darren(SA)
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| posted on 3/11/03 at 08:24 PM |
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Rear Spring rate?
Hi guys,
I was able to take my bodyless locost for a spin the other day to test out the suspension.
Very happy with the stiff but comfy front, but was disapointed with my floaty rear end. Besides the fact that I'm still on standard tyres with
plenty sidewall, the back was very 'floaty' and very slow to react.
What spring rates are you guys running at the rear? I want call it a road/race ride,not too comfy but at the same time I would like to keep my
kidneys I bought the springs ,I think from a renault 5 or something and had them cut but I think they're way too soft.
I'm going to have some new ones made up from scratch.
thanks
darren
[Edited on 3/11/03 by darren(SA)]
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Stu16v
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| posted on 3/11/03 at 08:41 PM |
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Darren, is it live axle, dedion or IRS? What shock absorbers are you using?
Dont just build it.....make it!
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darren(SA)
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| posted on 3/11/03 at 10:09 PM |
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Its a cortina diff (3.71), so I'll understand if I cannot get spectacular performance but just something to match the front.
Not sure what make the shocks are, definately not anything performance orientated! Got some spares from a unfinished project, hence the uncertainty!
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JoelP
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| posted on 3/11/03 at 10:32 PM |
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if they are cut down car ones they might be around 100lb/inch, i saw some mini ones that were 90lb/inch. Chop them down and you lose some travel, so
they may need to be positioned closer to the pivot, hence the wheel has leverage on the spring and they feel even softer. I think 180lb/inch is often
quoted, this is on vertical springs so the wheel has no leverage on it, if you see what i mean.
all guess work though cos mine aint moving yet...
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craig1410
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| posted on 3/11/03 at 10:55 PM |
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Mine were bought from GTS Tuning and are 175 lb/inch and are 7 inches long. The front's are 275 lb/inch and are 8 inches long. The rear ones are
mounted vertically and the front's at the usual angle.
I don't know what the car will handle like to be honest as it's not nearly ready yet but I the shockers and springs are
"designed" for a book locost so shouldn't be far away.
HTH,
Craig.
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darren(SA)
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| posted on 3/11/03 at 11:19 PM |
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My rear setup is not exactly like the book, My springs are (guessing) around 300-350mm, not sure need to measure. But they still remain vertical.
So you guys rate around 180+ lb/inch?
I'll take them off and get them tested from there maybe we can have an idea. Although it would be difficult to say i want them 40% stiffer cos
its not that easy
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Hellfire
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| posted on 4/11/03 at 12:35 AM |
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Spring Rating...
Our MK Indy rear's are 200ft/lb - I believe it's the same CEC or BEC on rear, only difference is fronts which on our BEC is 350ft/lb.
Of course we're not driving it yet so, should I book an appointment at the dentist already??  
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JoelP
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| posted on 4/11/03 at 09:40 AM |
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quote:
Originally posted by darren(SA)
My rear setup is not exactly like the book, My springs are (guessing) around 300-350mm, not sure need to measure. But they still remain vertical.
So you guys rate around 180+ lb/inch?
I'll take them off and get them tested from there maybe we can have an idea. Although it would be difficult to say i want them 40% stiffer cos
its not that easy
you could just add in a second pair of springs, to double the rate. depends if you have space or not.
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darren(SA)
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| posted on 4/11/03 at 07:43 PM |
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quote:
you could just add in a second pair of springs, to double the rate. depends if you have space or not.
Nice idea, however my chassis is all nicely powder coated and I'd rather not do any more welding.
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dozracing
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| posted on 4/11/03 at 08:55 PM |
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You might find that the feeling of floatiness is not spring related, but, could be a lack of rebound damping.
A firm rebound makes the car feel very tight and responsive.
Kind regards,
Darren
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mackie
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| posted on 5/11/03 at 01:05 PM |
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Indeed, I think the rule of thumb is that rebound should be twice or four times as stiff as bound.
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darren(SA)
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| posted on 6/11/03 at 07:49 PM |
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quote:
could be a lack of rebound damping.
Could you explain this a bit more to me plz?
thanks
darren
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Peteff
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| posted on 6/11/03 at 08:20 PM |
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Our MK Indy rear's are 200ft/lb
Indy are a bit heavier because of the angle they run at. If they are upright they need less poundage. If they are standard 5 springs they will be soft
as it was a bit of a bouncy car unless it was the GT. The 350mm, is that the shock not the spring?.
175 is average for rear on a locost type car with some people prefering softer springs with harder damping. If you are using standard car dampers not
for a locost type car your damping will probably already be hard so it sounds like spring rate is your only option. Are your dampers coilovers or are
the springs separate? You could try some bump stops on the shock stems if they are allowing too much travel.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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darren(SA)
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| posted on 6/11/03 at 11:20 PM |
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This is what my setup looks like
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