SC12 Overhaul ...

Re: SC12 Overhaul ... (worldwalker)

Wed, 27 Nov 2013 19:08:42 GMT

Looking forward to your bearing outcome. After finally getting my AW11 finished and restored back to factory (bar the pulley upgrade and manual conversion) the only problem I have is the SC bearings. I have a spare SC I haven't bothered to try but I'll be looking into that next and replacing the bearings on the current SCer once the spare is fitted.

Re: SC12 Overhaul ... (Knightrous)

Wed, 27 Nov 2013 16:25:38 GMT

maj
Wait for knightrous to have more time so he can CAD up a replacement housing for the bearings ;)

Here is one I did earlier...

Re: SC12 Overhaul ... (ozhummer)

Wed, 27 Nov 2013 14:54:17 GMT

No Need to cad up the housing - just need to open them up to 47mm. I have the replacement bearings now - Stainless steel fully sealed, working speed is up to 40,000 RPM - these are high quality units and are so close to std for size.

If I can get the housing 'eased' out I will get it together this weekend and fab a test bench using a spare induction motor.

I'll try to post the results this weekend ...

Re: SC12 Overhaul ... (maj)

Wed, 27 Nov 2013 14:47:45 GMT

Wait for knightrous to have more time so he can CAD up a replacement housing for the bearings ;)

Would be interesting if we could get a few units to trial to see if you can make the bearings more serviceable, run them on a machine to see if they last and don't produce excess vibration etc. Then deal with recoating teflon surfaces.

Re: SC12 Overhaul ... (Fab4mr2)

Wed, 27 Nov 2013 14:02:59 GMT

Lots of great information. Being able to make them last even for just another 10 years, or so, as you stated would not be bad at all. If you can actually get this accomplished for anywhere near $100 I think it would be a great deal. I also think the guy on MR2oc.com probably expected it to come out much higher in order to replace the bearings, plus he didn't even figure on trying to treat the lobes at all. The 3M material really sounds interesting.

Re: SC12 Overhaul ... (ozhummer)

Wed, 27 Nov 2013 13:02:36 GMT

Epoxy is clever, but I'm planning on getting a rebate cut in the housing so a retaining surclip can be used - similar to the idler bearings (which spin faster too).. The bearings are considerably narrower so there is room for this.
Ironically the rear bearings are in most cases ok - they have very little load and run completely sealed with the high quality gear lubrication which also acts as a coolant- I think they may be an everlasting item. The main load bearing is also the smallest - it runs dry and has little protection from dirt. This one and the one next to it (this has petrolium based lub - or it did when it left the factory) die, so are the ones I'm looking to replace.

As for teflon coating - if you takes out the rotors and look at the lobes you will see that they are scrapped and worn. 3M have an awsome teflon product that is almost DIY - One big problem with teflon is you are trying to get something that doesn't stick to anything, to stick to the rotor .. The 3M product contains an adhesive agent to you dont need to bead blast the primary surface .. It may be possible to lightly sand the lobe ends, apply the coating and seal it in a domestic oven (slowly to temp and slowly cooled, must be fan forced to create an even temp) - I also have a selection of computer controlled IR ovens used for the manufacture of SMT PCBS - with these I can create a heat/time profile. Teflon bakes at about 250 degrees so not too hot!

I don't think we will be able to completely rebuilt the SC12 back to factory spec, but if we can do it enough to get another 10 years (maybe with a loss of half a psi) and for less than $100 then I think we all would be happy with that!...

The other possibility is to source an equivalent spec SC .. I see Rotrex (They make awesome SC units) have just released a little one that is clutch operated - identical to our SC12 - If the volumetric/rpm characteristics are similar to the SC12 then it would be simple to fit it as they are the size of a small alternator.

Re: SC12 Overhaul ... (Knightrous)

Wed, 27 Nov 2013 12:37:14 GMT

If you get some machine work done, I'd look into a new way of retaining the bearings to avoid the whole epoxy injection method.

Re: SC12 Overhaul ... (ozhummer)

Wed, 27 Nov 2013 10:28:43 GMT

I've found bearings that may work.. they are 2mm larger than the oem (OD), ID is 17 so the shaft size will not need to alter .. I'm having issues finding a machine shop who has accurate enough machinery to CNC the housing .. the tolerance is very small 0.01mm max!

