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Thread: Idea: Roll Center Ball Joints for G20's

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2017-06-16 13:48:00
Idea: Roll Center Ball Joints for G20's
I started looking for possible drop in ball joints that would allow us to lower the control arm angle, which in return raises the roll center back up. Before anyone says this doesn't apply to our "magical" Multi-links, roll centers apply to all suspension designs, even beams. Have a read here.

Direct Fit:
Anyway, P10's use Moog K9633 ball joints, which also fit in P11's. After some searching I found that S13 guys use Moog K9633's for their rear control arms. If someone makes a roll center adjustment kit for rear of S13's, it would be a direct fit for us, that is a big if and I kind of gave up searching. But, being that S13's are very popular there has to be someone wanting to fix rear roll centers on those cars.

Modification to Maybe fit:
Moog used to be cool and would list size specs for ball joints and tie rods, but now it just redirects to federal-mogul site that just lets you buy, and not showing any specs. So getting dimensions was very hard.

Luckily I found this post by NismoPlsr
Originally Posted by NismoPlsr
S14 Front/Rear (moog K9820)
Taper low diameter 15mm
Taper High diameter 18.6mm
Taper length 23mm
Diameter where it presses in 41mm

S13 Front (Moog K9509)
Taper low diameter 15.8mm
Taper High diameter 18mm
Taper length 19.5mm 20mm
Diameter where it presses in 41mm

S13 Rear (moog K9633 [b12 front])
Taper low diameter 15mm
Taper High diameter 18.6mm
Taper length 23mm or 23.5
Diameter where it presses in 38mm

So if these measurements are accurate, S14 ball joints are almost identical to Moog K9633 aka, S13 rear's, and thus P10/P11 fronts. The only different is S14 ball joints are 3mm wider. I think you might be able to shave down our arms to get it to press in. Someone who adventurous can try it out, I would try it on spare arms and cheap aftermarket ball joints before spending $100+ on roll center ones.

I usually like to try things before posting it up, but with my 1" drop and my UCA's mount points lowered, my roll center is already a few inches above ground, raising it more could be detrimental (not enough roll to let the suspension gain camber on compression).
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