Which of these 4108 ring gears would you fit?

[pcatterall]

I have 2 ring gears. One is from a known working and starting engine ( which siezed!).
the other came with another 4108 of unknown history.
They look identical and have a common (part?) number 3121 1250 but different serial numbers 8491for the 'working' one and 8271 for the 'other one'.
The teeth on the 'working one' look quite worn compared to the other one.
I can see no difference in the 2 in terms of diameter, bolt holes etc and they have the same number of teeth (104)
I hope my pic shows the difference.
It would seem better to fit the one with the less worn teeth but I am concerned that I may have missed something and so am asking the experts opinion again!

 

[lw395]

Is the 8XXX number a date code?

 

[Heckler]

I have 2 ring gears. One is from a known working and starting engine ( which siezed!).
the other came with another 4108 of unknown history.
They look identical and have a common (part?) number 3121 1250 but different serial numbers 8491for the 'working' one and 8271 for the 'other one'.
The teeth on the 'working one' look quite worn compared to the other one.
I can see no difference in the 2 in terms of diameter, bolt holes etc and they have the same number of teeth (104)
I hope my pic shows the difference.
It would seem better to fit the one with the less worn teeth but I am concerned that I may have missed something and so am asking the experts opinion again!
View attachment 72304

All else being equal fit the less worn one

 

[Graham_Wright]

Thickness the same?

What make engine?

 

[VicS]

Thickness the same?

What make engine?

Perkins ?

 

[Heckler]

Perkins ?

Love your humour!

 

[ghostlymoron]

Less worn one.
Serial number is the identifier of the individual part enabling you to identify when and where made. Part number identifies what spec it's made to.

 

[RichardS]

The lower one looks less worn to me but the photo is a bit blurry (or it could be my eyes!).

If I've got that right, I'd fit the lower one.

Richard

 

[pcatterall]

thanks all. I fitted the less worn one and with the bell housing off and the starter in place could see that everything looked good regarding clearance of starter teeth and engagement when starter 'thrown'.
( didn't actually try the starter as no oil etc in the 'new engine'.
Parts4engines have been a big help ( as have all my mates on here!)

 

[DownWest]

thanks all. I fitted the less worn one and with the bell housing off and the starter in place could see that everything looked good regarding clearance of starter teeth and engagement when starter 'thrown'.
( didn't actually try the starter as no oil etc in the 'new engine'.
Parts4engines have been a big help ( as have all my mates on here!)

Not so much the ring gear, but the flywheel it attached to. Ring gears are usually heated up and shrunk on. Getting them off requires destroying them, grinding a chunk out until it lets go and will come off. Then getting the new one up to 'blue' and popping it on quickly. Only one go at this