mistergrumpy
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| posted on 17/11/07 at 11:33 AM |
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Spring Rates (again)
I am looking at upgrading my suspension before I've even finished the build! I was looking at spring rates but I'm not too sure.
I've had a look through past posts and it seems quite broad. I'm thinking 250 front 150 rear? Its on a zx9 locost with mostly me driving
on my own cos I've got no mates  Anyone else with a similar car comment on what they've got.
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mark chandler
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| posted on 17/11/07 at 12:53 PM |
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I think mine are 220/150 with a blade engine + light car circa 400kg.
However the front shocks point at the ball joint so zero leverage but the angle is quite steep, effective maybe 190lb ?
Indi rear are nearly upright but about 4/5 along to the hub so effectively 120lb on rear.
Friends have commented on the comfort of the ride, its is very grippy as well with soft tyres.
I run 4" ride height front, 4.5" rear, the bottom is completely flat and does not ground out (chopped the sump level to chassis)
any help
Regards Mark
[Edited on 17/11/07 by mark chandler]
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mistergrumpy
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| posted on 17/11/07 at 03:26 PM |
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Cheers Mark. What do you mean that the shocks point at the ball joint though? Bit confused there.
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ricklawn
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| posted on 17/11/07 at 05:34 PM |
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i m looking at changing mine on fury 1.8 zetec and factory recomends 180 front 150 rear. is that enough?
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procomp
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| posted on 17/11/07 at 07:01 PM |
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Hi By shock/damper point at the balljoint point . He is refering to the distance between the lower ball joint and the damper location.
The closer to the balljoint the damper is the more direct acting the damper is depending on its angle to the chassis though. The further away from the
ball joint the damper is the less effective the damper is and needs the damper valving ratios and spring poundages looking at say for instance on the
MK'S and GTS'S where the damper is a considerable distance away from the ball joint.
HTH cheers Matt
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mistergrumpy
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| posted on 17/11/07 at 10:20 PM |
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Ah gotcha. Cheers for that
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ChrisGamlin
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| posted on 18/11/07 at 05:58 PM |
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As always, the rates required can vary hugely depending on suspension geometry used, where everything picks up and what angle the dampers are at etc.
For a book chassis's Locost BEC with live rear axle though, aiming for reasonable track performance, 250 front and 150 rear isn't far off,
maybe 125 on the back would be better. Mine runs 225 front and 125 rear IIRC (R1 book chassis), although Ive slightly changed the front damper pickup
locations so my equivalent rate on the front is closer to 250 if comparing against what I used to have, ie stock book pickup points.
Chris
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mistergrumpy
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| posted on 18/11/07 at 06:19 PM |
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I've the wider GTS front bones so with the bottom mounting point being a bit off the bottom ball joint I should over compensate at the front
right. So 250 still?
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Bob C
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| posted on 18/11/07 at 07:36 PM |
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Just to put another viewpoint - I have soft springs on mine, 150lbs/" front 125 rear.
With just me in it's fine - with a lardy passenger it can hit the bump stops.
I have put some effort into reducing unsprung weight & have engineered a reasonable amount of travel in the suspension.
As you'd expect it's comfy ;^)
Corners all right though. Never had it on track so can't comment on its ultimate effectiveness - on queens highway it is arguably faster than
the stiffly sprung locosts because there's no heroism involved in just driving it...... (i.e. you can still see at 60+ )
Bob
[Edited on 18/11/07 by Bob C]
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ChrisGamlin
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| posted on 20/11/07 at 08:35 PM |
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quote:
Originally posted by mistergrumpy
I've the wider GTS front bones so with the bottom mounting point being a bit off the bottom ball joint I should over compensate at the front
right. So 250 still?
Tricky to say to be honest, the only proper way you can do it if your car is effectively unique is to measure up another car of similar weight which
you know handles well, and work out the effective wheel rate of that system knowing its actual spring rat, then transplant the effective rate figure
over to yours and work backwards to find a compatible spring rate.
Having said that, its fairly likely to end up somewhere around the figures above for outboard dampers on a seven style car assuming they're not
located at strange angles etc, so it may be worth budgeting for 2-3 sets of springs (not expensive) and experimenting to find the best setup.
Chris
[Edited on 20/11/07 by ChrisGamlin]
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