B Tune Swift Front & Rear Springs

[Ivan141]

It doesnt have to, but you need to do a lot of calculating, and everytime you change one factor, all the others change with it. For example I did some shabby calculations on spring compression of a stock spring (assumed 2kg/mm) vs. 8kg/mm. The 2kg/mm one would compress about 12,5 cm's @ 250kg cornerweight. 8kg/mm would only compress 3,12 cm's at stock length, effectively raising your car 9cm's
To have it at stock height you would need to get an additional 9,4 cm's of lowering from some close windings. You need to take in account the springs wire thickness and soon you'll end up with about 18cm's of useless windings just to get it back to stock height. But this would be incorrect because the springrate of the now much shorter top part would end up a lot higher than 8kg/mm.
Hope this doesnt expose me as being crap at maths but it's just to give you an idea of what the problem is with keeping full uncompressed length with high-rate springs. In practice a few more factors should come into play (the stock springs are actually longer than the suspension stroke so they are preloaded, you can have a shorter spring but it wont have much preload.)

[max_ae86]

Ivan141 Wrote:Tthe stock springs are actually longer than the suspension stroke so they are preloaded, you can have a shorter spring but it wont have much preload.

I just made some calculation if the preload spring length is 4 cm.
If OEM spring has 125mm drop, you can count on some 4cm of preload in the strut.
125-40=85mm
250/85=2,94 kg/mm
So, approx. 3kg/mm is max spring rate you can have in long stroke strut (for non-progressive spring!). With this spring rate you will have standard ride height, no free play in full extension and 40% more stiffer suspension.
I’m not sure how much is preload length of OEM spring. I calculate as 4 cm. Maybe I’m wrong.

[max_ae86]

I’ve just received an email from Mike@Btune regarding Swift Btuned springs for AE86:
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This is Mike at BTune. The freelength of front springs is 8.5 inches. And no there is no dealers in Europe. These are similar to the TRD springs.
Equivalent to the TRD drop.
We do have the BTune x Swift springs in stock.
Maybe we can work out a deal. The more you purchase the more discount you guys will get from us. If you guys set up an Account with us, You guys will be the first in Europe to have BTune x Swift springs. I think I already gave the specs for the BTune x Swift springs right? 8.5 inches freelenght. Hope to hear from you guys soon. Also, where in Europe are you guys located and do you guys have a website I can look at?
Thanks
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Now, 8.5 inch is something like 21.6 cm. I’m not sure how much stroke long AE86 yellow conis has? If somebody has this information, please post it.

[max_ae86]

Yesterday, I’ve pulled up front end and measured the preloaded spring length in strut, with out car weight. It was 30cm from top seat to bottom seat. So, any spring shorter then 30cm can not be replaceable with OEM spring.
Btune spring has 21.6 cm free length, so I will have around 8 cm of “free play”.

[SYM]

if you need B-tune swift springs let me know i have them instock. and we are also getting the spring spacers from japan this week.