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Previous Next Up Topic Engines / Corvair Power / Have mercy on my stupidity... (7477 hits)
By Rick M 333 Date 2011-03-13 02:54 Edited 2011-03-13 19:33
Ok, got my 'Vair motor back together and hooked up to a spare transaxle (less clutch) for starting and testing. I have a conversion unit from Starr, which consisted of a Weiand adapter plate, a 109 tooth converted flywheel and a conversion pinion for the Corvair starter (and adapter block). I also had ordered a high torque, reverse rotation VW starter from Clarks just to have it, figuring it would make a more simple bolt-in unit than the Covair. So... hooked everything up today and tried the Clarks' starter and.... rrriiingggg.... against the flywheel. Hmmm... not thinking forward enough, I saw that the end of the bendix was rubbing against the transaxle section where the starter bushing would go...figuring that what was holding the bendix back from engaging, proceeded to hollow enough out with the appropriate sized bit to clear the end of the shaft. You know where this is going, right? That, of course, wasn't the issue. Starr's kit came with a 109 tooth flywheel. The starter is meant for a 130 tooth, though that isn't make abundantly clear on the Clark site. So... now I've got a reamed hole for a bushing that probably isn't going to hold the bushing, since there isn't much left of the shoulder and a few choice words I've been muttering all night long. I think I may have a couple choices, though none are easy. My first inclination is to make a new mounting plate for the Clarks' starter. It's a generic high-torque starter with a multi-rotation plate on the end held by two bolts. The kicker is it's shaped to fit the VW starter hole so it sits flush, but I'm thinking I might be able to fabricate a simple plate to physically move the starter pinion closer to the ring gear (about 3/16" from what I can determine) so the pinion fully engages. Cons on this? The starter pinion is smaller in diameter than the stock VW or the Weiand, so I don't know if the pitch will match exactly on the ring gear, even though all the pinions are 9 tooth. And, depending on the metal that I make the plate from (I have both aluminum and steel in 1/4", the same as the "ears" of the starter), will the two mounting bolts be able to handle the torque?
  My next option is, of course, to fit the Corvair starter. The Weiand conversion gives you a Bendix with the right pinion gear on it to work with the flywheel. The downside is that the nosecone of the 'Vair starter has to come off and the pinion itself is supported by the bushing in the trans case.... which is now no longer viable. What happens, exactly, to an unsupported bendix? Does it just bind up?
  The next option, and most expensive, is of course to order a new flywheel from Clarks. That would entail removing the current one, held on be red locktight and heavily torqued bolts. Doable, but definately a pain in the butt.
  My last option which I'll explore tomorrow is to measure the shafts of the Clarks' starter, the Weiand conversion pinion and I think I have an old 6 volt VW starter laying about to see if any of them are the same. I'm half hoping that one of them will match the Clark starter - if so, I may be able to have a shop swap pinions out and solve the issue altogether, but I'm not holding out too much hope on that.

  So... faced with the stupidity before you all, what would be your choice(s) of action to follow?

*edit* I just had one of those 'oh crap' moments... all this might just be for nothing anyway - the transaxle is 12 volt; the comversion I bought from Starr is obviously for 6 volt. I can't run the 6v clutch and pressure plate anyway... right?

**edit** I second guessed myself into removing the flywheel and I'll be ordering the correct 130 tooth wheel in the next week or so. After sleeping on it and thinking of all possible solutions, even though it's going to cost, it'll be the right way to do it. Moral? Think ahead! Anyone want or need a 6 volt flywheel, clutch and pressure plate?
By Jeff GS Date 2011-03-14 16:53
I think the 109 tooth/6V set-up used a special "offset" starter bushing that went into the VW trans bushing hole - but had to be aligned correctly with the starter mounted position to work right.  And if I remember from the old 109 tooth modified Corvair starter I had, it did have the nose portion of the starter hacked off, and the pinion shaft then was suported (100%) by the new (offset) bushing in the trans, along with the special adapter piece attached the the starter to trans bolt interface.  You'll have to run a smaller 6V clutch set-up with this flywheel - probably not the best choice for a more powerful Corvair engine?  Maybe also some fiddling with using the right throwout bearing too (6V flywheel/clutch with a 12V trans).  I'm sure it can be done, but have heard mixed reviews about that offset pinion bushing and keeping it located properly in the trans.

I think your switch to a more usable 130 Tooth 12V flywheel is the best choice.  It will offer the use of the larger clutch package, and as you've found out easier to get a starter for.  Then you can run the high torque starter and not worry about the bushing hole (just plug it up).  I'd do some test fitting with starter in the trans first - before installing the engine.  Be sure the starter pinion engages the correct amount for your flywheel teeth.
Jeff
By Rick M 333 Date 2011-03-14 18:30
Good point on checking the tooth mesh, Jeff. I would have just thrown the flywheel on the engine and called it good... I hope to be able to order that shortly. $300 is a little scarce the moment!

I really need to get a weekend and come down to see your car... Maryland isn't that big :-)
By Jeff GS Date 2011-03-14 21:00
Hey Rick - you might also check with Kennedy Engineering.  I'm sure they offer a 'Vair to VW flywheel (likely where Clarks gets theirs).  Besides that, ebay is always a good soruce for used adapter kits and parts - could save a little on the flywheel cost?
I guess you could also put the 130T ring gear on your 109T flywheel?  You might double check the clutch size, for all I know the 6V adapter flywheel may actually take the larger flywheel clutch package?  I'm fairly sure Kennedy has the replacement ring gears available (in both sizes), just have to find a shop to machine the old one off and put a new one on.  I think it might even just be shrunk-fit ontot he flywheel?

Jeff
By Jeff GS Date 2011-03-14 21:36 Edited 2011-03-14 21:51
I looked up my old Kennedy literature.  The most common flywheel other than the 130 tooth version was the 127 tooth model.  Yea, just a few teeth less.  IIRC, the 127 tooth model was typically used with the normal Corvair rotation - feeding backwards into the VW transaxle compared to a normal VW engine.  This is the one I remember that took the modified Corvair starter and adapter bits and bushings (not a 109 tooth like I thought in the above post).
The 130 tooth flywheel was the standard "reverse rotation" set-up, using the standard VW starter, 200mm clutch etc.
I believe Bob E. found that a Porsche 928 starter worked great to crank up his "normal" Corvair rotation engine in his Deserter (ie: backwards from the VW rotation), but I'll have to check with him about that. Not sure what tooth flywheel he is using, but I can find out if you want?  It "might" save you from having to get a new flywheel (or change ring gears)?

I'm not too familiar with the 109 tooth flywheel in Corvair applications?  I'll see what I can dig up.
Jeff
By Rick M 333 Date 2011-03-14 21:59
I think, according to Starr, was that the flywheel I have currently is a "converted" or milled 109 VW unit - the ring gear is part of the wheel. It may also have been a special part manufactured by Weiand for a conversion kit - eveything that I bought is/was all part of the same kit. I'm fine with purchasing a new flywheel. After much brain racking I'm convinced it's going to be the better choice, since it'll give me more clutch options. I have a clutch and pressure plate here on another engine I can steal, so that's money saved there!

On a related note, but not for the same car, is there some sort of chart that you've ever come across that relates tooth count on a ring gear to the starter pinion tooth count?
Previous Next Up Topic Engines / Corvair Power / Have mercy on my stupidity... (7477 hits)

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