Re: spherical bearings in SCCA IT suspensions

[Richard Welty <rwelty@domain.elided>]

On Wed, 31 Jul 2002 13:55:10 -0400 AlfaNeely@domain.elided wrote:
>      Perhaps we should take this over to the Alfa Racing list,

perhaps, but we started it here, and some folks may actually care.

> but it
> has been my understanding of the rules that Heim joints are virtually
> free in the rear suspension of an IT car.  I have read the rules many
> times, both as a Scrutineer and as a competitor.  Amazing the way your
> reading of the rules changes when you change from a tech hat to a helmet!

my original (anti-heim joing/spherical bearing) interpretation was based on
the following logic:

in the PCS (Production Category specification), page 17, 17.1.1.D.5.d.4:

Suspension bushings are unrestricted. Adjustable Spherical Bearings or Rod
ends are permitted on all suspension components.

by contrast, in the ITCS (Improved Touring Category Specification,
page 16, 17.1.4.D.5.d.6:

Bushing material, including that used to mount a suspension subframe to a
chassis, is unrestricted.

the IT rule is much more constrained than the Production rule, and my
rather strict interpretation was based on the fact that material is
unrestricted, but not design (that is, you could go solid of any kind, but
not to a more sophisticated kind of bushing.)

but i talked about it with Kurt (who became chair of the SCCA comp board
this year, and who used to be a front running ITA driver in one of those
japanese cars), and he felt the intent had been to allow spherical bearings
to be substituted for bushings if they could be gotten to fit w/o
modification of anything.

>      I further understand that you cannot use Heim joints in the front
> suspension if that requires modification of the existing suspension
> components. 

yes

> That is, you cannot drill and tap your solid lower A arms
> to use Heim Joints.  In fact, with the torsion bars locating in the
> lower arms, I am not sure how you would do that anyway.  I guess if a
> Heim joint would just thread into the upper caster mount at the front
> you could use one there.  And IT rules do allow existing rubber bushings
> to be replaced with solid material.

you don't use a heim joint. you use a spherical bearing, with inner and/or
outer sleeves so it fits into the space where the original rubber and metal
bushing from alfa fit. two on the bottom, one up top.

it's probably doable both for 116/162 chassis and 105/115 chassis w/o too
much pain, but probably a little machining to get sleeves that fit
appropriately.

richard
--
Richard Welty                                         rwelty@domain.elided
Averill Park Networking                                         518-573-7592
              Unix, Linux, IP Network Engineering, Security
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