Friend needs a ‘74Tii ring gear or flywheel. Ideas?

[Son of Marty]

Makes you wonder where the flywheel manufactures are  sourcing ring gears.

[Henryn02]

Wallonesch was having a sale recently on new lightened flywheels.

 Not the cheapest option but

an option nonetheless.

[TobyB]

Any M10/M30 ring gear is fair game.

 

And Mike's totally right about the phasing- if you can heat the gear off, reinstalling it at 90 degrees off 'fixes' it for another 50 years...

 

A nice big strip of steel rack in the right pitch... wouldn't be the right solution.  But it'd work.  I strongly suspect

(as in, look, there's a weld right there)

that BMW made a ring and then hobbed that.

 

t

Starter mesh can be approximate.

[rms_sandiego]

Toby:  Everything else being the same, shouldn't that be moving the ring gear 45 degrees?  If the engine has 4 favored stopping points, moving 90 degrees would potentially hit the same spot again?

Edited November 19, 2021 by rms_sandiego

[jimk]

4 stroke engine cycle is 720 degrees turn of the crankshaft.

[TobyB]

To translate Jim just a bit, when you look at the piston phasing, every 180 degrees, 2 hit tdc.

One on compression, one on exhaust.

 

So when you shut down, finally one in compression doesn't make it "over the top",

and pushes the crank back a bit.  So the engine, statistically speaking, comes to a rest partway up one

cylinder's compression stroke.  Since the compression strokes are 180 degrees apart

(x 4 is Jim's 720) then there'll be 2 spots on the ring gear that 'usually' first engage the starter,

when it does all the damage.  90 degrees off of that hasn't had many hits, so off you go.

 

This is why, when your starter starts grinding, you fix it sooner than later.

 

t

 

[irdave]

I know some people dislike them, but I've used several aluminum flywheels.  One in the '72 tii I had, the other behind my s14 currently.  I'm not sure where the hate comes from, but I love mine (had 2 behind s54's, too.)  With the tii and with my current car, I can pull away from a stop without touching the gas pedal- don't know how much more flywheel weight ya' need...

 

The JB Racing one is what I've been using.  Has replaceable wear items.

[stone02]

all ring gears and flywheels are the same outer diameter

and therefore you can use any ring gear in good condition.

if you look at the back of the flywheel or the forward 

facing side, same thing, you can see the field of teeth that

are bad and those that are good. as mike said, you can 

heat and reset the ring gear so that the good teeth are lined

up where the bad ones were previously. so look for any

flywheel and switch the rings completely or move yours around.

good luck and let us know the out come,

stone