Skip to main content

Spring Rates

I've spent a bit of time mucking around with a springs and shocks to try and make something from parts I have on hand to suit the new suspension setup. Basically I want to determine if I should use a set of coil-over bits and pieces I had lying around or cut and re-shape the std springs.

 After dong the maths on it(below) the aftermarket coil-over springs I had lying about are most likely going to be too stiff, being 28% stiffer than the stock springs. If I cut one coil from the std springs it will be 50mm lower and 20% stiffer which might be a good compromise. If I want to lower the vehicle further without having to buy new springs I could always lower the, lower mount.

The numbers: 
Part Dimension Value Unit
STD Strut Length 635 mm
STD Strut Travel 190 mm
STD Spring Length 345 mm
STD Spring O.D 120 mm
STD Spring  Coils 5
STD Spring  Wire Dia 10.3 mm
STD Spring  Rate 16.89 N/mm
STD Spring Safe Max Travel 158.63 mm
Less one coil Length 295 mm
Less one coil Rate 21.112 N/mm
Less one coil Safe Max Travel 126.9 mm
Aftermarket spring O.D 87.2 mm
Aftermarket spring Length 223 mm
Aftermarket spring Coils 8
Aftermarket spring Wire Dia 9.7 mm
Aftermarket spring Rate 23.548 N/mm
Aftermarket spring Safe Max Travel 166.3 mm
Less one coil lower than Stock 50
Less one coil % stiffer than Stock 20.00%
Aftermarket spring 28%
http://www.acxesspring.com/compression-spring-rate.html

Comments

Post a Comment

Popular posts from this blog

Transmission Options

I ended up going with a 2008 RX8 S2 gearbox as it was stronger than the S1 gearbox and newer and cheaper than an RX7S5 turbo box. I considered the gearbox form an RX7 FD but they have a pull style clutch which would mean I couldn't use my existing clutch. The choice of the RX8 gearbox came down to availability, cost and the fact I could use my existing clutch. I think I'll need to change the Diff Ratio from 3.27 to 4.11 to make the gearbox more usable, below is a simulation with a 4.11 Diff and the RX8 Gear ratios shifting at 8000rpm with 15inch tyres. Some of the options Jatco 3 speed automatic box including torque converter $7,000 JK40C/CD transmission from 350/370Z Adapter kits: http://collinsadapters.com/index.php/adapter-plates/mazda-rotary-13b-20b-26b-to-nissan-6-speed-350z-370z-350zhr-370zhr-transmission-adaptation-kit.html https://www.rx7club.com/rotary-car-performance-77/jk40c-cd009-transmission-370z-13b-1090772/page9/ they all seem to need: Does Not include (but requi...
Post a Comment
Read more

Shortening the Diff

I have a Ford 8.8 inch diff from a EF/EB Ford Falcon with a Limited Slip Differential. I want to shorten it down to suit the 323. Due to the RX7 LCA in the front, the front tyres(205X50X15) now protrude from the front guards by 65mm. Making the overall front track width 1,675mm. With 225X50X15 tyres on the rear and the standard diff the rear is 1,610mm. Meaning that the rear track width is 32.5mm narrower on each side. To widen the rear when I shorten it, I'll make the rear axle 65mm wider than the standard rear axle. The standard 323 Diff width is 1,338mm and the Ford 8.8 is 1,547mm for a total difference of  209mm. So the Diff needs to be shortened by 209mm - 65 =  144mm or 72mm per side.
Post a Comment
Read more

The Journey continues

"It was the best of times, it was the worst of times" C.Dickens Long time no blog post, I guess most of the time I post on Instagram and neglect to come on here. In some ways it has been a good time for the shed and in other ways not so much. After moving house and getting a bigger shed I have more space, I've managed to purchase a Mill and a band saw as well as some other tooling. I've spend a fair bit of time mucking around with the front suspension and I think I have it how I want it now. Unfortunately with four children, the property, kids sport etc there is not a lot of time to spend in the shed, mostly later in the evening once everyone is in bed. I made a bit purchase and brought an RX7 FC, S5 13B motor in unknown condition with a MicroTech LT-9c for $3,000. I've started stripping it down and will clean it up and rebuild it, with the view of running it on E85. I've reworked the design of the steering rack location to have it correctly in f...
Post a Comment
Read more