Had the KJR pulley installed before the HKS SC system. In NA form it seemed to work fine. No rattles no humms...RPM moved on the tac much faster than stock. Felt a lil' better on the pedal. FINE.
Installed HKS SC after running the pulley for about 2 or 3 months, however did not think the pulley had to be replaced because it was stock size, it would not change the config of the belts, and it would help spool faster. I now have about 5500 miles SC'd...car was running fine, with a lil rattle/vibration in the engine bay...went thru a lot of searching to find that DANG noise...for past 2 weeks, my vc has been consumed with this irritating noise, that at 1st you only heard leaving from stop or red light just a lil rattle, which progressed to a loud rattle, at idle, and louder still when I turned on the AC.
OK, long story short, someone a while back said "I'm not sure about the KJR yet, NISSAN put the damper in their pulley for a reason" or something to this effect. I changed back to OEM pulley, PROBLEM SOLVED. The pulley was vibrating and resonating thru the whole engine bay! So to the member that was waiting to see how this pulley would do in the long run..I believe this is your answer. Given, I am supercharged which poss sped up the process, it VERY possible it will happen sometime...
After pulling the pulley off, I found that it was not seated well, and possibly not cut well ( in the key area). It looks as if the key valley was not wide enough (photos to follow later today). So it was either not cut well, or it was not installed correctly. (Research in progress)
In conclusion I believe that you can use this pulley for your NA car, but FI and hard driving may cause this to happen to your car.
Earlier this year I had a problem with the crank pulley from the SC, but this was a diff prob as the head of the center bolt snapped, and just made a mess. HKS and SP Engineering, took care of this problem. I wonder if when that pulley bolt snapped off, the Engine Crank Pulley warped and caused that pulley to vibrate..and get progessively worse? No real way to tell..
I do miss the light throttle tho...

 

I took mine off and sold it . A Vortech needs the serp belt pretty tight and with out a damper , it will do harm in the long run

 

Mine ate my crank and costed me a fortune...

KJR is the most worthless pulley you can get for the Z... its an investment that can possibly destroy your car!

thank god you got that thing off your FI Z also...

 

Mine is coming off when i get my engine built.

 

i'm curious why the KJR is worse than the UR pulley cause people have been running the UR pulley forever now with not much crank eating

most cases I've heard of a crank pulley eating a crank it turned out to be a bad install somehow or a cheap pulley that actually cracked or chipped a piece off

also, for people that had a crank pulley go bad and hurt the engine, were they running a lighter flywheel on the other side of the crank as well or was it still using the heavy stock flywheel?

I figure my KJR is 1/3 the stock weight and my ATS flywheel is 1/3 the stock weight and was installed on the engine when the engine was out of the car and has been about 3 months now

If I have a problem, I'll deal with it. Figure I'll blow up before the crank has issues, but anything is possible

 

booger: yep, the HKS has to be pretty tight too!

bobafettm: Sure glad it came off before I went and pushed the car at CALI-SPEEDWAY on Sat..Who knows if it woulda held up...most likely, NOT!

baptist: hopefully this happens soon, think about what happened to bobafettm? Just lookin out don't spend anymore money for repairs, than you have too...just my $0.02

does anyone know if the UR pulleys do any have this charactaristic.

Luckily, my cousin turned me to look at that pulley, as it is a common problem with the NSX'z...Some companies made lightweight pullies for them, and they did the same, and those companies either stopped making them or went out of business.

 

KJR was made by a kid that goes to wayne state... UR was made by a factory of employees... KJR is run by jon abooda... he is a kid about my age... when i was NA I didnt think much of it... FI it ate the key hole completely...

the metal was weaker... nearly ALL crank pulleys have a steel shell around the key spot... that allows for no shake there and no movement! but the KJR didnt and it just ate the keyway all the way through...


Stick to the stock pulley its not really worth the gain

 

oh I didn't know that bit about the metal around the key spot

all along I thought it was wether it was installed the right way and how balanced it was and the harmonic damper

 

yah... it wasnt that fact of misinstall... this has happened to a few others now too! its not the balance its the key way giving out and then the pulley eating the crank shaft...

crap product