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Understearing at MID OHIO

M

mystican

Experienced Member
Joined
3 November 2003
Messages
407
Location
Chicago, IL
Currently Ken and I are at a BMW drivers event at Mid-Ohio...we are definitely having fun!!!!!!!!!!!!!!

Mid Ohio is a technical track with lots of combined turns that have to be set up corrrectly in order to gain maximum fun factor...

My car has the Type R suspension with OEM 1991 wheels and RA-1 tires the rear bar is disconnected...

AOB performed an aggressive alignment on the car prior to tracking...I think I am running negative 2 degrees of camber in the front and less amount in the rear...

My tire pressures are running 37/38 PSI (Front/Rear) HOT off the track...

PROBLEM: my car is still understeering around the tighter turns...the rear end feels like it is getting good grip...but the front tires are a different story...the tighter the turn the more push/understeer...

Any suggestions with the tire pressures? Guess I need to get a pyrometer!
 
Your setup sounds pretty good,you might have to adjust your driving style/technique to reduce understeer,as there aint much left to do on the equipment you have.Try trail braking a little deeper and squeeze the throttle on exit rather than stomp on it. :smile:
 
I'd try lowering the air pressure in the fronts first and then mess with the sway bars.

Have fun! MO is an great track.
 
The above advice seems best,I use a comptech rear bar on soft with the r susp.I believe that cars that don't use a rear bar have front spring rates over 1000lbs,and rear rates over 600.
 
Andrie Hartanto said:
Put the rear bar back on!!

A lot of people don't understand that suspension has to work as whole package. The type-R was designed to use with rear bar!
Click to expand...


I agree. If you want less understeer u need a rear sway bar, the stiffer the swat bar the more it will oversteer(to a point).
 
It seems that there are two schools of thought on the use of the rear sway bar in the NSX...

Some have said to NOT use the rear sway bar...whereas others have said the opposite...

If I put my Comptech sway bar back on...which hole would you use?...furthest hole "OUT" or the furthest hole "IN"...

I currently have the front Comptech sway bar connected in the futhest hole "in"...which I presume is the stiffest setting on that bar...

correct me if I am wrong please...
 
mystican said:
It seems that there are two schools of thought on the use of the rear sway bar in the NSX...

Some have said to NOT use the rear sway bar...whereas others have said the opposite...

If I put my Comptech sway bar back on...which hole would you use?...furthest hole "OUT" or the furthest hole "IN"...

I currently have the front Comptech sway bar connected in the futhest hole "in"...which I presume is the stiffest setting on that bar...

correct me if I am wrong please...
Click to expand...

Hello,
I apologize in advance if the NSX bars are installed differently than on the BMW 850CSi, but this table applies to those circumstances where the ends of the bars points towards the rear of the car and the "hoop" part of the bar rides in front of the wheels (if that makes sense).

Sway%20Bar%20Adjustment%20Table.JPG
 
mystican said:
It seems that there are two schools of thought on the use of the rear sway bar in the NSX...

Some have said to NOT use the rear sway bar...whereas others have said the opposite...

If I put my Comptech sway bar back on...which hole would you use?...furthest hole "OUT" or the furthest hole "IN"...

I currently have the front Comptech sway bar connected in the futhest hole "in"...which I presume is the stiffest setting on that bar...

correct me if I am wrong please...
Click to expand...

I don't think there are two schools of thought. I don't use anti-roll bar on the driving wheels on my race cars because the suspension I put is designed to work properly that way. Your Type R suspension is not designed that way, and a rear bar will compliment it better.

You have to have a complete package. If you don't want to use rear bar, use different spring rate and shock.
 
mystican said:
It seems that there are two schools of thought on the use of the rear sway bar in the NSX...

Some have said to NOT use the rear sway bar...whereas others have said the opposite...

If I put my Comptech sway bar back on...which hole would you use?...furthest hole "OUT" or the furthest hole "IN"...

I currently have the front Comptech sway bar connected in the futhest hole "in"...which I presume is the stiffest setting on that bar...

correct me if I am wrong please...
Click to expand...

Closest to the end is softer, as you go further from the end towards the center of the bar the stiffness increases.

So your front bar is currently at the stiffest setting. You want to do the complete opposite to the rear bar (softest setting), and work from there.

