Wazman's NB8a

wazman · Postby **wazman** » Mon Jun 16, 2014 1:20 am

So i have finally uploaded some pics to photo bucket of my little gearbox Nissan s15 6speed gearbox conversion! (or 200sx delivered in Aus)

This conversion requires a fair bit of fabrication.
You need to get your hands on a mazda mx5 6speed bellhousing (to bolt onto the nissan box).

Someone (probably me but lets not point fingers!) forgot to do up the gearbox oil drain plug after the last gearbox out /stripped 4th gear incident. So my 6speed turned 5speed was now a no speed box

Out she comes!

After seeing plenty of other drifters blowing up RB25 boxs with only 250rwkw! (and believe me its more than just a few) i am not convinced i want to do a big conversion for a box that is getting harder to find and cost $800-$1200 !!! Im a low budget motorsport kinda guy...... So i looked to the 350z gearbox (because there was one at work on the floor next to the hoist ;) )
The 350z box's are holding up to 800hp reliably and they have good ratios......the down side is they weigh as much as my whole bloody car! and cost around $1600 (someone told me in passing that you can land them for $2k new from Nissan America...not sure about that). Anyways.....still out of my budget

Just some pics of the mx5 6speed so you can see the similarities between it and the s15 box later.

wazman · Postby **wazman** » Mon Jun 16, 2014 1:44 am

So I googled and drained my life reading internet whispers that Nissan s15 gearboxs are "the same" as Mazda mx5 6speed gearboxs....... same same but different! you know what i mean :roll:

I could not really find any direct picture matches on the net to solidify these claims on other forums......so i sort of lost interest.
Then i was having a look on "Driftsales" facebook page (this page is full of people that have no idea what things are worth and generally dont take care of stuff....so be warned) and i saw an s15 gearbox in sydney for $150 !! Cheap....bugger it may aswell see if it is the same for that price. So i buyed it :shock:

<< thats perfect drift sales ingrish too !

To begin removing the sections/housings of the Mazda 6speed box, you need to undo ONE of the two bolts close to the oil fill plug, undo the one that is closest to the bell housing end of the box.

Next undo this bolt that will allow the cast shifter piece to slide off with the rear housing.

Sorry bout the phone pics (blurry late nights after work). This is the with rear housing removed (mx5 box)

wazman · Postby **wazman** » Mon Jun 16, 2014 2:19 am

I figured that the only real reason i was doing this at all was because i was running no gearbox oil which caused the gearbox to fail ! So i figured there is nothing wrong with the mx5 6speed for drifting...... Nissan s15 owners will all swear the s15 box is weak and cant hold more than 240rwkw !..... Well my car only makes 223rwkw (and i actually turned the boost down to save on tyres so it dosn't even have that ATM) so i figure the s15 box is a good choice. Its light. its cheap. It has great ratio's.....and the best bit! Nissan owners dont want them!!!! yay

To get the front housing off the mx5 and nissan s15 6speeds you need to take off the LARGE "c" clips from around the outside of the bearings. The bearings will stay on the shafts and bell housing will slide off over them. You need to take off the thrust bearing fork aswell obviously. You can see i took off the small "c" clips as well but you dont need to!

Bellow you can see i took out BOTH bolts to separate the housings.....but once aprt i realised you only need to undo the bell housing end one.

I took out this bolt / selector guide pin......but not sure as to whether or not i needed too in order to separate the housings. The long allen key bolt that holds the selecto pivot thingy dose need to be removed to separate the housings.

And here is what using air for oil dose to your final gear !!!

This is the point where i was thinking i can just bolt my mx5 housings onto the Nissan box center section and away we go! ...... FOOLISH CHILD!
The cog on the bench has a small shaft through the center that is held in place to the housings by the TWO bolts that i removed that you only need to remove one of......otherwise it falls out like this......not hard to put back in so no stress.

Empty hole

HERE IT IS ! Back to reality...... or as my old man would say "It's never a five minute job!" The mx5 6speed input shaft (my damaged one) verses the Nissan s15 6speed input shaft !

wazman · Postby **wazman** » Mon Jun 16, 2014 2:40 am

You can see in the above pic that i have removed the bearing from the mx5 input shaft and that the length is the first obvious difference !

So what to do ? well the nissan one is bigger so why not just get it machined down and run a nissan clutch plate ? Fabricate a gearbox cross memeber and somehow attach the Mazda mx5's power brace.... Even if i went for a different box i would have to make these things so onwards and upwards :roll:

Off to the machinist for some love! Its hard to find a decent fitter and turner these days that has high lathe skills...... gearbox shafts are hardened and not so easily machined.

After you machine it then you need to harden it again.....otherwise it wont last long :evil:

So it needs to be heated up with an oxy until burnt orange/nearly red in colour, then quenched in oil (25 deg).... for this you use the apprentices coffee cup :wink:

and it should look a little something like this....... Is there enough spline there for the clutch plate i hear you ask ???? :shock:

as far as i can measure.....yes......just..... but i actually wasn't 100% sure until i drove it ! ha ha ha ha ha ha

wazman · Postby **wazman** » Mon Jun 16, 2014 2:58 am

So to get you input shaft out you need to remove one bearing and one cog off the lay shaft (bottom shaft). You can see that i left the bearing on the input shaft even while machining!
A decent puller is what you will need......i tried at first with a non hydraulic tri hook one.....but it was either to old and shoddy or not strong enough to pull. The one pictured was the winner.

Here is something that will make all the engineers cringe !! :mrgreen:

I use and elastic band to hold the selector pivot arm in place so you can get the LONG ALLEN KEY BOLT (thats the one that alot of people, including myself, mistake as the oil fill plug!). If someone knows how to hold this (*&^%#@*&^#@ of a ) thing in place without an elastic band please inform me!!

