u401768
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| posted on 16/6/05 at 03:17 PM |
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Rear suspension design
Why isn’t wide base (to the dif carrier) McPherson strut rear suspension used? The loads are transmitted in the chassis better than with a double
wishbone setup, and it is much more tolerant of wheel diameter/width variation, and the modification from a live axel/dedion very simple. Also as an
added benefit it would free up room for either a bigger boot (trunk) or allow the floor to be raised and add a rear diffuser? The design geometry is
very much easer to sort out, and very little if anything would be lost in terms of handling, etc.
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britishtrident
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| posted on 16/6/05 at 04:03 PM |
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I am a bit puzzled by your theory that a strut suspension "is much more tolerant of wheel diameter/width variation".
To make a strut work and fit with in the packaging room available the strut would have to be specially made not just front strut transplanted on to
the rear.
There was a discussion on this at length two or three months back, in which the advantages and disadvantages of the Chapman strut were discussed at
length. it is worth a look.
Significant Lotus themselves stop using the Chapman strut after the classic Elan and Plus2S and went on to a form of double wishbone for the 70s
Elite/Eclat.
Also a lot of classic Lotus Elan and Plus2 owners are spending a lot of money on converting thier cars to use Sierra based double wishbone suspension
at the rear not that disimilar to the MK Indy.
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u401768
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| posted on 16/6/05 at 04:29 PM |
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In terms of more tolerant - a double wishbone has to be designed round a diameter/offset, and when the wrong wheels are used the rotation point will
be in a space inside the tyre or under the ground dependent on the geometry. The strut projects the point down to the tyre surface, but the point will
move in/out depending on the size of the tyre/rim. As the rear is not used for steering - this has little to no effect on the dynamics of the car.
This is the reason why most of the rally cars use this setup (stratos, 037, 205-16) plus the load transfer is more direct in the chaise
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britishtrident
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| posted on 16/6/05 at 06:21 PM |
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quote:
Originally posted by u401768
In terms of more tolerant - a double wishbone has to be designed round a diameter/offset, and when the wrong wheels are used the rotation point will
be in a space inside the tyre or under the ground dependent on the geometry. The strut projects the point down to the tyre surface, but the point will
move in/out depending on the size of the tyre/rim. As the rear is not used for steering - this has little to no effect on the dynamics of the car.
This is the reason why most of the rally cars use this setup (stratos, 037, 205-16) plus the load transfer is more direct in the chaise
Where did I put my extra large pinch of salt.
Exactly the opposite is one of the big disadvantages of of strut suspension on the front is that fitting wider wheels implies increasing the scrub
radius. A large scub radius isn't desirable.
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u401768
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| posted on 16/6/05 at 07:00 PM |
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I fully agree about the front suspension - but for the rear, the flexability is a posative thing. And if u get a double wishbone setup wrong, you can
get poor/none operative suspension
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