na6 gearbox vs na8

steve123 · Postby **steve123** » Wed Jan 16, 2013 4:53 pm

hi everyone new to forum got some info on na6 na8 gearboxs thanks.Is the na8 a better box or same same need to rebuild the na6 is it worth bying the na8 or spending the money on the rebuild on the na6

Postby **NitroDann** » Wed Jan 16, 2013 4:55 pm

Buy ANY 5 speed second hand in good nick and drop it in.

Dann

koop21 · Postby **koop21** » Wed Jan 16, 2013 4:58 pm

steve123 wrote:hi everyone new to forum got some info on na6 na8 gearboxs thanks.Is the na8 a better box or same same need to rebuild the na6 is it worth bying the na8 or spending the money on the rebuild on the na6

As far as any differences between na6 & na8 gearbox i have no clue if they are internally different, but i do hear that the na6 gbox feels more direct and solid compared to na8. As for what's worth it, i'd say find a 2nd hand gearbox and get it fitted. You definitely wont get any benefits from rebuilding the gearbox unless your planning to never selling it.

93_Clubman · Postby **93_Clubman** » Thu Jan 17, 2013 3:13 pm

Unless you can do it yourself a GB rebuild could cost you over $2k, & that's what one forumite paid last year. So best to source another good 5 speed GB.

Very slight differences between NA6 & NA8 GB, but nothing to stop you using either, or that really elevates one over the other: http://solomiata.com/Drivetrain.html

"Mazda has two 5 speed transmissions. One is used in NA applications (AKA 'type 2' or Model M) and came on such cars as the RWD 626, 79-85 RX-7, 86-91 NA RX-7, B2000/2200 truck, and Miata. The other is a stronger unit that came on all turbo RX-7's, 929, B2600, and MPV.

Within the type2 versions only the bellhousing & tailshaft cases and gear ratio's are really different between models. All the guts of the Type 2's are nearly the same and mostly interchangeable. The major differences came in '81 when the shifter was made remote, in '83 where some bearings and shafts were made larger and in '94 with improved seals and a double cone 2nd gear synchro. Between models the input/output shaft lengths may differ slightly (~ 1/2") so always measure. The 79 through mid-83 tranny guts should be avoided if reliability and torque rating is important".