915 prob fixed. Big thanks to Pelican forums and John Walker!
 

Big thanks to the Pelican forums, and the sage advise of John Walker in particular. The instructions posted here from John addressing my problem turned what first appeared to be a major issue into an easily remedied minor inconvenience. Here is the story:

I installed a Seine GSK and Ed's coupler bushings into my '84 a few weeks ago. Both items are great, but after a bit of driving, I felt that I needed to fine-tune the coupler adjustment a bit. Since I already had a new-to-me replacement console (Parts Heaven) and leather shift boot/knob (AGLA) on the way, I figured I'd tweak the adjustment while I had it all apart.

Side note - I have found that while the coupler adjustment for side-to-side is well documented, the fore-and-aft adjustment is rarely—if ever—mentioned, either here or in the Bentley. And in my car with factory short shift kit, the fore-aft adjustment window for proper function of the reverse lock-out is quite small. I have to adjust the static neutral position well forward, very close to the fifth gear gate tab. Too far back and the lock-out won't trip into place. Perhaps this is caused by the short shift, I don't know.

So on Saturday, I removed my original, damaged console and removed the shift tower to have the GSK's tab welded. After that was done I proceeded to re-adjust the coupler. Somewhere in this process, it went sour. I'm not certain what I did, but I got the adjustment far enough out of whack that when I tested it by running through the gears, suddenly everything felt wrong. No matter how I adjusted it, there appeared to be gears missing. I appeared to have lost a good part of the side-to-side motion.

On further checking, it became obvious that most of the time, I had two gears engaged at once, and one of them was always reverse. While I don't read every thread here, this seemed familiar to me, so I searched the forum for "915 reverse stuck" and got numerous hits, mostly all relevant.

Several of these threads had posts from John Walker which recommended removing the reverse light switch and pushing the rod found there back into the transmission. Doing this should disengage reverse gear. John noted that sometimes the rod will go in fairly easily, but other times it might require a bit of effort.

I decided that to try to ease the process, I put the shifter into what would appear to be neutral, at which point only reverse itself was engaged. I had the left side of the car up as high as I could get it with my floor jack, and supported by jack-stands front and rear. This left the left rear wheel well up in the air. I released the parking brake, then pulled the reverse light switch and pushed on the small rod found inside. Wouldn't budge, but that didn't surprise me. So I pushed on the rod while jiggling the left rear tire back and forth, and that worked—the rod popped back into place and the rear wheel spun free! I was back in neutral!

After putting everything back and getting the car back on the ground, I proceeded to (far more carefully) adjust the coupler correctly, and then installed the new shift boot/knob and console.

Thanks to this forum and John's great advise, what certainly sounded like a really bad problem turned out to be a only minor delay.

A few questions remain—is there any fallout from this problem? Will it be more prone to do this again in the future? Or was it solely caused by my ham-fisted job at the coupler adjustment? If I keep the coupler and linkage properly adjusted and maintained, is it unlikely to happen again?

No ideas on whether I should be concerned about a relapse?

That is interesting. I purposely moved my shifter closer to me so I would not have to reach so much when I shift.

Maybe I need to revisit my adjustment and place the shifter via couple dead center as PAG designed. ??? I have no issues, but I hate to have the opposite what you are going thru with 5th.

As far as reverse issue, I think you are good now since all is properly adjusted. But time will tell. How long has it been since the correction?

Not long, I fixed it yesterday, have driven it a couple of times since. All seems fine now, all gears engage as they should, and the lockout is now working reliably. I don't know what actually causes a 915 to refuse to come out of reverse, but many cases that I read about seem to be prompted by sloppy couplers or poor adjustment, so I'm pretty sure I did it myself. Hoping that now that it is adjusted correctly, with all new bushings and such, that the reverse problem won't reappear.

I think with JW's help, you got it 5X5. Keep us posted, I am very curious of knowing if shifter must be centered fore/aft via the coupler or not.

My buddy, well known here did the coupler adjust just south of center and he had no issues. But I want to be sure.

I agree, if I could adjust mine farther back and still have a working reverse lock-out, I'd do it. But even adjusted dead center fore and aft on my car will not allow the lock-out to work. Adjusted that way the lever does not move forward far enough to allow the lock-out tab to spring back into place. I strongly suspect this may be due to the factory short shift on my car. With the pivot moved up as it is, the lever doesn't move very far that close to the fulcrum.

In any case good to read she is running again. RSD!

adjustment...they are so critical and the trouble is (esp with the coupler) that when you loosen it up to move it a tiny amount....it moves like an inch!!

I messed with mine WAY more than I should have had to also. I ended up removing the console to see what was going on (I was either nicking R or stuck somewhere) and found that I needed two more hands to help me.

After I "nailed it" about 1-1/2 years ago its been sweet ever since. I hope you got it now! I think you are fine and should not have any issues here forward on the matter.

I had the same stuck in two gears problem, solved the same way, it was a month ago and it has not re-occured. Have had the car out 3 times on some twisty roads and shifting fine.

W

Same problem last year after an engine re-build, same advice from John Walker, same results. For 94,000 miles, my 915 works pretty well but not before proper adjustment.

