Re-Design of front suspension

[jberg]

How about RC difference between front and rear in Cobra?

I just wondering that was RC location same in both end in origin suspension desing.

I have one book (Allan Staniforth 978-0854299843) and there is a lot of usefull hints that how to desing these suspension changes and how to correct these bumpsteer problems. There is also some words about RC differences between fron/rear and what that may cause (or what you may do with that if you wish...).

Sorry I'm just in start point with suspension parts so at the moment I have only guestions for this topic...

[PaulProe]

My build is a Hurricane - who is currently in flux right now. I will see the previous owners in a couple weeks, they may give me some history. I spoke to the new owners but they didn't have any input or suggestions to help.

More details on the suspension:
The rack is a Mustang II, bolted to the end of the frame rails. But the design of frame has a frame extension running forward to hold the cowl frame and quick jacks. The boss on the drivers side of the rack bottoms out on this extension, keeping it from going any lower.

The tie rod angle is about 2 degrees up. The LCA pitches up about 6 degrees, it is not horizontal.

Trying to move the outer tie rod end to correct for bump steer, it needs to go up about 7/8". But that puts it right in the middle of the steering arm. Moving the tie rod joint above the steering arm goes too far, worsening bump steer.

Laying out the suspension, the roll center ends up about 1/2" below ground. The more I read, this might not be all bad, books are saying -1" to +3". But then there are others that say +2" to +5"

If change the spindles, that flattens out the pitch of the LCA to almost horizontal but it moves the roll center to about 4 1/2". (I am doing layouts on this now to determine the exact amount and the degree of change)

The real dilemma is there are about 50 Hurricanes presently on the road and no one is really complaining about their handling. The old owners claim "we drastically reduce bump steer by ensuring the tie rod ends are as close as possible to level when the car is at ride height" As I understand it, level is good only if the LCA is also almost level. In this case, it isn't.

Dean owned and built a Hurricane. He said he never measured it on that car. He feels most manufacturers do the best they can to achieve a good look and never really get into optimizing the geometry or design. Kind of "close is good enough". He said it handled "OK" but realizes now, it could have been much better.

He said he was amazed at how much better his GT40 handled after it was corrected - And he thought it was OK before he started!

I've attached a picture of the front end

thanks for the help and dialog

Paul

[PaulProe]

Mickmate,
In another thread, you indicated you knew of a source of ball joints that extended the pivot point?

Steeda makes their X2 and X5 but they are press in types. Do you know anyone who makes a screw-in (small chrysler, Moog K772) that has a longer stud?

Paul