Mx5 input shaft installed in to Nissan s15 gearbox with mx5 6speed bell housing.

Here you have em side by side! Left Mazda mx5 6speed and on the right is the Nissan s15 6speed.

and guess what! the shifter hole dosn't line up anymore :roll:

wazman · Postby **wazman** » Mon Jun 16, 2014 3:16 am

So here all dumbied up for a trial fit. Gear shift stick will need a "Dog leg" modification. The shifter hole in the tunnel will need about 25mm cut out of the front of it.

The Nissan s15 gearbox has BIGGER/LONGER everything! The input and output shafts are longer and 1mm bigger in diameter (thats why i cant use the mx5 clutch plate)(and why i need a custome shortened tail shaft made with nissan tail shaft end welded on at the gearbox end).

So i made up some basic boxing to weld to the tunnel so the gearbox cross member had something decent to bolt up to. I welded nuts inside the box's for ease of fitment of the crossmember.

Here you can see i have cut the power brace and made a box on the side of the tunnel to bolt the brace to, also with captive nuts (welded inside).

the boxing is all made from 3mm plate steel and high tensile M10 bolts used.

Here is the actuall cross member i made to hold up the gearbox. It has a 6mm plate steel arch on one side for the exhaust to pass under/through it.

Pull box out, wack on some paint.

wazman · Postby **wazman** » Mon Jun 16, 2014 3:42 am

Yay for Nissan stuff being common ! I went to See Donny at http://www.forcedmotorworx.com.au/ For all the bits and pieces that i didnt have like a shifter and "c" clip to hold it in.
Donny at Forced has a few S15 gearboxs for spares usually and rebuilds box's (new bearings etc) in house. Cant recommend them enough! The shop is at Forced Motorworx
13 Podmore street, Dandenong, VIC 3175. Telephone:0397940791

Donny put me onto the Nissan CA18 clutch from Exedy. Its the same diameter as the mazda NB clutch

around $290 ish with new spigot bearing.

the part number for those interested...

Here is my new shortened tail shaft with Nissan end on it , I got it done locally in Dandenong. around $180 ish

Installed !!! yay i seem to have gotten my lengths right

Here you can see that....i have a small fetish....and that i had to make a alloy plate to cover the shifter hole and the bend in the shifter to stop me punching the dash with every shift.

I HAVE A BOSS COFFEE CAN FOR A SHIFTER! I WIN

wazman · Postby **wazman** » Mon Jun 16, 2014 3:46 am

And after all that it all worked great ! any questions ?

Im coming 9th in the Victorian Drift championship and love nothing more than thrashing my mx5

wazman · Postby **wazman** » Mon Jun 16, 2014 3:48 am

Me and my Team mate Catherine May

Little sucker is still healthy too !

plohl · Postby **plohl** » Mon Jun 16, 2014 11:22 am

Interesting write up man :beer:

Do you think you could get the rear end of the mx5 gearbox to mate to the s15 box? So you could keep the ppf etc? I assume you would have done that had it been easier. Hard to tell from the photos but the bolt patterns look somewhat similar.

Best of luck at the drift championships!

AndrewJZX100 · Postby **AndrewJZX100** » Mon Jun 16, 2014 9:39 pm

wazman wrote:Hi AndrewJZX100,
I modify my own knuckles. Mx5 knuckles are actually very simple, the tie rod end of the steering arm is actually on the same plane as the lower control arm ball joint....so all i did was shorten the steering arm part of the knuckle by 15mm ( be aware that wheel clearance becomes an issue very fast on mx5's with extra lock. i run 14x7.5 -19 on the front to clear lower control arms and tubs). I also have the GK tech s13 slip on spacers in my rack.

Ill post some pics of my knuckle and rod ends soon.

Is there less akerman effect with your set up too? I like the idea (and feeling) of less inner wheel drag as much as having the extra maximum lock, and I'm guessing the steering has quickened up with the shorter knuckle movement too.

Thanks for the info mate, I'm not planning to do anything drastic with my SE for the time being, but when I do - knuckles are high on my list.

wazman · Postby **wazman** » Mon Jun 16, 2014 9:53 pm

Sorry, bad pics. The s15 gearbox output shaft is much shorter (80mm ish) than the mx5 6speed.
So you would need to have the output shaft machined down.... But I don't think there is enough length of spline to do so.
Plus as a replaceable part I didn't want to have to pull apart the whole box every time and maybe even have to get the custom shafts machined again.

The gear that I managed to melt in the pics is final drive. The strongest gear In the box. So as long as I remember to tighten the oil drain plug I shouldn't have to get a new input shaft machined.

A.Chen89 · Postby **A.Chen89** » Tue Jun 17, 2014 11:03 pm

any other issues on the drive train? snapped any drive shafts yet?

wazman · Postby **wazman** » Wed Jun 18, 2014 1:53 am

I havn't had any broken drive shafts yet. (touch wood!) Ithought i had bent an axle on one once but turned out to be a loose bolt in the lower control arm. The good thing about mx5's as drift cars is that they are light and you only need 15" tyres.....so the load on the drive train is low compared to the setups that nissan owners run.

I pulled my turbo off tonight to get new bearings for it as the shaft had about .8mm fowards/backwards movment (this is a sign the end is near).
I should probably run a blow off valve of some sort to save the bearings since its a ball bearing turbo. Ill take it to Forced Motorworx in Dandenong as they rebuild them and have the rebuild kits in stock.

I got sick of blowing turbo to manifold gaskets....so i had the turbo rear housing welded to the manifold previously.