25% RARB stiffness increase. $0.00
1. I was a little dubious that I want a stiffer RARB for the street, so didn't want to spend $$$muchodinero on a new one, then have hours of fun of getting it in.
2. I might want a stiffer RARB for autocross.
Solution, add more holes to the stock one, and see how I like that.
Moving the holes inwards 16mm makes it 25% stiffer. It won't be quite that high as the linkage geometry is messed up a little, maybe 24%
I made a little drilling jig from an 8020 joiner.
The RARB is tough, hard stuff. You are not doing this with Horror Fright drill bits. I used some nice cobalt ones. The 13/32 I resharpened multiple times.
Squishing it flatter. One tool was an M10 bolt and washers. I wanted to minimise how much I squished, I don't want this cracking. The other tool was a hydraulic terminal crimper. I think it is rated for 10,000lb. That worked better than the M10 bolt. Best result was the side that I first squished with the bolt and washers, then crimped. One of my holes drifted downwards a little. But once the RARB is bolted back up, nobody will ever know.
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I took it for test drive to some big box stores. I wasn't able to ahem, 'properly test' the cornering, but it feels pretty good at about 80% fun level. I really don't think I want a stiffer one for the street. The ultimate test of this will be the colour of my underpants after my next 80mph interstate moose manoeuvre.
So far, I really like the feel of it. Steering is much more direct, car feels a lot more neutral. It feels like it has more grip at the front.
Those who have have a pathological aversion to modifying parts, may like to know that the NM engineering solid 22mm is going to be very similar stiffness, on its softest setting.
If I decide this is a good stiffness for the street, but AX needs more, I'll get a solid 22.