Wheel offsets questions

[jamieburke]

Are the offsets on the oem 1991 set up like that for reasons of handling or are there any other reasons? With larger wheels the offsets tend to push the wheels out more- is this aesthetic or a there any handling benefits?

i find it all confusing. I have driven my car with wider offset 17/18 wheels and it drove terribly in comparasin to the oem 15/16 set up.

most posts and info seem to focus on how light wheels are or how good they look. Please inform me beyond this point!

[Pride]

Are the offsets on the oem 1991 set up like that for reasons of handling or are there any other reasons? With larger wheels the offsets tend to push the wheels out more- is this aesthetic or a there any handling benefits?

i find it all confusing. I have driven my car with wider offset 17/18 wheels and it drove terribly in comparasin to the oem 15/16 set up.

most posts and info seem to focus on how light wheels are or how good they look. Please inform me beyond this point!

Hi jamieburke, for the first 15 years of ownership I drove my 92 NA1 with 17" front and rear Stilauto chrome wheels I bought it with. And boy did they look good.

About a year ago I bought and fitted the oem 15/16 wheels with Yokohama 888 rubber and it totally transformed, for the better, the way it handled. I only wish I'd tried it years ago.

This Monday I will be installing the SOS compliance pivot lock which is said to make it handle even better according to many Prime reviews but without sacrificing its ride comfort.

I find it very strange that although we NSX owners already know we have one of the finest handling cars ever made, we also strive to improve on it in our own minds eye. It's like searching for the golden Grail really.:)

I will let you know how I get on and what I think soon, hopefully for the better, but I'm not holding my breath.:rolleyes:

[UnhuZ]

Pride,

i made 2 upgrades to my NSX that completely transformed the handling for the better... a lot better (not counting with coilovers)

1 - NA2 NSX-R front swaybar.... incredible.... it's thicker and i can't believe how sharp the front became.
2 - NA2 NSX-R Steering Wheel... again, incredible....together with the swaybar, made the front like a go cart... immediate
(didn't use the OEM NSX-R MOMO, $1000, but used the MOMO Tuner, $160, which is the same with just a logo difference.

i would love to try the 15/16 OEM setup, but now i can't... i have the 2003 front and rear rotor sizes and the OEM 15 can't
go over the fronts :(

Nuno

[Pride]

Hi UnhuZ, forgot to mention that I too have changed the front and rear Swaybars with Dali street/race about 6 months ago and you're right it made a huge difference, as you put it, go kart like handling.;)

But Please explain if you could as to why changing the steering wheel made such a significant improvement in the way it handles as I can't get my head around that one.:rolleyes:

Thanks.

[UnhuZ]

Hi,

i wasn't expecting it either, but after experienced it, and comparing with other NSX still with
OEM steering wheel, i came to a simple conclusion: Steering wheel weight.

the NSX-R Steering wheel assy weight (wheel + hub/boss) is a lot less than OEM steering wheel.

- NSX-R Steering Wheel + Hub/Boss weight = 1120g + 970g = 2090g
- OEM Steering Wheel + SRS unit = 2970g + 1560g = 4530g

as you can see, it's less than half the weight ;)

As to why, i can compare it with OEM flywheel vs Lighter Flywheel (like JUN).

The mass helps to smooth the sharpness of the engine rpm variations to pass to the
transmission. You get a lighter flywheel, and you will have a more responsive throttle.
Your input in the pedal will be passed faster to the rear wheels, because the crank can
pass the power easier to the transmission as it has less mass to rotate.

On the steering wheel it's the same, you have less mass to deal with when you turn it,
and on the other hand, road input will be passed to you more easily, which will increase
your steering feeling - like when the rear tries to rotate ;)

When you use lighter wheels, like Advan or Volks, instead of boat anchor wheels, you
will also feel the same as with a lighter flywheel.

It's my only explanation.... that and if Honda use lighter steering wheels on NSX-R and
NSX Type S, they meant something...and not only to save weight in general ;)

Nuno

[darock]

From what I understand about the NSX suspension, you will screw up the scrub radius if you mount rims that don't have enough offset. This reduces the self centering of the steering and makes the car darty on bad road surfaces.

What I also experienced by swapping the heavy blingy 18/19 rims put on the car by DPO with a set of 17/18 advans is that the suspension does not like heavy rims. Its designed to work with lightweight wheels. Unsprung weight is always a big factor though.

@Nuno
I think I have to try the NSX-R swaybar ...

