We have a couple cars in the SE running this “eyebolt” type control arm bushing. I talked to the Shawn to confirm and they are indeed not legal. We will brief this to the participants at Roebling and then inspect CABs as part of a compliance inspection at CMP in May. That should be plenty of time to go back to normal lollypops.
Illegal Control Arm Bushings
cwbaader
#2
Scott, why are these illegal? They have the same offset as the “M” bushings and are probably stronger than stock.
Ranger
#3
I suppose they’re illegal because they replace the OEM lollypops, and there’s nothing in the rules that allows that. All it takes tho is for someone to write up a good case for them to be made legal and the directors could go for it.
I don’t recall that I ever saw any folks here debating re. “should Treehouse CABs be approved for use.” I don’t think the issue ever came up. A long time ago I asked Carter about them and he said “nope.”
cwbaader
#4
IMHO, they are a legal replacement part for the OEM piece. They have the same function and geometry and the bushing is also legal.
Som
#5
I’m in the “no reason they should be illegal” camp, but I’d say the rules are pretty clear about not allowing them (“clear” in the sense that while there’s a couple mentions of modifying the bushings themselves, there’s no mention of allowing a change to the carrier/lollipop besides the set screw). When I built my car, I had a set of the Treehouse bushings from my E36 M3 lying around that I was planning on installing, until I realized they weren’t legal.
While we’re at it, off topic, but regarding this line “9.3.6.1. Drive shaft may be substituted.” – does “drive shaft” include the half-shafts? As in, can we use http://www.catuned.com/e30-bmw-axle-shaft-rear-abs ?
(Okay, to be fair, that question is beyond just “off topic” and in the realm of “completely unrelated”. Sorry.) 
Som
Edit: To clarify, I would say it’s a slippery slope to consider the two bushings as being functionality equivalent. The reason I’d want the Treehouse carriers would be reduce potential deflection with the smaller bushing area. If the same thought process was used across other parts of the car, I’m sure there’d be a ton of little things we could go through and tweak. Not making a commentary on whether that would be a good or bad thing, just saying. In the case of the control arm bushing carrier, I’m not sure if the metal itself has the potential to deflect, but I would also imagine the little nubby eyebolt carriers would be less susceptible to flexing, too (though, again, I would guess – given how beefy that steel is – that the stock ones don’t bend… it was just a thought).
Ranger
#6
The halfshafts look fine to me. It’s not a matter of “substituted”, the halfshafts in your link look like normal OEM replacements.
Re. bushings and functional equivalent. That’s the wrong way to look at it. The reason it’s the wrong way is that it opens up the door to endless debate re. the functional equivalent of every little part on the whole car. The way to look at it is the simple matter of “is it the OEM design or not.” In this case, “not.”
If someone feels strongly about the issue, they should submit a rule change request and make a good case for it. It’s gonna be a hard one to sell tho.
The easy rules to “sell” are the ones that reduce costs, one way or another. Either the rule allows folks to use a cheaper part, or the rule has a long term cost savings effect because it’s protective in nature or lasts a long time. Since there aren’t a bunch of folks complaining about their aftermarket CABs wearing out, it’s tough to make a compelling case for the eyebolt CABs.
Note that I’m not the one to convince. I’ve no dog in this fight, nor do I have the power to make rule changes. I’m just one voice among many. Anyone that feels strongly on the issue should channel their enthusiasm into making their rule change request compelling.