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

[Sandnick]

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

[pete3799]

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 .

[Sandnick]

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.

[911pcars]

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

[dave99]

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

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??

[911pcars]

Originally Posted by dave99

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

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:


Sherwood

[lonewolf]

You can never go wrong taking advice from John.

[dave99]

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....

[Arne2]

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.

[dave99]

Definitely worth a try... Cheers

[Sandnick]

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

[McLaren-TAG]

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.

[sugarwood]

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.

[Arne2]

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.

[McLaren-TAG]

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.

[rwilner]

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...

[rwilner]

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...

[917_Langheck]

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

[RSTarga]

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

[917_Langheck]

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.