915 stuck in reverse, help needed

[motomiata]

I have just reinstalled the engine and transmission in to my 72 after some engine out work. I have replaced the shift fork seal at the bottom and in shift shaft input seal among other stuff.

Now the 915 is stuck in reverse and I can not access the 5th-reverse plane. It sort of shifts in to 1-2-3-4 but feels odd. I have not started the engine nor driven it.

I was pretty careful not to move anything when replacing the shift fork seal.

I have studied the various threads related to this topic, but has not been able to find a situation exactly like mine.

Thanks for any feedback

Is this as simple as the reverse light shift thing or something more serious😳

[mikedsilva]

Sounds like the alignment of the shifter when bolted to the selector shaft is a tad off?

[porschyard]

So what happens when you put it in 1-4 gear and try to let the clutch out, if the engine stalls it is stuck in two gears at the same time. If it still moves in reverse than it sounds like you may have a problem with the shifter bushings or the shift coupler bushings or basic adjustment.
More info will help in a diagnosis. I see you are saying that you have not started the engine, how do you know it is stuck in reverse ?

Richard

[917_Langheck]

I had this happen when I didn't have the shift rod secured properly and was out of alignment. After I selected reverse it got stuck there and had the same symptoms; I could row through 1-4 but getting into 5-R was difficult and any gear selected while running resulted in reverse and stalling.

Lift up the rear wheels off the ground to take the tension off the box and try to reset the shift rod at the front or the coupler as necessary. My issue was at the front as that was where I had worked prior.

[motomiata]

Thanks for the replies.

The transmission shifted flawless before I dropped the engine and the shift coupler was removed from the shaft using he set screw, i.e. no changes has been made to the shifter adjustment.

I have removed the shifter fork and checked the alignment of the 1-2 and 3-4 shifter shafts OK. The 5-reverse shaft is pushed all the way forward, as in reverse engaged. And I tried to roll the car and the engine tries to turn clockwise when pushed back. Sp reverse it is.

Depressing the clutch and moving through the gears makes no difference. I can not move the shifter to the 5-reverse plane. I have no idea to how this has happened with the transmission out of the car and no internal movements. It was stored upright with the bell housing down, but how would that screw up the box?

I will start checking the reverse light contact pin.

[john walker's workshop]

Push the pin in. Has the trans been apart in the past?

[motomiata]

Originally Posted by john walker's workshop

Push the pin in. Has the trans been apart in the past?

Will do and report back.

There is no obvious signs of a previous rebuild, but I can’t tell for sure.

[porschyard]

Originally Posted by motomiata

Will do and report back.

There is no obvious signs of a previous rebuild, but I can’t tell for sure.

If you want to do a quick check of the lockout bullet pin it is fairly easy to remove this plug and look in the bore to see if the shaft is visible or the lockout pin is above the shift shaft.
Grab the plug in the pic with a small pair of channel locks and twist back and forth while pushing up, they usually are not real tight as it is just a interference fit
If in doubt stick a slim magnet down the bore and if you come out with a lockout pin then that is a no-go, this will allow the trans to be in two gears at the same time.
Not saying this is your problem but it fairly easy to check and one more diagnosis to confirm or eliminate.

Richard

[PeteKz]

Ditto what Mike said. If it worked fine before you dropped the transmission, I would look very carefully at the alignment of the coupling and shifter. Did you do anything to the shifter while the tranny was out? Any possibility that the shaft going into the tranny got bent while removing or installing? Try this: Undo the coupler at the set screw and pull the long shift rod out of the way. See if you can shift the transmission manually from the shift shaft alone. Try rolling the car back and forth while shifting too.

[motomiata]

Solved!,

Pressing the reverse switch pin did the trick. And it was surprisingly easy.

My 2 cents : drain the gearbox oil, support the transmission with a jack, remove the transmission mount, remove the speedo cable, undo and remove the reverse switch (22 mm ring spanner), remove the pin using a magnet, insert a 4 mm drill bit (shaft side inwards) , place a small block of wood on the chassis and use a small prybar to push in the drill bit. My drill bit was approx. 80 mm in length and protrudes out of the gearbox allowing the trick with the prybar.

