3.7 to 4.1 FGR swap (NC)

deanb90 · Postby **deanb90** » Thu Oct 27, 2011 4:34 pm

I have just bought an NC 4.1 FGR ring and pinion from the US.

Has anyone done the swap in there NC?

Can anyone recommend me a workshop in Melbourne that is familiar with this type of work?

General chit chat and experiences much appreciated!

Cheers
Dean

PaulF · Postby **PaulF** » Thu Oct 27, 2011 5:09 pm

I believe Peter (pcmx5 on this forum) has done this. You can send him a PM if he doesn't post on this thread.

flycasta · Postby **flycasta** » Thu Oct 27, 2011 7:02 pm

As long as the 4.1 gear set is actually from an NC it wont be a problem. The NC is not really adjustable like the earlier Mazda stuff so are controlled by the diameter of the pinion head and crown wheel thickness. There was a member that tried to use a NA/NB8 crown wheel pinion set and it didn't work because the crown wheel was thicker and pushed the carrier across so far that the axles wouldn't fit properly.

deanb90 · Postby **deanb90** » Thu Oct 27, 2011 7:59 pm

Thanks for the replies.

Gear set is from an NC.

Does anyone know if NC1 and NC2 ring and pinions are interchangable?

pcmx5 · Postby **pcmx5** » Thu Oct 27, 2011 9:15 pm

I did do it but changed a complete diff centre with LSD for another one and that cost me about $380 to fit from memory.
You have saved by just buying the CWP but could probably expect a bill of $800 or so to remove the current diff and repace the CWP.

Any really good diff specialist should have no problems doing this.

Whatever it costs you will not believe how it will transform your car, first performance mod i would do to an NC.

Good luck,

Peter

deanb90 · Postby **deanb90** » Thu Oct 27, 2011 10:39 pm

Thanks Peter, cant wait!

I paid $350 all up for the ring and pinion to be at my door in 6 days so hopefully installation wont be to bad.

any recommendations for a decent Melbourne diff specialist? Possibly MX5 factory?

bootz · Postby **bootz** » Thu Oct 27, 2011 10:40 pm

Yeah, listen to Peter. The 4.1 is a sports ratio, 3.7 is for fuel efficiency. Should make the NC fly.

pcmx5 · Postby **pcmx5** » Thu Oct 27, 2011 11:01 pm

deanb90 wrote:Thanks Peter, cant wait!

I paid $350 all up for the ring and pinion to be at my door in 6 days so hopefully installation wont be to bad.

any recommendations for a decent Melbourne diff specialist? Possibly MX5 factory?

Sorry being in geelong don't know any melbourne diff specialists but it is a specialised field and the Mx5 factory isn't but would probably have a sub contractor.

You will be able to sell your old CWP to a yank, they in a Mazda piece of studity get the 4.1 but have high speed limits and love to get their hands on our 3.7's, while we have nanna state limits and a moonshot ratio!!!b Go figure!!
Peter.