Torsion bar opinions

[Those]

 Looking for opinions do I need new torsion bars. That car is a1973 Cuda. For the 5 years I've been driving it I've had a front end bounce at 65 mph and above. In that time I've rebuilt ever part of the front end. Nothing helped. I even tried Wheels and tires from 2 other cars and they didn't change the bounce at all. Out of ideas I lowered the front 1 inch, about three and a half turns on the torsion bar adjust bolt. Now the bounce is almost completely gone. I never read anything about torsion bars being wound to tight causing problems. They are original to the car so I'm thinking about going to 1.07 bars. Over the years of researching this problem I only found 2 or 3 cases of guys looking for solutions to a front end shake. I should add I could just barely feel it in the steering but I could see the front fenders bouncing or shaking when I reached 65 mph. Thanks for any thoughts.

[Cuda Cody]

What shocks are you running and how old are they?

[Those]

Started with new monroe shocks then switched to kyb's 2 years ago. There was a slight improvement with the keyboard shocks. Nice thing is the shake is 90 percent. Gone and the car rides much smoother. I'm running 225-70- 15 tires on the front.

[303 Mopar]

Never heard of t-bars correcting a high speed "bounce", but if you do buy new ones I would recommend looking at Hotchkis 1.10.

[HP2]

The t-bars hold the car up. Shocks control the motion.  Think of it in engine terms - shocks are like a camshaft, t-bars and leafs are like the valvetrain.  The cam or in teh case of a suspension, the shocks, determine the usable operating range and characteristics of the valvetrain or suspension. 

[Those]

I couldn't find anything about t-bars and bounce either but I was out of ideas and thought maybe shifting the weight by drooping the front and taking some of the pressure off the bars was worth a try. Lower control arm lbump stop is about 3/4 inch from the frame as it sits now.

[Bullitt-]

Something I never hear about these days is Tire Truing. I've only had it done once but my Dad swore by it and every new set he got would have them trued at the first sign of shimmy or shake.     Seems there's no perfectly round tire and this process will make them closer to round.   

[nsmall]

I'm one of the least experienced members here, but do you have a sway bar?  I changed my stock sway to a Hellwig tubular 1.25 sway bar and that sure helped a lot and it only cost me $150.

[Those]

I have the stock sway bar that came on the car from the factory. The issue is just about completely gone by lowering the front. As far as tires the wheels and tires were new 3 years ago and I also had them balanced 3 times including road force balanced the last time. Like I said this has been a 5 year process. I replaced the driveshaft and set the pinion angle earlier this year thinking it was a driveline problem.

[Skid Row]

A 225-70-15 is a tall tire at 26 1/3 " Could that have anything to do with the bounce?

[73_Cuda_4_Me]

Have you checked the front frame rails for integrity?? My 73 had some severe rust-out behind the power steering gear and along k-member mounting area, and I had similar shaking like you describe at higher speeds... I ended up cutting off driver's side rail and putting a safety cap on from core support to just behind UCA mounting area...

https://www.classicindustries.com/product/all-years/plymouth/all-models/parts/mm8124.html

[Burdar]

A couple things come to mind. 

1. Check the K-member for loose steering mounts.  The factory welds aren't very pretty and I've heard of welds breaking loose.

2. Have you had the car aligned?  If so, to what specs?  A goofy alignment could cause your problem too.  The factory specs are designed around bias ply tires.  Don't go by those specs when running a modern tire.  You said you lowered the car about an inch.  Raising or lowering the ride height will change the alignment.  It need to be check after making an adjustment.

Finally, these cars don't drive like new cars.  SOME of what you are describing COULD be just how these old cars drive.  Changing to a larger bar and high quality shocks(Monroes are not a high quality shock) should change the characteristics.  If something else(like the alignment) is bad though, just changing bars isn't going to fix it.

[nsmall]

 

Find a shop that specializes in aligning old muscle cars.  Nice thinking Burdar.  And yes, try to to compare your car to anything new, but this does sound like something that can be corrected. 

[Shane Kelley]

New larger T bars will definitely stiffen up your front end. When lowering the original T bars it makes them soft and the car doesn't feel stable at higher speeds. That's the reason I made the change to the larger T bars. It made the most dramatic difference with my car. Hotchkis or PST make a nice T bar.

[73_Cuda_4_Me]

Here is my 

If you are getting shake at a stiffer stock torsion bar setting, and loosening the adjusters smooths it out, that would indicate that the torsion bars are absorbing more of the vibration passed up to the frame/front fenders when set softer.

Putting bigger torsion bars in will stiffen the suspension, not the frame or front end, so may make vibration actually worse by passing more road vibration into frame. It does help with cornering and larger suspension variations (bump steer) that are problematic with stock TB's. I went to larger TB's, and it makes a world of difference in handling. It also raised my front end about an inch when I got them set to run firmer than stock bars with my small block - if I had a big block or hemi, it would be perfect!