915 linkage play

[OldSpool87]

I have a n ‘82 SC with fresh built 915 (2016), new tunnel bushing, new shift lever ball bushing, new Wevo PSJ and a Wevo shifter (older).

I have noticed this fore/aft play while the care in in neutral (engine off):

https://youtu.be/F1SS6ww2Lz0

The car shifts well with the exception of a slight kiss to reverse every once in a while in a 5-4 shift.

All the play seems to be between the PSJ and gearbox.

Is this normal neutral tolerance? It makes getting the lower part of the shifter vertical while adjusting a little vague.

Thanks for any feedback.


Sent from my iPhone using Tapatalk Pro

[gomezoneill]

Pull back the boot and do another video maybe the coupler is faulty. If that play is in the transmission that would mean the shift forks are loose, the dongle is worn,or the shift guide ( that's the small rectangular cover on the bottom of the trans) inside the trans may have come loose.

[OldSpool87]

Additional video:
https://youtu.be/GKkr25yEu04



Sent from my iPhone using Tapatalk Pro

[OldSpool87]

Trying again:

https://youtu.be/GKkr25yEu04


Sent from my iPhone using Tapatalk Pro

[nene]

I have noticed that my 86 Carrera's tranny has the same play and assumed that was "normal".

[914Ravi911]

I have the same play also and I thought it was normal and I didn’t want to go looking for more trouble.

[OldSpool87]

Good feedback and appreciated. Thanks.

[OldSpool87]

So I have had some conversations and conclude I can live with the play. What I can’t seem to remedy is an intermittent grind of reverse on the 5-4 shift. Just when things are seemingly set up in get the little kiss of reverse coming out of 5th. I’m thinking I need to turn the coupler ever so slightly while maintaining the length of the linkage (no fire/aft adjustment). I just have really no idea which way to go despite having read every 915 thread.

All bushings, coupler and gearbox are new.

Any help is appreciated.

Thanks.


Sent from my iPhone using Tapatalk Pro

[Flojo]

Originally Posted by OldSpool87

little kiss of reverse coming out of 5th. I’m thinking I need to turn the coupler ever so slightly while maintaining the length of the linkage

yes minimal adjustment.
and what I did a s well: I lengthened the reverse lock pin by winding it a little further in towards shift rod.

[OldSpool87]

Originally Posted by Flojo

yes minimal adjustment.
and what I did a s well: I lengthened the reverse lock pin by winding it a little further in towards shift rod.

Right. Thinking about that and putting in some stiffer springs to bring shifter into 3-4 plane more decisively.

Any thoughts on which way to turn the coupler?

[Flojo]

Originally Posted by OldSpool87

Right. Thinking about that and putting in some stiffer springs to bring shifter into 3-4 plane more decisively.

imho DON'T !
this will result in more springload and ogment noise from trans.
I'm going for even softer springs.

read:
Wevo shifter noise

[JSV798]

Originally Posted by OldSpool87

So I have had some conversations and conclude I can live with the play. What I can’t seem to remedy is an intermittent grind of reverse on the 5-4 shift. Just when things are seemingly set up in get the little kiss of reverse coming out of 5th. I’m thinking I need to turn the coupler ever so slightly while maintaining the length of the linkage (no fire/aft adjustment). I just have really no idea which way to go despite having read every 915 thread.

All bushings, coupler and gearbox are new.

Any help is appreciated.

Thanks.


Sent from my iPhone using Tapatalk Pro

DO NOT ROTATE the coupler. Your problem is that the linkage is too short. Loosen coupler and pull back GENTLY a fraction; this will lengthen the shaft. Tighten. Test and redo until you get a clean change.

[JSV798]

Sorry, that should read pull back GENTLY on the shift stick/gear lever. Don't lengthen by more than 1mm at a time. On the fore/aft play in the coupler I have this on a new one and don't think that it is a problem

[OldSpool87]

Originally Posted by JSV798

Sorry, that should read pull back GENTLY on the shift stick/gear lever. Don't lengthen by more than 1mm at a time. On the fore/aft play in the coupler I have this on a new one and don't think that it is a problem

I actually did this at lunch and did not have any grind. I hope it’s in it’s sweet spot. What was vexing was how intermittent the grind was.

[KTL]

You shouldn't be able to touchreverse if your WEVO shifter is adjusted correctly. Read the instructions and make sure the shifter is encountering the reverse lockout plunger inside the shifter. It should function similar to the factory shifter in that you must be clear of the reverse lockout mechanism by being in the 3rd-4th gear center plane.

https://www.wevo.com/Products/ShifterProducts/ShifterImages/WEVO_915_Shifter_INSTRUCTIONS_2009.pdf

If you look at how an original Porsche shifter works, it's a little bit clearer how this reverse blocking occurs and it's pretty simple how it does this. The lockout is accomplished with a spring loaded small teardrop shaped metal plate mounted on top the shifter housing. When the shifter is placed into 5th, the shifter lever encounters the teardrop and rotates it clockwise. When the shifter is fully into 5th gear, it will clear the tip of the teardrop, and then the teardrop is allowed to rotate back to its original position. Then when you move the shifter out of 5th, the shifter is forced to follow the shape of the teardrop. The teardrop is not allowed to rotate any further counterclockwise than its resting position and therefore the shifter is effectively blocked from entering reverse. Only when the leftward movement of the shifter has gone past the tip of the resting teardrop can the shifter go downward, and that is into 4th gear (or 2nd, God forbid......... ). At that point, the only way you can go for reverse is to deliberately move the shifter straight to the right and then pull downward.

