So, I have a 1999 civic coupe EX with a 4 lug. I'm working on a project to convert this into a 5-lug vehicle and eventually swap out a D16Y8 motor to a CTR B16B paired with the S4C tranny. Upon research, I noticed that CTR uses a 32 mm spindle nut and some youtuber said EX and CTR use a different spindle which requires a JDM knuckle. I don't have a tape measure, so I do not know if they are different in diameter. Does the CTR 5 lug hub only fit on CTR front knuckle and rear trailing arm or slide into a knuckle that's already on the EX coupe?

 

The 4x100 rear spindle is too short for the 5 lug hub.

 

So I simply need to buy a spindle for 5 lug right?

 

Yes.

 

Incorrect in 2023 - This is the way, for the rear: https://honeddevelopments.com/produc...r-hub-nut-kit/

OP, you kind of flip flop between you questions about fronts and rears so I hope I can address them successfully. For the fronts on an EX, you do not need to swap knuckles (spindles are a rear component). Press in a USDM ITR hub with a fresh bearing and you’re done.