I also run the Type-R suspension on my NSX along with the lower NSX-R chassis reinforcement bar. Stiffest setting on my front sway bar and 2nd from softest on the rear sway bar (Dali Street/Race)

Ken
 
As Andrie has said a well tuned suspension works as a unit and to my knowledge(I'm not an engineer like Andrie) the only folks who didn't use a rear bar with success was realtime and they used a huge front bar with 1200lb springs up front and maybe 800 lb in the rear but also had triple adjustable shocks.That does not translate to us humble hpde folks ,so who knows.If there are folks on this board toodling around with no rear bar and put down good lap times or have had instructer level drivers drive that car,and say wow this car is hooked up,let us know.I doubt it though :wink:
 
You may want to check this thread too: http://www.nsxprime.com/forums/showthread.php?p=456027#post456027

and this sheet from DaliRacing:

http://www.daliracing.com/v666-5/info/camber.cfm

I had the Type R braces (both), comptech sway bar stiffest on the front, middle on the rear, with Bilstein on lower perch, stock springs 17/17 oem tires/wheels running hot 33/40. I also have the Comptech shock tower brace. The car was understeering quite a bit at Laguna Seca. I stiffened the rear sway bar to compensate or balance the stiffness on the front and it seems to have helped as far as the feel of the car at Laguna Seca.

Yesterday I tried the same setup at THill with ambient temp in mid 90s and track temp at 135F; I was able to be within 2 seconds of my consistent previous lap times so I don't think it hurt my times. But I felt that I still had some understeer.

YMMV
 
I am currently at MID-OHIO right now...and this is what I did...you may not like this.... but ....

I totally disconnected the FRONT bar... and to re-cap...

I have the 1991 OEM 15/16 wheels, Type R suspension, NO FRONT or REAR sway bar, Toyo RA-1 tires...

Was their a difference? Yes... obviously... however the results are suprising...

In certain corners I can easily "kick out" the rear end and probably induce power sliding if I really wanted to...

In other corners...there really was n't much of a difference and I was still pushing/understeering...

I am talking with multiple HPDE/race drivers at the track and they suggested removing the front bar...and they have also suggested that Honda was way too conservative with the NSX handling and worried about drivers oversteering their cars (liability issue) and the 15/16 wheel diameter combo was a poor choice for the track...

I have been told to therefore upgrade to allow more tire contact patch in the front to compensate for the understeering...

What do guys think? Any advice greatly appreciated...Thanks...
 
Of course removing the front bar will have the same desired affect then putting the rear bar on. Will it help the balance, sure. Will it be better, overall? I don't think so.

Get your info from people that know this stuff. People that actually races and have some knowledge with the NSX.

Just like in racing, a data collected from a slow driver that don't use the car to the max, is useless. It only serves to confuse you.
 
mystican said:
I have been told to therefore upgrade to allow more tire contact patch in the front to compensate for the understeering...

What do guys think? Any advice greatly appreciated...Thanks...
Click to expand...
Did you reduce the front tire pressure?

I would go with both sway bars and the stickiest tires possible (on a 2nd set of rims just for the track use). The decisive point is not if it's 15/16 or 16/17" but how grippy the tires are. Remember (as it has been stated in other threads): Stickier tires overall reduce understeer, especialy during turn in. My solution was that I take my Yoko race slicks in front 2 degrees smoother than the rears.
Of course I have another suspension than you so your results may vary.
 
mystican said:
they have also suggested that Honda was way too conservative with the NSX handling and worried about drivers oversteering their cars (liability issue) and the 15/16 wheel diameter combo was a poor choice for the track...
Click to expand...
Nonsense.

As another instructor (and NSX owner) told you at the track, if your car is handling in a way you don't like, the first, most likely culprit is the driver.

He drove my car with the OEM 15"/16" wheels and R compound tires, and he said it felt very balanced.

He's one of the very fastest (and best) drivers I've had a chance to ride with...
 
To keep things simple, as I try to do; adopt the NSX-type R suspension completely. Get rid of the Comptech anti-sway bars; order and install the type-R front anti-sway bar ($90) and re-install the stock, rear anti-sway bar. You will be very pleased with the handling. If not, improve your driving technique.
 
disconnecting the rear sway bar would induce understeer.

so your rear suspension is more independent than the front producing better grip in the back than the front.
 
a lil offtopic,

but i didn't realize I lived 80 miles from a roadcourse!!?

haha i didnt know this track existed.

now al i need is a car to race..... :(
 

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