Suspension question

[ak]

I was looking through the FAQ and noticed that more sporty models of NSX such as, Type S, type-R etc all sport higher spring rate in the front than the rear, where as the regular NSX sports lower spring rate in the front. In case of Type-R, it even uses thicker sway bar in the front. It seems that the coilover suspension system such as comptech's also uses higher spring rates in the front. Doesn't this promote more understeer? Why did Honda/tuners come up with this? Can anyone explain?

 

[sjs]

The simple answer is that it all boils down to selecting the various components based on the car's weight distribution and suspension design. The most obvious difference between the NSX and the other cars is that it has the engine in the rear, and its rear-wheel drive. But as you mentioned there are still people with very different combinations on the NSX, and even the OEM approach varies from model to model.

Once the basics are set, the two big adjustments are springs and bars which both reduce body roll. (shocks/dampers are selected to match the springs) There are tradeoffs between more bars/less springs and vice-versa to achieve a given degree of roll resistance, but in general I think that you focus on springs to the point where combined with appropriate damper rates they are at the limit if acceptable comfort. Then you fine-tune with bars. But in the end people make different choices in achieving overall balance and it would be difficult to proclaim one right and another wrong.

 

[ncdogdoc]

I think there are two reasons for the higher stiffness springs up front.

One is less travel of the shock. Due to the low front end of the NSX, there is less shock travel distance, and thus much easier to bottom out the suspension on a hard turn. The stiffer spring helps keep the shock off of the bump stop, hopefully allowing the tire to maintain better contact with the pavement.

This next one is purely my opinion. The rear of a mid-engine or rear engine car can be a little bit of "fun" at certain points in a high speed turn. I think that just the opposite of the front end, by having more travel and less stiffness in the rear allows full use of suspension travel and tire contact in the rear as weight shifts coming out of a turn, allowing the car to squat and put the power down sooner (before track out).

I actually hope this starts a little debate, as I am setting up my suspension right now, and will take any advice given (as long as it is right

)!!

------------------
Gary Yates
1995 Red/Tan Boooleevard Cruzer
1992 White/Black Track Rat
2002 Red and White Cooper S - for sale, please inquire

 

[andreas]

ak, good question, the answer is that you have not taken the bump stops into account. these are long rubber sleeves that in effect act as progressive springs once the suspension has compressed enough for them to make contact with the damper body. the front spring rate of the regular nsx suspension is not nearly enough to keep the car off the bump stops during heavy cornering, at which point the effective front spring rate increases drastically. that means the front to rear ratio reverses and actually far surpasses that of the type s/r suspensions, resulting in heavy understeer.

see also my post on the same topic in the following thread:

http://www.nsxprime.com/ubb/Forum10/HTML/000930.html

 

[ak]

I wonder how it differs between Zanardi suspension vs H&R/Bilstein combo? Which one would be more neutral??