Bump steer, Bump steer kits.

[MetalSpikeRacing]

Hey guys,

Well, for the few times that I had the car out on the track I have felt something on the steering wheel.
Its some kind of feed back coming from the front wheels, when I take hard sweepers* or hard turns in general.

Its some kind of bumping, not exacly now how to describe it.

I am thinking it may be bump steering since the car has been lowered and there is not enough camber at the front, and at the same time because of not having enough camber I am thinking, It might just be roll steer.
Which would be an easy fix.

I've seen a couple guys running bump steer kits, I would like to hear why they went with it.

I am just having trouble indentifying it, feel free to please share your experiences with this problem.

My max front camber at the moment is, about -1.4 I will be installing the comptech kit and I will be setting it to -2.5.


-MSR

 

[SFNSXguy]

"Bump steer" refers to toe change as wheel goes through vertical bump/rebound arc. Taking the bump steer out (minimizing toe changes) of a race car is useful, especially if it has been lowered. Most normal street users wouldn't feel the difference.

 

[MetalSpikeRacing]

O.k,
Like I stated, the car has been lowered but I am not running any toe at the front.

So I should be able to feel it at racing speeds at the track then.

Well, I guess there is nothing for me to do about it at this moment, I will add more camber and see if it only was an understeer issue, like the car just washing off and bumping. (doubt it)

-MSR

 

[e.pie]

How much have you lowered your car? It is possible to lower a car too much.

 

[stuntman]

Measure from the ground to the front and rear jack points. What is the ride height? Should be somewhere between 3-4.5"

Also what size wheels/tires are you running?

 

[Hapa88]

O.k,
Like I stated, the car has been lowered but I am not running any toe at the front.

What are you other Alignment specs?
I would suspect that racing/tracking the car without the proper alignment specs might be contributing to what you are experiencing.

The factory spec has "toe out" in the front (which is to remove the "slop", which may be what you're feeling) and "toe in" on the rear. The Wiki has some helpful information on the NSX factory alignment specs and why they were set up that way:
http://www.nsxprime.com/wiki/Alignment

For more advanced settings and track advice, listen to ^ Billy (stuntman)

 

[StmpoRaceProducts]

Hey guys,

Well, for the few times that I had the car out on the track I have felt something on the steering wheel.
Its some kind of feed back coming from the front wheels, when I take hard sweepers* or hard turns in general.

Its some kind of bumping, not exacly now how to describe it.

I am thinking it may be bump steering since the car has been lowered and there is not enough camber at the front, and at the same time because of not having enough camber I am thinking, It might just be roll steer.
Which would be an easy fix.

I've seen a couple guys running bump steer kits, I would like to hear why they went with it.

I am just having trouble indentifying it, feel free to please share your experiences with this problem.

My max front camber at the moment is, about -1.4 I will be installing the comptech kit and I will be setting it to -2.5.


-MSR

Dude,

Your bump steer is caused by the suspension pivots designed by Honda. Comptech designed a solution that Ti-Dave refined to a better part and offered at a much lower price.

http://www.nsxprime.com/forums/showthread.php?t=91214&highlight=front+clamps

It's the best dollar for dollar suspension upgrade available for our cars... period!

Dave also has a sweet brushed finish on them with zinc plated bolts.

Email Dave directly for a more favorable pricing than what other "retailers" here sell them for. Tell him STMPO opened your awareness to them... he usually charges 185.00 for my referrals...

I don’t need to make money off other fabricators idea's. But your problem goes away with that phone call or email.

Regards

 

[stuntman]

Since the problem is not clearly defined or understood, I think it would be better to learn more about his setup and try to help him understand what he is feeling or to troubleshoot exactly what the 'problem' is before throwing parts at the car right and left.


0.02

 

[StmpoRaceProducts]

Since the problem is not clearly defined or understood, I think it would be better to learn more about his setup and try to help him understand what he is feeling or to troubleshoot exactly what the 'problem' is before throwing parts at the car right and left.


0.02

Billy,

Mike owns an NSX.. Nsx'es were built with this front suspension design.

The suspension pivot is the cast aluminum brace with the triangle gussets holding the upper and lower a-arms. The design from Honda intended that brace to rotate as the suspension hit a bump in the road. Ti-Daves clamps hold the brace to the frame eliminating movement of the arm's.

His question is related to bump-steer and this is a known flaw in Honda's design. I'm the last person that would ever recommend un-needed or non-functional parts.

The FXMD NSX along with many others have corrected the bump steer problem with this part from Dave.

If your daily driver doesnt have them... I recommend them to you as well... your knowledge of the cars movements on the track could help others understand the benifits of Daves product.

BTW - Nice 1:41.9 a couple days ago... thats insane fast at BW

Regards

 

[stuntman]

Thanks Ross, I was not familiar with this compliance beam or the NSX's suspension design before. Due to the negative affects of the car's roll center, bumpsteer, and overall suspension geometry when lowering the car; the only logical thing to do is to replace the entire upright, control arms, and modify the inboard mounting points to properly correct Honda's flawed archaic design that was intended for 15 and 16" wheels for a proper design that takes into account the new lower ride height. This can be had for 1,000 easy payments of $19.95. (Please note the sarcasm).

On a serious note:

It is still not clearly understood what the problem is or what the OP is feeling. It seems like he is not absolutely certain what he is feeling and is looking for outside help to help him understand what it is. I believe the OP is using the "Bumpsteer" comment loosely and is not certain that it truly is a bumpsteer issue. You can't take that brief comment as the exact issue. Knowing his wheel size and ride height will help to determine if it potentially even is a bumpsteer issue to begin with.

Yes I am familiar with the non compliance clamp, yes it has good value, no I do not have one on my car yet, yes i've driven numerous NSXs with and without it. At the end of the day, I will restate:

I think it would be better to learn more about his setup and try to help him understand what he is feeling or to troubleshoot exactly what the 'problem' is

It might just be as simple as him feeling the dynamics of the NSX as he is learning the limits and characteristics of the car as he gets faster.


MSR:

Please list your Alignment, Ride height, Suspension, and tire (model and size).



Billy

 

[MetalSpikeRacing]

I Understand Honda's pivot complaince solution for bump steer.
I have actually bought Dave's complaince clamps, But since I wont be going to the track untill the spring again I have not installed them yet.
I will probably do that at the track, so I can actually feel how is actually helping and where.

My ride height is about 3 3/4" all around.

Alightment:

Caster: L 8.03 R 7.83

Camber: LF -1.54 RF -1.20

Toe : LF -0.04 RF 0.01


Camber: LR -2.93 RR -2.94

Toe : LR 0.12 RR 0.14

All in degrees of course.


Cross weight: 50.07% With driver.

Front : 42.34%

Left : 51.22%


-MSR

 

[stuntman]

What suspension are you running - more particularly, what spring rates?

 

[MetalSpikeRacing]

JIC, 11kg front and 9kg back.