Like the title says, I am in the middle of swapping my transmission out for one from a '94 miata. I was wondering if it would be possible to use the mainshaft from the rx7 tranny instead of getting the one from the miata machined.

Also, can I use the bell housing and tail housing from my extra 12A tranny, even though the tranny is going into a GSL-SE? Its my daily driver and I dont want to take the tranny out for an extended period of time if I can avoid it.

And lastly, am I going to need to use the speedometer gear from the miata tranny or the rx7 one? And is my speedometer going to be even kind of accurate after the swap?

Thanks in advance for your assistance.

 

1: not sure, but
2: definitely. As long as the tail housing is from an FB, not an SA.
3. Use the drive and driven gear (including its housing) from the RX-7 trans. The speedo gear is only determined by rearend ratio and tire size.

 

Anyone else know if the main shafts are interchangeable?

One more qusetion: Is there some kind of tool I should buy for taking off those stupid snap rings? My friend is sick of busting his knuckels helping me get those off, and we have only taken one off so far...

 

a good cheap set of snap ring pliers is invaluable,check sears for those,just a question though,why the miata tranny? I was not impressed with the low end speed of the miata,my aunt has a 94.Does it improve in the rex,I could see the 6-speed,Sorry,I dont know about the shaft deal.

 

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.

Everyone asks me about changing the Miata 5th gear with that of the 2nd gen RX-7 so that their highway cruising rpms can be lower. The whole guts can be fairly easily transferred but individual gears, unless you are an experienced transmission repair technician and have all the proper micrometers and pullers (and have an idea what you are doing), is not a job for the average shade tree mechanic. The Miata trans also uses a different number of teeth on the input and counter shafts than the corresponding RX-7 transmissions so swapping to the RX-7 5th gears creates a different ratio than the advertised ones. See 5th Gear Interchange Chart.

found this at solomiata,go to drivetrain interchange and there is stuff about speedo's too.not the swimsuits.Whatever you do,dont look up miata tranny swap.scary results man.scary

 

nope, you gotta get the miata shaft ground down

this should help: http://myweb.cableone.net/currie/tom/RX7/trans.html

 

Wonderful link, thanks!

 

Dig it.

http://www.mazdatrucking.com/B2200/Transmission.html