Suspension

[DC2Iggy]

If you were in socal you could've tried my car.
All Spoon bush installed almost 2 years ago and I just installed GC's ITR set up with 550 springs at all 4 corners.
Car is lowered about an 1" F&R from stock.
24mm Mugen bar in rear.

It's only been a couple weeks but so far I really like it

That's great to hear. How is the ride on the street?

What are stock like 250 in front linear and 250 rear progressive? Jumping to 550 isn't bad? Just wondering if I'd be better at like 400-450 on all 4 corners.

If you're just getting them for daily driving with some spirited driving you could get something like 430f/350r. It's a nice middle ground spring rate that a bit firmer than the off the shelf kit. Not too bouncy over bumps but you will also get a bit more body roll compared to higher spring rates. Overall very comfortable on the street.

[Dave7CDMTYPER]

I have itr spec oem struts and koni yellows on my daily gs-r, Jdm itr rear sway. It's pretty nice handling, very neutral in the turns. That's a good option. I'd go with lower springs, but wouldn't be able to get in my garage, there's a ramp.

[aklackner]

Danger random brain dump follows (full disclosure I also have a head cold so mileage will vary):

“true” multi spring setups are very complex and generally require a long threaded shock body to allow placement of stops to control transition of the effective spring rate. At least I’ve had a hard time even getting the math to work out between available height (minus couplers, cages, etc), required travel (for street application), and workable effective spring rates for a street application. Softer spring rates just need more room for travel and preload, where there’s more flexibility with limited travel and preload of stiff race applications. Some manufacturers also make a small inner spring sometimes called a bump or helper spring which will replace a rubber/foam bumpstop and add to the effective rate of the main spring (allowing for a slightly softer main spring) but these require compatible dampers, cups, and travel height. Most of these I’ve seen are made for large shaft dampers (aka pimp shocks).

What you commonly see on (Honda) coilover setups is a keeper/tender spring (generally a flat profile coil on top of the main spring) in combination with a short high rate main spring. The keeper springs have an extremely low rate (iirc 0-30lbs/in) and really only serve to ensure short main springs remain seated at suspension drop, when the main spring fully unloads and would otherwise float. These don’t come into play with ride comfort since the keeper springs are completely compressed as soon as the suspension is under any weight.

For comfortable street suspension progressive or dual rate springs make sense by the numbers only as long as the transition height aligns correctly with effective weight and preload for desired ride height. The difficulty here is that most designers don’t have the ability to wind springs themselves for each application so don’t have much control over locating transitions. What’s packaged will vary in suitable and will have limited use in adjustable height setup as properly locating transitions requires a fixed preload.

I think a lot of the perception of progressive setups come in here since many report the progressive portion of the spring is fully compressed/doesn’t come into play under vehicle weight or in some cases once the spring is mounted on the damper. For example my H&R Street springs had the equivalent of maybe one coil to transition once mounted on the damper so would only have come into play at near full drop.

The valving/design of the damper will play a large role in ride for a given spring rate. These designs generally have a sweet spot and don’t account for significant variance in variable/multi-rate spring setups. This also applies to soft springs on high-end (generally race oriented) dampers which can yield a worse ride quality than when paired with a stiffer spring.

Also I’ve had issues getting spring rates below 350 to work (up front) in a lowered street application again due to required preload, travel, and bind (usable height of the springs). Limited clearance for barrel shaped springs also raises the potential for bowing on narrow diameter springs as they increase in length.

From what I’ve heard Koni (yellow) sport dampers suffer with a spring much above 550lbs/in. They also seemed poorly suited (bouncy/too stiff) on all but the softest setting with the H&R Street springs I ran (no published rates but some where close to OEM). Koni sports should do well with rates 350-500 unless re-valved.

Then there’s bump stops

To actually put some suggestions out there, personally (not trying to spark a debate, there are near infinite options, these are suggestions for a starting point, just where my head is at again personally):

For something that’s comfortable in primarily street use, OEM is probably best. Always do bushings first and see if you really need/want more.

If lowered (keep it moderate, the geometry does suffer as you go lower) but street use, I’d suggest GC coil conversion sticking around 350 rates in front, 300 in the rear. Probably Bilstein shocks (Koni sport have a larger diameter shaft which requires modification of upper shock mount bushings and dust covers or aftermarket mounts, don’t skip dust covers unless you like replacing shocks).

If primarily street but sees some track use too then take a look at bump stops as spring aids (common in the Miata space) as I believe this is the easiest/most approachable/lowest cost way to produce/tune an effective progressive setup. This approach can work with aftermarket or OEM suspension but you’ll need to replace bumpstops as they age.

If looking for even more option to get aggressive you can swap the Bilstein for a Koni or other adjustable sport shock, still use GC sleeves (but need Koni specific model) and street rate springs and pick up a set of spring rubbers and block coils to stiffen things up as desired before hitting the track.

[Totsie7944]

Thanks. Yea that's why I was just going to go with the tried and tested GC setup from them. Probably 500 on all four corners, Maybe 550.

Seems appropriate for the street and garage queen use I have nowadays with my R. And I'd only lower it perhaps 1". I don't want to need any camber kits or any of that nonsense.

[aklackner]

Thanks. Yea that's why I was just going to go with the tried and tested GC setup from them. Probably 500 on all four corners, Maybe 550.

Seems appropriate for the street and garage queen use I have nowadays with my R. And I'd only lower it perhaps 1". I don't want to need any camber kits or any of that nonsense.

Sounds like a good plan.

If increasing the spring rate up to 500 you may want to look at a larger anti-roll bar, too. The stiffer the springs the less effective a given roll bar will be, since it will be pulling against the increased rate of the new springs.

[97cwr]

i have a full set of spoon bushings on my R minus the rear trailing arm (OEM). Unbelievable quality and fitment was spot on for every bushing. The ride now is pure joy. No sacrifice in ride harshness at all. You will cannot go wrong with the spoon set.

[aklackner]

I agree bushings are a must do, especially when going with stiffer springs, (softer) old OEM bushings won't last long with against the increased forces.

The bushings I did were hardrace (street for motor mounts, hard rubber for all the suspension arms) except trailing arm bushing which is OEM. I initially ordered Spoon but it was going to be 3+ months to get them. It was my first time pressing suspension bushings (I had done wheel bearings previously). I used a 20 ton HF press and a lot of sockets, different cups to do all the bushings. The tooling was probably as expensive as the bushings but has come in handy multiple times now.

For me, it was a challenge to make sure the cup\sockets didn't cock or slide off the bushing (I actually destroyed one bushing and had to order a new FLCA bushing set to replace it). This is most likely due to my inexperience, working alone, plus the added challenge of a low quality press there's a lot of movement and it's not what I'd call square. The bushings themselves were all well fit to designated locations and were a huge improvement over 20 year old OEM bushings that they replaced. I can't speak to longevity since this was the 5 lug for the LS (now on 01-386) and it was rear ended basically a couple days after I got the 5 lug on. For the ITR, at least if they go quickly I know I have every thing I need to do pop in a new set in.

[97cwr]

i did mine myself as well. you def need a good press or forget it. Can't remember but i think i cooled down a couple of them in the freezer before installing.