Last night things didnt really go as planned, i pulled the motor out of the chassis and worked out some issues regarding the gearbox adapter, theres a few options out there for SR20’s and thats what im here to talk to you about.
My plan was to run an RB25 gearbox, having ran Z32 gearboxs (identical internals different shifter arrangement) since 06 and producing my own adapter plate with great success i thought i would try another setup. This time using an RB25 gearbox and bellhousing with an adapter plate from Dellow Automotive pictured above (10mm steel plate)
After fitting the clutch and then meausring the offsets of the input shaft to make sure it had plenty of engagement into both the spigot bearing (inside the crankshaft) and also spline engagement into both the disks on the clutch i was left a little confused.
So this conversion plate is meant to be used with RB25 gearbox’s allowing the bell-housing to be left unmachined? If i did this the spline would only engage on just one clutch plate not two like it should. I gave up on this after spending way too many hours trying to figure it out, plain and simple this adapter plate dosnt work.
So after tossing the Dellow conversion plate (by the way its the same as most of those ebay ones) i reverted back to my old faithful alloy conversion plate that ive been making since forever.
I was lucky i didnt sell the old PS13 Z32 gearbox as i quickly pulled both my RB25 gearbox apart and also my Z32 with the already machined bell-housing. Another half an hours work and the bell-housing from the Z32 was swapped onto the RB25 gearbox. Now making this setup identical to what i run in the 180SX.
So now i have proper spigot engagement, perfect clutch disk to spline engagement and perfect alignment while shaving off a few KG with the lightweight alloy adapter plate.
Now to give this gearbox a clean and fit it onto the motor.
I feel your pain on the Dellow stuff mate :-/
you did a kit up for my mate Sean just recently. He has an S15. We have had the bellhousing machined and everything dummied up in place, but it looks like the 6 speed ogura racing clutch he has is taller then the 5 speed clutch I presume you use in your 180. I believe the problem you were having here with the spline engagement on the clutch will be because you were installing to a 5 speed clutch.
Sean is having the opposite problem, where the snout on the gearbox is actually hitting the first clutch plate before the gearbox mounts to the engine. How would you feel about swapping an unmachined bellhousing and the Dellow adapter plate? I am pretty sure this would solve the problem sean is having.