Makes sense. They superceded the AP1 M12 (17mm head) bolts with the updated 19mm M12 bolts.


I would. You don't feel like they do much? I use them to keep my subframe on center.

 

I never had my subframe shift even hopping down the bumps at Sebring.

Now as far as a bigger head, since the flange is what clamps the subframe to the chassis, having a bigger flange means the clamping loads are distributed over a larger area. Does it matter when you have 6 huge bolts? Probably not.

 

Do much…yes they can center the subframe. Anyone good with a wrench can also center the subframe.

As far as solving a problem, they solve nothing. To say they “improve” something would suggest that the subframe is moving back and forth.

If that were the case, there would be a massive thud when the subframe moves, and it would be blatantly obvious. 10x more obvious than, say, a loose a-arm bolt.

Anyone who has a shifting subframe (which in my estimation is no one) simply needs to learn how the properly tighten the bolts.

Subframe collars will also not fit in all cars. There a small variations that prevent that in some cars.

There have been about 3 cars so far that they would not fit, due to subframe/mainframe variation. They become a long fight, and a waste of time. I no longer install them.

 

When centering the subframe, there's alignment holes, stick a big screwdriver in the alignment hole, and nudge the subframe if it's not lining up. You can also shift the subframe forward to get a little more caster, if you need more than the 8 degrees the compliance bushing gives you.

 

I thought subframe collars were snake oil until I installed a set for my friend.
They somehow make the chassis feel tighter and I was impressed enough to buy a set for myself.
I've since installed them on several peoples cars and everyone has been happy with them.

 

The problem with installing these is that everyone (myself included) wants to feel something from them. Someone who has a mechanic friend and daily drives their S2000 should do a blind test.

1. Drive to the mechanic in the morning, drop off the S2000, use their second car to drive to work.
2. After work, pick up the S2000 and drive it home. Leave second car at mechanic overnight.
3. Repeat steps 1 + 2 for a week. The mechanic will randomly pick one of those days to install the collars and set the alignment the same as it was before.
4. At the end of the week, the owner of the car has to guess when they were installed.

 

It is true there likely is some placebo affect going on but I 100% thought they weren't going to make a difference.
I'd also wager that the stiffer your suspension is the more you'll feel a difference.
I don't think they will make the car any faster around a track but they do make the car a bit nicer to drive

 

Subframe collars. This is oneof those mods where everyone that tries it says it makes a significant difference, and everyone that knows how stuff works says its impossible.

I often find that this scenario is bc the REASON people say it works is flawed, and it is doing something useful, just not what people think.

Like a jungle tribe that has a cure for a jungle disease, but they say it works bc chases away evil spirits. It does work, but not by that method.

In this case, what I speculate collars are doing is damping an oscillation. You've got this very long bolt. Long exposed shaft.

That goes through wider opening than shaft.



There are side loads. Imagine how that shaft could vibrate, like a guitar string. Collar fills a gap, changes string length, strings tune. Can still vibe, but at much different frequency, and much less oscillation. Car will have more solid feeling.

When there is significant antidotal evidence something works, but the theory doesn't make sense, maybe its placebo, but maybe its working for a different reason.