Concept 2

Hi

I am looking for advise for correcting roll center on a lowered C4 BP car.

It would be nice not to have to redesign the entire front cross member and pick up points to correct 1-2" of roll center.

Maybe a spacer / modified balljoint for the lower control arm?

Thanks Steve













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trackboss

If you your goal is to raise the roll center you may be able to find some longer ball joints for the lower arms.

Concept 2

Nothing off the shelf for this purpose, mustang, honda, you name it, but not corvette.

jtmck

Do you know the OD of the lower ball joint?

trackboss

http://howeracing.com/p-7940-howe-22424-fits-k6345.aspx

If those don't work you may be able to have howe put together something for you that fits in your existing arms and has a longer stud.

Another option is to build custom arms and use a taller ball joint.

You can also raise the roll center by changing the angle of the upper arm. Taller ball joint there or move the chassis end attachment down.

Solofast

In stock form the rear roll center of the C4 is pretty high. I don't think you would want to raise it back up to where it is when it's stock anyway. Somebody made a kit to relocate the lower links, and I believe this kit actually lowered them some more and that improved the geometry. Back when we were running a C4 in BSP we had all the camber curves and roll center motion curves and they weren't very good, there were limits as to what we could do with the car mixing and matching stock parts.

Also remember that the rear geometry between the early cars and later cars was different. We had a later rear suspension loaded under an 84 and as I recall we didn't have much travel once it was lowered. That is, once we lowered it and trimmed the bump stops there still wasn't much travel.

That said, when the car squatted (was under power) the back end behaved a lot better than it did when it lifted (under braking or when you did a throttle lift). Under those conditions the rear roll center raised up and the car got squirrely, which is also indicating that there was a lot of movement in the rear roll center.

I'd look at modifications to keep the rear roll center lower, and then fix the problem it had with moving up and down and you will be a lot better off. I think that can be done by moving the lower attachment points and making or buying new lower links, which shouldn't be too hard.

I think somebody made a kit to do that, but I don't recall who it was.

Concept 2

OD - 2 3/8 measured at end. (more specs at Howe) http://howeracing.com/p-7940-howe-22424-fits-k6345.aspx

It looks like the ones at Howe would work, but limited to 1/2" longer.

Concept 2

Great options, Thanks

Concept 2

Thanks, I am considering raising the batwing up a couple inches as well.

Solofast

Doug Rippie makes a lower control arm bracket that relocates the lower control link for C4's and that's a good start. I would call them and see what they recommend. Looks like the are sold out currently but that's what you need to get the geometry back to some semblance of normal.

Han Solo

A drop spindle would probably be the best fix on the front if you could find one.

Concept 2

Yah.. thats the first thing that came to mind, more custom fabrication.