lightened flywheel

[Kai Ju]

Originally Posted by chasbmw

Kai,

Yours shows benefits of CNC stuff. Mine is slightly lighter at 5.24lbs.

Is the picture of your old flywheel showing the starter side of the ring gear?

Yes it is, as per your request.

Yes mine was CNC'd. I have slightly lighter one but the machining went into the ring gear by about 3 mm and I don't know if it'll hold up. My machinist did exactly as I asked, I just asked for a bit too much.
It'll make a great lamp base eventually.

[chasbmw]

Kai Ju.

Thanks for the photos, big difference in the design of the ring gears, the older ones such as mine having the chamfer.

C

[Wirespokes]

My burning question concerns what exactly the problem is -

Is it a problem with the starter motor engaging the flywheel teeth? Does the starter motor start spinning and grind against the flywheel teeth without turning over the engine?

Or two - does the starter motor engage the flywheel ring gear, but can't turn the engine?

[disston]

^^^^^^^this^^^^^^^

[crazydrummerdude]

Originally Posted by supershaft

I think a couple of people here have said they have replaced the gear ring. Reportedly it's an interference fit.

Interesting.. I've never heard/read this before. Seems like a lot of work for something still relatively easy to find on ebay and ibmwr.

[Kai Ju]

Originally Posted by crazydrummerdude

Interesting.. I've never heard/read this before. Seems like a lot of work for something still relatively easy to find on ebay and ibmwr.

Except when you're in chasbmw's shoes where you have a modified flywheel that was balanced with the rest of the engine.

[crazydrummerdude]

Originally Posted by Kai Ju

Except when you're in chasbmw's shoes where you have a modified flywheel that was balanced with the rest of the engine.

Yeah, but what's more work; assuming his teeth are actually beyond repair, finding another flywheel with "good" teeth and 1) lightening it or not... or 2) pressing the ring gear off the new one, pressing the ring gear off the old one, and finally pressing the ring gear on the new one and hoping/assuming it's still balanced?

[Kai Ju]

All good questions, the most important one being whether he has a flywheel or a starter problem.

Reading some of the comments it seems that the v-notch may actually be normal. If so then I have to agree that the teeth don't look any worse than the ones in the pic I posted.
Which in turn means that this is a starter/battery problem.

[Wirespokes]

I don't recall ever seeing a flywheel without the angled tooth faces. They have always looked similar to the ones in question.

[Kai Ju]

Wirespokes, I've had four different flywheels pass though my hands in the past 6 months and none of them had the v-notch type tooth that chasbmw's wheel has.
Mind you, they were all '77 vintage as far as I know.

[chasbmw]

It's an interesting discussion about the design of the flywheels. Mine is from a 92 tooth early flywheel, did BMW change the design? Did the design of the starter motor gear change at the same time?

Mind you on my flywheel the V notch looks to be unworn. They main damage on my flywheel is to the front of the teeth, where it looks to have been bashed by the starter.

[disston]

I found almost 25 flywheels on Ebay in a search. There were even more found on Google. Some of these flywheels have the V shaped cut, or V notch. Not all but many of the unlightened 93 tooth flywheels have this. See;



If there is damage from a 9 tooth starter being used on a ring gear designed for an 8 tooth starter the damage will progress as the flywheel spins. It will appear at one edge of the notch in some places, the middle and then the other edge. Now I've never seen this but it makes mathematical sense. I've never seen a ring gear that didn't work. A few stories about this but nobody has ever taken a picture.

[chasbmw]

Originally Posted by disston

I found almost 25 flywheels on Ebay in a search. There were even more found on Google. Some of these flywheels have the V shaped cut, or V notch. Not all but many of the unlightened 93 tooth flywheels have this. See;



If there is damage from a 9 tooth starter being used on a ring gear designed for an 8 tooth starter the damage will progress as the flywheel spins. It will appear at one edge of the notch in some places, the middle and then the other edge. Now I've never seen this but it makes mathematical sense. I've never seen a ring gear that didn't work. A few stories about this but nobody has ever taken a picture.

Dissiton,

Any chance of that photo without the cobwebs, I can use a file to put back the facets on the lead edge of the tooth.

Cheers

[chasbmw]

I have cleaned up the ring gear on my flywheel, with a combination of hand file and Dremel.

It looks much better now, just have to wait until everything is done and we shall see how well the starter works.

[disston]

What do the teeth on the starter look like? Also the part directly under the teeth of the starter is a one way clutch. It should spin freely in one direction only and it should not be cracked. Often when these go bad they are cracked.