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Author Topic: Lakester rear suspension  (Read 6401 times)
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Interested Observer
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« Reply #30 on: February 02, 2017, 09:24:08 AM »

While OJ is correct to raise the consideration of  squat and lift, the description he gives of how to deal with it is not correct.  What he describes applies to an independent rear suspension system, while what is considered here is a solid axle on control arms, the control arms being the rear sub-frame and the suspension instant center being the sub-frame pivot point.  The relationship of the axle centerline and the pivot has nothing to do with the squatting characteristics if the axle is attached to the sub-frame.
Any time forward tractive effort is applied (at ground level), the reaction will be to raise the pivot point, and consequently the chassis.  The only way to mitigate this reaction is to lower the pivot point, giving zero lift when it is at ground level.  Likewise, any rear braking will induce squat to the chassis.
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oj
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« Reply #31 on: February 02, 2017, 04:37:45 PM »

I see the 'rear subframe' as nothing more than an extended 4 link.
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oj
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« Reply #32 on: February 16, 2017, 09:00:38 AM »

After thinking things thru I see it is more complicated than I thought.  It is quite a bit different from a 4 link, the problem as I see it the 2 lower attachment points to the chassis are more a hinge.  Hmm.
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Peter Jack
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« Reply #33 on: February 16, 2017, 09:46:07 AM »

The thing it's closest to is ladder bars with the engine mounted on the bars. Depending on where the engine is mounted in relation to the pivot point more or less weight will fall in the unsprung category. My feeling is it's way too much work for the dubious results that may occur.

Pete
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SPARKY
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« Reply #34 on: February 16, 2017, 11:45:27 AM »

 cheers
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« Reply #35 on: February 17, 2017, 12:33:26 AM »

On my Lakester, it is solid in the rear. My thinking is; No engineering is better than bad engineering.  wink Wayno
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Jack Gifford
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« Reply #36 on: February 17, 2017, 01:06:08 AM »

... The thing it's closest to is ladder bars with the engine mounted on the bars. Depending on where the engine is mounted in relation to the pivot point more or less weight will fall in the unsprung category. My feeling is it's way too much work for the dubious results that may occur...
I agree with all of that. Except that in my case the "way too much work" is offset somewhat by the fact that the nicely designed torsion bar suspension is already in place for the rear wheels. So the only "work" I'd be left with is design & fabrication of the subframe and its frame-anchored pivot. [While avoiding the "work" of mounting the rear axle rigidly]

With an A-shaped subframe, it's closest to ladder bars with their front pivots moved together. This would preserve the non-binding independent travel of each rear wheel.

As for "dubious results", I've seen a number of examples of satisfied landspeed racers using some form of suspended rear subframe.

Thanks for all the comments.
« Last Edit: February 17, 2017, 01:08:20 AM by Jack Gifford » Logged

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