Reverse lockout

[sparkysvega]

I’m trying to adjust shifter after transmission rebuild . Coupler will not go back enough to allow shifter to clear lock out . I have had it grind coming out of fifth before on several occasions, leading me to believe it has been this way since owning the car . Is there some modification needed with this after market coupler ? The only thing I can think to do is cut some of the shift rod off to allow more movement , or replace coupler with a stock one . As you can see shifter is all the way forward and lockout is not yet clear . Coupler is butted to the shift rod , can’t make it any shorter.
Could shift rod be wrong for the car making it longer ? So many problems I’ve had to deal with . Car Is a 76 912E with 3.2 transplant and 915 box .

[Arne2]

Do you have a short shifter in the car? That can have an effect on the lockout adjustment.

[sparkysvega]

I’m not sure if it’s stock or short shift , but I was beginning to wonder if that could be it. I will have to measure shifter link to tell I’m guessing ? If so what are my options?

[MichaelSJackson]

I'd be very surprised if the the coupler has different dimensions than OEM. But I've been wrong lots of times.

Loosen coupler.
Put trans in reverse by hand.
Shift shifter in reverse (pass lock-out).
Now if you stir the shifter you should feel it follow a small rectangle of slop?
Place the shifter in the middle of this rectangle, so that it's not resting on any of the sides.
Tighten the coupler. You're now adjusted to shift past the lock-out.

Now try shifting to 1st. (Farthest travel from reverse, so if 1st works so will the rest.)
It should shift into 1st and also not be pressing on any of the sides of it's rectangle of slop.

If fine adjustment is needed, shift back into reverse and loosen coupler.
Pick a slightly different location in reverse's rectangle, to correct for the travel needed.

Repeat until happy.

Remember these adjustments are going to be reverse of the change needed, because all the sift motions are reversed by the ball swivel on the shift lever.

For example, if the shifter needs to travel further left to get into 1st, pick a spot a bit more right within the rectangle. Same applies to all four directions.

[sparkysvega]

Thanks michael, I’ll give that a try next time I go out . I measured the shift lever best I could with it still in the housing. It definitely looks like it could be a short shifter. Does that change this procedure any ?

[911pcars]

Is it possible you have a 901 shift shaft in the tunnel? It's a little longer than a 915 version. That extra length along with that aftermarket shift coupler may be the reason. Can try to revert to the previous setup to confirm.

My best guess,
Sherwood

[JSV798]

I think you need to make the linkage LONGER! I had this problem of catching reverse on downshifting from fifth; it's because the linkage is too short. Loosen the coupling and pull back GENTLY on the gear lever; this will lengthen the linkage. Don't move it at the coupler end more than 1mm at a time. Tighten coupler and road test. Repeat until satisfactory.

[sparkysvega]

If I make it longer by pulling back , when I shift forward it will bottom out sooner, still not clearing lockout mechanism because it will be longer , Stopping it before clearing . It’s already bottomed out at the coupler and making transmission engage 1-3-5 at a hard stop , not allowing lockout to engage in 5th.
Did 912e have a 901 ? I will have to research that , good point 911pcars .

[JSV798]

At the moment when you pull the gear lever back you are engaging reverse before you hit the lockout; this means the linkage is not long enough. What have you got to lose in trying my suggestion? It worked for me. Don't over think it.

[gled49]

+1, post #6, been there, 901 shift rod.

[MichaelSJackson]

Originally Posted by sparkysvega

Thanks michael, I’ll give that a try next time I go out . I measured the shift lever best I could with it still in the housing. It definitely looks like it could be a short shifter. Does that change this procedure any ?

sparkyvega,

A short shift kit will not change this procedure. It will make the tolerances tighter. Short shift kits basically change the ratio of the levers of the stick shift above and below the ball swivel on the stick itself. However, they must keep the bottom of the shifter at the same level so it fits into the existing shift rod in the tunnel. The bottom lever travels farther relative to the travel of the top lever.

After market shifters do other things than shorten the shift. (spring to return the shifter to the 3rd-4th plane, other lockouts, etc.) However to my knowledge, these all function on the upper lever arm (except Wevo gate shift) and the location of the connection of the bottom of the shifter and the shift rod in the tunnel is maintained.

(Of course there was an exception to this rule. Early inexpensive short shift kits used the OEM housing and a shifter with a longer lower arm. This required a spacer to lift the housing or a spacer to lower the connection in the tunnel.)

Clear as mud?

[911pcars]

Originally Posted by JSV798

At the moment when you pull the gear lever back you are engaging reverse before you hit the lockout; this means the linkage is not long enough. What have you got to lose in trying my suggestion? It worked for me. Don't over think it.

The range of point-to-point shift lever distance is limited by the opening in the rubber buffer in the shift housing. To provide complete engagement in each gear, the shift lever must be vertical while in neutral and the shift shaft length must allow full engagement in each fore and aft gear position w/o hitting the rubber buffer. If the shift shaft is too long or too short, some fore or aft gear positions won't fully engage.

