How to rebuild a Z32 gearbox to fit ca18det S13

[shogun]

We all know how bad the feeling is when the original gearbox give in at about 350-400Bhp.
This is how I rebuilt a Z32 gearbox to fit my car (200sx S13 with ca18det).


The good thing about it is that you can reuse the nice clutch you already invested in for your S13. I have a twin disc OS Giken clutch, bought for my S13 gearbox. Both gearboxes have the same dimensions on the ingoing splined shaft, release bearing, sleave etc. This makes it an absolute fit. The gear ratio is slightly higher. My car had before a top speed of 282km/h at 7800rpm. With the ratio of the Z32 gearbox and new tyres it will make aprox. 305km/h. Hope you like it.

Clutch: Same as S13 (clutch, bearing, release sleave, starter motor, flywheel)
Weight: A bit heavier because of internal dimensions
Length: A bit shorter (reuse the yoke from the Z32 and the rear part from theS13 and make a new, longer prop shaft)
Gear ratio: A bit higher (~5%)
Shift stick: Reuse the one from Z32 or buy a new short shift
Welding in cast aluminium: You need a TIG or go to a welding shop (sand blast the weld area to make it clean and easier to weld)

Z32 original gearbox from a Twin Turbo 1994

[shogun]

Disassemble the clutch housing (Z32)


Parts to remove to disassemble the clutch housing. Not shown are the screws on the outside (remove), attaching the cluth housing to the gearbox.


Remove all screws around the cover and carefully lift it off


Remove both snap rings and the stopper ring


Be careful not to lose any important washers or shims


Important! First remove the screw, spring and ball before removing the complete interlock assembly, the ball might fall into the gearbox.

[shogun]

Before you disassemble the clutch housing of the S13 gearbox, you have to make a centering device. Use a plexi glass plate (10mm) and drill a 16mm hole in the centre, put the plate over the shaft (snug fit) and carefully drill 4 small holes exactly in the centre of the holes where the gearbox is attached to the motor. Remove the plate and carefully drill the holes just as big to get the screws in


Result


Remove the clutch housing from the ca18det S13 gearbox. It is more or less just to remove the screws on the outside of the clutch housing, remove the cover and one snap ring.


Remove the snap ring under the cover


Comparision between the both gearboxes. One is useless over 350-400Bhp, the other last well over 1000Bhp and more.


Use an angle cutting machine and cut off the flange from the S13 gearbox ca. 50mm, take it to a machine shop and have it grinded down to 45mm. Important to get it absolutely flat and equal all around.


Use an angle cutting machine and cut off the flange from the Z32 gearbox ca. 40mm, throw away the flange and take the rest of the clutch housing to a machine shop and have it grinded down to 355mm. Important to get it absolutely flat and equal all around.


Both parts after grinding, cleaning and reattaching the clutch housing on the Z32 gearbox

[ByReaL]

this is pure gold, i have in mind to do exactly like you, i have a spare 200sx gbox i'll just have to find a 300ZX gbox,

can i ask you if the 300zx gbox is from a vg30de or a vg30dett ?

[shogun]

Put the S13 flange snug to the Z32 clutch housing and attach the centering plate with four screws


Side view


Top view. Important to align and rotate them like on the picture

If you do not own a TIG-welding machine, you go to the machine shop again and have it carefully welded together, both from the outside and the inside

((((space for picture...after welding))))

to be continued with installation, shift stick, connection shaft...

[Drifter]

Both the non-turbo and the turbo use the same gearbox. The bellhousing on the non-turbo is a little smaller internally, but I doubt that would matter when using a 20sx clutch

[shogun]

this is pure gold, i have in mind to do exactly like you, i have a spare 200sx gbox i'll just have to find a 300ZX gbox,

can i ask you if the 300zx gbox is from a vg30de or a vg30dett ?

I added some new text in the first post.
My gearbox came from a TT 1994. I heard something that they improved the sync rings after 1992-1993.


cheers
Tim

[Fake Ben Taylor]

this is pure gold, i have in mind to do exactly like you, i have a spare 200sx gbox i'll just have to find a 300ZX gbox,

can i ask you if the 300zx gbox is from a vg30de or a vg30dett ?

i was gonnna say the same thing!

