Difficulty getting reverse on 915

[Roger 911]

I have a '72 911 with a stock 915 5sp. I was at a DE last weekend and when I got in the car for the last run session, I was unable to get the car into reverse. All 5 forward gears worked fine, but when I tried to engage reverse, I always got 4th. I loosened the coupling and I was able to move the shift rod back and forth and twist it, but I could not get it to twist over far enough to the drivers side to engage reverse. This was true with the engine running or not. I grasped the coupling with a pair of pliers and was able to "pop" it over to reverse. I didn't have to apply massive pressure, but clearly more than I could apply with my bare hand. Reverse then worked fine until I shifted back into any forward gear, where once again, I could only get 4th when I tried for reverse. I repeated this process when I got home to get the car off the trailer and into the garage, and again, after I engaged the forward gear, no more reverse.

Here are my thoughts;

1. I am replacing the coupling with a Stomski. I don't necessarily think this is the entire problem, but my old coupling is pretty loose and this can't hurt.
2. I have read on this forum that if the tranny grinds going into reverse, that the clutch may need adjusting. At the moment, I'm not getting the grinding, I just cant get it into reverse gear. Regardless, I will check the adjustment of the clutch, probably tighten it a few turns.
3. If the above two actions don't fix it, I'm inclined to think that a fork is bent.

Does this make sense? Also, the tranny was rebuilt a few years ago. I use the car primarily for DEs. I would suspect I've done about a dozen DE weekends since the rebuild.

[ipacketeer]

It is all in the shift coupling adjustment, once you get it right, it will come out of 5th easily and go into reverse with a gentle pressure on the gear shift without grinding. 915 shifts just as good as any other tranny when it is healthy and the components set up right.

[Roger 911]

It seems to come out of 5th fine and when I "pop" it into reverse it doesn't grind. I just cant get it to happen with the shifter.

I suppose I could drive around with the cover off of the coupling area and a pair of vice grips attached to the coupling. Whenever I need reverse, I'll just reach back and yank on the vice grips.

Yes, I'm kidding.

[Eagledriver]

There are a couple of possibilities here. The connection in the tunnel could have slipped and made it so the neutral position of the for and aft motion of the lever is not aligned with the gate to move the lever to the right for the 5th/reverse location. If this has happened you can't move the shift lever to the right from the 3/4 plane. The coupling could have also slipped to the side so that the 5th/reverse plane of the gear lever is now aligned with the 3/4 plane of the transmission shift rod.

I'd disconnect the shift coupler and play with the shift lever exploring it's range of motion. Then get the tranny into 3rd gear (or put it there before you start this) and place the gear lever where you think 3rd should be and lock down the coupler. Shift gears a few times and adjust as required. You need to get the for/ aft motion set so the gear lever can go into the 5th/reverse plane while in neutral.

Don't think the clutch is your problem.

-Andy

[Richard Burns]

It sounds as though the reverse lockout is jammed. Lift your shifter cover and check what is happening as you try to get reverse.

[Roger 911]

I'm pretty sure it's not the shifter. Again, I can get ALL forward gears just fine, including 5th. When I loosen the coupler I can move the shift rod going into the tranny pretty easily into each gear EXCEPT reverse. To get reverse, I have to twist the rod with a large pair of channel lock pliers. I would probably have to amend my original post and say that I do have to apply a fair amount of force to get it to "pop" over to reverse. It really feels like something is jamming inside the tranny.

[dentist90]

That is weird. If you can rotate the coupler clockwise by hand to engage 5, but have to twist with a pair of pliers to get R it doesn't make much sense.
As you can see from the diagram the arm sticking out from the selector rod falls into the notch on the 5-R fork shaft. From there you either slide it up into R or down into 5. 5 and R are on the same shift plane because they share this same shift fork and sleeve.


Even with a bent or loose fork it would still engage the tab and slide fore-aft, the gear just wouldn't engage properly. This is truly strange.

[Roger 911]

I probably need to take it out on the road and make sure that indeed I am getting 5th. It feels like I am getting 1, 3, and 5 up top, but maybe I am only getting 1 and 3. If my "popping it over" actually engages the 5/Rev fork, this would still seem to imply something wrong internally. I guess the good news is that I can probably see the problem by taking off the nosecone.

[Roger 911]

A little update here...

It is indeed NOT going into 5th or reverse. Its not the shifer, coupler,etc. It is definately something inside the tranny. Again, it moves freely through the 1-2 and 3-4 planes. The only way I can get the shift rod over to the 5-R plane is by applying force to it with a pair of channel locks, effectively "popping"it into that plane. Reverse then works fine (no grinding, etc.) until you shift back into the 1-4 gears, after which you can't get 5/R.

I drained the tranny and removed the inspectin plate. I found no chunks of metal in the oil and the fork on the plate was tight. At this point, I am inclined to drop the motor/tranny and remove the tranny nosecone to ispect the 5th/Rev area of the tranny. It

Does anyone have any suggestions of things to try BEFORE I do this?

Thanks.