Did you also do anything with the rear sway bar?

From my personal experience, normally you will get more understeer when you only stiffen up the front.

Bernhard

[UnhuZ]

Hi Bernhard,

nope... my rear swaybar still is the OEM that came with the car.

About understeer, none here... i thought i would get some with the weight savings,
but nothing... it's like a go kart... i turn the wheel and it instantly turns the front...

Nuno

[darock]

Hi Bernhard,

nope... my rear swaybar still is the OEM that came with the car.

About understeer, none here... i thought i would get some with the weight savings,
but nothing... it's like a go kart... i turn the wheel and it instantly turns the front...

Nuno

What are your alignment specs?

Bernhard

[Pride]

Hi,

i wasn't expecting it either, but after experienced it, and comparing with other NSX still with
OEM steering wheel, i came to a simple conclusion: Steering wheel weight.

the NSX-R Steering wheel assy weight (wheel + hub/boss) is a lot less than OEM steering wheel.

- NSX-R Steering Wheel + Hub/Boss weight = 1120g + 970g = 2090g
- OEM Steering Wheel + SRS unit = 2970g + 1560g = 4530g

as you can see, it's less than half the weight ;)

Nuno

hi again Nuno.

What size is the standard OEM diameter 320 or 350???

As you know my 92 is a non pas model so would it be better to fit the 350mm model???

And lastly any idea on what the steering boss part number is but please don't worry if you don't.

cheers again.

[UnhuZ]

Hi,

Bernhard, i use OEM alignment, i.e. what the alignment machine on the tire shop has.

Pride, the NSX-R and Momo Tuner are 350mm.... our OEM is a little bigger, 360 or 370mm

Momo Tuner it's also available in 320mm, but i think it's too small.
For the Steering Boss, the Honda NSX-R OEM one is a MOMO, and the part-number is 78512-SL0-Z01

Thanks,
Nuno

[Pride]

About understeer, none here... i thought i would get some with the weight savings,
but nothing... it's like a go kart... i turn the wheel and it instantly turns the front...

Nuno

Hi Nuno, well today I installed the Cedar Ridge Compliance Clamp, it was so so simple to install and WOW!!! what a difference it has made to the way it turns in and just feels through the wheel, I strongly recommend this device to anyone who thinks their NSX has perfect handling.

http://www.cedarridgefabrication.com/NSX_Suspension

A big thank you to Kaz for suggesting to try it, it certainly has given me exactly what I was hoping for in terms of handling.:)

Cheers

[markc]

Pride, the NSX-R and Momo Tuner are 350mm.... our OEM is a little bigger, 360 or 370mm

Momo Tuner it's also available in 320mm, but i think it's too small.

The OEM airbag steering wheel is 367mm in diameter. A 350mm wheel is just under 5% smaller, so the amount your hands have to move for the same angular rotation, for example a quarter turn, is similarly 5% less. It is this that makes it feel so much more direct. The weight will only make a tiny, probably unnoticeable, difference.

My EPS equipped Type S came with an airbag wheel and when I changed it, for a 350mm Momo tuner, I was also surprised how much effect it had :)

I agree that the 320mm (14% smaller) wheel will be too small and likely feel very (too) heavy.

Cheers

Mark

[Pride]

The OEM airbag steering wheel is 367mm in diameter. A 350mm wheel is just under 5% smaller, so the amount your hands have to move for the same angular rotation, for example a quarter turn, is similarly 5% less. It is this that makes it feel so much more direct. The weight will only make a tiny, probably unnoticeable, difference.

My EPS equipped Type S came with an airbag wheel and when I changed it, for a 350mm Momo tuner, I was also surprised how much effect it had :)

I agree that the 320mm (14% smaller) wheel will be too small and likely feel very (too) heavy.

Cheers

Mark

Thanks Mark, great info, I was actually struggling with the thought of the weight of the wheel making all the difference in how the car feels and responds, so the 5% smaller diameter with the Momo would no doubt make all the difference as you suggest.

Now fully happy with that explanation I think what I will now do is retrim the very worn, totally smooth and very very slippery old leather wheel in Alcantara, that, I think would then give me instantly a terrific feel, grip and great looking red stitched new-old wheel.

Also for just over £100, that's approximately a quarter the price of the Momo, boss, Honda horn button and technical issues trying to retain the cruise control functions as well as keeping the airbag feature, I'm surprised other NSX owners haven't done this before, but if they have I would love to know what they thought of the end result.

