Suspension and Geometry set ups help

[Hadrien*]

Hey everybody,

Asking for a bit of help here, just refreshed my whole NA1 91 suspension with the following and i have a few questions.
- Every bushing ( though it was rubber but they are AS Racing Polyurethane )
- BC Coilover with swift springs 8kg/10kg
- Rear non compliance toe link and pillow bushing from SOS
- All the front knuckles, links, etc are new.
- Both front Type R strut brace
- Front Type R antiroll bar

My questions :

1) I have horrible squeak from the front only, any idea where it can come from ? My guess is the poly bushings, i wanted new rubber but had to buy the complete arms so i went with that might have just stick with my originals... Maybe there is a way to get rid of the squeak ?

2) The suspension feels good, but very similar to my old originals shocks and springs. ( I am in the middle setting, 7 clicks from 14 )
It doesn't really feel like an upgrade, is it normal ?
The rear non compliance toe link and bushing are really fantastic the cars feels much more stable and predictable.

3) But my main problem is the steering, it is now heavier than a USSR war truck. The car was even weird to drive at first, steering felt vague for 100miles then got much better ( guess everything was new and needed setting up or breaking in ). Now it feels ok from turning like 45degrees left or 45degrees right but above, at any given speed it is 3 times heavier than it was before, from a standing still it won't move with any force given.
The car is lowered from the original height by 20mm, i run the oem fatfives 15/16 with yoko AD08R, and my mechanic who knows NSX well, did a standard alignement.

I have read the thread about the geometry and i am willing to try something else.
Does this heavy steering feel comes from the type R sway ? the type R strut brace ? Maybe the standard alignement doesn't work with those upgrades ? Or the poly bushings ?
I did lot of karting and usually the heavy steering comes from a lot of caster.

Long fast corner are weird, if wanna change to another lane in a high speed corne the steering feels like it is stuck, it will go but not in a linear smooth way it will be kind of grubby.
The front end doesn't wash out and has good stable grip in roundabout or tight corners and the rear is very stable too and doesn't rotate on me at all. I really like the overall balance I just don't like the front right now.


Thanks a lot for the appreciated help or feedback

Hadrien

 

[NSXninja]

I am by no means an expert on suspension or the NSX in general, but I've learned over the years to start with the simplest solution. Are you sure your tire pressures are correct?

 

[Hadrien*]

I am by no means an expert on suspension or the NSX in general, but I've learned over the years to start with the simplest solution. Are you sure your tire pressures are correct?

Yes of course that was the first thing i checked... 36psi( 2,5bar) front and 36psi rear.

 

[Soundeffects]

That’s a lot of variables. I’d suggest a shop drive the car and give you advice. Congrats on the upgrade decisions.

 

[Hadrien*]

That’s a lot of variables. I’d suggest a shop drive the car and give you advice. Congrats on the upgrade decisions.

Nobody knows about NSX in France... I used to race professionally so for me there is a bit too much caster and the car might be too low making it hard to steer because of the steering link being not flat anymore but slighlty upright.

I am gonna try raising the car a bit and then change a tinny bit the alignement at a professional laser alignement place.

I have to say i now did 1000km's more and it feels the bushing are getting softer and steering is getting better.

 

[docjohn]

is your front swaybar hitting the battery tray when the car is on the ground?

 

[tomatoto]

Did you finally solve your problem?

 

[CB72]

The NSX is very sensitive to the geometry setting.
The factory recommends -3.5 mm of toe out in the front and +6 mm of toe in at the rear ( reduced later by Honda to save on tire wear)
With my 17 and 18" wheel combo the car never felt really safe and a local car racer ( Delage Sport in 47300 France) said this is crazy you must have toe in in the front...
He successfully raced BMW's for many years so I accepted his advise thinking that I could always go back to the original setting.
Let me say the car was transformed with a very gradual and linear increase in effort as you turn the steering wheel.
My setting is 2.5 mm toe in upfront and 4.1 mm toe in in the rear with 2°25' camber front and 2°30' for the rear.
Last but not least don't lower the car too much!
I'm at 110 mm front and rear measured from the lift rail running underneath the car.

 

[goldNSX]

a local car racer ( Delage Sport in 47300 France) said this is crazy you must have toe in in the front...

Did he explain why toe-out was crazy?

 

[docjohn]

Toe in will make the front feel less darty going straight ..but won't help your lap times.....the delage is an old car...

 

[CB72]

Did he explain why toe-out was crazy?

He didn't but [MENTION=4282]docjohn[/MENTION] is right the car will feel safer down the straights.
In fact it's quite obvious: as you begin turning the steering, the inner wheel starts pulling you in the turn while the outer wheel doesn't help.
Then as you turn further all of a sudden the outer wheel starts taking it's share of the lateral G force.
The issue, in my view, is that the feedback is not linear.
I remember that when my car was misaliged with too much toe out the car understeered until it violently oversteered.
Interestingly enough, the Mercedes F1 team can change the toe in as the car is driven to bring the front tires to temperature!
Now is it toe in or toe out I don't know?

 

[goldNSX]

The issue, in my view, is that the feedback is not linear.
I remember that when my car was misaliged with too much toe out the car understeered until it violently oversteered.

Then it's more a function of your expectations of having a linear feedback.
The choice of springs, swaybars and last but not least the driver play a big role.

I'll continue with my settings: slightly toe-out in the front but not as much as OEM. The main problem of the front tires is to build up reasonable temperature compared to the rear.
My suspension professional was about to set it at 0 in the front. Different cook, different taste of the same meal.

 

[CB72]

Then it's more a function of your expectations of having a linear feedback.
The choice of springs, swaybars and last but not least the driver play a big role.

I'll continue with my settings: slightly toe-out in the front but not as much as OEM. The main problem of the front tires is to build up reasonable temperature compared to the rear.
My suspension professional was about to set it at 0 in the front. Different cook, different taste of the same meal.

One must also take into account the amount of camber.
I'm running with 2°25' that cannot be obtained with the standard setup...

 

[stuntman]

Toe in will make the front feel less darty going straight ..but won't help your lap times.....the delage is an old car...

Toe-in usually will make the car MORE darty on-center, when going straight. It also makes the initial turn-in sharper and more responsive, but slightly reduces front grip steady-state, mid-corner by decreasing the suspension's ackerman angle.

This is counter-intuitive but think of it this way: With toe-out, both front tires are pointing....out. When making a left turn, before turning the wheel, where is the right front tire pointed? (to the right). It takes some steering input to just get the outside tire, with the most steering response, load, grip, and authority, to just point straight. It then takes more steering input and time to generate slip angle in the tread and carcass of the tire to then load the sidewall of the tire, to then make the car change direction and finally turn to the left.

With toe-in. The tread and sidewalls are pre-loaded and are 'scrubbing' with slip angle. When negotiating the same left hand turn, the right front tire is already pre-loaded to an extent and pointing to the left. Any steering input immediately is transmitted to the contact patch as response to make the car turn left. The left front tire starts to unload and has less authority as it takes time to point straight, then left and into the corner. Due to the steering's ackerman angle, the inside unloaded tire turns sharper, and quicker than the outside tire, so the inside tire starts turning to the left with a given amount of toe-in, quicker than the outside loaded tire starts turning left with the same amount of static toe-out.

0.02

 

[docjohn]

My thought process was based on the toe in making the tires want to both scrub to the centerline of the car like the rear toe in makes the rear more stable going straight I figured the same was true of the front..I will educate myself on the angle of Ackerman as always thanks for the input.

 

[asylum]

AD-08 give a very heavy steering.