Question regarding rear springs and SPL buckets

RN SHARK · 08-17-2019, 03:40 AM

So I recently bought Powertrix Ultralight racing coil overs, which are NOT the true type coils. I got the Swift spring option and plan on using them with the SPL spring buckets, but those only accommodate a 2.5” ID spring. The springs I have are 6” ID. Now Charles at Powertrix will swap them out for 2.5” ID ones for me, but is asking how long do they need to be for the SPL buckets. Does anyone know the answer to this?
Thank you in advance!

gomer_110 · 08-17-2019, 10:49 AM

I used 7" free length springs on my setup with 900lb/in springs. Probably should have gone with 6" but was able to get the 7" ones to work.

The corner weight and spring rate will affect the free length needed. iirc, SPL had a excel sheet calculator that could tell you what length spring you need. You probably just need to look around on their website or give them a call.

OptionZero · 08-17-2019, 06:49 PM

First off, i think you have the wrong measurement - there's no way you have a SIX INCH INNER DIAMETER.

Anyways, you want six inch LENGTH swift springs.

Seven inches is only for people running insanely high ride height. Seven inches creates headaches

When I spoke to SPL, they said works for virtually everyone unless you're at stock height

do yourself a favor

get six

Spooler · 08-17-2019, 08:10 PM

I used 7 in. I didn't want to go too low. If you want low, get the 6 in. I am lowered about 3/4in in the back. Any lower than that, you want the 6 in.

TMRN370z · 08-25-2019, 03:46 PM

I went with the 6” spring. The SPL arm gives you a lot of height adjustment.

08-17-2019, 03:40 AM	#1 (permalink)
RN SHARK Track Member Join Date: Jun 2011 Location: Delafield, WI Age: 44 Posts: 618 Drives: 09 370Z, 14 SRT GC Rep Power: 35	Question regarding rear springs and SPL buckets So I recently bought Powertrix Ultralight racing coil overs, which are NOT the true type coils. I got the Swift spring option and plan on using them with the SPL spring buckets, but those only accommodate a 2.5” ID spring. The springs I have are 6” ID. Now Charles at Powertrix will swap them out for 2.5” ID ones for me, but is asking how long do they need to be for the SPL buckets. Does anyone know the answer to this? Thank you in advance! __________________ ___________ '09 6sp/Z1/PowerTrix/SPL/Swift/SRP/Whiteline/F.I.LTH&CBE/UpRev by Seb/CJM/Stillen/Ings+1/RJM/TrackSpec/Sparco/Motul/Wavetrac/Coolerworx/Verus/CraftSquare '14 SRT Grand Cherokee; '08 TL Type-S

08-17-2019, 10:49 AM	#2 (permalink)
gomer_110 A True Z Fanatic Join Date: Aug 2011 Location: Perrysburg, OH Posts: 17,992 Drives: '11 Nismo #528 GM Rep Power: 36941	I used 7" free length springs on my setup with 900lb/in springs. Probably should have gone with 6" but was able to get the 7" ones to work. The corner weight and spring rate will affect the free length needed. iirc, SPL had a excel sheet calculator that could tell you what length spring you need. You probably just need to look around on their website or give them a call. __________________ '11 370Z Nismo #528 Fast Intentions \| Stillen \| Motordyne \| Uprev \| CSF \| Zspeed \| Z1 Motorsports \| AST \| Swift \| SPC \| SPL \| Whiteline \| Hotchkis \| Bride \| Schroth \| Robispec \| Cusco \| Nismo \| Volk \| Forgestar \| Hoosier \| RJM '17 Titan Bone Stock

08-17-2019, 06:49 PM	#3 (permalink)
OptionZero A True Z Fanatic Join Date: Apr 2011 Location: Sacramento Posts: 3,235 Drives: 15 370Z Nismo 6MT Rep Power: 214100	First off, i think you have the wrong measurement - there's no way you have a SIX INCH INNER DIAMETER. Anyways, you want six inch LENGTH swift springs. Seven inches is only for people running insanely high ride height. Seven inches creates headaches When I spoke to SPL, they said works for virtually everyone unless you're at stock height do yourself a favor get six __________________ OptionZero Build Thread

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08-17-2019, 08:10 PM	#4 (permalink)
Spooler A True Z Fanatic Join Date: Jun 2014 Location: Ga Posts: 13,834 Drives: 2013 Nismo 370z Rep Power: 2684392	I used 7 in. I didn't want to go too low. If you want low, get the 6 in. I am lowered about 3/4in in the back. Any lower than that, you want the 6 in.