one of my friends had the best thought about using the Na drivetrain in a bigger power car. he put a 20B in his FC, and i told him he needed to change the trans an diff, and he said, he would wait for them to break and then swap it (not his only car), and so far so good...

I've went through 2 na trans in my stock vert already. Both from input shaft bearings going bad

Maybe these trans could have handled the power good some less abused boxes still maybe can but generally these trans are at least 25 years old and have been in sports cars taking abuse...just go with the stronger t2 box especially if you took time building your engine and what not.

I had the input shaft bearing go bad in one box, and the gears in another one started whining. I decided to make one good transmission from the 2 (found pits on the gear faces of all gears when I pulled it apart) and it lasted about 12k miles before it started singing to me again. And that was under stock NA power, and respectfully driven at that.

They're not really well thought out, and they seem to be made of some pretty cheap materials. And yes, I've jammed it in reverse and 1st at the same time before. Not fun.

I got a T2 gear box (coupled to a ~350ish whp t2 engine) and slammed on it countless times. This gear box is full of awesome. What's surprising is that the NA rear end and axles have held up so well.

My NA drivetrain held up at the drag strip on slicks for around 50-75 passes or so. I grenaded the spider gears in the open difff first, followed by stripping the cluster shaft gear while racing a new mustang on the highway. This was with a "calculated" 325 WHP...car ran a 12.0 @ 116 MPH. Launching it at 6500 :)

Yup. You only need the correct series cross member. You can drill out the holes to make a na into a turbo crossmember.

Pretty awesome .

i ran a turbo 6 port on the dyno with the stock n/a transmission in a vert @350whp, the transmission would make a funny whirring noise after the higher power tuning sessions were done until the transmission had a few days to settle back in, then the noise would go away.

it was a very disconcerting sound, and why i drove it easy back to the shop. as far as i know, the tranny is still going, but ugh... i hate doing a job half done, even when the car was originally planned as a stock port n/a but went through about 5 different phases afterward.

My old FC had an S3 'SE transmission in it with an S4 n/a engine in front of it. From what I recall, the S3 'SE trans is the same as the S4 trans with a shorter shifter linkage, slightly different mount, a smaller second gear synchronizer, and negligible difference in ratios. I tried to launch on grooved/textured concrete once and grenaded a stub axle in the diff. The diff is the weak point. These are not factory drag cars.

The synchronizers are easily weakened by missed shifts, and the bearings don't like running dry/old oil (duh.) If you find an S4 trans that has good bearings/syncs in it, replace the front gasket/seal and tail housing/drive shaft seal. Put good quality oil in; It should last a long time.

That 'SE trans is still going to this day. The current owner double clutches second gear every time he runs it hard. I'm sure it's running low on oil by now because it leaked as fast as you could put it in.

Mazda isn't the best at auto transmissions, but they aren't bad about manuals. I don't like their bearings though. They are the failure point in my opinion.

I know Aaron Cake has had some luck with the non-turbo transmissions; and IIRC he's pushing some respectable horsepower.

My full bridge N/A (road race/slalom car) eats N/A transmissions like candy. Going T2 swap on it.

+1000 on the NA trans being rubbish. My car had 60k on it when I bought it and 2nd was already grinding. I changed the fluid to redline and babied it until 70k. Finally, 5th started going. This was with 130whp lol. Ultimately, I just put in a t2 trans to handle my current motor set up.

The second gear synchro in the NA just flat out sucks to begin with. Combine the garbage 2nd gear synchro with the rather wide ratio change from 1st gear to 2nd and you have a pile of super suck.

I just had my transmission rebuilt. The only things reused was the transmission case and the gears. I had upgraded bearings installed, and when I mean barely anything was reused, replaced the hubs, forks, rods, the whole nine. Everything was ordered from mazda and I even made the shop show me the PO's for proof to make sure they wheren't giving me the D.

It's silent, smooth, but 2nd gear still sucks. It doesn't grind or clunk, but you can just tell when switching from 1st to 2nd it's working really hard to do its job. At the enormous expense of that undertaking I could have gotten a used TII trans and all of the supporting hardware.

there's always the RX8 transmission, which has double cone synchros for all the gears, has an extra gear and is about halfway between the n/a and the turbo transmission as far as torque handling capability.

for the headache i think the turbo transmission is still a better choice, but it shifts like a truck compared to the RX8 tranny.

But then you are having to move the engine around to get the RX8 shifter in the right place not to mention all the fabrication for a mount due to the RX8 having a PPF.

I'd rather have the TII trans and it shift like a truck.

just giving current upgrade options that don't involve a large list of modifications to work.

I'm thinking about a second gen rx8 trans. Supposedly alot beefier than the first gen. I already have a t2 trans swap, so I can use the same clutch, flywheel and starter. The only thing I need is a new slave cylinder and possibly another custom driveshaft lol