Hey guys.

I'm in aussy land. My 12A popped after 245 000 KMS.

Doing the rebuild atm, I have a 1982 GSL engine from the daily, and a spare donor engine from a 1985 GSL 12A.

Anyways.

I know the 1982 rotors are meant to weigh 4.6kgs, and then 1985 rotors are meant to weigh 4.3kgs

I have the complete rotating assembly for the 82 GSL motor, and the complete rotating assembly for the 85GSL except i don't have an auto rear counterweight for the S3 motor.

What would happen if i used the 85GSL rotors and the 82 front and rear counterweights.

I think the obvious this is the engine won't be balanced properly, but maybe it would be. Whos tried who know. Or how knows as a hard fact it will or won't work.

 

It has been done, and people claim it works, but has "Some vibration".
In my mind, ANY vibration is too much.
Either use the matching rotors/counterweights, or plan to have a shakey engine, that doesn't last as long as it should before it wipes out bearings.

 

2 rotor bearings: 41.40
2 stationary gear bearings: 25.82
12A e-shaft: 253.38
gasket kit: 130.86

sub total: 451.46

S3 auto counterweight: 147.56

Grand total.: 599.02

The numbers speak for themselves, how much do you wish to risk. If using the 82 counterweight in the 1st rebuild, the above list is the minimum in parts you will need if the balance issue eats your bearings and e-shaft.

 

Hey

My builder is adament that Australian S2 and S3 rotors are identical other than the later ones being nitrided. I myself weighed the two on a dodgey set of scales and couldn't pick them appart using weights as a guide. They both came up at 4.6Kgs.

Is it possible we have model differences compared to you guys. My builder seems pretty good at his thing. And I know hes been trained by mazda, has heaps of cred, heaps of experience, is a real jack of all trades, has IPRA customers etc, so I can't see him saying something like that unless hes sure it will be good.

Have any of you guys built an engine, and found that it doesn't work, or had someone tell you that its definetly a really bad idea?

 

this SA ....85 stock 12-A with 81 flywheel, kevlar clutch and 2600 lbs pressure plate. I used the 81 flywheel as it is the lightest stock flywheel... 21 lbs