My last thought on it is this pic from the manual. It's the s5 manual, but I think the s4 is probably identical. This was another issue I had when reinstalling the block... and took me a couple times to get it right. Once you pull it apart and see what engages what, it makes more sense.

 

Also I'm assuming you can't shift into gears using the shifter. If that's incorrect and it just doesn't center, I apologize!

 

Earlier you asked about whether the ball and pushrod mechanism (that centers from 5/R) might be causing your issue. Have you tried removing them to see if they are interfering? It may be worth it just to rule them out as the culprit.

 

The spring and ball-bearing are responsible for returning from one side, and the centering spring is responsible for returning from the other side. I can never remember which is which.

I do know that if you don't put the ball-bearing, spring, cap, etc back in the right order it will bind up and won't return. I'm guessing this is your issue. Here's an old picture of mine that I found:



There's a little detent in that round part. I don't recall the exact order, but I think I put the round part in first, then installed the ball-bearing with it's spring and the bolt, making sure the ball-bearing lands in that detent. Finger-tightened until it was applying some pressure. Then put in the other spring that engages into the round part, and the little plate after that. Then tighten it all down to spec.

I might not be 100% right about that. I've done this more than once but always just played with it until it was right. I'm confident this is your issue.

 

Can roll through gears just fine. Just doesn't return from 1/2 lol

 

Hmm interesting. Let me give that a go. I'll pull the check ball and plunger to see if that makes a difference. Will update later today. I appreciate the feedback

 

Alas, the check ball was not the issue. I removed the bolt, spring, check ball, plunger, and the other spring. Still would not return. Then tried with just the plunger and spring, still no luck.

What the hell could be wrong here? Weak spring? It's brand new, so would rather not parts cannon if I don't have to. Here is a video of shifting with the check ball out. I also did a closeup on the spring flexing.



Here is a picture of how the check ball/plunger is installed:

 

Hmm. Three things come to mind:

1. Did you replace the shifter bushings? On fresh bushings the shifter can be really tight. Try loosening the three bolts for the shifter a bit and see if it starts to return.

2. With the check-ball & plunger and related parts removed, does it return it all from either direction? If it doesn't that implies there's still something up with the return spring.

3. When you install the check-ball and plunger, are you sure you have the springs in the right places? I think I recall they can go in backwards, but it definitely feels wrong when you tighten it so I suspect you would have noticed.

EDIT: I just went out to the shed and checked my S4 T2 transmission (alas, also with a broken return spring) and it will return from 5-R but not return from 1-2. The check-ball/plunger assembly is in-place.

 

1. Yes the bushings are brand new. It's a mazdatrix short throw which came with new bushings already. I'll try loosening it up to see if it'll snap back



2. From my understanding, the plunger and check ball are only there to return the shifter from 5/R. The return spring does 1/2. Coil springs don't really fail, and I think Mazda realized it was dumb to have 2 different styles of spring, hence why later Miata transmissions use coil springs for both sides.


3. I'm almost positive the springs are right. They're 2 different sizes, so kinda hard to get wrong. The small spring goes inside the bolt and sits on top of the check ball, and the larger spring sits inside the plunger

 

Do you (or did you ever) have the OEM shifter? I can't understand how the short throw shifter might possibly be the culprit here, but you would at least be able to eliminate it if the OEM shifter did the same thing.

 

I figured out the issue. Wondrousbread was correct in saying that the bushings are tight. I loosened the 3 bolts that hold the shifter in, just a tad, and it now returns. I guess with them tight all the way something is binding?


Now that I know what's causing it, I have to find a workaround for another issue. With the bolts semi-loose, there are gaps between the transmission shifter housing and the spacer, and between the spacer and the shifter. There are gaskets that normally go here, and with there being a gap, my concern is that the gear oil in the shifter turret will leak out. How would you go about sealing this?


Gaps that appear when bolts are loose (slightly exaggerated for photo)

 

Stupid question... but now that you know its binding - and before you get to a spacer/shim... have you tried putting gear oil on the pivot ball that rides on the bushings? Since that whole area is designed to hold oil and all...

Otherwise, Id suggest taking the cylindical spacer that the shifter bolts to and tracing it on a piece of 18ga or 16ga aluminum sheet and making a shim. Then RTV it together (there is gear-oil specific RTV), drop your bolts in and go.
Or just use it as is until it breaks-in and starts working.
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This has been a very good thread so far, thanks. With a short shifer I would assume some things are different. An s4 picture for refrence. Perhaps a factory gasket/spacer there?

 

Replacing the shift centering spring on 81-91 NA or TII is an easy 15 min job. Attached is a brief writeup on the process.
Atkins Rotary has replacement springs.

 

I will likely need to make some kind of spacer. Even with the shift ball oiled, it still binds up. Will update

 

The Atkins shift centering spring is a near perfect reproduction of the Mazda NLA factory spring. However, it doesn't have the tension of the original factory spring. You can correct that lack of tension by bending the spring prior to install.
Here's pic of a new Mazda factory spring:


Here's pic of the Atkins Spring:


Use an 8mm deep socket with extension to bend the spring and align with factory spring position.


Spring reformed to match factory spring position: