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Token Engin-nerd
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Should all wheels be perpendicular to the fish line; hence zero toe?
I will also re-read this and other threads for the answer to that question. I remember from earlier reading that some people setup front wheels with a tiny bit of negative or toe-in; which pulls back a little (to near zero or maybe some positive toe) during acceleration... right? -No wrong, see post-40

My goals are DD with best possible tire wear.
0 rear toe on this car would be challenging to drive at highway speeds. 2/32-3/32 per side is what I run. That means the difference between the front of the wheel and back of the wheel measurements is 2-3/32.

The toe in/out with acceleration theory is, frankly, wrong. Until I see someone actually prove it on a real car with instrumented measurements, I won't believe it. In all my testing, including DD and aggressive autocross, 0 front toe is best.
 

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Old Phart
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44,596 Posts
From what I've seen front toe varies with FWD/RWD and suspension design.

Looking at a VW Rabbit (where I saw the Focus style first) they actually call for a bit of toe out, with similar commentaries on the FWD pulling it straighter under power.

Same style suspension on a RWD car like a Porsche 944 uses toe in, as typical for most RWD cars.

Other FWD suspensions that have similarities also go with "zero" like the Honda Civic.

Remembering exceptions, I checked back for the FIAT 128 specs.. Different lower arm arrangement, and as I thought I remembered it uses a small toe in at the front (FWD).


My conclusion is that this type front lower arm (and similar) when used with FWD likes zero toe or even a little toe out as a static measurement. With wheeled vehicles usually preferring a little toe IN, it looks like the toe in with power on many FWD setups is reasonable.

(For an oddity, snowmobiles prefer toe OUT of the skis for stability. They dart side to side with straight or toe in)


P.S. - FWIW I remember the Focus/VW/Porsche style lower arm promoted for anti-dive geometry, so there's a reason for the style.
 

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Registered
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15,560 Posts
Old thread.............

'(For an oddity, snowmobiles prefer toe OUT of the skis for stability. They dart side to side with straight or toe in)'

Never had to think about it until now but it makes perfect sense, they use the packed triangle of snow under the mobile as a direction reinforcement there, the two tracks and machine weight compact the triangle tighter at the back point to steady the back end. It doesn't side jump like a car does with toe out front as the snow has too much slip.
 

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Old Phart
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44,596 Posts
Actually Bud, my assumption is that the reverse snow plow arrangement puts extra drag on the tails of the skis, forcing them towards straight with the free play in the steering that's always there.

Toe in to a plow arrangement, they'd tend to toe in more and one side or the other could alternately grab sending it off to the side.

Typical alignment is actually notably off, let them take a set in the center of their free play and measure about 10mm wider at toe than tail (from the extreme of the straight side sections).
 
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