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Old 12th July 2010, 12:20 AM
7ishNZ 7ishNZ is offline
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Default Rear shock angles

Just a thought... the rear shocks are sitting close to 45 degrees over... all the books I have read suggest that for best handling suspension, the closer to vertical the shock is the better the damping/ springing etc.
With a 250 lb/in spring on the rear, the effect spring rate comes down to 176 lb/in at 45 degrees (0.7071)
Is there any reason the rear shocks couldn't be positioned closer to vertical? I have room on my build to get them nearer 30 degrees... is it worth it?
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Old 12th July 2010, 09:39 AM
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HandyAndy HandyAndy is offline
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Quote:
Originally Posted by 7ishNZ View Post
.. is it worth it?
Hi,

I,ll be totally honest & say that I don,t know much ( read very little ) about suspension setup etc but in answer to the above question , here,s my point of view......

As I,ve said many times, I,ve been a passenger in Spud,s Roadster many times both on the open road & on Track ( very fast track sessions) & again being totally honest I am amazed at the handling the Roadster has, it seems so "planted" in the corners, as if its on rails
& the odd occasion when the rear broke traction it is/was very easy to control.
Without sounding like a bore .... having been a semi pro bike racer, having ridden very well set-up bikes on track, the Roadster surprised me at how well it handles, in fact I have never been in a CAR that handles so well.
So in answer to your question "is it worth it".........I,d say no.

But that is just my humble opinion & not an educated opinion

cheers
andy
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Old 12th July 2010, 11:14 AM
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DStanley1809 DStanley1809 is offline
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Cars like the Ariel Atom, Ferrari Enzo and F1 cars seem to do perfectly fine with their suspension laying almost horizontal.

I don't think it would be worth the effort to redesign the dimensions only to, possibly, ruin the handling. As Andy says, the book design has been well proven
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Old 12th July 2010, 12:47 PM
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deezee deezee is offline
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Quote:
Originally Posted by 7ishNZ View Post
Just a thought... the rear shocks are sitting close to 45 degrees over... all the books I have read suggest that for best handling suspension, the closer to vertical the shock is the better the damping/ springing etc.
With a 250 lb/in spring on the rear, the effect spring rate comes down to 176 lb/in at 45 degrees (0.7071)
Is there any reason the rear shocks couldn't be positioned closer to vertical? I have room on my build to get them nearer 30 degrees... is it worth it?
We talking McPherson strut geometry or double wishbone? McPherson is more prone to suspension angles because the damper angle controls the camber. On double wishbone these elements are separate and aren't so important.
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Old 12th July 2010, 08:59 PM
Pavel Pavel is offline
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Woah woah, I think three people are on about three different things!

OP - You're absolutely right, it's a massively un-ideal set up. As the shock is mounted at such an angle, and the upright moves (almost) vertically, your actuation angle increases even more which means you need more vertical movement from the upright to compress the shock by the same amount. Problem with this is you get falling rate setup - the more the suspension compresses, the easier it becomes to compress it further.
Option 1 - try and design an inboard-shock system like what I'm in the process of doing.
Option 2 - get some non-linear, rising rate springs which increase their rate faster than your suspension causes it to fall.

Andy - Just because it handles amazingly, doesn't mean there isn't room for improvement (just ask the F1 guys!)

DStanley - They run horizontal shocks using a pushrod activated system (whereby you've got a tube pushing a rocker around a pivot that then actuates the shock). Indeed one of the advantages of using a pushrod system is that you can actuate the shock at the correct angle, and can even build in rising rate.

deezee - you're absolutely right, on a roadster the shock angle doesn't have any immediate impact on suspension geometry (it does have an indirect impact in that a falling rate setup as it currently has will cause the suspension to compress more than otherwise, and this should give you a bit more camber).


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