Re: SC12 Overhaul ... (spike10000)

Wed, 27 Nov 2013 10:03:06 GMT

David, you need to show us this 89 one day!! " />

Were the case bearings legitimately expensive, or only deemed expensive in the eyes of the commonplace AW11 owner?

Re: SC12 Overhaul ... (Fab4mr2)

Wed, 27 Nov 2013 09:54:41 GMT

Really looking forward to hearing more on this proposed project. There is someone on MR2oc.com doing some SC12 rebuild work as well, but they gave up on trying to do the case bearings as being too expensive. They do however, do some nice work on the pulley's and the pulley bearings. You might want to look at what they are doing on those parts to see if you can incorporate that into your work as well. If the case bearings can be done though I might look for a second hand SC12, pull it apart, and ship the necessary parts to have your work done, if the shipping doesn't kill me, lol. Would be worth it, to me, to have a near perfect SC12 in the '89 SC I have otherwise restored.

Re: SC12 Overhaul ... (Knightrous)

Tue, 19 Nov 2013 12:42:01 GMT

I've an SC12 in pieces, not sure how good they are, but they came with the SC14 I bought. PM if your interested :)

Re: SC12 Overhaul ... (ozhummer)

Tue, 19 Nov 2013 12:35:14 GMT

Anyone willing to part with an SC12 ? - I need another for parts ?

Re: SC12 Overhaul ... (ozhummer)

Tue, 19 Nov 2013 12:33:47 GMT

Good post - Having gone the rotrex route and seen boost in the vicinity of 26PSI, I've decided to go back to period specific for the car. Shannons insurance de-valued the car and after a lengthy chat with them they agreed that I could re-value if the car was totally stock and 100% perfect. That's my challenge now, hence the rebuild of the SC12.

Re: SC12 Overhaul ... (Knightrous)

Tue, 19 Nov 2013 12:28:48 GMT

spike10000
I will be watching with interest too as I have a couple of SC12's stashed away which I would like to rebuild as spares. Have you already found someone who is able to recoat the lobes?

dennis the menace
A quick thought off the top of my head . . . is it going to work out cheaper per unit to do a run of lobe re-coating? There may be a few more SC owners out there who could be in for a group effort on this project.

Jon Bond Performance does re-coatings for the Eaton range of superchargers, might be worth contacting them to see if they could also do the SC1x's

Re: SC12 Overhaul ... (Knightrous)

Tue, 19 Nov 2013 12:24:38 GMT

Hoping to contribute a bit of food for thought via a bit of thread derailment... If your just wanting to rebuild the SC12 to keep the car period correct and not chasing more performance, you can probably ignore the rest of this post :D

I looked at similar ideas of fixing up the SC14 superchargers (like how hard is it to get some bearings to fit and do a little machine work???), but decided to go with a better super charger since spinning the SC12/SC14 any faster brings diminished returns as it just converts crank HP into fire (I believe the rotors expand under extra the heat and this leads to the teflon chewing itself off against the casing). I ended up deciding on the Eaton M62 supercharger, which can be had for a couple of hundred on ebay. The M62 is a 1L/Rev, has a recommended max rpm of 14000rpm and has been proven to run on a large amount of motors from 1.6L to 4L with varing boost pressures.

The reasons I like the Eaton besides them being cheap, is the fact they are completely rebuild-able, they have many configurations (used on many factory cars), it has a factory by-pass valve, and you can still buy parts brand new for them. All the bearings, rotors, snouts, couplers, pullies, all serviceable! Check out the range of parts available from Jon Bond Performance (JBP) - https://jonbondperformance.com/

For the eventual restoration of my SC AW11, I bought an M62 from a Buick for $300.

In comparison to my SC14

Now, as you see, it is too long to fit where the stock SC12 goes, however JBP have a 2.5" long snout drive that will fit the M62.

I can either cut down the rear inlet of the Buick M63 housing or swap over to a Nissan X-Terra/Frontier M62 case.

Alternatively, you could fork out the cash for Mercedes M62 which is a more compact unit and has an electric clutch on it. However these go between $800 - $1600 on ebay.

With either shortened down M62, it should fit quite happily along the side of the 4A block