This is a continuation of the thread about "No reverse". After replacing the shifter lever bushings with no improvement, I dropped the tranny. This is 1980 4 sp manual. Take a look at the picture.

You can see here that I removed the ends of rods in which the shifter rod slips into. The gear that you see here with the fork is reverse. There was no problem with that fork. Of the three rods, from left to right you see reverse, 3/4, and 1/2. I have drift in the reverse rod in this photo, so I could try and move it. The 3/4 and 1/2 rods move up and down with no problem as expected as those gears had no problems. However, reverse would NOT budge. This was the problem from the gear shifter as well, as the shifter lever would not even move to the right side.

Anyway, keep in mind that the tranny was filled with sludge, it was thick and nasty. I had to tap on that reverse rod to finally get it to pop in. The tightness does not appear to be in the gear/fork/syncro. It seems to be the rod itself. To pop it out of reverse, I had to use the plastic hammer on the fork. Cleaned it with some solvent and then I kept spraying it with penetrating oil and working it back and forth and it is getting much more loose; it pops into reverse quite easily, but it is harder to pull that rod back to pull that synchro off the gear as seen in the photo. I can pull it out now without using the plastic hammer.

I am interested in your thoughts. Also, I'm thinking of dipping the whole unit into kerosene to try and flush it. I have flushed tractor trans with kerosene before and it worked good.

Thanks!

 

Sounds like you are on the right track. Can you pull the rod out and polish any areas where there might be corrosion? I'd consider stripping the whole thing, replacing as many bearings as you can find. If it was gummed up enough to stick that shaft, all the bearings were bathed in the same muck.

 

Were it mine, I'd finish tearing it down, clean it, polish the sticking shaft (pay close attention to the sticking gear bore), replace any damaged parts, reassemble, cross my fingers and test.

 

so why not continue with it in that thread? it keeps things all together in one place. so u have 3 threads going just on this trans.

 

So I got it cleaned up pretty good. Amazing how much smoother those gears turn now. I can also move the shift rod into reverse by hand. I put the rear housing back on and was able to move the shift lever receiver (where the lever seats down into) and I could put it into reverse, which was confirmed by spinning the shaft and watching the other shaft spin the opposite direction.
Then I put the shifter lever on to test it out. Same problem with the lever not moving to the right. So it appears to be in the linkage-control rod. Can someone tell me exactly how this pin and spring work shown in the photo? I realize that it acts as a guide for the shifter, but is it supposed to slide down and then pop back with the spring? Because it does not. The spring was contracted, i.e. the pin was all the way down. So I tapped on it lightly and turned it with a pair of pliers and to my surprise it came right out. You can see that there is an indentation in it near the bottom. It appears that this controls how far the lever moves to the right (i.e. moving the metal reciever cup to the left). I don't see it in the parts diagram. Can anyone shed some light on exactly how this piece is supposed to work? I cannot even find any pictures of it online.
Thanks!

 

So I'm getting this figured out It's all coming together. There is a passageway built into horizontally and vertically into the shifter frame which houses a steel ball and spring. You can only get access to it by drilling out a cap (I'll patch that later). That pin with a groove shown on the table fits down into the the vertical passageway, and the steel ball fits into that groove, right at the point where it intersects the horizontal passageway. Then, when you push down on that pin, the steel ball moves horizontally into the passageway out of the groove, allowing the pin to "contract" or push down vertically. It is then supposed to pop back up due to the spring on it, and the steel ball pops back into the groove because of its spring located inside the housing, and that ball holds the pin in place when it sets back into the groove. I think that is how it is supposed to work. Mine does not push down in, and I think that explains why I cannot move the shifter to the right side in order to get it in reverse. The pin is pitted along with the ball, so nothing is moving smoothly.

I'll replace the ball and sand up the pin a little to allow them to slide together as they should, hopefully. Please let me know if you have any thoughts on this, especially if you know of where I could buy those parts specific to the car (I doubt it, I'll probably have to improvise).
Thanks

 

I'm learning things here, this is a good thread. Keep going thru it and posting details and solutions.

Peeps, this is why changing fluid on the regular in your tranny is important. Lots o small things start tripping up as the oil gums up.

 

You should be able to clean up the pin with a wire wheel and scotchbrite. New ball bearings can be had at the hardware store or a place like Grainger's. I see a pair of calipers, use those to measure it first to get the right size. I might stretch out that compression spring some too, before going back together. Can you plug the un-capped hole by drilling and taping the end for a setscrew? Here's a link to some additional parts that may be useful:

https://www.ebay.com/itm/Mazda-RX7-4...53.m1438.l2649

 

Got it. That fixed it. I cleaned up the pin and got a new ball bearing (5/16). Put a little oil in it. That pin is now able to bottom out vertically as the ball bearing slides out of the way horizontally. This must be why you have to jerk the shifter lever to the right harder than when moving it to the left as you need the force move those pieces. Should I use grease instead of oil? It is a tight fit right now.

Great idea on tapping a thread on that opening. Should be easy since it is aluminum.

Something I wonder about. My cousin said that shifting in reverse gradually got harder and harder over several years, until it would no longer go in. That must of been those parts wearing out, and I wonder if his continued shifting into reverse with the pin not fully depressed allowed the reverse rod to not be "pushed on" perfectly plumb down the linkage line, which is why that rod is now much tighter than the other two, currently? Just hypothesizing here.

I might as well order a clutch kit as well while I got it off the car.

Thanks

 

It is good to see that you persevered and solved your problem. There is no telling how many future tranny mechanics will benefit from reading your thread(s).
Thanks

 

I would guess that the bearing is 8mm, but 5/16 would be close enough. It's only .003 smaller Some light assembly grease would be ok. All this will be lubed by the gear oil you eventually add splashing around. Did you notice any scarring or other signs of interference on the rod or shaft bores anywhere? I'd make sure any nicks or burs are dressed down with a stone or fine file. It could have just gotten gummed up and eventually corroded stuck.

From your other thread you posted a pic of a 5 speed lever. See below, the longer, straight lever is a 4 speed. The shorter one with 2nd, reverse bend is a 5 speed. Also notice that the distance from the pivot ball to the smaller ball is longer on the 4 speed lever. You say its a 4 speed tranny, could the shift lever have been changed out and could that be adding to your problems? Your sure its not a 5 speed?

 

My '79 S 4 speed that I've owned since July, '80, has the 2 bend shifter and I'm reasonably certain it has not been replaced post delivery.

 

I recently saw a 79 4 speed for sale here and commented about the shift lever. That owner thought it was the original lever too. https://www.rx7club.com/market/1148338

I always thought the 4 speed came with these longer levers, but maybe not? Here's an example:



The parts fiche illustrates the straight lever but I also notice it shows the same picture and P/N on the 5 speed diagram? Maybe they did use both styles, one thing I've learned from this forum, is that you are always discovering new things about these cars.