Ok . about two weeks ago i had my SC belt smoke up at high RPM'S under full throttle . i smelt the burning rubber smell through the vents , it smelt great .
but was also concerning as i was sure it was not the tires .
i drove it home carefully and had a look around for a cause . with the engine running i could hear what sounded like grumbly bearings in the SC , so disconnected the belt . and sure enough it was then quiet .
i ordered this eaton SC rebuild kit ,

Fits Jaguar XJR XKR S-Type M112 Supercharger Rebuild Kit Snout Needle bearings | eBay

it comes with the two snout bearings and seal , two rear needle bearings (pre greased) , gasket sealer and the correct amount of GM/FORD speck eaton SC oil . and finally a green solid (upgrade?) coupler .
after purchasing this kit i noticed it does not have the rotor bearings included .
i emailed the seller, and they said they do sell a kit with them and sell them separate , but they are hardly ever needed . and it is not a DIY to re time the rotors . i asked our local turbo reconditioners to see if they can re time the rotor pack . and according to them it must be sent to eaton .

i removed the SC and found the 1.5 powerhouse pulley had slipped and walked off the shaft about 7mm , my guess is the slip and grab of the pulley on the shaft caused the belt slip . still i had a kit so carried on dismantling .

so after inspecting the rotor pack for scuffs and wear and having no way to re time it decided to reuse it .

next i pressed the old rear needle bearings out , still had beautiful blue greece in them.
and the new ones in .
same with the snout bearings . to be honest the front snout bearing was the only bad bearing in there as far as i could tell .
but the original plastic spring coupler was shot , so i figured the noise from inside was that and I'm still sure it was . most posts about a crook couplers mention a noise of some description.



as you can see all the stops were smashed from the drive pins hitting them , and the spring had jumped over the loaded drive pin and was damping under boost rather than deceleration ! whilst boosting it was then forcing the spring round past were the stops should be hence my noise .

i fitted the new coupler and threw the car back together .
fired her up - and crap it sounded average at best . but a different sound .
i used a stethoscope to trace the sound and sure enough it in right were the gears and front rotor bearings are . so i called powerhouse to see if they would rebuild my rotor pack , there reply was this ,
Eaton pean the alloy rotor bearing housing to retain the bearings .
there for it is not a serviceable part they can re coat the rotors , but advise to replace the blower if the front bearings are if'y . they too said its unusual
to find these bearing failing as they are semi submerged in oil .

they went on to say that it is inherent of the solid coupler to accentuate the sound of any backlash in the gears through the blower housing .

mainly at low rpm and under deceleration . in which describes my new sound perfectly.
the grumbling sound i started out with has gone . the new sound was just as alarming as i expected a silent blower after this many new parts .

i had plans to take the car 1000kms to see the scope classic race meeting at rurpuna race way in Christchurch and hopefully back . so decided id take the car and stop and check the noise every 50km . and i did ! happy to say the 1000km road trip was sublime , the racing was awesome , and the supercharger sounds exactly the same as when it went back together . so it looks like this chatter caused by the solid coupler is here to stay for now .
just a heads up for any one with a high milage STR or Eaton m112 SC jag for that matter that goes with the solid coupler as a replacement . it can be heard in the cabin but only with the climate& stereo off.

 

ps . the supercharger with the 1.5 powerhouse pulley or smaller can be removed by a good bit of maneuvering it through the thermostat coolant manifold , with out removing the manifold .
just remove the coolant sensor first so you don't break it on the way past .

the coolant manifold must be removed first if you have a stock pulley .

 

Thanks for explaining the sounds due to solid coupler. I replaced the coupler 1 year ago and now have the sound you described. I was a afraid that the bearings were on their way out. I feel more confident now as I hated the thought having to take the supercharger out again. Maybe I might even upgrade the pulley then. But then again I'm at 130,000 miles without a major rebuild other than oil and coupler.

 

i just had my supercharger off to do the 2 hoses underneath and put on the same green solid coupler and changed the oil....the oil was stinky as you know what, but, no metal and plenty of lubricity left...while i had the snout off i checked for play and found none...after reassembly and start up, i got the same rumbling as described in the thread and was a little alarmed...after doing some spirited driving, i find the boost to be a little more responsive and also the noise goes away at the slightest throttle increase....i also have the upper pulley that requires no machining...after reading this post my concerns are put to rest....my rotor pack has 90 to 95% of the coating intact, so I feel good about that also....I was in a time crunch so bearings will get done in winter when it is not 100F here...I already had the coupler so I put it on....now that I know my way around the removal process, I can do it in less than 3 hours I am sure