Kiwi7
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| posted on 13/8/14 at 11:04 PM |
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Spring rates and wheel rates
Hey guys,
I'm Jason, from New Zealand, and this is my first post on here.
I have a locost type 7 that I scratch built. It's only used as a race car.
It's 100mm longer and wider running a mk3 cortina rear diff and hubs.
Iv been running some unknown brand shocks and springs since new.
It's time to upgrade to something a bit better and adjustable.
I'm going to get gaz from the uk.
My front wheel rate is exactly half the spring rate due to geometry and the rear shocks are vertical.
The front is quite heavy as it runs a black top zetec with a eaton m90 supercharger and a type9 gearbox.
What wheel rates do you guys run for racing?
Cheers Jason
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theprisioner
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| posted on 14/8/14 at 10:22 AM |
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Never been into it in that much detail so I looked up google of course
This resource seams fantastic if one wanted to calculate it:
http://www.hypercoils.com/spring-calculator
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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Kiwi7
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| posted on 14/8/14 at 10:49 PM |
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That calc works, except it assumes that the spring has no preload when at full extension.
in the pics are my current "no name" shocks. any one recognize them?
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johnemms
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| posted on 15/8/14 at 08:24 AM |
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Those are Nitron Shocks - supplied originally by GTS - (do a search on here)..
They get you up and running but are not ideal..
I swapped mine for Protec dampers made for the job - (do a search on here).
I have a Blacktop - front springs 275lbs - live Axle - 150lbs
Lots of information on here ... 
Own chassis & Build - First time pass!!
"7's" aren't really "cars", they are 'experiences"
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Kiwi7
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| posted on 15/8/14 at 09:34 PM |
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Just weighed my car with 4 digital corner scales. Numbers in kg.
Fr160. FL160
Rr170. RL170
With a full tank of gas and No driver.
Current wheel rate is front 110lb per inch and rear 180lb per inch.
Do I want front to be up around the same as the back?
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alfas
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| posted on 17/8/14 at 08:33 AM |
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Nitron´s are are differnt league than protec, gaz, avo and spax.....much more expensive...so i would rahter keep them..or if you want to do them a
favour refurb them..or let the factory refurb them....
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Kiwi7
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| posted on 17/8/14 at 09:33 AM |
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I don't think mine are anything special at all. They look like they are just a modified oem shock from a small car converted to coil over
platform.
Plus I need my shocks to match my new 308 wheel hp supercharged zetec!
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Camber Dave
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| posted on 18/8/14 at 09:00 AM |
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Hi Kiwi
From Staniforth the formula is 187.8 x Root of wheel rate/spring rate
This give the frequency of the sprung Mass in CPM
I use 100 to 120CPM for fast road/track day and 130 upward for racing depending on track bumps, power output, antiroll bars, and driver experience.
Front and rear should be similar but lighter on the rear for traction.
Estimating your unsprung weight at 60lb front and 85lb rear you get 120 front and 148 rear
So for a shake down I would leave the front and reduce the rear 20%.
Then raise them in proportion.
Dave
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Kiwi7
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| posted on 19/8/14 at 08:30 AM |
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Thanks Dave,
I just measured the unsprung weight. With 15x8 wheels and r888 tyres.
Front is 63lb per wheel and back is 88lb per wheel. So you are very close!
I have been racing this car for about 7 years. I think it's a bit soft. Our Nz tracks look much faster than your uk ones.
Maby I go 260lb front springs and 180 lb rears?
I do plan to make some arb at some stage soon.
Cheers jason
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