I am working on an LT-1 swap for my RX7. I have a manual and i want to go with an automatic for the 350. But im not sure if i'm thrilled about the 4:10 gear in the stock rear end of my RX7, with the 4L60E 4speed. Is there anybody that knows of somewhere i can get a 3:73 or 3:42 rear gear for the RX7. Also any added info about the manual to auto conversion would be helpful.

 

Hey,

I'm putting a 383chevy into mine (86 rx7) with a 200-4r auto tranny. I too was worried about the gearing, and I've looked and asked and I haven't found much on smaller gears for the rear. I have 15" wheels on it right now, putting 16's will help a little... but we'll see.
Also, getting an auto shifter to fit in the car and look nice is going to be harder than I thought. A lot of guys suggested using the stock rx7 shifter... but auto rx7 shifters are few and far between, and they only have P-R-N-D-S-L.... so you wont have a 1st gear "option," just 2nd 3rd and overdrive.
A lot of guys use B&M shifters, but you have cut some, and it really sticks out from the mazda's interior. But I'll let you know what I end up doing, I'm trying to keep things looking nice!
brandon

 

Hey,

I'm putting a 383chevy into mine (86 rx7) with a 200-4r auto tranny. I too was worried about the gearing, and I've looked and asked and I haven't found much on smaller gears for the rear. I have 15" wheels on it right now, putting 16's will help a little... but we'll see.
Also, getting an auto shifter to fit in the car and look nice is going to be harder than I thought. A lot of guys suggested using the stock rx7 shifter... but auto rx7 shifters are few and far between, and they only have P-R-N-D-S-L.... so you wont have a 1st gear "option," just 2nd 3rd and overdrive.
A lot of guys use B&M shifters, but you have cut some, and it really sticks out from the mazda's interior. But I'll let you know what I end up doing, I'm trying to keep things looking nice!
brandon

 

I believe that there are other options with the 7" rear(3.90 from an auto) and possible some other gears from other Mazda cars have been rumored to fit the 7". When discussing the TII rear i think the only option is 4.10, and with the 3 to 1 first gear in the 4l60E first gear will be interesting, and OD will put you around 3000 rpm at 65 mph (approx). Getting a larger diameter tire will make a good amount of difference, effectively taking the gear to 3.90. There arent any aftermarket 3.73 or 3.42 gears for any of the diffs, that I know of.