Suspension tuning - dampers, spring rates, etc.

[DC2Iggy]

From what I’ve consumed, it’s generally very hard to correct double wishbone geometry once lowered. If a lowered a small amount (LCAs are level or angled slightly up to the inside, under weight) I believe you’re better off running OEM ball joints.

If lowered aggressively (LCAs point down to inside), to reduce center of gravity, and running stiff race suspension then raising the roll centers (front and rear) may be desired since the shift in geometry will move the roll center further from center of gravity increasing effective roll forces.

I don't believe I'm lowered enough where I've affected the geometry (maybe less than an inch lower than stock) which is why I'm wondering if the RCA kit would even do anything. Never installed one on my old GSR and that thing was quite a bit lower. Unfortunately, it's been so long since I've had my GSR that I can't remember what the driving feeling was like compared to my ITR.

Honed out of the gate caught my interest since they were originally engineering driven with data. The Honed updates have been marketing oriented lately, but they have a rollcenter kit for front & rear.

Sadly, this was the project I was about to install prior to theft. My Honed kit was in the car, so I never got a chance to drive/track so I'm unable to offer direct feedback. I can ask a few that have tracked with the kit for direct / none "influencer" feedback.

The main thing these days is to get out and get seat time. I spent way too much money over the years simply because I enjoyed projects / wrenching on the car.

Yeah, Honed seems to be the only manufacturer that's done their own testing. The person who bought my old GSR threw in the Honed kit and said it felt great. However, from my experience of owning that car and doing all the major suspension modification, I remember the car handling like it was on rails. So it's hard to say if the kit did anything or if it's just a butt dyno thing.

I'm trying to diagnose this unsteady feeling I'm getting when going over bumps at high speeds at my local track with the R. It's like the car is just not stable/steering feels loose over bumps to the point where I have to let off on the throttle. Already did the steering rack adjustment and replaced most of the suspension bushings (just have to install the Mugen compliance bushings still). All the steering components also feel tight with no play. The ball joints don't seem to be an issue either but I would like to replace them as my ball joint separator mangled the threads.

So general consensus is to just stick with OEM. Easy enough.

[coolhandluke]

I like your approach of identifying a specific problem to solve, then researching options. I've pinged a few community members for feedback on your specific issue, as they are more experience with on track suspension tuning.

[Xian]

What's the general consensus on extended ball joints/roll center kits? Did some looking into them this afternoon but most threads are 2010 or older and the opinions are divided. A lot of companies made/make them but Honed Developments seems to be the only one that's done "testing" and has posted their findings online.

I need to replace the ball joints on my ITR and wondering if I go with the oem length ones or go with extended ones if there are benefits. My car is slightly lowered on GC/Koni and lately it's been more of a autocross/lapping car than just daily driving. Any point of going with extended ball joints?

From what I’ve consumed, it’s generally very hard to correct double wishbone geometry once lowered. If a lowered a small amount (LCAs are level or angled slightly up to the inside, under weight) I believe you’re better off running OEM ball joints.

If lowered aggressively (LCAs point down to inside), to reduce center of gravity, and running stiff race suspension then raising the roll centers (front and rear) may be desired since the shift in geometry will move the roll center further from center of gravity increasing effective roll forces.

Honed out of the gate caught my interest since they were originally engineering driven with data. The Honed updates have been marketing oriented lately, but they have a rollcenter kit for front & rear.

Sadly, this was the project I was about to install prior to theft. My Honed kit was in the car, so I never got a chance to drive/track so I'm unable to offer direct feedback. I can ask a few that have tracked with the kit for direct / none "influencer" feedback.

The main thing these days is to get out and get seat time. I spent way too much money over the years simply because I enjoyed projects / wrenching on the car.

Take it with a grain of salt since this is second hand info buuuuut I know Eric (Kutil) was super impressed by the Honed parts. He was a diehard “stiff rear” setup guy but swapped their parts, dropped rear rate, etc. and got faster. IIRC, the car was also easier to drive since the (lighter) rear end had rates more suitable for the load…

[Xian]

From what I’ve consumed, it’s generally very hard to correct double wishbone geometry once lowered. If a lowered a small amount (LCAs are level or angled slightly up to the inside, under weight) I believe you’re better off running OEM ball joints.

If lowered aggressively (LCAs point down to inside), to reduce center of gravity, and running stiff race suspension then raising the roll centers (front and rear) may be desired since the shift in geometry will move the roll center further from center of gravity increasing effective roll forces.

I don't believe I'm lowered enough where I've affected the geometry (maybe less than an inch lower than stock) which is why I'm wondering if the RCA kit would even do anything. Never installed one on my old GSR and that thing was quite a bit lower. Unfortunately, it's been so long since I've had my GSR that I can't remember what the driving feeling was like compared to my ITR.

Honed out of the gate caught my interest since they were originally engineering driven with data. The Honed updates have been marketing oriented lately, but they have a rollcenter kit for front & rear.

