blower maintenance

JonS

SCCoA Member
I have a used S port of unknown pedigree. I have a snout rebuild kit at the ready. Before I dig into that, I'd like some advise on what to look for in terms of wear and tear.

The rotors appear to have a bit of wear, but not bad. I could provide a pic or two on that. The whole thing makes a bit of noise when I turn the spindle - I haven't even opened the fill port to check fluid level yet.

I potentially have a stock low-miles 95 blower for donor rotors, but am hesitant to cannibalize that. If I were to, what are the possible pitfalls with clocking, etc.?

I am open to the suggestion of letting a pro do a rebuild, but enjoy doing this myself as time allows.

any words are appreciated
 
I'd grab a set of used GTP rotors and pop them in there. A little searching should help you find more info. You'll have an alignment dowel that needs moved (which is a bigger pain than it sounds! lol)

There shouldn't be any wear on the rotors except on the front/back of the lobes, but no scoring. If there places where you can see that the rotor faces have been touching something, I would just find another set.

Rebuilding the SC snout is fun, I think. :)
 
Rebuilding the SC snout is fun, I think. :)

It looks fun and straight forward enough.

did you use a press for the bearings? I have a home made compression tool (threaded rod, washers, and bolts) I use for race bearings and cups on bikes I was planning to try.

Rotors and alignment scare me
 
It looks fun and straight forward enough.

did you use a press for the bearings? I have a home made compression tool (threaded rod, washers, and bolts) I use for race bearings and cups on bikes I was planning to try.

Rotors and alignment scare me

Both times I've done it, I used the freezer / oven method. I have a shop press now though, and will probably use that next time. I don't know if your compression tool will work for pressing bearings onto the shaft.

Unless you bought a "more advanced than usual" rebuild kit, you won't be taking the rotor pack apart and replacing the front rotor bearings...that's why I mentioned getting a GTP rotor pack that was in good shape.
 
Unless you bought a "more advanced than usual" rebuild kit, you won't be taking the rotor pack apart and replacing the front rotor bearings

you are correct - I only have the snout rebuild kit, oil, seals, bearings, etc.

So I'm asking exactly what you're suggesting - what about the rotors would make me get a new rotor pack or cannibalize my other blower. I'll look into a GTP kit
 
Might want to talk to Charles at MagnumPowers.com if you’re interested in coated rotors. He sells them for our superchargers and sets them up for you if needed, etc. Not sure I would just grab a used pair and toss them in ;)
 
Might want to talk to Charles at http://magnumpowers.com if you’re interested in coated rotors. He sells them for our superchargers and sets them up for you if needed, etc. Not sure I would just grab a used pair and toss them in ;)
 
Might want to talk to Charles at MagnumPowers.com if you’re interested in coated rotors. He sells them for our superchargers and sets them up for you if needed, etc. Not sure I would just grab a used pair and toss them in ;)

I thought the 94/95 rotors where coated from the factory but I could be wrong. If they are coated I was wondering if they are better than those.i have a 95 charger so was just curious
 
I thought the 94/95 rotors where coated from the factory but I could be wrong. If they are coated I was wondering if they are better than those.i have a 95 charger so was just curious

yes, 94/95 rotors are polymer coated, better tolerance, etc. My S-port rotors are coated, and seem to have some flaking starting
 
Magnum Powers makes a brand-new rotor pack with abradive coating...it's a soft coating that really helps seal them up. I have a set and it's awesome. This is the best way to have a completely rebuilt M90 supercharger on the car, as disassembling to replace teh front rotro bearings will require the rotor timing to be set-up. I've read that it requires a specific jig to do it properly, but I'm not sure. It's definitely not usually done by the typical SC gearhead.

89-93 rotors are bare...the 94/95 SC's have a harder (than the abradive) coating...almost like thick paint that can flake off. The GTP's also have a hard coating that can flake off, but is thought to be an improvement over what the 94/95's have.
 
you are correct - I only have the snout rebuild kit, oil, seals, bearings, etc.

So I'm asking exactly what you're suggesting - what about the rotors would make me get a new rotor pack or cannibalize my other blower. I'll look into a GTP kit

I am suggesting that if your current, bare rotor pack has spots where there is wear on the rotors, your front rotor bearings may be getting worn. If you can find a used set without wear marks, you'll likely be better off. Of the GTP and SC supercahrgers I have disassembled (probably about 10-12), most of the rotor surfaces were still in really good shape.
 
To rebuild the supercharger (minus the front rotor bearings) is only $100-$150 or so. I've gotten used rotor packs for $5-$30 at junkyards.

If you want a completely rebuilt supercharger (using MP's rotor pack)...you're talking $800+. Or, MP will rebuild your rotor pack and you do the snout....$600+

That's why you might consider using a good set of used rotors. ;)
 
I've read that it requires a specific jig to do it properly, but I'm not sure. It's definitely not usually done by the typical SC gearhead.

I've seen that jig in operation at Charles' shop - the rotors are installed, then spun up to a certain RPM, for a length of time and monitored for a specific sound frequency. When it hits the right freq., they're done. Seems like a good way to also validate the coating process without having to run on the car first. Pretty cool method, I think.

Ken
 
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Unless you bought a "more advanced than usual" rebuild kit, you won't be taking the rotor pack apart and replacing the front rotor bearings...that's why I mentioned getting a GTP rotor pack that was in good shape.

can you help me with the right rotor pack to look for? Gen ? I'd assume getting the whole blower is most straightforward approach, and then pull the rotor pack out - making sure the rotors turned quietly and the coating was good, right? would any re-clocking be required, or does the pack just go right back in? lastly are the front pins all same size, or is there a certain year / gen I need to look for?

thanks in advance - this is helping me
 
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