tokyo_james

I agree with Steven here, there is a specific piece of road that I drive regularly, which is adverse camber and has "ruts" in it from heavy lorries going round the corner. The corner is quite a sweeping corner, which I took first time at probably about 35mph. The passenger in the car at the time gave me a very worried look as he felt the back step out and much as I did!!!!

Even at about 30 the back will step out a little on this corner. However, as Cedric said, this is to be expected in a lightweight car with rigid chassis and sports suspension..... mmy friends GT3 steps out at only slightly higher speeds on that corner (we tested it because I was worried there was something wrong with my S2000 )

Tonky

[QUOTE]Originally posted by stevenleith
[B]
it is simply the process of going round a corner, driving over a sh*te piece of road and feeling the car skip a few feet left or right.....theres nothing you can do about it when driving through that piece of road.....the rear wheels cease firm contact with the road surface and the car alters its shape.

I never equated bump steer to actual "speed bumps" - surely these should be taken at 10/15 mph in a straight line - and shouldn't really induce significant bump steer.

Mole

Im classing bump steer as going round a corner hitting a raised part of the road the car doesnt absorb the bump so well as say BMW, as you would expect and skips slightly making the back step slightly out of line. Is this correct? If it is I 100% found the s03pp induced it more. But as I said before they were 225 and not 245.

stevenleith

[QUOTE]Originally posted by Cedric Tomkinson
[B]
How many feet is " A few?"

N-a-$-t-Y

I suppose until one has experienced both its unfair to comment.... but ive had a pretty bad, panty wetting experience with my rear end and it put the willies up me....

I'll be honest and say that I was to blame on my occassion and that i was overtaking in the wet on a slight bend and over a slight rise in the road.... i was just lucky i managed to control it and still overtake.

But Ive also had this bump steer and it is a totally seperate issue. Slow speed (25-ish mph) and it felt like a bumpy ride for a few seconds. I kinda liked it though

Cyberorth

I think this is a rare situation where I actually can compare my ITR and S2K. I have experienced a bump steer on a turn that I take daily. A pretty fast curve (~80mph). Both cars are very rigid and I drive the turn very neutral, so the 50/50 weight dist. of S should be advantageous over the ITR (~62/38). But I feel it more in the S. I think it is mostly because of the seating position, being almost immediately in front of the rear axle. That is probably why there are differences of opinion in the issue of bumpsteer, as some might go by the feel of it and some by the overall reaction of the car.

stevenleith

Yeah, its all cool until it turns into........

Turtle

There's a little confusion on this thread.

Bump steer is when the toe angles of a wheel changes as the suspension compresses. It is purely related to the link lengths, angles and suspension setup. Skipping around over bumps isn't bump steer - it's just a side effect of the S2000 having a pretty rigid chassis.

Here's a more detailed explaination. When a wheel moves along it's suspension travel, the design of the suspension controls how the wheel moves - it's not just going up and down. The S2000 uses wishbone with some links. Now the links aren't all the same length, or for that matter attached in the same places. I'll use the front as an example. The steering rack is fixed. There's a link from this to the wheel. The link is of a fixed length (okay, it wil compress/stretch a bit, for not enough to matter). So as the wheel moves up and down, the distance from where the steering link attached to the wheel to the steering rack changes. Since the link's a fixed length, it keeps the distance the same - by turning the wheel. So as the wheel moves up and down, this different makes the wheel turn slightly. That's bump steer. It's the same at the back - except the link is fixed, rather than being the steering link. (It's this link that's adjusted to set the car's rear toe when it's aligned.).

Hope that made sense, and was useful.

-Brian.

Mole

Bmarshall, thanks for that, I thought the same as the majority, I think!
So when the suspension moves up and down your saying that this can make the toe angles change slightly which in turn can alter the cars direction, thus the term bump steer. is that correct?

Frenchie

[QUOTE]Originally posted by bmarshall
[B]There's a little confusion on this thread.

Bump steer is when the toe angles of a wheel changes as the suspension compresses. It is purely related to the link lengths, angles and suspension setup. Skipping around over bumps isn't bump steer - it's just a side effect of the S2000 having a pretty rigid chassis.