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S15 Six Speed Problems

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Hi there I saw in a couple of posts mention that the six speed box is stronger than the five speed found in the 13 and 14. I also saw that the issue is with the circlips becoming loose and causing damage. I am living in Trinidad in the West Indies and currently have an S15 that I am upgrading and would like the gearbox to handle over 500HP although I'm shooting for 450HP. Do you'll have any sort of pictures or direction you can give me as to what needs to be done to the box to allow it to handle the bigger circlip? I picked up an extra six speed box for a ridiculous price, the equivalent of $80USD, yep seriously, so I wanna open it and do the needed and used this box on the rebuild. Thanks in advance for your help.
 

Nicely

Moving on...
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I PMd you back, but I'll post it here too:)

Nicely said:
If you're looking to run 450-500bhp, you are going to have to change the gearbox, I'm afraid. Even with the circlip issue fixed, it simply won't be able to handle that power or, at least, not for long...

I haven't got any photos, I'm sorry. I haven't personally done the fix. If you take a look in the workshop manual at the counter gear layout, its the 3rd/4th counter gear snap ring the needs checking. I'm told that its a case of mechining a new groove and fitting a new tighter ring/circlip.
 
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upgrade to a S14 or S13 gearbox, the S15 input shaft is smaller than the S13/S14 one.

You can buy full 6 speed cross missions from Nismo or HPI (nismo internals) but they aren't even rated to 500HP. The Nismo is rated to under 400 and the HPI is rated to somewhere around 440HP.

Buy a S13/S14 box and get an OS Giken or PPG gearset for it and you'll be laughing. Or upgrade to a RB25 gearbox.
 
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For the RB25 box I guess I'll need an adapter plate? I so happen to have an RB25 and RB26box in my garage. I am also doing an S14 RB26DETT swap as well and am planning to use twin S15 turbos on it for now until I save for the big single. The S15 is getting a GT3076R top mount setup with a Power FC D-Jetro and all the headwork but stock bottom end.
 
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For the RB25 box I guess I'll need an adapter plate? I so happen to have an RB25 and RB26box in my garage. I am also doing an S14 RB26DETT swap as well and am planning to use twin S15 turbos on it for now until I save for the big single. The S15 is getting a GT3076R top mount setup with a Power FC D-Jetro and all the headwork but stock bottom end.
If your aiming for that sort of power i'd worry more about the bottom end (Dont keep it stock!!!) rather than do the head work...
 
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Well here is a list of things I already have in my possesion.

Full Race Manifold, custom T3 and T4 flanged
740CC injectors
Greddy Intake Manifold
Z32 MAF - Thinking about getting the Power FC D-Jetro and doing away with the MAF
FMIC
HKS SSQV
Apexi 3" Exhaust
HKS Downpipe
Brian Crower Springs and Titanium Retainers
Brian Crower Stage 3 Cams for the S14/S15 keeps the VTC
Tomei Solid Lifters
Custom Shims
Greddy Sump
ARP Head Studs
ARP Connecting Rod Bolts
Complete Gasket Kit
Apexi Gauges
AEM Wideband
Nismo 260Km Instrument Panel
Nismo Mounts
Nismo Shock and Spring Combo


Things still needed,
Boost Controller
Turbo - thinking about a GT3076R or GT35R, shooting for 450WHP not BHP
Power FC
Splitfire Coils
Braided Lines for turbo oil and water


Maybe some other stuff but all I can remember right now.
 

Topper

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Quite a list you hae there.

What about the Z32 mac... something box a read about, remember seeing it mentioned as a good upgrade.
 
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Z32 MAC? I have a set of brembos from a R33 GTR that are going on so brakes-wise that should be alright along with braided lines and gonna be getting traction rods and adjustable arms and whatnot. I'm thinking if I opt for the GT35R I would need at least 850CC injectors. Thinking about getting the Z32 box and getting the adapter plate for it onto the SR from Mazworx or do you think a machine shop could handle this for me? I would still like to hear about the RB25DET box, would it be the same setup like how the Z32 box would be with the adapter plate? Also has anyone done the RB25DET box conversion?
 
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