rebuilding 6 speed box

[DeanS15]

i'm just curious as to whether anyones ever had thier 6 speed box rebuilt in the uk and at what cost/result??? can it be done/can the parts be sourced out??? i know that eventually extra power will get to the gearbox as the weak link, and wanted to get a feel for the options when that happens. as i understand it its bearings that suffer more than anything - if it was rebuilt with heavy duty shaft bearings (if possible) does anyone reckon this would improve its longevity? i dont think i'd be able to trust a secondhand box not to be hiding issues of its own and would prefer this route if its possible as there is normally warranty or some sort of comeback/support.

cheers in advance for any info:thumbs:

 

[DeanS15]

anyone???

 

[_Wing_]

all the parts can be sourced from nissan, be it over there in the UK, from Japan or even from Australia. a gearbox workshop that knows nissan gearboxes will be able to rebuild it for you with the specs from the FSM.

Regarding bearings - bearings are normally the last thing to die, more than likely you'll first either punish the synchros till you start crunching gears or break the gearset, be it stripping the teeth off a gear or having the lovely circlip go for a walk, so don't waste money on fancy bearings

there are three major things that will tell you if you box will or will not last:
1 - power: how much you making/wanting to make?
2 - clutch: how many plates/pucks/padles, spring/damper, material type?
3 - you: drift/drag/circuit/clutch kick/side step/throttle on/off x 999999?

if you want an upgrade there is no GOOD aftermarket support for anybody wanting to keep the 6 speed Everything revolves around converting it back to 5speed (which isn't such a bad thing!) - the only question is: how much do you want to spend?

 

[DeanS15]

well first and second are becoming a little noisy (not terrible but they arent getting any better) and the layshaft/input shaft bearing has a little noise off clutch on tick over - none of it is drastic and its driving perfectly but it will need looking into eventually....it's running 357bhp and 344 ib/ft. used for fast road weekend car, no track or drift. clutch is a near new 6 puck exedy hyper single paddle with new release bearing - its quite aggressive but only in first really. any hints on what you think my best bet is? i really would like to keep the 6 speeder as when i use it i like to take it up the motorway to events etc... if a good rebuild would cost around the 600-00 mark i'd much rather have that than chance a secondhand box...

:thumbs:

 

[craig8585]

Would you consider a Z23 gearbox conversion Dean?

http://www.sxoc.com/vbb/showthread.php?t=228568



I dont know much at all about the 6-speed boxes, but remember reading a fair bit about a certain circlip failing first of all, leading to everything else eating itself!??

 

[DeanS15]

i have considered it mate but its more designed towards the lhd models as far as i could tell when i saw one, when fitted to our rhd cars the gearstick is in the wrong position and there is a bell housing cover not fitted which apparently makes it noisy??....the gearing is meant to be very good with a 5th as long as our 6th and a silly top end but i'd like to know if there was a way of solving these little niggling problems with the shifter before going ahead with it, otherwise it means running it without a surround and gaitor and smacking it into the plastic every time you want second, fourth or reverse. i still cant believe that there are so few options for transmission on cars that have so much aftermarket parts availability and potential for big power....

 

[Auss15]

There are two NSCC members who have fitted the Z32 box to their cars with basically a modified bell housing and single peice driveshaft and they had no shifter issues

 

[_Wing_]

Auss15 - are you rusty Phil by any chance? And are you referring to Ben and Shane?

 

[_Wing_]

That bearing noise will stay like that till you break it or sell it or rebuild it and IMO rebuilding it because of bearing noise is not worth the time and money. I get quoted rebuilds take 2 weeks including sourcing parts and labour and waiting - I've rarely had any shop quote me a timeframe and stuck with it but anyways, 2 weeks out of action and around $1000-$1500aud for new bearings and seals, maybe a synchro or two or three - the more you replace the more they charge. (I'm based in Australia so I don't know what UK prices are like sorry)

You can go the cheaper option of having them re-profile the teeth on the synchros but two things here - is there enough meat left to do it, and if it does and you do it then you're left with less meat on your snychro teeth to handle your punishment when it gets put back together, sooooooo it'll wear even faster than before. (Hope I'm making sense I'm sh!t at explaining)



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357bhp and 344 ib/ft - if that's at the crank then the box should be happy, if it's at the wheels it's not a matter of "if", its a matter of "when'.

fast road weekend car, no track or drift - you're nice to the gearbox which is good

6 puck exedy hyper single... quite aggressive but only in first really. mid-range clutch in terms of "agressiveness" so you're not too bad here in terms of gearbox longevity, but there are nicer clutches out there for the gearbox.