The fore-aft play is not in the shifter linkage when you've got nice fresh bushings. The play is primarily internal to the transmission and there's really nothing you can do about it. The "slop" you feel is the clearance inside the transmission between shift rod dongle (nice word, I know) and the receiving block (s) on the shift rod, along with the clearance between the dongle and the support gate. There's also a bit of play in the area between the gear engagement sleeve and the brass shift fork.

Gordo2 here on the forum put together a very nice video of the transmission operations going on inside, showing you what happens when the main shift rod is operated by you the driver with the shifter.

https://www.youtube.com/watch?v=LLEWjNRjJTI

It's pretty cool how the forward-backward and side-to-side action of the shifter is translated into forward-backward and rotational movement to operate the main shift rod of the transmission, which only moves forward-backward and rotationally. This main shift rod translates the shifter movement into action that engages the gear selector rods for either gears 1st & 2nd, 3rd & 4th, or 5th & Reverse. Note how gears are paired with each other because they share a selector rod, which means they are adjacent to each other inside the transmission.

When watching the video, note that the slop you feel is the forward-backward clearance of the dongle when it is inside the block on the rod and the clearance of the dongle within the gate. In other words, note how there's a some clearance between the fat tip of the dongle and the "window" of the block when he rotates the dongle into the block. Later when he holds the removable plate in place underneath the dongle, you can see how the gate supports the dongle in its hole, which creates a pivot point, and that support forces it to move forward and backward. You can also see there has to be some clearance between the fat area of the dongle (where the hole is located) and the inside edges of the gate.

So there's basically three points of clearance:

-Tip of dongle inside the window
-Body of dongle inside the pivot gate
-Pivot point hole in the midpoint of the dongle.

All those clearances add up to make up the slop you feel and it's an unfortunate circumstance needed to allow those parts to move freely and not bind.

Plus the other thing to keep in mind is that this dongle movement shows how important that removable plate is. Most notably the gate itself. Unfortunately the weak point of the plate is actually where the gate mounts to the plate. The force of selecting gears is hinged on that gate and the three 6mm studs threaded into the plate to hold the gate can sometimes pull out of the plate and strip the threads- in hindsight it would have been good if the plate was made out of steel instead of aluminum. So make sure those studs are tight in the plate. In some cases the plate needs to be repaired or replaced. I found on my racecar transmission that the plate was drilled out for longer bolts that pass thru the plate. Plus the heads of the bolts were tack welded to the gate.

third gear squeal

[OldSpool87]

^ awesome post and thank you. So does the Wevo do away with the “tear drop” in favor of the lock out plunger on the top plate?

[KTL]

Yep that's correct. The WEVO has that plunger pin that contacts a steel button that is on the shifter lever (I think WEVO calls their lever a beam) and that's what determines whether the shifter is guided by the plunger or blocked. This part of the WEVO instructions refers to that:

"With the hex bolt in the pinch clamp all tight, check that 5th gear can be selected and that moving the Gear lever out of 5th gear into neutral can be achieved cleanly – without being fouled by the Reverse lock-out plunger (27). The gear lever will try to stand vertical as soon as 5th gear is cleared, positioning itself in neutral of the 3rd / 4th gear plane. If the Gear lever is set too far forwards, you will not be able to catch and depress the Reverse lock-out plunger (27), if the Gear lever is set too far back, you will not be able to cleanly select neutral from 5th without fouling the Reverse lock-out plunger. "

So if you're touching reverse, I think your shifter is too far forward and you're not activating the reverse lockout when you go into 5th. Because as I understand it, you're able to come out of 5th and grind reverse. Which means you're not being blocked from it.

I know from experience what that feels like. When I unknowingly had a crumbled ball socket bushing in my factory shifter, on top of it probably being poorly adjusted, the reverse lockout teardrop wasn't falling into place like it should. I downshifted from 5th and leaned on reverse (thankfully it didn't actually engage) at like 5000rpm and almost 100mph

Reverse is not synchronized and therefore that probably saved me from being able to select it? Reverse is just two rounded gear faces that engage each other directly. Here's what it looks like- take a look at the top picture with the small gear and the fat blunt teeth. You can see the face of teeth is all chunked from years of crunching reverse. Not all at 100mph, but that one time surely didn't help.....