I am new to the forum. I have been reading the posts for a while.

I have a question about rebuilding a '92 SC. First some history. The SC was rattling and so about six or seven months ago, while replacing the water pump, I pulled the nose off and replaced the coupler with a ZZP coupler. The noise went away, until this week.

The rattling is back but much worse (very loud like a diesel when idling). The rattle does go away when I accelerate though. When I checked the pulley for any "play" there is none. I did notice that when I turn the drive shaft back and forth, there is a clink which sounds like two metal pieces coming together. The engine has also been starting and stoping kind of rough lately (much like in another post on here).

Anyway, I took the SC off last night and pulled it apart. I checked the coupler closer and it seems fine. There is no noticeble wear or wobble. I don't feel any grinding in the nose gears, but I planned on replacing them and the coupler anyway. The rotors appear to turn freely, but I notice that one seems to have more wobble (back and forth play) than the other. My concern is that this is the problem. So my plan was to replace all of the rotor bearings also, which brings me to the questions I have. Does anyone have experience in this? I was going to have a machine shop press the gears and bearings on and off, but are there special things I need to know? I am concerned about rotor interference, clearences, etc. Can anyone give me some good insight? Thanks.

Have you checked the harmonic balancer?

No. What do I need to look for? The rattle appeared to be coming from the SC.

Harmonic balancers usually feel like a skip in the motor or like bad bearing in the bottom end.

Sounds like you have thoroughly diagnosed it to be the supercharger. Willwren has a post you can search for in here about rebuilding a 93. Probably very similar. He'* currently at West Coast Bonne Fest...but send him a message..

I'm sure he'd be happy to discuss with you.

OK, checked the harmonic balancer, or what I could see and feel. It looks OK, doesn't feel loose, no cracked rubber, etc.

Also looked closer at the SC since I have it in pieces at the moment. A couple more things I have noticed. The outer drive shaft bearing (nose piece) has a rough spot as I spin it. The inner bearing is smooth, but if I replace one I will replace both. The rotor, with the coupler, has been rubbing on the mounting plate. This is evidenced by the scrape marks (not deep,but noticeble), whereas the other has no such marks. There is no grinding noise from the rotors and as far as I can tell the bearings are smooth. There seems to be some slop between the rotors, but never having one apart before, I don't know what is normal. Is it possible that grease or replacing the back needle bearings might clear up the slop problems? It sounds like the snout bearings are in need of replacement. The coupler looks good. I don't want to have to pay $500 for a rebuild if I can replace the afore mentioned bearings for $60 and be done. Any other thoughts would be appreciated!

Willwren is at WCBF and probably has not had a chance to see your thread yet. Meanwhile here'* a link to his thread on his rebuild.

Do me a favor, neighbor. With the drive belts on the car, pull on one. Do you see the crank pulley/Harmonic/dampener move at all? If yes, remove the SC belt, and start the car. Still hear the clank? (Don't do this on a warm engine, do it cold, and not for long, because that'* your water pump belt also).

It still sounds very much like a Harmonic to me. I have the same problem on my 95, and I'm replacing it today.

If it is the SC, it would indicate that the bearings are shot, allowing something to hit, but it might also mean that if it'* been doing this, the SC may not be worth rebuilding. Replacement rotors and gears cannot be purchased.

I'll also warn you that doing a FULL rebuild on the SC is possible, but a real challenge. You really have to know your ****, and you'll need specialty pullers and hydraulic presses. Ultimately, for most owners, www.canadiansupercharger.com may be the best option, but let'* rule out that crank pulley first. Your hard starts are pointing this direction. The interruptor rings that tell your crank sensor when to fire your ignition and fuel pulses is on the crank pulley.

I totally agree with Willwren. I went through the same exercise and it was the harmonic balancer.

I pulled on the belt but didn't see anything move, as far as I could tell. The supercharger is off the car and in pieces. I am going to put it back together and put it back on the car tomorrow, so I can test the damper as you have suggested (by starting the car for a minute or less). I'll let you know what I find out.

Well I put the SC back on the car and started it. Guess what! Without the belt on the SC the sound was still there. It sounds like you all are right, again. I ordered the balancer. Thanks for your help! I'll keep posted if anything else comes up.