tegwin
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| posted on 5/2/07 at 11:23 PM |
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Effects of different track widths front and rear?
I have been trying to visualise/sketch/calculate what effects varying track widths would have....
Im sure its quite an elementary question, but its bugging me...
What would be the handling charactersits of the following?
Front track and rear track the same width.
Front track wider than the rear.
Front track narrower than the rear
What would be the optimum?
Chears.
Dunc
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macnab
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| posted on 5/2/07 at 11:36 PM |
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At a wild totally unqualified guess I'd say the front and the back should be the same so the car rolls more equally. If it was say narrower at
the front (an extreme example would be a robin reliant) the front would dig in more at the corner.
Just waiting though for my theory to be blown out of the water by someone though...
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907
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| posted on 5/2/07 at 11:50 PM |
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I was under the impression that a book Locost is wider at the rear.
Mine is a +4 (i.e. 4" added all the way down the centre) and that has a wider rear.
Paul G
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C10CoryM
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| posted on 6/2/07 at 03:37 AM |
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Generally the front track is about 1" wider than rear. It allows for better front end stability. Think about extremes like say a trike. Same
idea. Also I would guess it helps reduce jumping around in ruts.
Cheers.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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Avoneer
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| posted on 6/2/07 at 07:31 AM |
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The Avon is a lot narrower at the front and it handled really well at Elvington.
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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britishtrident
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| posted on 6/2/07 at 07:48 AM |
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Dosen't matter anything like as much as you might think.
Changing the the wheelbase has a much more noticeable effect.
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zetec7
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| posted on 6/2/07 at 09:37 AM |
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Think of it this way - in Formula 1 (where price is no object, and ultimate handling is the holy grail), some cars have a wider front track, some have
a wider rear, some are the same. They can vary by several inches in some cases. The same goes for the various Lotus and Caterham Sevens - there is a
wide variety of front/rear track ratios, and they ALL worked well. So...as long as they're not widely different, don't woryy about it
!!
http://www.freewebs.com/zetec7/
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xico_ze54
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| posted on 6/2/07 at 11:16 AM |
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my past searchs in the Locost world (Internet), included sevenesque kit-cars, says the rear track generally is wider than front.
in my car the rear is about 100mm wider (I put spacers/PCD converters in the rear and wheels with less offset then front) and it has good
handling.
I'm tempted to say these cars handle well in all type of sets (I think). But larger the rear, tendence for less overstear then with larger the
front. Please correct me if I'm wrong.
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SaveTheDodo
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| posted on 6/2/07 at 03:48 PM |
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I remember an old article in CCC where Steve Broughton (of SBD Engines) widened the front track of his racing Westfield SEIW to match the rear - this
meant that any kerb missed with the front wheel would stay missed with the rear.
The same could well apply to any road car driven enthusiastically??
Cheers
Andrew
Andrew
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procomp
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| posted on 6/2/07 at 04:02 PM |
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Hi been as how westfields have been mentioned it might pay to do a bit of reasearch on the effects of wider front track on westfields and caterhams.
cheers matt
[Edited on 7/2/07 by procomp]
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TangoMan
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| posted on 6/2/07 at 09:53 PM |
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Going back to my karting days (and I accept that we are not talking karts!!) a wider rear track was used to remove rear grip.
A narrower front track was generally used in the wet to improve turn in, although this had as much to do with wheel offset as it did track.
On a car with suspension there are other considerations. Widening the track, with all other things being equal, will increase the angle of leverage on
the springs so will effectively soften your springs on turning. No extra leverage going straight at if both springs compress equally there is no extra
leverage.
On the fronts, it depends whether you widen the track with deeper wheels or with longer arms. Deeper wheels will have a grater effect as they will
exagerate the effects of castor and KPI on turn in loading up the inside tyre much harder.
Summer's here!!!!
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britishtrident
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| posted on 14/6/07 at 04:19 PM |
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Honestly changing the track dosen't make any real difference, car handling is balanced by changing the roll resisstance at one end.
Track and wheel offset has no effect at all on KPI or Castor.
As for the point that has been made about if the same track is used front and rear the wheels will follow the exactly same path in a turn is not
correct. With the car setup for neutral handling simple geometry dictates the front (ie steered) wheels will always follow a wider radius than the
rear --- to prove it just plot it out the ackerman geometry on a sheet of paper.
Of course tyre slip angles come into play at anything over a walking pace and reduce the effect.
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TangoMan
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| posted on 19/6/07 at 11:16 PM |
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quote:
Originally posted by britishtrident
Track and wheel offset has no effect at all on KPI or Castor.
Only partly true I am afraid!!! Although the statement is technically correct with regard to track, what you have failed to grasp is the effect of
moving the wheel further out from the kingpin line with a larger offset. Think about it, or build a model.
If you have for example 10 degrees of KPI and 10 degrees of caster, when you turn the wheels the outer wheel will try to move around the Kingpin line
in an arc, lifting forwards and dropping backwards. Now move the wheel further away from that line with a greater offset and see how it exaggerates
the movement. It is simple physics. The further away from the kingpin the greater the circumference of movement pushing the wheel down or lifting it
against the suspension.
Summer's here!!!!
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RK
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| posted on 20/6/07 at 01:57 AM |
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I'll let you know once my wheels go on. Should be in about two years.
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