Sadly, this was the project I was about to install prior to theft. My Honed kit was in the car, so I never got a chance to drive/track so I'm unable to offer direct feedback. I can ask a few that have tracked with the kit for direct / none "influencer" feedback.

The main thing these days is to get out and get seat time. I spent way too much money over the years simply because I enjoyed projects / wrenching on the car.

Yeah, Honed seems to be the only manufacturer that's done their own testing. The person who bought my old GSR threw in the Honed kit and said it felt great. However, from my experience of owning that car and doing all the major suspension modification, I remember the car handling like it was on rails. So it's hard to say if the kit did anything or if it's just a butt dyno thing.

I'm trying to diagnose this unsteady feeling I'm getting when going over bumps at high speeds at my local track with the R. It's like the car is just not stable/steering feels loose over bumps to the point where I have to let off on the throttle. Already did the steering rack adjustment and replaced most of the suspension bushings (just have to install the Mugen compliance bushings still). All the steering components also feel tight with no play. The ball joints don't seem to be an issue either but I would like to replace them as my ball joint separator mangled the threads.

So general consensus is to just stick with OEM. Easy enough.

Apologies if it’s on an earlier page… but what’s your current suspension setup and wheels/tires? Also, just to clarify, the unsettled feeling is bumps mid-turn or even when going straight? How’s the stability under hard braking (straight line)?

[DC2Iggy]

Apologies if it’s on an earlier page… but what’s your current suspension setup and wheels/tires? Also, just to clarify, the unsettled feeling is bumps mid-turn or even when going straight? How’s the stability under hard braking (straight line)?

Only minor suspension mods:

Koni Yellows
GC 430/350
Skunk2 UCA
Rear Camber Arm

-2.5 front camber / 0 toe (i think...maybe a little bit of front toe)
-1 rear camber / again maybe 0 toe but i can't remember

The unsettled feeling is only when going straight. When the car is loaded on one side it has no issues. It feels fine under hard braking as well. I do also have a cusco diff so I'm not sure if that could be contributing to it or not.

[aw614]

I saw you mentioned you haven't installed your new compliance bushing yet, maybe try to install it and see if it fixes the unsettled feeling when braking straight? It sounds like that was the last part of a suspension refresh that you have yet to do?

[DC2Iggy]

I saw you mentioned you haven't installed your new compliance bushing yet, maybe try to install it and see if it fixes the unsettled feeling when braking straight? It sounds like that was the last part of a suspension refresh that you have yet to do?

Yeah I'll do that this spring/summer. Just to be clear, the unsettled feeling is when just driving straight, over bumps, at high speeds. I don't feel like the issue is there when braking or cornering. But yeah, once I refresh everything I will also take it for another alignment. Not too confident at the last shop that did it since I had to go back twice.

[Xian]

Apologies if it’s on an earlier page… but what’s your current suspension setup and wheels/tires? Also, just to clarify, the unsettled feeling is bumps mid-turn or even when going straight? How’s the stability under hard braking (straight line)?

Only minor suspension mods:

Koni Yellows
GC 430/350
Skunk2 UCA
Rear Camber Arm

-2.5 front camber / 0 toe (i think...maybe a little bit of front toe)
-1 rear camber / again maybe 0 toe but i can't remember

The unsettled feeling is only when going straight. When the car is loaded on one side it has no issues. It feels fine under hard braking as well. I do also have a cusco diff so I'm not sure if that could be contributing to it or not.

Appreciate the detail

I’m wondering if it’s a case that you’re bottoming out the suspension travel. Are your Koni’s standard length or shortened? How low is the car?

[DC2Iggy]

Appreciate the detail

I’m wondering if it’s a case that you’re bottoming out the suspension travel. Are your Koni’s standard length or shortened? How low is the car?

Sorry for the late response. I don't think that's the case either. They are standard length and the collars are as high as they go without raising up another perch. I can get an actual measurements but I have about 2 finger gap up front and roughly the same in the back. It's maybe 1/2" lower than what it was stock.

Once the weather gets nicer and the snow melts, I'll start with replacing the compliance bushings and ball joints and go from there. Will probably get another alignment as well.

[Xian]

Appreciate the detail

I’m wondering if it’s a case that you’re bottoming out the suspension travel. Are your Koni’s standard length or shortened? How low is the car?

Sorry for the late response. I don't think that's the case either. They are standard length and the collars are as high as they go without raising up another perch. I can get an actual measurements but I have about 2 finger gap up front and roughly the same in the back. It's maybe 1/2" lower than what it was stock.

Once the weather gets nicer and the snow melts, I'll start with replacing the compliance bushings and ball joints and go from there. Will probably get another alignment as well.

Yep, agreed that bottoming shouldn’t be an issue at that sorta height.

Also agreed that it’s time to start looking at other parts and prying on stuff with a bar/screwdriver to see what moves. I’d look over everything… upper and lower ball joints, tie rod ends, compliance bushing, etc. in an effort to see if something has some play in it. Could also be a loose camber adjustment at the front or a worn toe link bushing (or RTA bushing) at the rear.