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Mats has a very good point. Once you understand the relationship between the splines at front & rear of the torsion bars (Greg Gordon’s guide is a good one) you can move your front ride height any number of increments of 1.5 mm. It can be damned hard to visualise, but if you mark the torsion bars sockets with white paint marks front & rear and try rotating them, you’ll get the idea. It’s actually a very neat method. I raised my car by “8 splines” (so I could get in the driveway without scraping my headers off), for a 12mm change which came at right as near as I could measure.

I’ll throw in another point here – maybe that lowest is not always best. One theory is that if you lower the front to the point where the A arms point downwards towards the centre line of the car, then the roll point will be below the road & with the centre of gravity near the middle of the car somewhere, adversely effect the handling. Especially when the suspension starts to compress – so goes the theory. Which to my meagre understanding is one of the reasons for using drop spindles.

I’ve actually thought about rasing my car a little more as my A arms do point down, but I don’t know that I could tell the difference in handling anyway.

AL.

I don't beleive the following aspect has been covered in the thread.

Lowering the car without other supplementary spring rates will actually soften the ultimate maximum operating rate of the torsion bar.

Here's why:

(The numbers quoted serve only to illustrate the examples, they are not factual.)

Imagine the car during a very hard conering manuvre. The suspension has moved to its maximum position against the bump stop. Let's assume this has been an arc of 30* from the standard rest position.Let's also assume that for this 30* torsinal twist, a 23mm standard bar has generated a resistance of 225lbs.

Now take the same scenario except that your car is now lowered. Assume that from the lowered position, the maximum rotation to the bump stop now is 5*less. Therefore the maximum rotation of the bar is only 25* resulting in less resistance than before due to less twisting of the torsion bar.Since the rate is exponential, a small angular change would affect a substantial spring rate change.

How much less than the original 225lbs would be proprtional to how much it is lowered. So apart from other problems that lowering a road car produces, you would also need to supplement the roll and bump resistance to make up for the loss.

Remove the bump stops, they are evil absolute to road grip.

MD +1

However, to lower the front I have used Greg Gordon's method many times.

Actually it's like this:

The TB has a spring rate which is constant. Changing ride height does NOT change the spring rate at all in any direction. Changing the LCA length would.

What will change is the distance between the front center of gravity and the roll center. This "lever" determines how much weight is transfered to the outer wheel at any desired lateral accelaration.

IF the RC is lowered more than the ride height (CoG) the front suspension is effectively softer (in cornering - not bump).

As homework anybody wanting to lower his front can do the math to see what the outcome really is.

Homework #2: How does this apply when lowering the rear ride height?

Micke,

I have done some homework and you are correct. The spring rate on the TB is linear and not exponential. What I did find is even though it is linear, there is cumulative torque as it is rotated and so the less it is rotated, the less resistance there is being generated against the body roll. Would that be correct?

That is correct. That is the characteristic of a normal linear spring.

Torsion bar: M = c * angle

Just like a coil spring: F = c * x