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Spring rate/ length 
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Joined: Tue Oct 30, 2007 8:44 am
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Location: Chester le Street
Post Re: Spring rate/ length
We did all the sums at Newark and with the data Bob provided {Very accurate it was too.} we worked out that his Libra should be running with 200 lb/in front springs and 310 - 320 lb/in rears.

These would put the car at the upper end of the sports car wheel frequency range.

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Sun Jul 06, 2008 7:56 pm
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Post Re: Spring rate/ length
I've decided to update to 2.25" springs and new dampers -- which is it to be -- 450/250 as per original spec or follow your route with 300/200? Any chance of an update on your experience?


Mon Feb 16, 2009 6:54 pm
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Post Re: Spring rate/ length
I tried the 300/200, well 325/200 and didn't really like it. The ride was better but the handling wasn't as good. I run anti roll bars and found that with the rear set to it's softest setting it spun the inside rear much more readily. I have gone back to 425/250.

I am about to have a Z Cars rear fitted so I have given up messing with tham for now.


Mon Feb 16, 2009 9:33 pm
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Joined: Sat Sep 29, 2007 3:45 pm
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Location: SL2 4JW
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Post Re: Spring rate/ length
Update

Yes luckily I did manage to find some time last year to play around with this.

Rover engine'd [1800VVC + PG1 box] car without anti-roll bars.

Took our calculations along to Andy Robinson Racing and his recommendation was 8" 300lb rear, 8" 200lb front.
I opted for 10" 300 rear 8" 200 front [because I already borrowed and tried 10" 300's] which was a mistake because I had trouble raising the front of the car.
Spoke to Andy [unequal length of spring causing problem ?] and he said to try 8" 225's on the front.
So I put my 8" 250lb's back on and hey presto problem gone.

I would now opt for 8"300lb rear, 8"225lb front [if I could afford to keep changing them].

Apparently GTM are now supplying 8"250lb rear, 8" 225lb front on a Honda engine'd car with anti-roll bars. If you have a Rover powered car without roll bars we are basically on our own.

Other factors you need to consider are front and rear Toe-in and Tyre pressure's.
Both play a major part in your set up.

At the end of the day it's all down to personal preference.

Good luck.

Bob S.

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Tue Feb 17, 2009 6:11 pm
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Post Re: Spring rate/ length
My Honda b series libra has 9x250 front and 9x450 rears. I need to send the shocks away to gaz as two are leaking. Do people think these sprigs are OK for fast road use?


Sat Nov 12, 2016 10:55 am
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Post Re: Spring rate/ length
You will probably be close enough with the front springs but the rears are likely to be at too stiff.

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Sun Nov 13, 2016 9:43 pm
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Post Re: Spring rate/ length
octance wrote:
My Honda b series libra has 9x250 front and 9x450 rears. I need to send the shocks away to gaz as two are leaking. Do people think these sprigs are OK for fast road use?


My Honda B18C Libra is on 450 rear 250 front too, not sure on the lengths. A few people have ended up with the same or near as damn it and the Honda engine/box is a bit heavier so can't be a million miles away?

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Mon Nov 14, 2016 11:11 am
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Post Re: Spring rate/ length
I'm on 425 rear, 250 front on my Spyder, both 8". TBH feels about right. Rides the bumps fine on the road with the dampers turned down a bit and firms up nicely on track with the dampers wound up. I've no ARBs though and I do get quite a bit of body roll on track even with the dampers set pretty hard so I'm thinking of going down the ARB route and maybe then softer rear might be in order. Mine is a VVC K series.


Mon Nov 14, 2016 6:55 pm
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