915 shifting symptom help

[ahh911]

Hi Happy New Year!

81sc 915 stock.

Question:
With cooler weather, 10C/50F or less, so it seems.
Car shifts fine into all gears for first 10-20 minutes.
Then the issue always starts with shifting 3 to 4th, the shifter no longer wants to go into 4th but instead vibrates/buzzes. I'll wiggle the shifter, no help, go back into neutral then try to get it into gear again but just a vibrating stoppage. I'll try to go into 3rd, no go, 2nd it seems no go, same vibrating shifter and reluctance to go into gear, car rolling more slowly now, suddenly it goes back into 2nd and all gears return as though nothing ever happened. As the car continues to warm up it will shift nicely from there on. This whole episode lasts less than a minute, but it's just at the point where the car is warming up and you're merging onto a highway, lets say. What is going on?

Thanks,
Phil

[47silver]

Check
Shifter coupler bushings in the tunnel.
Shifter cup and bushing on the shifter mechanism
Change transmission fluid with the forum consensus fluid. You will find that there is no consensus but swepco seems to be the go to for 915’s.
Before draining transmission, remove tge fill plug.

[john walker's workshop]

Yeah, a linkage go-thru is in the cards. Don't like swepco much for the street, good for gear faces racing.

[ahh911]

Thanks guys,

Have taken out the shifter over weekend.
Ball socket shows vertical movement (~ up down 1/8 inch, horiz 1mm), new one on the way, is vertical movement 1/8 inch normal?
Friction bearing ( 56 914 424 224 00 Friction ring) that centers the gear shift rod is good. New one on the way, but don't expect any miracles.
Shift rod coupler looks very decent.
(I think someone has replaced the 3 items at trans rebuild prior to my purchase, ~ 30k miles by now.)
Kendall 80-90. The store brand used earlier started to show the same symptoms.



Phil

[john walker's workshop]

Might be just a simple coupler adjustment.

[ahh911]

Thanks John,
It's weird I get this for such a short period of time in the middle of warmup on several gears at once, will adjust coupler again tomorrow. Haven't tried front to back yet. One more day before the snow returns, thought I might sneak this in.
Phil

[john walker's workshop]

Shift lever centered front to rear, in neutral, pulled all the way left and coupler twisted all the way right usually does it. Assume all trans and engine mount bolts are tight and mounts in good condition? Doesn't really seem like an internal issue, being that it gets better later, but gotta check the easy stuff first.

[ahh911]

John,

Loosened all tran/engine bolts slightly, banged carriers around with mallet, retightened. I had an engine cross bar that was bent on the left side at one point, since been replaced but I didn't relieve the diagonal strain/alignment of the engine/tran until now, that should no longer be a possibility.

Did the coupler adjust as you've recommended, shifter centred and to the left. The rotational free play in the gear shift rod was balanced between 5th and 1st after setting.

25 minute drive, maybe a difference, too soon to say, but 4th seemed stiff right away, which is better than later in the drive, but it needs several drives sometimes to expose.

The ball joint cup under the shifter seems to have too much play, will reply once that has arrived and installed, most likely the next drive will be springtime with new parts.

Thank you,

Phil

[john walker's workshop]

The cup is held to the rod with a set screw like the one at the coupler, and they can get loose.

[ahh911]

Yes, pinned down the set screw to the shifter rod over weekend (the cup one). You are correct, it was not tight but not backing out either. The factory goop on the threads was holding it in.

Phil