I will try my best to explain the two methods i have been using to make Z32,Z33 and RB25 gearboxes fit CA and SR engines.
The reason why i use Nissan gearboxes are because they use the same spline, so you can still use the same clutch.
They have ratios that match the diff pretty well and they are cheap new.
How much the input shaft sticks out over the flange is what is cruicial, the shafts are all the same but the amount of "stick out" is different.
CA/SR = 18mm
Z32/RB26 = 16mm
Z33 = 12mm
I aim to get the "stick out" same as it is stock on a SR/CA transmission.
It`s better to have 1mm shorter shaft vs 1mm too long.
For that reason i always make the housing a couple of mm too long before welding.
Then i can machine it down to the correct length.
For alignment it`s a good idea to bolt it to a block, vertically.
There is also a cast seam on the top of the gearbox and the flange wich needs to match to get the orientation correct.
Method number 1:
This is how i did it on a RB25 gearbox:
Ca flange over the RB housing:
Cut the RB flange of:
Machine the housing:
Mount the finished machined CA flange to the centering device
:
Tack welding it:
Finished welding and is going to be machined again (warps when welding):
Finished:
Mounted in car:
Method number 2:
This one is a little more advanced, its the same when cutting and machining the housing, but instead of welding on a flange from a donor box i use a blank watercut flange and machine the bolt-pattern and guides after the welding is done.
The flanges are cut with a groove to match the cast seam on the gearbox.
It`s a more accurate but also more complicated method.
Here`s a photo of the watercut blank flanges, its made in pieces to save material and are bolted together to the guide plates shown.
These bolt holes miss the stock bolt-pattern and is not used after welding.
The "guide rod" wich centers the blank flange is shown here:
Here`s a photo of some housings welded but not machined:
Machining:
Machined:
I have probably missed several things, please feel free to ask.
Also excuse the quality of the photos and all the SR realted photos, they are the ones i have the most pictures of.