Bob-
I had a similar experience at Grattan last summer. Started to get
comfortable at the track, and really started to push the car going
through the corners. Amid all the racing sounds, I thought I could
hear/feel a grinding sound. Decided to back off a little, and the
sound went away. I dropped from 1st to second place, but still
finished the race. Left front wheel rim was just 'burnshing' the brake
balance tube in right hand turns. I shouldn't have that problem any
more, now that I'll be using 15" rims, but it was a good reminder how
things can flex when you really start to load things up.
With a fresh set of slicks, a roadster is capable of pulling 1.5g in
the corners. That's easily double what the original intent was for the
design. I do lot's of crack detection and magnefluxing of parts in the
off season. Most of us racers are still racing on a stock based front
suspension, but we're starting to migrate to more radical changes, as
time (and budget) allow.
Happy roadstering,
---
Chris Coker
1969 1600 Street Car (SPL311-24529)
1966 GP SCCA Race Car www.risensonracing.com
On Jan 27, 2004, at 9:44 AM, RWM wrote:
> FWIW, a whole lot of years ago, after my first few autocross passes
> with
> Bridgestone RE71s on 7" rims, I noticed the suspension had flexed
> sufficiently
> to allow the rims to chafe the front brake caliper balance pipes.
> Just because
> there's no interference at rest, don't make the mistake of assuming
> something
> isn't happening under heavy load. If you're exercising the car, a
> periodic
> visual inspection is mandatory, even if you aren't going to the extent
> of NDT.
>
> And as Mike said, the fatigue effects of added loads do a job on the
> A-arm
> bushings and ball joints, too.
>
> - Bob Mann. '68 2000 Solex -- new balance pipes
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