All the best
Pride

[UnhuZ]

Hi,

well... i tried a Integra Type-R steering wheel, that had similar weight but smaller diameter and
the steering feeling was similar of that of the OEM steering wheel.... i still think that the more
than half weight saving is what changes it all.... but to each his own.

Retaining the cruise control function is pretty simple with 2 easy solutions:
1 - Sparco $50 cruise buttons
2 - 2 buttons elsewhere in the console

Nuno

[Hagasan]

Have a search on Prime. An S2000 wheel is slightly smaller, thicker-rimmed, retains and airbag and can be used with cruise buttons specific to tthat wheel. The S2000 didn't come with cruise in the UK. I have one on my car and fitted a couple to other members cars on here.

[Pride]

Great info guys, thanks for your help.

[Pride]

http://www.scienceofspeed.com/products/suspension_performance_products/NSX/ScienceofSpeed/non-compliance/pivot_clamp/arrow.jpgI drove my car again today along some familiar favourite twisties along the A273 towards Goodwood and I truly cannot believe the difference the compliance clamp has made to the way the car handles at both low and now very high speeds with much more feel and confidence in my driving.

This is how it works:

The factory front suspension includes a device called the compliance pivot assembly. The assembly consists of an upright member that secures the front control arms. This member pivots and is dampened by rubber bushings to absorb shock to the chassis to improve rider comfort. Besides the rotational movement, the rubber bushings allow inwards deflection of the front control arms which leads to dynamic toe change during load. These clamps fix the upright assembly into place decreasing toe change during braking and cornering which improves handling and stability with out noticeable decrease in ride comfort.

Installation is easy, and can be accomplished within a half hour. High grade mounting hardware is used. 10mm socket cap bolts use special zinc plating for a high durability and high strength finish (will not corrode like black oxide bolts).


One things for sure, it's never coming off.:)

Cheers.

[UnhuZ]

Hi,

i also got them from Dave and i will install them.....but it will be a big while until
i drive my NSX again :(

Nuno

[jamieburke]

Re offsets again- does anyone know are the oem wheels set in close to the body and not further out to 'fill the arches' as it were to facilitate handling or are there other reasons? I'm presuming the oem 15/16 sits in there for a purpose and I'd love to know what that is and if it's part of the handling Magic the nsx has.

[Pride]

Re offsets again- does anyone know are the oem wheels set in close to the body and not further out to 'fill the arches' as it were to facilitate handling or are there other reasons? I'm presuming the oem 15/16 sits in there for a purpose and I'd love to know what that is and if it's part of the handling Magic the nsx has.

Hi again jamieburke.
One of the many features of the origanol 15/16 oem design was the use of high profile stiff sidewall tyres, this gave a more comfortable compliant ride while still filling up the wheel arch with rubber. Also when high speed cornering, the stiffer than usual tall side wall tyre maintained keeping the maximum tread footprint on the road surface.

By the early to mid nineties tyre technology for high performance road cars leapt forward a pace and it was no longer viewed acceptable for supercars to have such small wheels, so larger wheels with very low profile tyres were all the vogue with the added benefit of allowing larger brakes to be installed and a mindset with tuners that the bigger the wheel coupled with ultra low profiles the better, hence 15/16's were looked down on.

Having had 17/18 chrome wheels on my car for the first 15 years of ownership it wasn't until last year that I decided to refit the origanol 15/16 wheels wrapped in 205 50 15 (front) & 245 45 16 Toyo R888 rubber that I came to realise as to why this car was declared by the worlds motoring journalists at the the time to be amongst the finest if not the best handling supercars ever made.

It completely transformed the way it handled before then and now after replacing front and rear Swaybars with the Dali street/race set up along with compliance pivot lock, I can honestly say it feels more akin to driving a luxury go kart and a long long way from how it used to feel. In fact to the point now that I'm going to change the steering wheel with a Momo 350mm tuner to complete the ultimate transition.

And to think I had in mind of upgrading my suspension and installing the bigger brake set up which would have cost 4 times as much to do. I'm so so pleased that I took this route instead.:)

[britlude]

also the smaller front wheels were adopted as not to compromise the driving position.

smaller wheels meant smaller wheel-wells, and subsequently the pedals can be positioned in front of the driver, rather than toward the centre of the car!

[UnhuZ]

Hi,

for 15/16 setup, i think the best is the NSX-R 15/16 enkei wheels.... same size, but lighter.