OK, thanks to all for the feedback. I knew that I was far from the first to have the "stuck in reverse" problem, and how those issues were resolved. But I had not seen any feedback on long-term fallout, if any. Good to hear that the problem does not seem to come back (unless I were to botch the adjustment again).

moving the shifter location
 

if it's about personalizing our cars, anything is possible

we have been doing that for years in Manx VW buggies

what we have to do is cut the shiftrod shorter - VW guys sell a replacement coupler to install once we do that


.

Very interesting to read this. I have a '86 with a 915 gear box. Mine shifts OK, but not great especially engaging 1st and up or down into 2nd. I have read many times that there should be a little play in the shifter when in 5th gear, but mine is rock solid in 5th. I am thinking about going through the adjustment procedure, but am I opening up a can of worms?

I had the same problem, twice, when I first bought my car, I later attributed it to running the wrong gear oil. Since I switched to regular gear oil I haven't had any issues.

What do you consider "regular gear oil"?

Oh my, don't go there, someone may have an aneurysm :eek:

For a 915-

Non synthetic, non limited slip, cheap ass, 3$ a qt. generic frikken gear oil. :)

I am using Kendall 75 or 80/90W.

Oh you've done it :D

P.S. I am not racing in Fla.

I just did exactly the above. Eds new couplers, had it shifting really good apart from 5th was a beeatch. Decided to adjust it one more time this evening and it became stuck in reverse gear. I had to get my wife out of bed so I could push it back onto our drive. She wasnt pleased.

Finaly it seems to of dropped out of reverse and its now in neutral. Had to walk away as i was tired and its dark.

Fresh eyes and daylight at the weekend should fix it.

So what transmission oil is everyone using? Did someone say swepco? Or kendall? Perhaps I should start a thread on it? ;-)

ED

Got out of reverse...
 

Thanks to all the perfect advice and especially JohnWalker's incredible knowledge, I put my car on stands yesterday and removed the reverse light switch. Car had been stuck in reverse, shifter in neutral position, same as all the other "cases"...
Funny thing was, that it seemed like there was no pin present, which is why I just stuck a drill into the hole and pushed it in, using an allen wrench as a lever. I was able to push it out of reverse rightaway and had a freespinning wheel! Now I have to adjust the shifter so I don't stick it right back into reverse...
Thanks a lot guys, you really are the bomb! I really don't call myself any sort of mechanic at all, but even I was able to do it!!;-)

I do have 2 questions though: 1) Is it possible that the pin inside the reverse light switch is completely missing? 2) Do I have to top my tranny oil off, since I did loose some of t in the process....

I will have to put he car on a lift anyways, since one of the cables of the reverse light switch broke off ( it was very loose already when I opened it)

Thanks guys!
Nick from Germany

If the pin is missing the reverse lights won't work.
Shift into reverse and test the switch with an ohm meter.
If there's continuity the pin is in there. If not could be a bad switch or the pin is missing.

Do a search on reverse pin. Someone here made one out of a drill bit with all the dimensions included .

Thanks Pete... If the pin is missing I'll probably just order one at Porsche, depending on the price of course..;) I did see the post on the "homemade pin" though.

Seemingly small adjustments at the shift coupler can result in enough actual movement to either over or under-shoot the desired gear position.

The factory shift housing provides a window around the shift lever (actually the rubber buffer under the top carrier plate) that defines the limit of shift lever movement in all four directions (fore-aft, left-right). As such, the lever must start in a mid-position to fully access all 6 gears. BTW, one can enlarge the rubber buffer opening slightly to provide a little more leeway. The shift housing also provides some fore-aft/left-right mounting play with its connection to the tunnel.

Ideally, the shift lever should sit vertically while in neutral. This should provide an equal range of motion in all directions. For example, if the shift coupler is adjusted so the shift lever favors the driver in the neutral position (non-vertical adjustment), this decreases the distance the lever can travel before hitting the rubber buffer and may decrease the needed travel to fully engage one or more gears.

Same with the left-right adjustment. This could also result in the gap between reverse and 4th gear positions not being "in sync" with the fixed position of the reverse lockout pawl.

Remember. All this happens inside the gearbox with the longish shift tube and articulating linkage all contributing to the proper movement of the shift forks to select the proper gear.

Hope this helps,
Sherwood
SeineSystems.com

Mine shifts into gear every time but if I'm too quick changing gear it crunches :eek:

I heard these boxes were known for that but I have to be really careful. My brother drove the car yesterday and could not change gear without crunching. Should it be that bad??Checked oil level and clutch adjustment and all looks ok.

Do I live with this or does it need a rebuild??

If all linkage settings and adjustments are to spec, could be an internal issue (e.g. worn synchromesh). Do all gears "crunch"? Upshifts and downshifts too? Typically, 1st and 2nd bear the most brunt from rushed gear shifts and most overworked synchronizing activity. A partial blame could lay with the previous owner in terms of his/her driving/shifting style.

