Tips on suspension settings

[asylum]

I did a "few" modifications on my track toy in the last 3 years and I am experiencing the fact that harder, more complex and more expensive is not always better if you cannot set the whole thing together. To summarize the mods :

- a lot of weigh savings, which mean a (very) light front end
- 215/615R17 & 260/640R18 Hankook F200 slick tires, on 8x17 ET40 % 9.5x18 ET30
- OS Giken LSD
- KW Clubsport coilovers
- Full metallic / spherical bushings front & rear including non-compliance pivot clamps
- Dali front and rear race sway bars
- Type R front reinforcement bars
- Stoptech ST40 big brake kit
- front home made undertray and spliter
- APR GTC-500 wing (set pretty flat)

The last mods which I think I did not take the benefit they should give are :

- the KW Clubsport that replaced old Tein Flex (not even the "mono")
- the metallic / spherical bushings

My alignment specs remained almost the same. Camber 3.30 ° front / 3.00 ° rear. Toe - 1mm front / + 3 mm rear. Caster around 8 °.

I had the front sway on the middle hole and the rear at the softest hole. As I encountered a bit of understeer at the exit (full gas) of fast corners, I set the front sway to the softest too.

Over all feeling :
- I did not totally eliminate the understeer at fast corner exit with full gas but it is better. I plan a Type R front hood to give some downforce (or eliminate lift) to counteract this.
- The front end is strong. I mean, I never feel the front loosing grip even when tailbraking in a downhill.
- I am more afraid of loosing the rear in this situation. I had one or two situation where it lost grip but I could react.
- The front tires still have a bit (5 mm) of unworn surface at the outside edge.

My analysis :
- I feel that I can use more of the front end by tail braking more. I feel that I can get benefit of the 5 mm unworn outside edges of the front tires and to do this I can tailbrake more agressively. For this reason, I am not into softening the front (sway or dampers) as I did it already with one hole on the sway or reduce the camber (3.30° seems right with slicks and the wear is ok). Nor stiffening it as I feel I can extract more of the current setting (spare outside edge of tires) and I would not stiffen a front end that is already so light (no beam, light battery, no spare tires, no front headlights, no AC condensers, no interior, ...).
- It seems that going "stiffer" / less compliant with the spherical bushings and the Clubsport on a very light car was perhaps not a direct benefit without other changes. The old Tein Flex I had had perhaps a bit harder springs (10/12 vs 8/8) but the damping on the Clubsport is a lot lot stronger. You feel it by trying to move the car up and down by hand that it is night and day difference. If on the front, I feel I can take advantage of this increase stiffeness after just reducing the front sway one hole, I am asking myself if the increased stiffeness on the rear is a bit too much and the more floppy rear induced by the Tein flex was helping a bit.

What do you think of the following changes ?
- replace the rear Dali track sway by the stock one.
- perhaps less rebound rear ?
- softening a bit the compression front to well compress the outside tire as the front end is very light ?


Thanks a lot for your inputs.

 

[Honcho]

I think softening the rear suspension and sway bar will result in more understeer, not less. Considering you already have the Dali track bar back there, I'd focus on softening the front of the car and making the rear stiffer (or keeping it as-is). The reason it's feeling better when you trail brake is that you're inducing a bit of oversteer, as trail braking tends to do. As you gradually lift the brake pedal through he turn, you're keeping some of the weight off the front suspension in the turn. This means that the NSX is understeering too much for your style of driving. I'd reduce compression and rebound in the front and see if it gets better. A more extreme solution is to go to a smaller sway bar in front. Obviously too much rear-bias and the car will spin like a top, but it sounds like you're used to a more neutral setup than the standard NSX understeer-bias.

 

[docjohn]

do you have any data? lap times pre post mods, or hot tire temps across surface? The big unknown is that rear wing, it could be lifting or pushing down....do you know which?

 

[Track Addict]

You can’t take a bunch of weight out of the front end, add a big rear wing and expect the front end to grip.

Put a splitter on that thang.

My front end would swim at ~80mph until I made a splitter/undertray setup.

fixed all my under steering issues, and brought back a balance to the car.

What ate your corner weights?

 

[asylum]

Already have a flat bottom front. I added a Type R hood recently and have to test.

 

[Track Addict]

Yeah that really isn’t enough to add downforce. It can reduce lift, but won’t be enough to balance the big wang.

If you seal the radiator and hood that might be enough, but you can never have too much front end grip in the NSX