extending a SC shaft? bearing mounts?

[sassyness77]

Hello was debating on an interesting project here, looking for some help on a couple questions.
Also, this isn't a debate on turbo or SC, i,m determined to adapt a SC. And i know its been disscussed but I'm trying to basically replicate the m62 kit for the grand am, it just seems to be an extended shaft with a mount. The castings for the intake aren't an issue.


Using an m90 SC.
Looking to extend the shaft about 15", i found a write up on how someone extended the shaft of one using a solid rod with threading.

The original SC shaft was modified, removed the pully and threaded about 4" down (the snout was also modified). Then another steel rod/shaft was threaded inside and the two were screwed together the opposite direction of how they would spin to ensure they wouldn't loosen. And there were mounts made to keep everything straight. Does this even sound safe to you guys? I have a friend with serious equipment, just seeing if its safe before beginning.

Also building the extra bearing mounts to hold the extended shaft in place seems tricky. Where can i find bearings that would be safe at those speeds? Could i simply use another snout from an m90 for the mount, or at least parts of the snout? I have multiple SC'S here just collecting dust.

Looking for a little help from you guys before starting something crazy, which hopefully will work.

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[neophile_17]

You should have no problem finding a bearing that can do 15,000RPM which is more than what that shaft will see. I'd probably look for a way to extend the shaft by cutting splines rather than threads but that may work as well. If you're worried about alignment you could use a Lovejoy but you'll then need 2 bearings to support the shaft extension.

Or you could do what this enterprising Lemons Racer did. What could posibly go wrong?

http://a3.sphotos.ak.fbcdn.net/photo...82_1349929.jpg

Good Luck.

~sam

[NateD4]

On your bearing question... there are many many sources of bearings. And also many types. I'm guessing you could get away with a regular ball bearing or possibly even a sealed needle bearing.

A few manufacturers to look into:
Timken/Fafnir
SKF
Dodge
NSK

You can find these bearing companies online and probably locally. There are a ton of bearing to choose from. What you'll need to have an idea on is the operating temperature, speed and forces you'll be putting on.

there is a conversion for HP to torque and then from torque to force. Torque = (5252*HP)/RPM.

That will give you torque in ft*lbs at a given shaft speed. From there you convert ft*lbs into inch*lbs such that: Inch*Lbs = Ft*Lbs *12.

Once you have this you divide the torque by your average drive pulley radius and you'll get a force. This force is approximately the force the bearing needs to handle.

I would then multiply by at least 1.5 as a safety factor.

If you go with ball bearings you'll probably want an ABEC 3 or 5 bearing. This is a tolerance ratio, the higher the number the more tightly the bearings fit... which is good until they get hot.

In all honesty all the stuff above is explained in most bearing engineering catalogs... however this is the simple version that'll get you close as long as you have the HP curve for the super charger.

There are additional factors like service life and oil/grease temperatures that effect bearing life but you can always over size.

Another good source for bearings is McMaster Carr. You can mail order almost to spec.


As to your shaft questions. There's nothing wrong with threading if it is done right and rotation is in the tightening direction... however, you really should cross drill for a pin. When you let off the throttle there is a minute chance the momentum (inertia technically) will reverse load the torque converter and could unthread the shaft.

There are a few other options all of which have a register fit (smiler to a dowel pin, where one part is cut to an exact size and the other is cut with a mating hole that is almost the same diameter as the other).

One route is to pin the joint with 2-3 pins (vary their orientation by 90 degrees and space them at least 2-3 diameters apart).

You could use a press on fit.

Or as mentioned before a shaft coupling, however you'll need to make sure you have the right bearings in the support end near the pulley.



As a last comment, any mechanical system with rotating parts requires a proper alignment for optimal life and to avoid vibration. I'd have a shop do an alignment heck when it is all assembled.



Just my thoughts. Feel free to interject other thoughts.

[kwhauck]

Just do it right and be done with it, they do any custom length up to 20" I just talked to a product manager a couple months ago for my personal project.

http://www.magnusonproducts.com/drives.htm

[onefastV6]

You coule always try something like this

[sassyness77]

i did send an email to the company, have to make a call tomorrow but im thinking the price will be very high, and i have the ability to make it myself. Also what is that picture of exactly, do you mean just extend the ducting from the SC instead of making a longer shaft? Because i dont believe i can squeeze it anywhere closer in the grand am engine bay.

[sassyness77]

Also is there enough room after removing the pulley to safley cut splines into the original shaft to add a longer extension? I'm just not sure how much of the shaft there is to work with after the snout housing. It would be easy to just remove pulley, cut splines, add extension and be able to use all the original snout and bearings. I'd only need one extra bearing mount which i'm hoping to just use from another snout cut down. Between the 2 bearings at the greatest distance apart should only be 12". That should be solid and everything will be mounted to the engine

[kwhauck]

i did send an email to the company, have to make a call tomorrow but im thinking the price will be very high, and i have the ability to make it myself. Also what is that picture of exactly, do you mean just extend the ducting from the SC instead of making a longer shaft? Because i dont believe i can squeeze it anywhere closer in the grand am engine bay.

When i talked to them it was between $400-$500 which was completely reasonable to me. I am also replicating and m62 kit. I used to have one but knew the m62 wasn't gonna get me enough power. I don't understand why you are going to keep messing around with a crappy m90 when you could get a much better supercharger. If you are going custom you should make it worth your while.

Also when I measured the kit it was 13.9 in for the shaft. Also I have a copy with all the measurments of the mount that hold those type of shafts if you are interested....

[sassyness77]

This is more for me and the interest of making it work, im not after a ton of power, and that is a very good price! Yes i would be very interested in the info on mounts and anything else you have. Its a little project car and I'm trying more intense projects on it after this which sound rediculous to everyone else. I keep those ideas to myself. But $500 for a new shaft is a great deal, is there any sort of warrant or anhthing along those lines?

[JerryRigg]

Here's what the V6 Ford Probe guys have been doing for superchargers:









They run a countershaft across the front of the motor supported by bearings, with pullies on either side. Should be easy for a machine shop to make if you can't do it yourself. Just some ideas