Coilovers. GC vs Tein vs RS*R vs KW etc.

[Racecomp Engineering]

Originally Posted by ZDan

Personally, I'd much rather have a top mount with camber adjustability than 2 damping knobs, as long as the damping is in the ballpark for the application and spring rate out of the box. Either way, decent dampers with a highly digressive curve are a MUST.

I honestly don't think I'd bother with coilovers that didn't provide camber adjustment up front, which this car *desperately* needs. I'd just get sportline springs and Konis, and crash bolts if I didn't want to spend the $3500+ for KW ClubSports or Ohlins DFV.

KWs and our RCE coilovers use a slotted front lower strut mount, so you can get plenty of camber down low without plates (arguably the better place to add camber anyway). You can still add camber plates.

Skip the sportline springs if you're going for handling.

- Andy

[ZDan]

Originally Posted by Racecomp Engineering

KWs and our RCE coilovers use a slotted front lower strut mount, so you can get plenty of camber down low without plates (arguably the better place to add camber anyway).

Don't you quickly run into issues with wider wheels/tires? My approach would be to keep offset similar to stock and try
Could be argued that adding camber by moving the upper mount inboard is "better" due to more camber gain with bump...

You can still add camber plates.
Skip the sportline springs if you're going for handling.

I dunno, I haven't really investigated, but I would strongly consider aftermarket linear-rate lowering springs with ~50% greater stiffness with appropriate digressive damping (konis?).
After my Tein SS experience, I'd be very wary of lower-cost aftermarket coilovers...

[7thgear]

Originally Posted by ZDan

Don't you quickly run into issues with wider wheels/tires? My approach would be to keep offset similar to stock and try
Could be argued that adding camber by moving the upper mount inboard is "better" due to more camber gain with bump...

by changing the mounting point at the top you are decreasing the angle betwen the LCA and Strut, this brings about hard to qualify geometry changes

most notably the scrub radius and camber gain due to wheel position (rather than compression due to weight transfer)


if you only change camber via pivot of the wheel hub then you maintain more of the OEM design while getting the required camber

yes.. you won't be able to mount 9" wheels.... sad panda

[ZDan]

Originally Posted by 7thgear

by changing the mounting point at the top you are decreasing the angle betwen the LCA and Strut, this brings about hard to qualify geometry changes

most notably the scrub radius and camber gain due to wheel position (rather than compression due to weight transfer)

I've put together a quick/dirty model based on fr-s strut geometry I found (accuracy unknown): https://docs.google.com/spreadsheet/...EcC1rbVE#gid=0
Moving the top of the strut inboard by 15mm gains 1.56 degrees negative camber, and scrub radius is increased by 9mm (-66 to -75). 9mm lower offset wheels would have you back at stock scrub radius.

FWIW, this geometry gives a front motion ratio of 0.925:1, NOT 1:1. If true, 9kg front springs gives you 9*(.925)^2 = 7.7kg/mm wheel rate, quite a bit less than 1:1 gives you.

if you only change camber via pivot of the wheel hub then you maintain more of the OEM design while getting the required camber
yes.. you won't be able to mount 9" wheels.... sad panda

I'd rather move the tops of the struts to have wide wheels and correct scrub radius with lower offsets, which you'd have to use anyway (presumably).

[7thgear]

Originally Posted by ZDan

Moving the top of the strut inboard by 15mm gains 1.56 degrees negative camber, and scrub radius is increased by 9mm (-66 to -75).

...

9mm lower offset wheels would have you back at stock scrub radius.

can you simulate wheel turning?

you'll see what i mean if you 3D model it...

you can also do it with a pencil and post-it note...

damn it i had some pictures somewhere

[Racecomp Engineering]

Originally Posted by ZDan

Don't you quickly run into issues with wider wheels/tires? My approach would be to keep offset similar to stock and try
Could be argued that adding camber by moving the upper mount inboard is "better" due to more camber gain with bump...


I dunno, I haven't really investigated, but I would strongly consider aftermarket linear-rate lowering springs with ~50% greater stiffness with appropriate digressive damping (konis?).
After my Tein SS experience, I'd be very wary of lower-cost aftermarket coilovers...

We're running 245's with plenty of camber and OEM style group N top mounts without issue. I don't recall how much room we have.

My hesitation with Sportlines is the excessive drop and lack of bump travel.

EDIT: I'll take the lower SAI you get with adjusting camber at the lower mount.

- Andy

[ZDan]

Originally Posted by 7thgear

can you simulate wheel turning?
you'll see what i mean if you 3D model it...
you can also do it with a pencil and post-it note...
damn it i had some pictures somewhere

I have it in 3D. Doesn't seem to be much effect of moving the top of the strut inboard. It's such a long way off, the angles don't change much.
In the end, more than one way to skin a cat...

How much camber is gained at the front from lowering the car 1"-1.5", and how much from camber bolts? If that added up to 2.5degrees, I wouldn't be worried about it for street/track usage. For pure track setup, more adjustability highly desirable...

[ZDan]

Originally Posted by Racecomp Engineering

We're running 245's with plenty of camber and OEM style group N top mounts without issue. I don't recall how much room we have.
My hesitation with Sportlines is the excessive drop and lack of bump travel.

That is something to consider. Are most coilovers able to give a fair amount more bump travel in the FR-S/BRZ?

EDIT: I'll take the lower SAI you get with adjusting camber at the lower mount.

An additional 1.5 degrees SAI doesn't amount to much camber loss at most real-world steering angles.
It's all a compromise. How much camber can you get with 245s (well tucked in) only adjusting at the bottom of the strut? If it's ~2.5 degrees, I wouldn't worry about the upper having camber adjustment for a street/track car that's not competing in a class where hundredths are critical.

[OICU812]

Using stance LCAs in rear and say Ground Control camber plates up front you can gain a solid inch of bump travel on coils like KWs and Tarmacs to note.

[448hpsti]

Originally Posted by OICU812

By sung stance LCAs in rear and say Ground Control camber plates up front you can gain a solid inch of bump travel on coils like KWs and Tarmacs.

GC plates rock. I also like the GC koni setup(race) on my car and the racerx lca gives me security trackside

[OICU812]

Originally Posted by 448hpsti

GC plates rock. I also like the GC koni setup(race) on my car and the racerx lca gives me security trackside

Good to know as I have V plates up front now and plan is if I need more bump travel up front I'll swap for GCs.... You have used and like the GC coils? There are so few that have them hard to know what they're like from a street to auto X coil... FULL race as I understand and as you re enforce they're good.

[The Slow One]

Originally Posted by OICU812

Using stance LCAs in rear and say Ground Control camber plates up front you can gain a solid inch of bump travel on coils like KWs and Tarmacs to note.

I have this setup basically, except i have the full GC coilovers as well. Love the suspension travel, the only thing is my car sits extremely low. I have very little room to raise the rear now. Not a huge issue, but the times I do take the car on the streets to hang out with my buddies, I can barely clear some of the Houston streets. I've been having a blast on the local tracks though

[448hpsti]

Originally Posted by OICU812

Good to know as I have V plates up front now and plan is if I need more bump travel up front I'll swap for GCs.... You have used and like the GC coils? There are so few that have them hard to know what they're like from a street to auto X coil... FULL race as I understand and as you re enforce they're good.

Softer springs than most on my car. GC coils are custom wound eibach

Yes I track my car as hard as I can and like the setup I'm am on. Details are in my build thread off the top of my head I forget my exact coil rates...
I found the point at which it gets too low to handle right