Argh! Sudden trouble shifting into 1-2 plane.

[tirwin]

@#$%^&

My '83 suddenly developed a problem shifting in the 1-2 plane. I was out for a drive and had trouble downshifting from 3rd to 2nd. Thought it was just a fluke. Then it happened again. And then a few more times. I was able to limp home easily enough. Got home and a played with shifting in the driveway with the car off. Here's what's happening:

- shift in 3-4 plane is fine
- shift in and out of 5th is fine
- shift in and out of reverse is fine
- shift INTO the 1-2 plane is erratic
- shift within the 1-2 plane is fine
- shift out of the 1-2 plane from 2nd to 3rd is fine

When I say "erratic", I mean that if I let the shifter center and then try to shift into 1st or 2nd then it sometimes slides right in and sometimes it doesn't. When it doesn't it feels like it is being blocked.

I installed a Seine GSK a while back and it has been super ever since until today. Also replaced the ball cup bushing at the time. Last year I did Ed's shift coupling bushing. Everything has been great. No short shifter. Stock 915.

I thought maybe the tab on the Seine was binding but it is not. Am I looking at a something easy to fix here or did something really bad just happen? Looking for suggestions on what might be the cause. Thanks in advance!

[McLaren-TAG]

I'd start by getting in the back and then adjusting your shift coupler and see how that works out.
Shifter Adjustment Procedure for 83 SC

[timmy2]

Start with the coupler adjustment, then check the shifter bushings in the tunnel and on the shifter, something has changed.

[Rodsrsr]

All the above and also check the bushings on the coupler itself.

[Arne2]

Also engine/transmission mounts.

[tirwin]

Thanks, guys. All bushings are new. I should've gone straight to the coupler. I'll have a look after work today. Hmmm.... hadn't thought about mounts.

[pete3799]

I've had the set screw loosen on the back side of coupler before.... might want to check that.

[tirwin]

Originally Posted by pete3799

I've had the set screw loosen on the back side of coupler before.... might want to check that.

Pete, my wife ALWAYS tells me I have a screw loose! But I'll check that one in particular.

[tirwin]

Ok I spent about an hour messing with this tonight. I had my daughter shift through the gears while I inspected the coupler in the tunnel. The set screw was tight as was the shift rod linkage.

There is more rotational play in the linkage than I suspect there should be. Imagine the line going from the transmission to the shift rod as the axis of rotation. I can grab the coupler and twist it from the driver side to the passenger side about that axis. It seems that if I hold the coupler at a certain spot about that axis, it will not shift into gear in the 1-2 plane. If I twist off that point in either direction it will shift into gear.

Let me re-emphasize -- neither the connection to the transmission or the shift rod are loose at the coupler.

Now the ball cup end of the shift linkage in the shifter housing may be loose. And I didn't have time to check that. But what is troubling me is this spot on the transmission end where it won't shift into gear. Is that normal?

Also had a look at the transmission mounts and they appear to be ok.

[Nickshu]

Originally Posted by Arne2

Also engine/transmission mounts.

+1. After years of playing with my coupler I installed new engine/trans mounts and it felt like a different (new) transmission!

Made me wonder how many 915's get rebuilt only to find a new coupler and new eng/trans mounts would have fixed the shifting problems.

[tirwin]

Well, I had a look at the transmission mounts and nothing looked amiss. Is there any way to tell just by visual inspection?

[Nickshu]

Not really. Mine looked similar side by side with new ones. Maybe slight sag but almost unnoticeable. Trans mounts are most vulnerable due to their unprotected position. I put in the stiffer oem cabriolet mounts. I have Eds coupler and factory short shifter.

I'm not saying this us your problem for sure but your symptoms sound similar to mine before new mounts. Plus mounts are not too expensive and worth a shot if yours are original they probably need to be replaced anyway.

[tirwin]

Good points. I'll add that to the list. Now I need to research Wevo vs Rebel vs Elephant.

I guess I need to open up the shift housing and see what's going on in there next.

[911pcars]

Have you checked the shift shaft bushing? Your symptom sounds like there's excessive wear at that location. Excess play at that location prevents adequate rotation of the shift shaft.

Sherwood

[tirwin]

Sherwood,

I haven't looked at the shift shaft (say that 10x fast) yet. I had a look at it back when I installed the GSK and it seemed ok then.

The thing is that when it won't go into 1st or 2nd it feels like something is binding. Since the GSK is affecting those gears, I'm going to wager it's going to be something I did. The shifter will slide over to the driver side from neutral fine but not move up into 1st or down into 2nd.

When it first happened I was worried it was a tranny problem but now I'm less worried about that. Hoping to get back to it tonight.

[notmytarga]

Is the extra tab mounted on the shift lever for the Siene gate binding/out of alignment?

[tirwin]

No, that was the very first thing I checked. Instead of welding the tab to the shifter I used the collar method. I thought maybe it had come loose but it hasn't budged. It seems almost random as to when it happens. It's like there is something that is catching if it's just a hair off. When it binds the only way I can get it to not bind is to wiggle the shifter in the neutral plane and try again.

[tirwin]

Well, good news. I finally got some free time today to get back to it. Opened up the shifter housing and discovered that the set screw on the end of the shift rod that holds the ball cup bushing had come loose.

Took it out for a test drive and it was good as new except that I need to slightly adjust the coupler in the rear tunnel again. A shift I made from 3rd to 4th nicked reverse.