915 transmission 3rd gear won't engage

[dpl356]

Hi everyone,

I need your expert advice on the following: I have a '72S with early shifter. Recently, I cannot shift into 3rd gear - it's as if something is blocking the shift rod engagement. The problem is present with the both the car off and running. All other gears are fine. Within the past year, the shift coupler and shifter bushings were replaced. All the published methods for shift adjustment do not fix the issue.

Thank you for your help on this.

David

[edmayo]

The only thing you might check before going into the trans to replace 3rd gear synchro parts and slider, is to pull the shift rod fulcrum plate and check that the fulcrum securing nuts are tight.

[TheTorch]

On top of what Ed said, I would pull the plate and see if the 3/4 shift fork has moved (towards 4th). This happened to me.

[dpl356]

Many thanks to all.

I will pull the plate to inspect. Question, if the shift fork has indeed moved towards 4th, can this be corrected without pulling the transmission?

I recall before the issue (probably going into 3rd), the shifter behavior was like being in neutral where I could not find a gear. I had to pull over and go through the gears, including reverse, to resync matters to get home.

[TheTorch]

I don't think you could properly tighten the 3/4 fork bolt from the plate opening. But maybe getting creative you could bend a 13mm up there -- I can't recall the angle and amount of room you would have. If nothing else, you may get lucky per Ed and it's just a loose pivot fulcrum, or get an idea what the problem is (fork moved, worn synchro/slider, etc.) before going to all the trouble of pulling it. Obviously you may wish to drain the oil first, or you will be draining it via the plate.

[RSTarga]

I think JWest makes a kit to eliminate the problem of the fork loosening. If that turns out to be the problem. I would double check all the shifter bushings, I got a batch that failed in just a couple of years.
Here you go:
https://www.jwestengineering.com/915...rade_p_59.html

[catelluseng]

If indeed the 3rd/4th fork has moved, I would be reluctant to try correcting the problem without setting it up correctly using the set-up plate. That means pulling the transmission, removing the front cover (nose cone) and its contents, and finally removing the gear housing. I dunno, I am obviously being conservative and suggesting a bunch of work which may not be needed.

David, unless I misunderstand, the JWest kit addresses a (perceived) issue with the fork in the side plate, not the 3rd/4th fork on the shift shaft.

[dpl356]

Gents, thank you for the thoughtful inputs. I double-checked the shifter, bushings, and coupler today as well as shifter alignment. All gears are perfect except I cannot shift into 3rd, driving or standing still. The gate pattern for 3rd is ever so slight in that I can feel it's location but cannot move into the gear.

For completeness, I will drain and pull the side plate for inspection this weekend.

If indeed the transmission needs to be pulled, I would be grateful for any shop recommendations in the Austin / San Antonio area.

[RSTarga]

Ed Mayo (above) is in Ft Worth and Jones Autowerkes is in San Antonio. Both great shops. I've heard there are a couple of guys in Austin, you might want to check with some of the early 911 owners there.

[john rice]

If you don't mind posting the results of exactly what is wrong? That and good luck.