Differences in McCulloch & Paxton Superchargers
Other than the drive system, the nameplate and the carb. boxes, what were the other differences between the units used in '57 & '58 to the units used in '63 & '64? Thanks, Dan
The "nose" of the VS-57 output shaft pilots in a bushing in the end of the input shaft. All the lube going to the ball drive goes through there. The SN-60 output shaft ends before it gets to the input shaft, ( the real meaning of "short nose"?). There's a restrictive bushing in the end of the input shaft, to control oil flow.
There's a table of part #'s @
http://vs57.y-block.info/indextech.htm . See "Parts Interchange", "VS-57/SN".
Jim's idea of "parts interchange" was a little different from my intention to list "what it came with"; but, I think what he published is excellent!
Mounts and pulleys, all the installation parts, are different.
Last edited by Mike; 02-15-2012 at 07:29 PM.
The VS in the VS57's is for "variable speed". The front pulley sheaves are able to separate and change the drive ratio. (Much like a snowmobile drive).
This was operated by an electric solenoid under the name plate, and a kick down switch hooked to the throttle.
Avanti Paxtons, used two narrower belts, rather than the wider ones on the McCulloch and Lark and Hawk Paxtons.
Some McCullochs had fiber spacers under the drive races.
Later Paxtons had a different rear seal, rather than the piston ring type.
Having the handle SN-60, I had to put My two cents in! The Granatelli Brothers noticed in testing that the critical 'drive element' would be starved of lubricant at high RPM due to the piston in the internal oil pump
floating. They supposedly came up with an improved piston and heavier return spring to help rectify this situation. In truth, The SN Paxtons probably burnt up as frequently as the earlier VS McCullochs did.
It may seem odd that I didn't mention the variable ratio pulley on the VS-57. Of course it's the most significant difference between the VS-57 and SN-60. I'd call that the "drive system"; and Dan asked about differences other than that.
In the chart I mentioned above, the '57 & '58 Golden Hawk is "VS57S". "Avanti SN" superchargers actually had serial #'s beginning with ML although Studebaker referred to them as type SN.
VS-57A & B, (Kaiser), had fiber discs behind the ball drive races. The races weren't pinned to keep them from rotating. McCulloch used clutch terminology in referring to some of these parts. Their patent papers explain that the races are supposed to rotate in the housing to keep the ball drive from being over stressed if it's driven too fast. An early SAE paper says they never had an output shaft fail in testing! The C version, which was sold in kits, and Stude's S version had pinned races. Depending on what races are used, they may have steel shims behind them.
As you can see in the chart, part #'s for the oil pump and it's individual components are the same for all units shown. Illustrations in the McCulloch service manual, which seems to be written for Kaiser, show a pump with the pickup offset to the rear, opposite of how part # 37055B is made. Maybe the very early version was 37309, and the offset was the difference.
It's possible Paxton/McCulloch didn't always change the part # when they redesigned a part, or that the parts lists we used to make the chart showed only the latest version of each part when the list was printed. Sources for the part #'s, and their dates of publication are listed after the footnotes.
Stude may have also substituted upgraded parts under an existing part #. Lots of folks have told me they got German ball drive parts from Stude, although the engineering drawing specifies the lower quality American parts. The chart shows drive balls and races the same for both Stude superchargers. Maybe that reflects what they supplied in Jan. '61 for the VS-57S, and Dec. '63 for the Avanti. It would be interesting to see if the #'s for the VS-57S parts are the same on a parts list from 1957.
Last edited by Mike; 02-16-2012 at 02:12 AM.
I worked on an R2 Avanti with an early SN-60 supercharger, however, it still has the McCulloch badge over the non functioning solenoid hole. The output shaft was still the long type that centered in the drive element.
The supercharger for the R3 I restored, was rebuilt with a new bronze ball driver, and new larger piston oil pump. These are upgrades that help longevity. Any damage to the impeller, even if it is just corrosion, or a very slight nick, should be cause to throw it away.
It can spin up to 50,000 rpm, so any unbalance will create destructive forces. Early blowers has magnesium impellers, and new ones are aluminum.
Thanks guys, and is it safe to assume maximum boost to be similar and would that be about 5 PSI above normal (normal varrying with elevation) ? Appreciate your responses, Dan
Early SN-60's still used the solenoid cover with about 33% of it sliced off (a bit crude looking). Anyone ever see an SN-60 that spun in the opposite direction made for, I think, Chevy Corvair installations?
I had been planning to photo shop a reverse scroll as an April Fool's joke, claiming it was for use in the Southern Hemisphere; when Jim Moody sent me an article about an early version of the Corvair supercharger kit, that used a reverse rotation Paxton SN-60.
I thought the supercharger was originally intended for boats with a reverse rotating engine. If it was already on the shelf, it was a natural for the Corvair, when it came along. I think all parts were standard, except the scroll curved the other way. I'm sure I still have the article somewhere, there are pictures. I've never seen anything about a reverse rotation Paxton anywhere else.
It was one of about three different ways of installing a Paxton on a Corvair. I think the kit with a reverse rotation supercharger was just a prototype. Most of the kits sold used a standard supercharger mounted at a slight angle to the engine, and driven by a belt twisted into a figure eight. The mount was spring loaded, to control belt tension.
SN-60, All Corvair applications were Turbos, and If I'm not mistaken, were similar if not identical, to the units used by Oldsmobile in '62 & '6 on their 215ci, aluminum V/8, in their Jetfire. That application utilized an unorthodox alcohol/water injection systyem. Dan
The stock Corvair Spyders were turbocharged. I was talking about aftermarket Paxton kits. Here's one with the standard SN-60:
Mikee, sorry, you're way ahead of me there> Dan
Originally Posted by CarCrosswordDan
The Corvair and the Olds Jetfire turbos were similar, but not the same. Interestingly, the Corvair, with the smaller engine, used a larger turbo than the turbo used on the larger Olds F-85 Jetfire engine. The Olds used the alcohol/water injection system, the Corvair did not.
Don, thanks. Yes, that's what I meant about the Olds using the injection mix. It is very interesting that the output was larger on the Corvair than the Olds. Do you think they expected the Olds to turn tighter, or what? Dan
To: Don Jeffers,-------Alchol/water injection??? No No No----- According to Oldsmobile it was.................. TURBO ROCKET FLUID!!!!!