I've heard it said several times that SA gearboxes sometimes jam in third. I've had it happen to a buddy of mine at Road Atlanta, where getting off the course uphill is a real pain in the ***. In his case (aws140) the gearbox never came out of third. It either broke the linkage or just stayed that way until the tranny was replaced.

The reason I ask is that the SA gearbox I'm using now sticks in third real badly, but always comes out after some fenagling. If I tug on the shifter and maintain force on it while I clutch in, it always pops out, but if I forget to load up the shifter and I'm coasting with the clutch in, it hangs. The only solution is to press forward, then back toward neutral over and over. It sometimes takes a full minute or two, in traffic, to get unstuck.

Any idea why an SA tranny would do this?

 

I have had the same problem. My SE has SA guts in the tranny (the SE tranny was burned up due to the previous owner running it without oil). I was an RX-7 noob at the time and bought a tranny that was supposed to be out of an '82 (was really an SA tranny). I dropped the one out of the SE and saw it was nothing like the tranny I just got. Luckily, I knew of a local guy that did machine work on engines and stuff and modified the SA guts into the SE case. Worked well, but a few months later, I downshifted into 3rd and it never came back out. Sure made it interesting getting it back home with only 3rd gear (lived up a steep hill too).

I since had the tranny rebuilt and all has been good since then. I guess what happened is the fork went too far forward and got stuck. I don't know if it was due to too much slop in the tranny or what (that would be my guess).

Sorry..not much help. I would guess slop in the guts, worn fork, or some combination of the two. I also know that some of the SA trannys have screws instead of roll pins, so perhaps these screws loosen up and cause slop in the fork or something.

 

I've actually got the rare late-build pinned SA tranny in the truck, if that helps. I was so excited to realize I had one that it got installed without much troubleshooting. I can gently place it into third, and once I'm ready to shift it's jammed up good. It's not as if I'm pushing the fork to its rearward extent (forward shifter is rearward fork), but maybe the helical gut to the gears work to jam it further into gear.... I'm just hoping that I'm not gonna need a new tranny. I'd like to be able to repair this one if the time comes, just because the forks, rods and tailshaft are special.

 

3rd actually seems to get the most abuse too, if we had a taller rear gear it might be second.

 

Mine always makes a 'scuffing sound' when I downchange through 3rd

 

Crit-- of course you know, my SA tranny go stuck in 3rd during Zoom-Fest 08'. I tried with everything I had in me to pull it out of gear and it wouldnt budge. To avoid the problem I put in a later FB trans, and at Zoom-Fest 09' I blew out reverse. Damn, I need to stop going through trannies. haha.

 

i have broke 2 sa trannys in 3 months both in 3rd. the 1st one got stuck in 3rd shifter would not move. the 2nd one went in 3rd and the shifter would move and flop around but would not change gears. altho i had no problem getting home even tho i was 30+ miles away. i got a 4.77 gear and i strong street ported motor

the fix is put a better trans in lol T2

 

I've never had a problem but now that I've read this, sure as **** it's gonna happen tomorrow.

 

I'd guess it's the same misalligned and worn shifter fork issue that causes all FB, NA/FC, and Miata trannies to stick in 5th or Reverse.

 

I know 3rd in my 85 spec7 gets finicky at times and just gets to be a pain in the rear to get in to so i wonder if its all related

 

I had my SA trans lock in 3rd a few years back. Felix on the 1st gen mailing list indicated it's a fairly common problem - caused by shifter fork wear. The excess wear allows the slider to overshoot the normal stop position, which allows the key to pop part way out, locking the slider in position. His description sounded quite reasonable, as I had been driving in a spirited fashion at the time, and may have shoved the shifter into 3rd more aggressively than normal.

I ended up swapping over to an S5 TII transmission setup, and never did disassemble to check actual failure mode.

 

This is not really the case. Think about it, if the shift fork is wore out it will not move the slider as far as it would if the fork was new.

What I have found to be the problem is the synchro key springs have a tang that index into the hub and for some reason the tang will break off and allow the spring to rotate inside the hub. Once the synchro key and the open space in the spring line up it allows the key to pop out too far and will not allow the slider to move the other direction.

 

What's special about these parts?

 

If slowly shifted into 3rd, I agree. If one shifts rapidly, the wear on the other side of the fork will allow the slider to overshoot.

I went back through the old mailing list, and refreshed my memory. It ends up, I did disassemble my transmission after failure, and even took a picture showing the jammed key!


Felix indicated this was a relatively common problem on earlier rx transmissions. The cause was described as a combination of mainshaft endplay and fork wear. The solution was to replace the fork and/or use spacers to limit axial movement of the shaft.

 

^precisely what i've experience in the earlier trannys. if the, what i call a shifting collar, manages to slide too far(happens when jamming 3rd at the drags, ask me how i know,lol) that little piece will flip up and it'll never come out of gear.

 

The last few months of SA production trannies had the selector rod on the same axis as the FB tailshafts. The shift rod heads were also shaped like the FB heads such that they're interchangable with the FB tailshaft and shift rod. A late SA tranny can have an FB tailshaft bolted onto it and be installed in either chassis.