires with weak sidewalls will cause the car to wonder.

But as suggested, bad shocks can make a car evil as well.
 

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I’d replace all of the rod ends and bolts first. Even if they aren’t the problem they should be replaced. And send your shocks out for to be rebuilt if the problem continues.
 

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I'm not saying anyone is wrong but I just can't wrap my head around a vertical mounted shock being so worn out that it causes side to side movement. I just don't see it but then again I am no chassis expert...lol. I'm with Richard. If it's an old car just buckle down and spend some money on all new rod ends and hardware. Whatever ya find OP just update us please and let us know what it was. Good luck.
 

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When all the cars swapped to radial tires we had a quick lesson on radial wobble. Their pretty picky. It does just as your experiencing, and for a while we pondered on just how to fix it. It turned out a simple shock setting was all that was required to stop it. I notice you have single adjustables, so I would suggest putting everything full tight, at least for one pass and see how high gear is. Then start loosening them up until it rebels again. If this cures it, go buy a better pair of shocks
 

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.

My cars are all old and I just went through and replaced every nut, bolt & heim joint.
It's cheap insurance and piece of mind.

Did you consider it could be air wrapping around??
On one of mine, it would do the same at ~140, so I put the small stock spoiler back on and it made all the difference.
It broke up the air enough to keep it planted.

Good luck, race safe!!

.
 

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Yep. A single bad rear shock can create a vicious rotating motion of the entire car, pivoting around the bad shock. The shock could be binding of sloppy loose and the result is the same. It happens.
 

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Discussion Starter · #12 ·
"wanger 714, post: 73369902]
When all the cars swapped to radial tires we had a quick lesson on radial wobble. Their pretty picky. It does just as your experiencing, and for a while we pondered on just how to fix it. It turned out a simple shock setting was all that was required to stop it. I notice you have single adjustables, so I would suggest putting everything full tight, at least for one pass and see how high gear is. Then start loosening them up until it rebels again. If this cures it, go buy a better pair of shocks
Yep. A single bad rear shock can create a vicious rotating motion of the entire car, pivoting around the bad shock. The shock could be binding of sloppy loose and the result is the same. It happens.
Thanks guys for the good suggestions and I will follow them. I’ll update the wobble but more issues to resolve first. Growling rear, broken rocker. Sooo much fun!
 

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I had a similar problem with my car. What type of tire are you running? I replaced rod ends, adjusted shocks, and even straightedge a slightly bent rear housing. All of those helped slightly but switching to bias plys fixed it completely.
 

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Discussion Starter · #14 ·
I had a similar problem with my car. What type of tire are you running? I replaced rod ends, adjusted shocks, and even straightedge a slightly bent rear housing. All of those helped slightly but switching to bias plys fixed it completely.
It started with Hoosier bias ply. Tried another set of Hoosier’s - same thing. Tried M/T Pro Drag Radial
- same thing. A friend of mine from the track saw my last pass and said, “ How are you driving that thing?” White knuckled was my response. I even did a pit alignment check for toe in / out. Didn’t move anything but the tires were toed in, as they should be. I’m going start with the shocks and go from there.
 

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It started with Hoosier bias ply. Tried another set of Hoosier’s - same thing. Tried M/T Pro Drag Radial
- same thing. A friend of mine from the track saw my last pass and said, “ How are you driving that thing?” White knuckled was my response. I even did a pit alignment check for toe in / out. Didn’t move anything but the tires were toed in, as they should be. I’m going start with the shocks and go from there.
What kind of tires are on the front of the car Bias or Radials?
 

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Have you checked the rear axle for toe? A bent housing with toe in/out makes them drive horrible.
Doug
 
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