Wheels weight is something easily overlooked, and affect tremendously the handling of the car.

About the offsets being so inward... it has to be for aerodinamic reasons. I mean, it is common
knowledge that the further apart both wheels are, the better the car will be planted in a corner,
but if you stick them out too far out, they wheel come out to the airflow and also increase the cx.

Nuno

[Pride]

Hi,

for 15/16 setup, i think the best is the NSX-R 15/16 enkei wheels.... same size, but lighter.

Wheels weight is something easily overlooked, and affect tremendously the handling of the car.

Nuno

You are dead right Nuno.
The 15 and 16" wheel weight upgrade are on my short list of things left to do now.
But finding them could take quiet a while I think but definitely worth doing when you read below the benefits you gain.:)

"The unsprung weight of a wheel controls a trade-off between a wheel's bump-following ability and its vibration isolation. Bumps and surface imperfections in the road cause tire compression—which induces a force on the unsprung weight. The unsprung weight then responds to this force with movement of its own. The amount of movement, for short bumps, is inversely proportional to the weight - a lighter wheel which readily moves in response to road bumps will have more grip and more constant grip when tracking over an imperfect road. For this reason, lighter wheels are sought especially for high-performance applications. In contrast, a heavier wheel which moves less will not absorb as much vibration; the irregularities of the road surface will transfer to the cabin through the geometry of the suspension and hence ride quality and road noise are deteriorated. For longer bumps that the wheels follow, greater unsprung mass causes more energy to be absorbed by the wheels and makes the ride worse"

Cheers.

[Nick Graves]

From what I understand about the NSX suspension, you will screw up the scrub radius if you mount rims that don't have enough offset. This reduces the self centering of the steering and makes the car darty on bad road surfaces.

What I also experienced by swapping the heavy blingy 18/19 rims put on the car by DPO with a set of 17/18 advans is that the suspension does not like heavy rims. Its designed to work with lightweight wheels. Unsprung weight is always a big factor though.

@Nuno
I think I have to try the NSX-R swaybar ...

Did you also do anything with the rear sway bar?

From my personal experience, normally you will get more understeer when you only stiffen up the front.

Bernhard

That is a very good explanation, Bernhard. It can also do weird things to the passive RWS. And reduced offsets can shorten wheelbearing life by increasing loading.

All of this matters less on cars that never venture off a smooth track.

But when was handling ever primary to stance? There are some wonderfully ruined NSXs across the pond.

[jamieburke]

In regards to the steering wheel, has anyone fitted one and missed the cruise control?

would it be straightforward to return the original wheel (and cruise) if so desired?

regards

jamie

[Pride]

In regards to the steering wheel, has anyone fitted one and missed the cruise control?

would it be straightforward to return the original wheel (and cruise) if so desired?

regards

jamie

According to Nuno it can easily be retained:


QUOTE
Retaining the cruise control function is pretty simple with 2 easy solutions:
1 - Sparco $50 cruise buttons
2 - 2 buttons elsewhere in the console

Nuno

[Kaz-kzukNA1]

Personally, I won't recommend using NA1 Type-R 15/16 OEM Enkei wheel on the standard models that are much heavier with different weight distribution.

To prevent IP complication, I'll neither confirm nor deny the following info and I won't disclose the source of info so please use your own judgement.


I heard from someone that the above wheel may not be strong enough if used on the standard model.
Enkei wheel is not forged but very sophisticated casting. During the development stage at Nurburgring, quite often, Type-R was seen using the standard 15/16 forged wheel due to the above strength concern until Enkei developed the final version.


Regarding the cruise control, if you have non-DBW model, it's very simple circuit.
All you need is a high level signal into the SET and RESUME port on the Cruise Control Controller located behind the passenger glove box.
For the DBW model, the cruise control is done inside the ECU through the stepping motor on the TH body so you need to deal with the ECU harness and extra care required but SET and RESUME logic is the same as the non-DBW model.

If you want to use the OEM switch module, you can try something similar to what Sudesh done for another member nobby.
http://www.nsxcb.co.uk/showthread.php?6702-NSX-Refresh&p=73950#post73950

For UK pop-up retractable headlight model, the centre console switch area is already occupied by other functions so you need to be creative in order to keep the OEM look.


Or, since you are going to remove the lower column cover, you can install small switch like on my NSX.
http://www.nsxcb.co.uk/entry.php?1419-KSP-ABS-Upgrade-Loom-Cruise-Control-switch-02


Kaz