Hi everyone,

Long story short. We have a new motor on the floor and want to break it in properly.
The new motor is for a 5 - speed manual but we have a 6-speed manual transmision fitted to the car. Our concern is if we swap the flywheel from the old motor to the new one, will it affect engine balance especially in regards to breaking the new engine in?

I think it won't be a problem but then again I may be completely wrong.

Thanks for any input guys, waiting on some seasoned recommendations from you so we can proceed.

 

The flywheels should be identical between all trans / engine options. Yes the flywheel is part of the balanced assembly and if you have an aftermarket flywheel you need the appropriate counterweight. But stock for stock they're all the same.

 

Cheers, Thanks...

 

Mazda did have a different flywheel/clutch on the 5-spd engines, but the 6-spd components will all work. It’s been done quite a few times on the forum. The difference is the 5-spd was used on the low-power engines and the 6-spd on the high-power engines. It didn’t require the same level of power capacity or high rpm capability. You wouldn’t really want to swap those in over the 6-spd components.
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Yep, that is exactly the case. The car came with the 5sp gearbox and a flywheel to suit.
So we changed to a 6sp long ago with a lightened flywheel with the necessary counter balance.