Torsion Bars... Best Diameter for a Lowered Street / Autocross car?
If you don't agree with what I have to say- that's fine move along. My interpretation of the question and my answer is based on my information from 40 years in this hobby and having been a professional mechanic for 20 years- yes even back when these cars were modern. Torsion bars do need pre-load otherwise they twist backwards and snap. There is a left and right side for a reason. I have seen them break when cranked up too high or driving around lowered. Driving on the bump stops are not what these front ends were designed for.
The unequal a-arms on these cars from the factory were designed to operate within a certain range. End of story. If you operate them off the bump stops and you will damage the parts, the ball joints are also bottoming out...they are designed to operate with the shaft at a fixed center starting point and not at the edge of the seal. They need as much movement left of center as they do right of center. The factory has a ride height measurement for a reason. Modifying a car for a particular form of racing is not factory settings so I understand you may not agree with what I am saying.
If you dont like the information that's okay- we can agree to disagree.
Oh boy. If you think you can “bend the torsion bars backward” then you have a fundamental misunderstanding of how the suspension on these cars work. What you’re describing is physically impossible.
If you fully unload the torsion bars, the adjuster bolt comes off of the lever on the hex end of the LCA. Once that happens, moving the LCA further in that direction doesn’t apply any force on the bar at all. The adjuster, and therefore the LCA, can only put load on the torsion bar in one direction. I don’t care if you’ve done this for 200 years, it doesn’t change that.
My car doesn’t ride around on the bump stops. It is lowered, but the short bumpstops and QA1 LCA’s provide plenty of travel. And, because the torsion bars on my car are 3x stiffer, they don’t need as much travel. I almost never hit the bump stops on my car. Which is better than these cars do with factory components. They’re frequently contacting the bump stops with stock bars and at the stock height. Put a dab of grease on the bump stop if you don’t believe me.
The factory geometry was based on bias ply tires. The best geometry for bias plys and the best geometry for radials is different. And don’t give me that Rick Ehrenburg “over-angling” the ball joints nonsense. I checked the range of travel on my suspension, it’s not an issue, the ball joints are fine, they operate well within their capabilities and are not bottoming on anything.
You have to consider why the factory put the settings where they did. When you change things, a lot of what the factory did is no longer relevant. The more parts you change out, the less important the factory settings are. The OP’s suspension is highly modified from stock. What those components can do is far above and beyond the factory settings. You have to understand the changes and the capabilities of the components. Not just parrot the factory manual.