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6 SPEED OPTIONS:
================
Standard gearset - waste of money.
Nismo gearset - inherited the same issues with the OEM box.
HPI gearset - same as nismo's case.
PAR gearset - piece of sh!t might as well use the money to wipe your a$$.
z33 - $8000aud..... lol? nonturbo z33's break their boxes


5 SPEED OPTIONS:
================
s13/s14 5 speed - cheap and weak but better than standard OEM 6speed
z32/r33 - expensive and strong, indestructable if you don't run tripple plate unsprung metal monsters with drag slicks and redline launches but both conversions run inherent risks and dodgy methods (like half the gearbox has no bolts holding it on!!, flywheel adapters, paper thin adapters plates, drilling out threads, cutting chassis, shifter hitting trim...)



ENIGMATIC OPTIONS:
==================
Do the circlip mod - I did this to mine but just before I took the plunge to have I realised something. Even if the magical circlip doesn't come off the inherent issue with ALL SILVIA/SR20 gearboxes is that they are designed for meagre power: small gears, large angles, small tooth profile, weak shafts.... We've easily double the power output and now triple the output is fast becoming the new standard power lol. So I went 5 speed (all of them)

There is an Australian company that has recognised this issue and is currently working on a true bolt-on bullet-proof gearbox with no half-arsed adapters or spacers and more spacers, and most importantly to me is there is no cutting of your chassis or drilling out parts required. There is actually a prototype already made

 

[DeanS15]

hey bud - cheers for the info. its 305 at the wheels, so in theory the box should be happy. im hoping eventually to get her up to just under 400 at the flywheel so just weighing up options. i wont be getting the box sorted before it breaks - i still think its got loads of life in it as it still performs but has just become noisy thats all. i'll keep an eye out for that gearkit solution the aussie firm have come up with - but cant imagine it'll be as cheap as re-build money but time will tell

 

[Auss15]

Auss15 - are you rusty Phil by any chance? And are you referring to Ben and Shane?

Yep its me Wing, in a different coat, and I was referring to Ben and Shane:nod:

 

[LuPix_S15]

lol just posted a thread about close ratio gearboxes and not seen this?! :wack:


Does anyone know whether it's worth changing the gears of the stock S15 box for summat like the OS Giken close ratio set? I know this will alter the format to 5-speed but willing to suffer this if acceleration and responsive performance is considerably improved


Cheers - J

 

[DeanS15]

the os giken kit is designed for the 5 speed s14/a box and as such would require the box, prop, flywheel and clutch from an s14 or s14a. from enquiries i made it wont fit into the 6mt box....

 

[Auss15]

^^^ And the diff, as the 3.69 for the 6 speed is to tall for the 5 speed

 

[DeanS15]

lots of the s14 boys fit the s15 diff, whether they just fit the helical part i dont know but they like them much more the the old silvia diffs...

 

[Auss15]

Thats interesting, because the guys here find that they lose off the mark pickup with the taller ratio's. It's almost like lag,but once they get mid range speed it winds out to much higher top end speeds in each gear.
I've got a mate who is replacing his S15 stock diff (he has a 5 speed box) with a 4.1 ratio to get more response. He has got it up to 185kph(115mph) in 3rd gear but it takes too long to get there.

 

[LuPix_S15]

Thanks for the info guys...


So would it be worth getting the OS Giken cogs + S14a box + S14a clutch/flywheel fitment and possibly the S14a diff all for better response lol??!! mmm.... starting to look very expensive and I'm not keen on losing the S15 diff cos it's brill out on track

 

[Auss15]

If your doing a bit of track/drift work its worth considering a Dog box.
Dale(dcoghlan) has just put one in his S15

 

[_Wing_]

HI PHIL!
Those boys have awesome gearboxes, Shane's one is the best OEM-type I've seen
And I wanna check out Dale's car! Dog box sounds insane!!!


it's true the 3.6/3.7 ratio is too tall for anything other than a 6 speed, it sux TBH lol

a gearbox and diff conversion + a gearset mainly for response? not worth it at all! here's my post from the other thread:



if you get closer ratio's on the s15 you'll be like my friend with a rally car - he needs to row all gears to to get to the suburban street speed limit (60km/h) ROFL

the s15 6speed is an awesome box with sweet and close ratio's as is, i say leave it the way it is you can already spin up 1 2 and 3 with the "standard" bolt on power mods so any lower gearing or closer spacing and its spin 4 and 5 too, making you slowest of all :|

anyways, if you're still keen to get even shorter gears then get a shorter final drive (numerically bigger), you got heaps to choose from like 3.9 4.1 4.3 4.6... 4.9 = 6th gear wheelspin? lol