Non-compliant toe-links and beam questions

[KingsCourt]

If the following questions look familiar to anyone, it's because they were posted as a response to another thread. I didn't get much of a response, so I thought I might get some more responses if it stood out a little more.

Two quick questions:

1) By installing the toe-links and beam, will this allow you to improve handling/stablility, AND improve tire wear at the same time. The reason I'm asking is because like with camber where it's set a little negatively (top of tire tilting inward) to make the tire flat on road when loaded, the toe-in has to be be set a little extra normally, to accomadate the changes that it will experience when loaded. Does this mean that with the non-compliant links/beam set-up, can you set the toe-in to let's say 2mm instead of 4mm and achieve the same level of handling as before the modification, since there is less variation when loaded? IF this is the case, it would be a plus/advantage for street use, by improving tire wear while maintaning performance. Is this the case?

2) Do the links go together with the beam, or do can you experience improvement with the links alone?

 

[the nsxnut]

a good question that deserves a response.

My car is equipped as you describe. You are correct in your description of the affect on performance; the susp. settings can be much more discrete, since finer adjustment is available. I'm not sure if there will be a corresponding increase in tire life; I don't drive my car enough on the street to use up a set of street tires in a year. My susp settings are aggressive and track specific, tire wear is not a consideration, since I'm on R-compound tires more than street tires. Anytime I travel more than 50 miles from home, the car gets trailered. Street driving is strictly local, and mountain drives.

the toe-links and rear-beam go hand-in-hand; one is not effective without the other. Additionally, it should be noted that, although upgrading those bits to non-compliance are a good step forward, there are something like 22 compliance points in the NSX suspension; so, doing the rear beam and toe links is just the tip of the iceberg for non-compliance.

 

[KingsCourt]

Great to get some kind of response. What got me thinking about this potential benefit is something that I read somewhere. I just discovered that it was right here on NSXPrime a while back.

In the FAQ section under wheels and tires, if you click onto alignment, at one point they have this part that's titled "WHAT SHOULD I KNOW ABOUT CHANGING ALIGNMENT?" At the end of the "Suspension Tech Session by Don Erb, Comptech USA," it states the following:

Toe Setting: The toe on the front of the NSX should be approximately 4mm or 3/16" toe-out. This is a good spot to start with. If the car seems slow on turning into a corner you can add more toe out to give you more aggressive steering. Be careful, there is no such thing as too much toe out, but it will increase the tire wear and will decrease the straight line stability. Remember, what is comfortable for your friend may be different for you. Unless you are racing I would not recommend going over 8mm out.

Rear toe should be about 3-4mm toe in. The more toe in you have on the rear the more stable the car will be down the straight and the more stable understeer you will have in the corner. Some factory settings on certain models had up to 8mm toe in. This was to keep the car more stable. The tire wear was very high and many owners complained about it, so the next year they went back to lower settings in the 4-6mm range. In an ideal world, as the suspension moves the toe would never change, but it does. This is why we make the low compliance rear beam and toe links. If you don't believe me, do this simple test. Look at the rear wheel out your door and roll you car backwards and hit the brakes, see the wheel move in and out? This is toe change! The less you have the better.

This is what made me think that a street NSX could benefit from the toe-link/beam modification. But then I read up a little on the forums, and it made it seem like the only benefit is at the extreme limit of handling. If anybody has any additional input regarding this, I would appreciate it. I don't really track the car, and if I ever do, probably not on a regular basis. Therefore, I would consider this modification only if my theory of increasing rear tire life while maintaining performance is realistic.

 

[ScienceofSpeed]

The car's factory rear suspension will experience some toe out movement during braking load. The toe in setting will keep the car stable under straight line braking and cornering. Some of the toe in is likely built-in by the factory to compensate for the compliance of the factory rubber bushings. I've never thought about the rear toe links for tire wear, however, your chain of thought makes sense to me. With the links and beam bushings, we run slightly less toe-in as it makes the car much more easy to throttle steer. The car with the non-compliance parts with less toe-in than factory is much more stable under braking and cornering than with the factory bushings.

You can find more info here:
http://www.scienceofspeed.com/produ...mance_products/NSX/suspension_accessories.asp

Cheers,
-- Chris

 

[Larry Bastanza]

Chris,

I agree for sure. It is interesting that the rear beam and toe link combination is specifically installed to remove the "wiggle" in the rear at the handling limit, however on one car that I have done this mod to (Pete Mills) he has mentioned many times that ever since then his rear tire life has increased dramatically. I am refering to street use/tires. When we corner balanced and aligned Pete's car I did reduce the total rear toe-in to 2-2.5mm, which I think is the main contributor to the street tire life. That said, I decreased it for the very reason we are talking about, which is less need to "over compensate" for the soft stock bushings.

HTH,
LarryB