Difference between revisions of "Suspension"

Revision as of 14:23, 14 November 2011

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Shocks

?

Springs

I think we should contemplate mostly copying CSP rates to start with, depending on final motion ratios. CSP apparently goes with ~750/450 lb springs right now.

According to Shaikh (http://forum.miata.net/vb/showthread.php?t=146016), the stock spring motion ratios are 0.66 F and 0.72 R. That's spring travel / wheel travel.

Since we will be designing new control arms, we will need to pay attention to wheel rates, not just spring rates. Wheel Rate = Spring Rate * (Motion Ratio)^2. Changes in CG, track width, roll center, desired ride frequency, sway-bar stiffness, and David's calorie intake will all affect this decision.

Swaybars

Do we even want to run swaybars? Maybe just a front bar?

Control Arms

Currently Stock. Presumably dealing with this as part of the Uprights project.

Spindles

Currently ABS stock spindles all around. Need to remove dust covers for now. Working on creating drop spindles with the Uprights project.

Bushings

The control arm connections will all be changed to solid heim components.

What else are we going to change? Subframe bushings are allowed to be changed (16.1.H.)

Steering Rack

I believe it currently has a manual steering rack on it, but it might be depowered. In any event, we need to switch to a de-powered power rack. This also gives us the option of putting in power steering down the line.

Assess how much to space the steering rack off the subframe for bumpsteer correction.

Solo Rules

16.1.F.1. Steering components, including the steering rack and/or box, tie rods, idler arms, power assist devices, and related components, may be replaced, added, moved, or removed. The steering column, within the passenger compartment, is specifically excluded from this allowance.

Subframes

Front

Front subframe got an upgrade in 1999 to revise the suspension pickup points for slightly better roll centers. I have a 99 subframe in the garage to throw on the car at our leisure.

There is a new SSM rule for 2012 that allows the creation of custom front subframes, but suspension pickup points have to stay identical to stock and the weight has to be at least that of the stock piece it's replacing, so I'm not sure it's useful for us.

Rear

Rear subframe has to stay stock. To my knowledge the same subframe was used all the way through the 90-05 range.

Solo Rules

Section 16.1.E of the Solo rules states:

"Suspension components are unrestricted as long as they use the original attachment points. For the purposes of this rule, “suspension” is defined as any item that is designed to move when a wheel is deflected vertically. This includes shocks and struts, control arms, steering knuckles, uprights, etc., but not tie rods, steering racks, and subframes. In addition, shock absorber/strut upper mounts are to be considered suspension components."

This allows the use of fully custom uprights and A-arms.