Rear 'tuning fork' swap

[maytag]

I'm with racer-boy on this. That rear "tuning fork" (what a stupid thing to call a trailing link) is not on the list of things frequently replaced by the fast guys. (And there's a hint: if you're looking for mods to help you go fast, don't copy mods from someone who is all about stance and pose). The ONLY thing that link positively locates is the front / rear distance. The exception here, is when adjustable LCA's ("coffin arms", to the "tuning fork" crowd) are fitted with enough spacer (to gain camber) that they need an adjustable trailing link to correct caster.

I'm also wondering how someone who says they taught hpde for a decade gets to a point where they post the following:
1) I'm racing on the streets and got schooled.
2) I'm blaming the car, but can't really describe the problem, just a vague term like "twitchy".
3) I don't understand how the suspension works in my car.
4) I'm running on mismatched tires.
5) I don't have a clue what my tire pressures are. Nor my wheel-offset.
6) I know I have a suspension or wheel-offset issue because the wheel rubs on the strut (But it hasn't kept me from racing on the street)

I mean, ALL of this sounds like something we'd hear from someone brand new to cars, and especially to high performance driving.

If you can help us more, we can help you more. What exactly IS the driving problem you're experiencing?

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[beater986]

I'm going to ignore the bit of snark since I understand how the post may come off and I see you've actually contributed some decent information here.

The initial post lacked some information because I was just attempting to see if deflection is a known issue and happen to come across that post below speaking about it and swapping the trailing arm.

From my previous experience with 90s Hondas, the trailing arm bushing disintegrating over time would cause the trailing arm to deflect in a similar manner.

The cause of the contact was actually a horribly bent wheel. Visually it looked only slightly damaged and held air, but when we put it on the balancing machine it was drastic.

While this explains the strut contact, it likely does not an explanation for the feeling. Specifically, there is quite a bit of body roll coupled with some under-steer in the front; though the under-steer does not seem to come about consistently.
When I was on a square setup, the car was definitely a bit tail-happy, but in a very predictable and controllable way.

I plan on logging more seat time in the car, freshening up the tired old suspension itself which I am sure is shot, and then attempting to further dial in anything else by adding a rear bar.

At this point, I'm attempting to research what shock/spring combos everyone seems to be going with. The PSS9s look like your standard choice, but given this is a daily driver and canyon car, I am unsure if they will be streetable enough. The ROW 030 seems like an option, but for the price maybe Koni FSD? Not sure how those compare.

Originally Posted by maytag

If you can help us more, we can help you more. What exactly IS the driving problem you're experiencing?

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[maytag]

Originally Posted by beater986

I'm going to ignore the bit of snark since I understand how the post may come off and I see you've actually contributed some decent information here.

I'm humbled. Truly.

Originally Posted by beater986

Specifically, there is quite a bit of body roll coupled with some under-steer in the front; though the under-steer does not seem to come about consistently.
When I was on a square setup, the car was definitely a bit tail-happy, but in a very predictable and controllable way.

Was that in this car? Are you getting the body roll and under-steer in the same places at the same speed all the time? (you see where I'm going here)

Originally Posted by beater986

I plan on logging more seat time in the car, freshening up the tired old suspension itself which I am sure is shot, and then attempting to further dial in anything else by adding a rear bar.

At this point, I'm attempting to research what shock/spring combos everyone seems to be going with. The PSS9s look like your standard choice, but given this is a daily driver and canyon car, I am unsure if they will be streetable enough. The ROW 030 seems like an option, but for the price maybe Koni FSD? Not sure how those compare.

There are TONS of people on this forum who have MUCH more knowledge and 986-specific experience than I do. (In fact; search just a little bit and you'll find my admission to several major gaffs along the way, haha.) But one thing I've learned to be the absolute BEST advice is the same thing my golf-pro tells me: Until you can repeatable results, don't change ANYTHING. In the driving world, that equates to "make sure your equipment is all working as it should so you have a consistently reliable platform, and learn to drive THAT first. Then address the issues as needed.

Were I you, I'd do exactly as you've said above: freshen-up what you've already got, and get it working correctly first. And, even being the boy-racer around here (notice, I'm not "racer-boy", that's somebody else here, haha) I'd still tell you that the stock 986 components in good working condition will allow just about ANY shenanigans on the street. In my opinion, it's pretty tough to find weaknesses in the 986 (other than hp) until you hit the track. And I'm not one of the slow guys.

NOW: if you're like me, you look at replacing parts as an opportunity to upgrade. I get that, and I'm the same way. You mention coil-overs (PSS9's). again; imho that doesn't make sense unless you're building a focused-on-the-track car.

[Qingdao]

A trailing arm has no effect on the distance from the inside rim of the wheel/tire assembly to the strut.

A twitchy feeling or unstableness could be caused by a bad wheel bearing, bent wheel or just flat out terrible alignment.

Terrible alignment could stem from a bad wheel bearing (most shops don't shake down the rear wheels when doing an alignment; I don't unless I feel something off during the test drive). OR you could have a bent spindle.