Just had a closer inspection on the crank pulley that was previously used on a Comptech SC kit.
Not certain on mileage on this but it was used in track competition so lots of hard use for sure.
Is this normal and no problem to use?
Guess safest bet is to just drill and tap a new pulley but wanted to check with you guys first if it's unnecessary.

Front side there is only this tear


Back side, there are seven cracks or tears. The smaller ones is might be hard to spot in the picture.


These are the two bigger ones.

 

I wouldn't chance it; you definitely do not want that rubber isolator failing and allowing the outer ring to separate, especially with a supercharger pulley bolted to it. New OEM crank pulleys aren't too expensive iirc, I'd just start with a fresh one. Age plays just as important as a factor as mileage on these things. I'd imagine over time that rubber will eventually start to dry out and crack depending on conditions. Even though my original pulley was in good shape I still had TTS machine me a brand new one for my supercharger kit; not something I'd want to have to do twice if I can help it.

 

New OEM one from Japan is over 200USD for me, I wish there was an upgraded or better than OEM available that fits with a SC pulley.
Is it possible to get a new drilled and tapped OEM pulley from any company in the US?
I'm probably going to try and modify my original one that I just pulled out, it's only done 43k miles and has no signs of cracks or tears in the rubber.
If I mess it up then I'll just get a new

 

agree on not chancing it. If there are visible cracks in the isolator it will only get worse

 

I was able to acquire one from ScienceofSpeed a year or so ago. Send them an email or call and they should be able to help.

 

Was it for a Comptech SC? I think they are slightly different compared to their own SC kit.

 

I believe they're the same but contact ScienceofSpeed to be 100% sure. Wade and the guys over there helped me with getting some items that I wanted to refresh since I bought my SOS Novi1200 kit used. Finally will be installing mine in the spring/summer after sitting for 2 years . If you'd like I can PM you pictures of what they sent me.

 

Managed to drill and tap my existing pulley, wasn't much room for error here.


But everything lined up great.
I used new M5 12.9 hardware instead of the previous 10/32 x 1.25" bolts provided by Comptech.
Just need to get a bottoming tap so I can get max thread engagement, maybe touch up that rust as well.

 

Can't you just drill them all the way through? Then no need for bottom tap.

 

I guess it's possible but not sure if it's needed or even advisable?
There is plenty of thread engagement and the threaded hole is already slightly poking through the bottom of the belt groves.
The other pulley looks the same so I did not mess up the drilling, I will try and clean it up some though, don't want to risk damaging the belt.
I borrowed a nice bottom tap from a friend and done all the holes, picture is right after tapping so it might look worse than it is.