The factory adjustment via the shift shaft clamp with either 901 or 915 shift shaft is adequate (I have used both). I haven't confirmed using the longer 901 shaft and an aftermarket coupler.

Sherwood

[911pcars]

Short shifters reduce the throw between gears. Most do this by changing the fulcrum point of the shift lever (longer lever below the fulcrum point). As a result, this should provide more fore-aft motion range of the lever relative to shift shaft motion. This should provide add'l lever movement and allow a longer shift shaft with an aftermarket coupler, but this is theoretical and to be confirmed.

Sherwood

[Walt Fricke]

It is easy to get lost with this stuff. The shift lever motion is reversed in the shift tower. For gears 1-4 the motion is reversed again inside the transmission. But not for 5/R, but happily following how all that works isn't needed here.

This picture shows that the horizontal parts - mainly the long tube and the coupler - are adjusted to be too long. That's why the shaft of the shift lever had not moved forward enough to let the pawl spring shut.



To engage 5th you are moving the horizontal parts back. The gear change part won't move any farther back inside the transmission. Otherwise, all the gears work fine (because there is some plus/minus in their engagement space).

You have figured this out, so the advice you need is how to shorten all that.

I would disassemble the shift coupler. Loosen the clamp and pull the splined end of the long rod out of the coupler. Maybe remove the hose clamp, but first pull the large black bellows boot so you can see how the coupler is attached at that end.

If it is possible to move the attachment more toward the transmission, do that. You don't need much. But the stock attachment there is with a grub screw into a short hole in the transmission shift shaft, so it isn't adjustable for length or rotation - those you do at the front of the coupler. But look.

If you can'd do anything there, it looks like you can shorten the clamp by grinding its rear end. Your photo seems to show the splined rod ending before it bumps into the front of the coupler. You don't need much, and that should do it. But this is assuming the clamp is a separate piece, and looking again at the picture maybe it is integral with the joint which is nicely covered by the orange rubber. These are a common high end coupler replacement, and I've never needed one.

In that case you should remove the whole coupler to examine how to shorten it on one end or the other. That might be easier than trying to grind the splined end of the long rod with a grinder while it is in the car, and removing it from the car is a huge PITA. Perhaps if you ground off the forward end of the coupler you could reinstall it a bit forward - to the end of the rod's splines, as you have now. Or do both - shorter coupler end, shorter (just a bit) splined rod.

Or install a stock coupler. Be sure to buy and use the plastic bushings which have a round, and not an oval, hole where the cross pin goes. That gets rid of the obnoxious slop in the stock couplers, and shifts every bit as well as this fancy aircraft grade part - which you can sell.

The only other place where there is a separate part which is part of the length of the long shift tube system is up front under the shift tower. The cup whose bushing holds the ball on the end of the shift lever is a separate part, held to the long shaft by a grub screw. The screw can get loose, but that would effectively shorten the rod a bit, so that's not the issue. If the bushing is worn, that too would shorten things, so a worn bushing (which is common) isn't the issue.

I've had this adjustment not quite right on occasion, and I had to remember to really force the lever into 5th as far forward as I could. You want the shift tower boot pulled up while doing all this, so you can see what the pawl is doing - as in your photo. Once a normal push into 5th makes the pawl snap every time, you are good.

[sparkysvega]

Thanks Walt . I think I will either shorten the shift rod about a quarter inch between coupler and clamp. Can’t do it on transmission side, it has stock connection with grub screw . I might also look for a shift rod for a 915 since I will be pulling engine one more time . I also found one other problem when I removed the shifter . I found it with this aluminum 2 hole spacer, and The rod guide bracket was dropped down beneath tunnel like shown . I thought this was normal but have since seen a photo with rod guide mounted to tunnel on the single rear shifter bolt seen here. I tried removing spacer and bolted the guide properly To see if this corrected the problem . The shifter now binds . I’m guessing this is a home made short shift adaptation. Also , thank you everyone else for your help. I appreciate and value everyone’s input . It is nice that you all gladly share your knowledge . I

[walt]

Yes, aluminum spacer used for short shifter.

[john walker's workshop]

Buy a used, stock shifter assembly and get rid of the stupid short shift stuff. Likely your whole problem. The 912E came with a 915 trans of sorts and a 915 shift rod, so unlikely that someone put in a 901 shift rod.

[sparkysvega]

Thanks John . I think I will look for a stock shifter .

[john walker's workshop]

A visit to the 911 used parts forum usually turns one up.

[911pcars]

All you need to revert to as-factory equipped:

a. Remove that rectangular spacer
b. Replace the existing SS lever with a factory shift lever

However, I don't think that's the solution to your shifting issues. Can we assume it shifted ok before installing the helicopter U-joint? If so, that's a clue.

Sherwood