Does anyone know if i can use an sr20de
clutch on a modified for sr20de clutch
ca18det flywheel?

They both run 225mm clutches with the same splines and shaft size

But the kit is listed as a different #
Cover plate and bearing are listed as different numbers
Without them both infront of me I couldn't tell you if there is interchangability

But I don't understand the question
You want to use an SR clutch on a CA flywheel thats drilled for the SR clutch ?
If so... then of course the pressure plate bolts up... the splines are same on driven plate
Both flywheels are flat... its just the beearing thats different
Why would you bother modifying the flywheel to take the same size clutch ?

If you were going to use a SR turbo clutch at 240mm I could understand it

Or have I missed something ?

the sr20 clutch kits are more common and cheaper for single and twin plates in japan.
The ca18 ones are rarer and dont often come up for sale.
So what should I do? redrill the ca fly for the sr20de clutch?

Do you mean turbo kits... that are 240mm... or non turbo kits that are 225 ?

If it fits in the box and theres enough meat on the flywheel to redrill I'd go for a 240 any day over a 225

If I remember when at work I'll get a CA18det SR20et and CA18de clutch together and see what the differences are

I know what you mean with the 15mm extra, it will bite better yet
after trying a 7.5 inch twin disc race setup, I see a smaller 225
as more than adequate for pulling our featherweight 1000.
I suppose I could go for the 240mm single plate carbon/organic
setup if it fits within the pintara's 71 series ca20e bellhousing?

Some of the CA18's run a 240mm cover but still run a 225mm plate
So be careful of this

ummm the mix gets even trickier and muddier