The only tricky bit was inserting the wires in to the switch.

Lesson learned: keep the transmission in neutral when removing and installing!

Thanks all.

[blur911]

Originally Posted by motomiata

Solved!,

Pressing the reverse switch pin did the trick. And it was surprisingly easy.

My 2 cents : drain the gearbox oil, support the transmission with a jack, remove the transmission mount, remove the speedo cable, undo and remove the reverse switch (22 mm ring spanner), remove the pin using a magnet, insert a 4 mm drill bit (shaft side inwards) , place a small block of wood on the chassis and use a small prybar to push in the drill bit. My drill bit was approx. 80 mm in length and protrudes out of the gearbox allowing the trick with the prybar.

The only tricky bit was inserting the wires in to the switch.

Lesson learned: keep the transmission in neutral when removing and installing!

Thanks all.

That's great you figured it out. I had that once when I got a gearbox from a wreck, it was in reverse, but could get all the other gears too.
I ended up taking the drivetrain out again, front cover off the transmission and popped it back out of reverse. Didn't think of the switch pin, brilliant.

[PeteKz]

Gotta remember that too.

[mikedsilva]

ok... what stops it from happening again?

[tsuter]

Should be in every engine drop check list......"keep the transmission in neutral when removing and installing....."

[blur911]

Originally Posted by mikedsilva

ok... what stops it from happening again?

Transmission interlocks should keep it from happening. On mine I think it was the impact of the crash and inertia of reverse gear that made it move forward and lock into gear, normally the gearshift rod would be in the right position to pull it back out of reverse, but not if it goes in by itself.

OP's shifter rod must have moved when he replaced the shift fork seal

[tsuter]

Here's a pic of exactly where the shift rod arm/lever should be when the fork is out and you are replacing the seal.
You can manually manipulate the rod to get things back like this before you reset the fork in there.
Get it right!


When you set the plate w fork back in, make sure you straddle the arm/lever.

[motomiata]

Originally Posted by blur911

Transmission interlocks should keep it from happening. On mine I think it was the impact of the crash and inertia of reverse gear that made it move forward and lock into gear, normally the gearshift rod would be in the right position to pull it back out of reverse, but not if it goes in by itself.

OP's shifter rod must have moved when he replaced the shift fork seal

I’m pretty convinced nothing moved when replacing the gasket for the shift fork cover. And I’m really puzzled about it could happen. One question as for the shifting mechanism: the lever attached to the main shift rod (and hold in place by the shift fork) engages 1-2 and 3-5. The main shift rod turns further to engage the 5-rev shaft via tang that slots in to a cutout in said shaft. Pushed rear wards engages 5th, pushed forwards engages reverse. So what stops the main shift rod from turning away from the 5-rev shaft other than the gating at the gear lever?

[blur911]

Originally Posted by motomiata

One question as for the shifting mechanism: the lever attached to the main shift rod (and hold in place by the shift fork) engages 1-2 and 3-5. The main shift rod turns further to engage the 5-rev shaft via tang that slots in to a cutout in said shaft. Pushed rear wards engages 5th, pushed forwards engages reverse. So what stops the main shift rod from turning away from the 5-rev shaft other than the gating at the gear lever?

If it's in reverse or 5th the lever that shifts between 1-2 and 3-4 will hit the side of the shift guides if you try to move the shifter sideways. It can only move sideways when centered so that the end of the lever moves through the notches on the shift guides or in the case of 5th and reverse, out of the notches and beside them.

[motomiata]

Originally Posted by blur911

If it's in reverse or 5th the lever that shifts between 1-2 and 3-4 will hit the side of the shift guides if you try to move the shifter sideways. It can only move sideways when centered so that the end of the lever moves through the notches on the shift guides or in the case of 5th and reverse, out of the notches and beside them.

Got it! Pure logic. Still, how the box ended up stuck in reverse remain a mystery

[blur911]

Originally Posted by motomiata

Got it! Pure logic. Still, how the box ended up stuck in reverse remain a mystery

I'm waiting on a nut to finish putting a transmission together so could move stuff around while looking inside and figure it out, at least that's how it appears to me.