[Drifter]

I have to say I was tempted to cut and shut the flanges like this on my Z32 box. Cast aluminium is a twat to weld, so went with the adaptor plate. I might investigate this though, see who can do it in the area

[RohanC]

Sweet thread! Getting fed up with the sloppy, knakered g'box on my s13 to this give another option, instead of putting another sloppy, knakered 2nd hand box on it!

[ODINN]

questions...

weight - is it the same or slightly different ?
gears ratio - i belive, theres bigger difference...
does ANY - s13 clutch will fit in 300zx gearbox like this ?
And stupid question - short shifter - which one will fit ? any for s13 ?

how will it work when car is to be used for example for drifting ?

Damn those mutated s13 frankenstein monsters...

[Buffy]

good work mate

[GreeceS13]

This gearbox can handle 1000bhp??? wow!!!
Is it really so stong?

Well done for the tutorial!!
This mod is really important!!

[kalin]

Welldone, now, after reading that post, I should think to putting a 300zx gearbox into my lovely 200sx

[shogun]

Reuse the shift stick bracket from the Z32 gearbox. You have to cut out some small triangles from it, bend it to a Z-shape to fit the S13 under body and then weld the cut outs together. (borrowed picture)


The new short shift


A small change of shift stick position compared to the original (borrowed picture)


A plate to cover the hole at the shift stick (borrowed picture)


A bracket to hold the gearbox in place (borrowed picture)


Aligning the gearbox with the rear axle. Put a steel tube in the gearbox, aim it towards the centre of the rear axle flange and find the final position of the gearbox bracket. (borrowed picture)


Side view (borrowed picture)


Front view (borrowed picture)


The prop shaft. Mount the Z32 yoke in the gearbox and the original flange on the rear axle. Measure the centre distance between the loops in the yoke and in the rear flange. Use this measure and go to your local prop shaft supplier and have him to make your new prop shaft. The shaft rotate at about 10.000rpm at max speed so it has to be dimensioned for the forced and also balanced.
(I will edit this post and put in a better photo and necessary dimensions)

[John Bennett]

Top effort

This gearbox can handle 1000bhp??? wow!!!
Is it really so stong?

A good condition one might be, but for how long it debatable . Certainly going to be a lot happier at 400+ than the S13 cheesebox though.

ODINN
The 300zx gearbox is about 15kg heavier than the CA18 one (I got 57kg when I weighed one).
I'll add the gear ratios to this thread in a minute:
http://www.sxoc.com/vbb/showthread.php?t=208965

They're somewhat desirable over here as people use them for auto to manual Z32 conversions, so good luck finding good ones for a reasonable price (it is possible )

[shogun]

This gearbox can handle 1000bhp??? wow!!!
Is it really so stong?

Well done for the tutorial!!
This mod is really important!!

It is that strong. There are rather many 300zx tuned cars with about 1000Bhp that still run with the original gearbox. I have heard about (non confirmed) one specific case where a guy had 1300Bhp and run the same gearbox (no info about life time on that tranny).

For me, with 600Bhp it is an excellent gearbox.

[shogun]

Some more parts belonging to the drive train:


Replaced the internal parts with a really good Deftforce LSD from ATS in Japan


The part number if you plan to buy one yourself. It is an easy exchange; out, move over the tooth ring, clean, mount new sealings, in, oil...ready


OS Giken Twin Disc clutch


Disassembled clutch (discs, pressure plate and flywheel in one lightweight unit)


Before switching over to five stud hub


The new hub set (is on the car now)


Result

[Birdy_sx]

Nice to see it complete Tim! Im doing the same as you, to much work to get an adpater plate. But im short on casch so I cant afford it untill in a couple of mounts Had to buy new pistons, crank, block and head fore this year

When will your car be out? The rest of the motor done?
Will you be at elmia this year?

Regards Staffan!

[George]

Is anyone else having trouble seeing the pictures in this thread?