As shaft rotational speeds become closer, the synchros have less work to perform. When upshifting, wait for the engine rpms to drop while applying slight pressure to the desired gear.

When downshifting, the synchronizers work the hardest to synchronize shaft speeds for eventual shift completion. If worn, it'll be harder to downshift. Forcing it in only exacerbates the wear and breaks things. I suggest learning how and why to double-clutch for smoothest downshifts and for long service life.

Lot's of unintelligible and incorrect youtube attempts. IMO, this is the best explanation so far:
<iframe width="560" height="315" src="//www.youtube.com/embed/zy0BfG_CG2Y" frameborder="0" allowfullscreen></iframe>

Sherwood

You can never go wrong taking advice from John.

Thanks for that,
It happens going up and down gears. I never miss a change, it just grinds on the way in if the revs aren't right....
:eek:

Sounds like the synchros are all tired, to me. Either that, or the gear oil used is too slippery. The 915 synchros don't like synth oils. Here in the States, the oils that work best in 915 transmissions are Swepco and Kendall - non-synth in both cases. Worth an oil change to see if it gets better before going the rebuild route.

Definitely worth a try... Cheers:D

Good morning 911-friends...

I do have another question regarding my reverse light switch/pin...As I mentioned before, I have the impression that the pin inside my reverse light switch is completely missing (I used a drill bit to get the tranny out of reverse). Now here it is: Is it possible that the pin gell INTO the tranny and if so, might it cause any damage if it is not removed before driving?

I am going to adjust my shifter/coupler this weekend (haven't touched it since I got reverse out), and I wanna make sure that I don't do more (serious) damage....

As always, thanks for your expertise....
Cheers,
Nick

Adding this info in this thread since it seems to be the more complete 915 Reverse stuck thread.

Couple of tips for those that are doing this with the engine/tranny in the car.

You'll need a 22 mm wrench to remove the reverse switch. More than likely you'll not have enough room with a regular ratchet so use a 22mm crow foot or maybe a 22 mm offset wrench.

You'll also lose tranny fluid so prepare for that. Depending on how much time you wrestle with the pin you may lose a pint of fluid.

I had a ***** of a time as manual pressure didn't do it and fiddling with the rear wheels didn't do it for me either. It's about a thumb's width in there so there's not much you can do for leverage and I tried a wooden handle and other things but they were no able to get deep enough to push the pin.

What ultimately worked for me was using a 14 mm allen 1/2 inch socket and I wedged it into where the switch goes, making sure it was pressed up against the pin and then a small pry bar wedged against the socket using the seam of the car for leverage and pulled the bar, pushing the pin in. it took a fair amount of force and there was no doubt when it finally went in.

Thanks Pelican for always having the info that allows me to afford the P car hobby.

Can someone quickly explain how the car is even drivable if it's stuck in reverse?
This seems like a lot bigger issue than "something seems off".
I am picturing a car loudly grinding b/c the reverse gear is getting shredded as it goes forward.

The car is not drivable - that's the point. In fact, the transmission is completely locked up when it is in two gears at once. Let the clutch out and the engine stalls and dies. Can't move at all.

Not drivable is not necessarily the case, if your get it out of the non reverse gear the car is then drivable in reverse. The problem (at least for me) was that reverse remained engaged and you can not get back into it to disengage it. That's where the reverse lockout comes from.

Just wanted to mention, I have all the symptoms described here after a recent gearbox rebuild and I'm highly encouraged that this may fix it. I hope getting the reverse switch out is not too painful.

Things I wish I had done before bolting it all back up...

Ok. I took my reverse switch off and there's no pin in there.

Is there supposed to be a pin?

Where can I get one?

I put the shank of a 5/8 drill bit in there and tried to lever it while rocking the wheels...no joy for me. But I don't think the drill bit shank was 100% aligned.

Any thoughts or ideas?

See attached pic...

http://images.tapatalk-cdn.com/15/09...67370c65d1.jpg

Bringing this thread back up... (pun disliked at the moment)

'84 US Carrera, standard trans. 1st and 2nd sychros and dog teeth, and shift sleeve (930.302.411.02) replaced 35k mi. ago.

Pulled into a parking spot this morning - drive to work was normal, no issues, bad sounds, etc. Went to back out just a little and couldn't get reverse. Not unusual as sometimes these boxes line up tooth tip to tooth tip so I selected first and got no forward movement. Tried reverse again and no reverse. Let out the clutch in neutral and had reverse! Grr.

Just want to get a consensus from the group to see if this issue is similar to the stuck reverse pin problem. I've checked the coupler bushings and they are intact, and there is no apparent movement by the coupler on the shaft from its prior fixed position - everything is tight and moves as expected.

As mentioned, the trans has been fine, no clutch issues, no changes to any components, no offroading or harsh potholes run through, no racing or tracking since November last year.

Thanks

Did you check the bushings at the base of the shifter and on the selector rod in the tunnel?

The shifter bushings were looked at just a while ago and they were beautiful and intact (both shift bushings and coupler replaced May 2014). Not too sure about the tunnel bushing, but people who have had total failure of that specific item have not mentioned this as a result, just less than solid shift feel.