So I took my supercharger out since I had the clunk. I took the front nose off and saw that the coupler was stock, I took the coupler off and spun it it by hand and I still get a clunk, so its either the front or rear bearings, i know the rears are a PITA but the fronts are easier, however, how do I get to the fronts? All I see are the (2) gears. Also, is my pulley supposed to have a bolt securing it or a plastic cap? I want to say the supercharger was never rebuilt considering old coupler but I did see some etched numbers on the gears, "5.0" maybe or "50", cant really make out what it says, also have some numbers with a permanent black marker on the nose cover. Here is pretty much what the blower looks like currently.

 

Rolling Performance Home

 

yea, i saw that video which made me realize that the rears are a PITA but how about the front bearings? does the whole thing come off? btw, what is this part called and can I reuse that black gasket that goes between that and the blower in the rear?

 

OK, so I bought a replacement blower, the pics of the left blower is my old one that made the clunk and the right blower is the other one I bought, which makes NO clunks, however, why does my old blower have brown blades while the new one I got has clean bare metal blades? Does that mean that the new blower was rebuilt at one point and my old one was never rebuilt? Also, what are the numbers on the gears, my old says "50" while the new one says #47" and I also noticed that my old blower's stock coupler is slightly bigger than the stock coupler on the newer one I bought, is that normal? TIA

 

Rotors should be coated. (brown)

As the rotor bearings wear, the rotors start to touch the case and each other and the coating is knocked off. The supercharger with the shiny rotors with lumps of dirt/sludge on them has very badly worn bearings. It doesn't knock because the squishy dirt on the rotors is dragging/holding them apart.

The one with brown rotors has worn bearings, but not as badly worn. There are three sets inside. "Snout" bearings are in the front driveshaft part and they control axial and raidal play. (end to end and sideways shaft movement) These commonly wear and need replacing. The rear rotors bearing are needle rollers and control radial play. These commonly wear and need replacing. (telltale is the coating rubbing off the rotors, or the rotors rubbing on the sides of the supercharger case) The front rotor bearings are ball bearings and these control radial and axial play. These are less prone to wear. (telltale is the rotors rubbing on the ends of the supercharger case)

Snouts are easy to swap. Rear rotor needle bearings are not too tricky but need care. Front rotor ball bearings are a pain in the bum to change. You need to pull the gears off the rotor shafts with a puller, then press the rotor shafts out of the bearings. You then have the "front bearing carrier plate" with two ball bearings in it. These are pressed into position at the factory, and then the bearing carrier plate is peened (bent) over to hold them in place. You have to grind this peened part off, press the bearings out, press new bearings in, then TIG weld on some bearing retaining rings to replace the peened over bit. Then it's time to press the rotors back in. These need to be pressed in a certain distance from the bearing carrier plate (there's a small gap between the rotor and the bearing plate). Finally, you need to time the rotors and press the gears back on. Timing the rotors is like "meshing" gears; those rotors should never touch each other/there should be a precise gap between them. You need to maintain this gap as you press the gears on and check it again afterwards.

Cheap "rebuilt" superchargers only have the snout bearings and the rear bearings replaced. Properly rebuilt superchargers get the front bearings too, ad these are substantially more expensive.

I wouldn't fit the "shiny" supercharger - that one is scrap. I might replace the snout bearings and the rear needle bearings on the "brown" superchargers. Parts are available from DaRossi. What I'd probably do is buy a supercharger from a low mileage wrecked X350 and fit that. The "generation V" supercharger from those vehicles will fit the X308 with only minor mods - search avos' posts.

 

Great explanation of some of the finer points!

 

I pretty much told the seller what you said about the coating and this is what he said in quote:

" The Teflon coating that covers the rotors peels over time because of the heat, not because of the rotors impacting one another, if you are concerned about any pieces falling off, I would recommend removing and stripping all of the coating off, I would not re coat them as any performance gain would be negligible.

I checked the snout bearings and coupler before it left, and they felt good, I did not feel any grinding in the bearings, or excessive play in the coupler, having said that, I did not extensively check the needle bearings at the back of the supercharger, so cannot comment on the condition of those.

The supercharger was removed from a running engine, and functioned as it should on that engine."

Thoughts on what he said?

 

Finally someone who gives accurate info. After buying a fancy puller to remove the rear needle-races I found that they are dead easy to remove because they are not in a blind hole. The video in this post is not for the correct SC. Mine is a 2002 XJR. All you need is a socket and a hammer to drive out the old bearings at the rear and I will be using a G clamp to push in the new ones. A lot of misleading info floating about as usual !

The two round items in the photo of the rear outside are the rear bearings. Type number is FC65477.

 

@ newbie phlemes -

Generally the needle bearings at the back don't need changing, they're high grade and not cheap for what they are, any old thing won't do as you know these spin at double engine speed. Better to repack with Easton's high temp grease or use the correct spec'.

as you said easy to remove, but to replace front bearings isn't as easy. Have you refreshed them also?

I like the 'misleading info as usual' comment - the forum supplies free information, some outstanding, that's saved untold dollars to it's members. You take what you need from this site, and thank the members that helped, not pour scorn on it. I don't see your right up on this job to add value to this thread...or thanks, just saying.

 

Mine were the source of the noise, one was worn very badly. $20 for the pair, same as OEM, very reasonable I thought. Front bearings were fine.

This was meant as a comment about the Internet generally - you do have to sift the information carefully as there are a lot of people who post misleading info which is worse than no info. My comments were designed to help the next person. You seem to know a lot about these superchargers and it would have been really helpful to me if you had commented on the video to the effect that a blind bearing remover was not needed with the version fitted to the Jaguar.