You can machine the cover, you can machine the spider. but once the sheaves touch, Overdrive has stopped.
I machine all 4 aspects of the clutch. Sheaves, Sheave angle, Spider clearance bottom and top, and I machine the faceplate lighter than any "aftermarket cover" and remove the KEBC braking nonsense Along with that I machine the COMPLETE outer movable sheave so it sits back closer than stock to the belt. So belt-sheave gap runs Less than 1/8th inch. so there is instant engagment.
With mods like a Muzzy, Dyna and rejetted. I can get the Teryx to pull the front wheels off the ground (traction permitted) just by modding the clutch and changing a 20.00 spring
far greater performance than anything you can buy today and bolt on to the clutch.
Machining the cover for me is/was a stage 1 clutch. I don't even sell that anymore.
Machining the spider. for consumers that is going to be a VERY hard IF not impossible part to replace for the average guy. AND IT WILL INVOLVE CLUTCH PULLING. where the faceplate does not. so more cost is involved just to get that "bolt on" part on the machine.
If you have taken the cltuch apart. you will find some spiders DO NOT want to separate. this is where too much force snaps the 3 sets of fins off the bottom of the clutch.
I had to CNC a jig to alleviate the cracking problem with stubborn clutches.so it holds ALL the fins instead of 3 nubs of a fin
along with replacing the spider, you should always shim the buttons to Zero-.004 on average clutches need a .002-.004 shimstock to keep the buttons tight. binding hampers performance, loose buttons can bind and cause higher RPM shiftout. Most people don't have access to shims
the only way to get the belt to the top of these clutches is to machine the complete clutch. the more overdrive you can give the lower geared Teryx ....the better.