"dieseldub" (dieseldub)
02/20/2020 at 20:23 • Filed to: None
4
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"dieseldub" (dieseldub)
02/20/2020 at 20:23 • Filed to: None | 4
| 10 |
Well, a couple friends and I were scratching our brains on various ways Mercedes could have accomplished that wild, on-the-fly toe adjustment where the car appears to toe in pulling the steering wheel back, and toe out pushing the wheel forward.
I was overthinking this at first, then heard Scarborough suggest that maybe the entire rack was being moved with the steering column.
That’s when the light bulb went on. That has to be it! That’s the simplest solution, least amount of weight and modification, the rack itself doesn’t need to be anything special, it just needs to be movable.
So, I made a real fast, shitty sketch on how that would work. It can work one of two ways, but my sketch is making the assumption that the rack and thus the tie rods are in front of the steering axis.
So, at the top, this is driving down the straight with the steering column/rack pulled towards you. If the rack and tie rods are in front of the steering axis, you would need the rack to be behind the tie rod ends, so the tie rods are angled forwards now and this is pulling the wheels to be more straight.
Push the column and whole rack forwards to make the rack more inline with the tie rod ends and it will push the leading edges of the tires outwards (toe out) to get the improved handling.
The other way to go about this with the steering rack behind the steering axis, with the wheel pulled towards the driver, the tie rods would need to be more parallel with the rack to increase toe in. And when you push the rack forward, the tie rod ends are now behind the rack, the tie rods themselves angled backwards in relation to the rack, pulling the rear of the wheels closer together, and thus the front of the tires further away from eachother (toe out).
This is the what makes the most sense in my brain, it’s mechanically simple and doesn’t require a special steering rack, just requires a mounting point that can be moved by the driver by moving the steering column in a telescopic manner.
Pardon the imperfect drawing, but hopefully that gets the idea across.
The Crazy Kanuck; RIP Oppositelock
> dieseldub
02/20/2020 at 21:35 |
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You idea makes total sense, but there is a very slight delay between moving the steering wheel & the toe angle changing. Maybe there is a spring of sort in there.
Chariotoflove
> dieseldub
02/20/2020 at 21:46 |
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I read the FP article. What you say makes sense. It certainly can’t be power assisted, and this doesn’t have to be.
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dieseldub
> The Crazy Kanuck; RIP Oppositelock
02/20/2020 at 21:55 |
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I don’t see any delay, but the rate of toe change can certainly change thanks to the geometry, the “swing arc” of the tie rod and of the steering axis.
The rate of toe change vs. position of the steering wheel fore and aft is not going to be perfectly linear.
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dieseldub
> The Crazy Kanuck; RIP Oppositelock
02/20/2020 at 21:57 |
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I’ll also add that the camera angle combined with the relative roundness of the tire sidewall can create a sort of parallax error in how you perceive the motion.
BeaterGT
> dieseldub
02/20/2020 at 22:35 |
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I wish we could have seen the drivers initial reaction when they were informed about this new system.
A Boy and His Longtail
> dieseldub
02/20/2020 at 23:41 |
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Interesting thoughts on the system. Now we wait and see if it actually helps.
RacinBob
> dieseldub
02/21/2020 at 08:40 |
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I definately think that it will help. Put a car on a friction circle and it will do it’s best with toe out. Go down a straight and it will do it’s best toe neutral as toe out scrubs off speed. Here you get the best of both worlds.
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RacinBob
> RacinBob
02/21/2020 at 08:44 |
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By the way, that is exactly what he is doing in the video. You can see the curb as he exits the corner with him to e’ d out, and he pulls the wheel back as he goes down the straight to eliminate the toe out
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RacinBob
> The Crazy Kanuck; RIP Oppositelock
02/21/2020 at 08:45 |
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The interesting question is what happens in this setup under braking, does it slam the wheel toweards the dash?
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dieseldub
> RacinBob
02/21/2020 at 10:58 |
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That’s what’s really cool about how they set it up. You want to push it forward as you’re braking because that toes it back out, aiding with braking slightly and also setting it up with the toe setting it’s going to need in the corner you’re braking for.
They made the angle change correspond with the forces in the car. Pull back when accelerating on straights, push forward when braking or just before a corner.