Improving commuter alignment
 

First off, car is a commuter on stock suspension and stock alignment. 14 FRS with HKS supercharger on HKS base tune on stock exhaust save a CSG MXP cat back. Baseline suspension in front, but I added camber bolts on a recent realign for new tires a season or so ago. I haven't tinkered beyond stock alignment yet, but they're in there. Have an MCA traction mod and adjustable LCAs sitting on the bench ready to go in. Looking for alignment numbers to improve the handling in the corners.

I've read to max out the front camber with the new bolts and match the left/right exactly versus the spec window. And I've read more or less toe on the rear will alter turn in on both front and rear wheels. 1-1.5 degrees more caster as well up front.

Not finding much searching, so looking for feedback. Some numbers to start with. Trying to plan the install of the benched in the next month and don't want to put the same alignment in, I want to improve on it.

You have the camber bolts, stock front camber is abysmally low even for street-only, so yeah, just maximize front camber with them. Left/right don't *need* to be *exactly* the same. +/=0.2 degrees is no big deal at all.

You don't need MCAs or LCAs, IMO you won't see any benefit from them. You don't need more caster, it's not adjustable with parts you have anyway.

For alignment for your usage and "improved handling", maximize front camber, zero front toe, and zero to 0.1 degrees total rear toe-in.

Do you have numbers for what your current alignment is?

I liked these two combinations. For lots of highway driving avoid front toe. I have 30km highway commute daily and toe out doesn't bother me, but it may bother some.

0 toe front, 1/16(1.5mm) toe in rear
1/32(0.5-1mm) toe out front, 1/16(1.5mm) toe in rear

If you wanted more front camber you can add roughly 2° camber via camber bolt+ crash bolt combo or camber bolt+pedder strut Mount.

I’m currently testing a new street setup with Potenza Sport 215/17, these are my numbers:

Front camber: -2.2
Rear camber: -1.7

Front toe: 2mm out total
Rear toe: 3mm in total

Front caster: +7.5
Front SAI: 17
Et35 rims
22mm front bar
15mm rear bar
7kg/mm springs
Ride height front: -30mm
Ride height rear: -22mm
Hot Tire pressure: 2.4bar on both axels

Pyrometer showed no more than 10 degrees difference from inner to shoulder on both front and rear tires, handling is good and those tires work really well.
Anyway I’m on coils and I do have a stiffer front bar, stock suspensions need probably a bit more camber front and less in the rear, you can also use less toe out for a better wear and traction mod in my opinion would help at stock ride height, especially with a SC.

Tip: It’s important to torque properly rear cam adjustable toe arms otherwise they’ll slip very easily. Correct torque is 100Nm.

On stock suspension and normal height MCA Traction Mod can help. But if you drop your car 1 inch with springs they won't be necessary. Dropping 1 inch get the rear camber near -2.0. Better to have no toe at all on the street.

If you still have the stock suspension, I think you might want to change the shocks. 2017+ are a little bit better than the previous model maybe you can find a mildly used kit. I would look at changing the suspension before doing an alignment. A better suspension on this car really makes it more enjoyable and yours are almost 10 years old. You'll have to change sooner than later.

You could get coilovers (RCE, Tein Flex A CSG, KW3, ST Suspension...) or aftermarket shocks (Bilstein, Koni...) with aftermarket springs (Eibach, RCE...) if you don't need or want adjustement.

Important question:

What tires are you running?

Michelin Pilot 4s (or is it s4), the 300 TW summer tires on stock wheel spec RPF1s. OEM wheels have Michelin Pilot A/S of their top flavor for winter rain driving in the PNW.

I now have some notes to run on for the work. I did search alignment and just didn't find numbers, thank you for concrete input. I am putting the rear end parts in for more long term goals than immediate. I've read the MCA kit works well and am going to try it. I mentioned it since I have it. I know it won't help alignment, just providing full disclosure being it is a suspension related item. The LCA will definitely provide more adjustment than the stock allows though.

I had good feedback from a guy at work who tracked and autox'd his car real hard, but lost track of him through the pandemic and him selling his car and moving on from the platform. He mentioned the need for rear LCAs to fully extract the suspension potential. As a mechanical engineer by trade, he had elaborate experience and kept the notes. I just never talked numbers, it was always the more here, less there changes the slip when neutral or pushing it hard.

Have you ever experienced a lack of grip, whether front or rear end?

Rear end is a bit tail happy, hoping to tune alignment make it stick a little better. It's the stock 14 FRS suspension and stock alignment currently. My typical traction loss is a hard corner where the rear inner loses too much weight and it slips a bit, nothing too puckery. Becomes much more pronounced when tire wear is last 1/16" inch before they hit the wear bars. For reference, all 6 sets of expended tires have worn nice and flat to end of life.

You can't tune inner rear grip with alignment.

Sounds like a well tuned LSD is actually your solution, IMO.

I was just thinking that today. If the tighter LSD was in place, the inner wheel wouldn't break loose as much and I'd keep more grip.

I can also see how the MCA may help here over the commuter bumps a bit to reduce the vertical instantaneous vector during high rev/torque acceleration out of the corner over what I affectionately call the roads of the sunken grade.

I can tell you from my own experience with the MCA Traction Mod on stock suspension, it made a BIG difference in the twitchiness of the rear end, and it seems to load the stock diff more progressively and put the power down much better out of corners. Even more so over bumpy roads.

With the Traction Mod relocating the pickup point about 50mm lower, it would take a 50mm drop (WAY too low for this car) to have an equivalent effect when it comes to geometry change, so IMO it's worthwhile for lowered cars as well, even though the effect would be somewhat reduced.

Thanks, that's the feedback I'm looking for. I need to install those first as I suspected.