Hello,
I built a 406 sb last year and only got about 200 miles on it before the new Mini starter went out on it and it had to go into storage. So then I put a Brand new AC Delco Factory Mini Starter on it Over the winter and now this Mini Starter Shaved a couple of Teeth off of the Fly Wheel with about 10 starts on it. I talked to A Mechanic friend of mine and he said that I may need to go with a Gear Reduction Starter built for higher Compression. I Never ran across this problem before so I'm leaning that direction.
My question to you is this, Is there any other Variable that I should be looking into. I don't want to spend an other couple of Hundred dollars only to do this again.
The Flywheel that is on it right now is a "SCAT" externally Balanced 400sb wheel. It is missing some teeth now so it is SCRAP. I have the original flywheel and am going to put that back in it since it is in perfect shape. My engine has a compression ratio of almost 11:1. and I have Ceramic coated Headers.
My plans are to replace the Flywheel with the Original, buy a Reduced Gear Starter for compressions higher then mine, and I know that my starter is an "Offset" bolt pattern but my friend said that we can convert to a "Straight" bolt pattern. He said that this is how he sets up his track cars and has no problems. IF you have any ideas, please let me know.

A gear reduction starter will help, but what size cable is run to the starter? If it has low voltage the engine could be kicking back against the starter causing broken teeth.

I'm not sure what guage wire is under there. I replaced them last year but can't think of the gauge I replaced them with. I will check, thanks.

do you have a flywheel or a flexplate? you can change the ring gear on a flywheel.

I've never seen a mini-starter that wasn't a gear reduction type?

You want fat battery cables, positive and negative. 0 or 00. aught or double aught.

RIght. I know that they are one or the other( 0 or 00 gauge). cant remember. I have a Flexplate. That is what I ment. The mini starter that I started with was a high horse starter but it wasn't reduced enough.

Ha I just went threw the same thing what my problem was I didn't have it grounded good a nuff. I had the battery grounded to the frame but I didn't have a cable runing from the block to the frame did that and all fixed, I really just went trew the same exact thing to a tee. And I had to replace my flexplate! So that's how I fixed mine so check to see if you have your block grounded to the frame and your battery gounded to the frame fixed me right up!!

if possible, run the battery ground cable directly to the engine.

I'm going to go one step further than Tom and recommend grounding to the starter mounting bolts. Starters can pull 300 amps: you don't want those 300 amps seeking what ever path they may choose, and you don't want to depend on ground wires to the frame to conduct that amperage. Even if you have a trunk mount battery, run double ought to the starter for the best ground, and run the ground wire to the frame from that point. Clean the frame well and use star washers to bite into the frame.

Connectors for '00' cable can be made by flattening a piece of copper tubing, drilling a hole in the flat part, and soldering the cable in the tube part. Solder ALL connections and finish off with shrink wrap and everything will look 'store bought'.

Thanks everyone. I hope that I have this bug figured out. I've never had a problem like this with starters. I think that I have it figured out. Thanks for your input. I will try to post some pics later this spring. Getting married so probably wont be online for a couple of weeks.
Thanks again.

Also to add to this..
The first starter probably did the inital damage from not checking engagement. The second starter just finished it off.
Seen this one quit a few times. You GOT TO CHECK clearnces of starter teeth to flywheel teeth.

Randy B.

After you get new parts, this website may help. Are you using a hanger bracket to support the free end of the starter?

http://www.autozone.com/az/cds/en_us/0900823d/80/11/ba/09/0900823d8011ba09/repairInfoPages.htm

Also use new, correct starter bolts. (they are knurled) Using incorrect bolts, or bolts that are bent will cause starter problems.