Here is one peculiarity that has baffled me for thirty years. The rear shocks on the RC10 are angled forwards whereas the A-arms are angled backwards.
I think I finally discovered a reason for what seems to be this misalignment between rear shock angle and rear A-arm angle (squat). (It would seem natural for the shock to be mounted on the rear A-arm at exactly a right angle to the A-arm squat angle.) The literature (manual) or box advertising (I can’t remember which) mentions that the RC10 has an adjustable wheelbase. Sure enough, the rear suspension mounts have extra holes made for shortening the wheelbase. The forward/backward dogbone angle on the stock RC10 also leaves a symmetry for shortening the wheelbase. It seems, based on rough estimations, that shortening the wheelbase by using the alternate rear suspension block mount holes would place the shocks at a more optimum angle, or perhaps even alter the shock angle too much and place the shocks at an acute angle with respect to the rear A-arm squat angle. However, the rear bulkhead prevents us from using the shortened wheelbase, unless the rear bulkhead or the rear suspension mounts are physically altered. The front edge of the rear suspension mount already practically touches the rear bulkhead, preventing such a configuration. My guess is that the rear shock angle is a remnant from the original design which was to place the rear suspension mounts slightly more forward. My guess is that Associated lengthened the wheelbase after the prototype was made and that they added the wheelbase adjustment claim to the literature, not being aware of the full situation.
Another quirky fact is that in the early Edinger manual the photos for the rear shock standoffs (top of shock) show the white flanged bushing with flange to the rear, placing the top of the rear shock further forward. Yet, in the text to the very same manual instruction step the printed instructions tell you to disregard photo and flip the plastic white flanged bushing the other way around, placing the top of rear shock more towards the rear.
In any case, the slight angle misalignment of the rear shock with respect to A-arm arc of travel (squat angle) is not a big deal. The rear suspension still seems to be very effective for an early car. I experimented with putting a nylon spacer-bushing at the bottom of rear shock mount surrounded by strong steel washers as a way of getting the bottom of the rear shock more forward, but that design leads to too much flex in an already flexible rear A-arm (flexible by today’s standards of slightly improved materials).
(Continued in next post.)
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