sn89 failure and sn2000 problems. rebuild vs new brand of blower

**88t.birdsc** · 07-21-2007, 05:23 PM

Unfortunately, I haven't had much luck with the Paxton ball bearing type superchargers. Each was run with the 6" crank pulley and 4.25 blower pulley(Factory sizes?). The sn2000 was bought new and the sn89 used. The sn2000 was taken up to 6000+ rpm but only on breif occassion. I don't even think it has 1000 miles on it. When 1st installing the sn2000 it would produce 1 psi per 1k rpm, from what I've been told is normal for these blowers. It's performance now is 3 psi @ 5-6k rpm. Thinking the blower was begining to fail I installed the used "rebuilt" sn89. This pulley wasn't as tight as the sn2000 and didn't bind. After putting 10+ miles on it with 2-3 hard runs, boost never went over 2 psi. I began to think belt slip on both and was going to install a cog set up that was lying around just to eliminate that. However the sn89 pulley was now binding and had to be opened up. These blowers are supposedly easy to rebuild but I could not find any spec sheets on them. I definately don't want to just "throw it together" Maybe this style blower is wrong for me because of the hard use, but imho it should stay together longer than that. If oil/cooler lines have to be plummed into the charger, special belts, constant oil changes, and opening them up to tweak or rebuild, maybe it's time to look for another more reliable charger. If you could point me in the right direction, I would appreciate it.
Speedy, to me the a trim looks alot better than these. What do you think?

**F=MA** · 07-21-2007, 06:31 PM

I don't know what to tell you, man. I've beaten mine hard at the track dozens of times since I cheapy rebuilt it with new races and I have no trouble making rated boost and power levels. I'm throwing shifts at about 5800 rpm. Hell, the things had the throttel stick open twice and banged off the limiter for a few seconds, all w/o injury.

Thsi blower has been dead nuts simple to operate and rebuild, for me, at least.

F=MA

**88t.birdsc** · 07-21-2007, 08:49 PM

Originally Posted by F=MA

.

Thsi blower has been dead nuts simple to operate and rebuild, for me, at least.

F=MA

F=MA, would you happen to have an overhaul manual? It seems as if the impeller hit the vollute, but only on 1 side. Maybe the impeller is bent. It doesn't look like the fin's webbing were machined correctly, unfortunately I know nothing about these. I do have some mechanical ablility and appreciate the help :happy:

***speedytang*** · 07-21-2007, 10:09 PM

Your problem would either be bad impeller shaft or the balls are not round and causing the unit to wobble around the impeller shaft. A-Trim is a good unit but never built as much power as the 'SN' unit stock for stock.

**88t.birdsc** · 07-21-2007, 10:44 PM

Will the scoring on the case keep this unit from working properly if new balls and impeller shaft are replaced?
Thanks

***speedytang*** · 07-21-2007, 11:07 PM

Nope, If you want emery cloth and sand it down and it will be as good as new but a little ported. LOL

**88t.birdsc** · 07-21-2007, 11:17 PM

Cool,
Is there any way to check the run out on the impeller shaft? I'm assuming the balls could be checked with a mic.

**pavement pounde** · 07-22-2007, 03:39 AM

If in doubt I would replace the balls, they are not pricy.
I have some pic's and instal diagram here: http://smg.photobucket.com/albums/v1...ton%20rebuild/
That could be usefull.
The biggest importance is the have the correct ball tension and proper distance shims between the impellor and the back side of the blower.
I have beaten my SN 93 and later the VR4 very much and no problems with mine exept for my own stupidety.

**88t.birdsc** · 07-22-2007, 04:27 AM

That indeed is a big help. Many thanks for the pics! I should then change the balls and shim the impeller futher out. Does the impeller definately need to be changed? The ones you have seem to be of better quality.
Thanks again!