Weird motor locking up issue - KA vs RB flywheel - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

ch1873857 · 05-02-2013, 06:30 AM

OK. So most of you know Im not a rookie but Im a little stumped on this one. Searched a bit. I google probably 50-100 things a day. Havent found anything useful for RB motors (if it matters).

Ive done probably 4 swaps with this same setup and no similar issues. Ill make this short and to the point.

Problem: rb25 swap. go to first crank. motor locked up. known good motor

Setup:

Stock rb25 s2
RB20 trans
KA white bunny clutch setup
stock driveshaft/diff

Situation:

Motor spun freely before install weeks ago when i replaced the front end (t belt water pump, oil pump). very clean inside.

installed clutch. had a KA flywheel around which is the same flywheel essentially. removed pin on the crank to fit. *didnt spin the motor since front end install*

Rb20 trans spun fine tail and input. lubed up good, went on like butter.

Once I finished the wiring, i roughed everything in. wired the power plugs, start sig, and ground, just to test power and wiring splice. Went to crank and the sound it made was exactly that of a locked up motor. I knew the starter was good because it was the one on my drift car.

Tried.
changing batteries, charging batteries, and jumping batteries. Power is GOOD
changed starter
checked wiring, fuses, battery cables
starting with clutch disengaged (was 5spd swapped prev.- neutral safety jumped)
putting a breaker bar and a 27mm on the crank. no spin

SOMETHING is keeping it from spinning and I THINK its the flywheel. Ive used the white bunny clutch on the 25 multiple times but always used the 25 flywheel because of the pin. This was a last resort thing. I am worried the backspacing it wrong and the flywheel is ON the block keeping it from spinning.

If the motor is know its good and the trans too. clutch seems to be working fine, cant think of anything else. I have read conflicting things about using KA and RB flywheels interchangably and havent found an solid evidence that is does or does not work.

Anyone?
Ray?

05-02-2013, 06:30 AM	#1
ch1873857 Nissanaholic! Join Date: Sep 2003 Location: Andrews Air Force Base Posts: 1,906 Trader Rating: (1) Feedback Score: 1 reviews	Weird motor locking up issue - KA vs RB flywheel OK. So most of you know Im not a rookie but Im a little stumped on this one. Searched a bit. I google probably 50-100 things a day. Havent found anything useful for RB motors (if it matters). Ive done probably 4 swaps with this same setup and no similar issues. Ill make this short and to the point. Problem: rb25 swap. go to first crank. motor locked up. known good motor Setup: Stock rb25 s2 RB20 trans KA white bunny clutch setup stock driveshaft/diff Situation: Motor spun freely before install weeks ago when i replaced the front end (t belt water pump, oil pump). very clean inside. installed clutch. had a KA flywheel around which is the same flywheel essentially. removed pin on the crank to fit. didnt spin the motor since front end install Rb20 trans spun fine tail and input. lubed up good, went on like butter. Once I finished the wiring, i roughed everything in. wired the power plugs, start sig, and ground, just to test power and wiring splice. Went to crank and the sound it made was exactly that of a locked up motor. I knew the starter was good because it was the one on my drift car. Tried. changing batteries, charging batteries, and jumping batteries. Power is GOOD changed starter checked wiring, fuses, battery cables starting with clutch disengaged (was 5spd swapped prev.- neutral safety jumped) putting a breaker bar and a 27mm on the crank. no spin SOMETHING is keeping it from spinning and I THINK its the flywheel. Ive used the white bunny clutch on the 25 multiple times but always used the 25 flywheel because of the pin. This was a last resort thing. I am worried the backspacing it wrong and the flywheel is ON the block keeping it from spinning. If the motor is know its good and the trans too. clutch seems to be working fine, cant think of anything else. I have read conflicting things about using KA and RB flywheels interchangably and havent found an solid evidence that is does or does not work. Anyone? Ray?