Postby Hasbeen » 29 Jan 2009 03:59
OK, so I'm a worrywart, but I am a bit concerned with the high local
stress points this boxing builds into these arms.
From full compression to full extension, of the rear suspension,
from side to side, [inside wheel off ground], there must be between
8, & 10 degrees of twisting in these arms. The stock rubber
suspension bushes would have absorbed much of this.
Now we fit urethane bushes, & the mounting points, & the arms must
absorb this twisting, mostly the arms. The open arm has no trouble
doing this, in fact it would not even notice it, but the boxed arm
has to do it, in a very short, localised area. Roll on stress cracks.
If I was going to do this, in a road car, I would use rubber bushes
in the front mount, & keep an eye on the mounting point, & the arm,
where the boxing ends.
For a competition car, with beefed up mounting points, using
urethane all round, I would still keep an eye on the same things, &
change the arms after a couple of thousand Km.
In defence of my careful attitude, I did race an aging Lotus open
wheeler, which taught me to expect stress cracking, EVERYWHERE.
Hasbeen
