woodsy144
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| posted on 9/5/20 at 02:10 AM |
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Caster thoughts on a mid engined car
Hello all,
Would like some feedback on what people are running for caster,
Especially for a mid to rear biased weight distribution.
I'm designing around 5deg but thinking it may be a bit small.
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Duncan Grier
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| posted on 9/5/20 at 07:02 AM |
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Below table gives you a flavour of the lotus setting for reference
 
Lotus geo settings
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AdamR20
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| posted on 9/5/20 at 07:04 AM |
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Sounds close enough. Lots of other things to take into account as well (tyre size, camber, toe, ackerman, probably more I've missed), so very
hard to calculate at this stage. I run 4 degrees with 60% rear weight and haven't noticed any issues.
[Edited on 9/5/20 by AdamR20]
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tilly819
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| posted on 9/5/20 at 09:59 PM |
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It's in the right ballpark. Many other factors to consider though. If you're interested in optimisation I recommend 'The automotive
chassis' by Jornsen Reimpell, Helmut Stoll and Jurgen Betzler. Best thing to do is build in a bit of adjustability then you can always tune the
chassis and suspension to get your desired dynamic performance.
Cheers,
Tilly
F20C Haynes roadster 440 BHP/Tonne www.youtube.com/handmadeextreme
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woodsy144
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| posted on 9/5/20 at 11:18 PM |
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Thanks guys. Completely understand that heaps of other items affect this and the vehicle feel. There will be adjustability in the system but I have to
have a starting point. And I'll start at 5.
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johnH20
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| posted on 10/5/20 at 05:55 PM |
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Yes lots of variables but one is actual front axle weight. My Cyclone only has 230 kg and even with 9 deg castor it failed IVA initially on
returnability. The problem was friction in the new high ratio rack I had fitted and lack of 'geometric downforce' so beware.
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Oddified
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| posted on 10/5/20 at 07:35 PM |
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Lots of variables as already said, i started with 5 but is currently at 7. Balance/feel was better on road and track and also steering return /
loading was improved. Weight dist 45/55 split front-rear respectively.
I tried increasing it up to 9 deg, didn't like it..
Ian
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procomp
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| posted on 11/5/20 at 01:07 PM |
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For reference Radical run 3.8 Deg as a starting point and dial in to suit individual driver when on track testing.
As mentioned give plenty of space to enable adjustment to be made but in general you will not want to be going further than 7 Deg as it will start to
give un desired side effect with camber control when cornering. focus on camber control and weight transfer before going into finer detail of caster
as long as it has adjustment.
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