915 Transmission - No Fifth or Reverse

[kpsoerensen]

Car was shifting fine this weekend, went to take it out tonight and the reverse gear was not working. I pushed it out of the garage and took it for a drive to see if warming the transmission up would help - it didn't - and also revealed that I cannot enter fifth gear either.

Previously I would get a small amount of grinding on 3rd gear shifts, I double clutch now and no problems. And sometimes I am not able to engage 4th gear.

I pulled back the shift boot and the bushings look yellow/worn, I will replace these. I also took a look at the shift coupler, I don't have anything to compare it to but there is no obvious signs of anything broken.

There is a fair amount of play in the shifter when in neutral.

I'm going to try and adjust the coupler this weekend. I see this has happened to folks in the past, and am curious if changing out the bushings fixed the problem, or if it was something more serious.

Thank you.

[Url]

I hope for you it's just misalignment/bushings/... so check all those and readjust the coupler.

Does the lever go in the 5-R plane? If not, could be something (a tooth f.e.) in the gearbox blocking the shift fork.

[kpsoerensen]

Yes, the lever goes into the 5-R plane, it shifts through the lockout thing but not all the way into gear.

It feels like it is almost there (almost in gear), but not quite, if that makes sense.

[Flat6pac]

Kind of sounds like the selector guide on the inspection plate may be loose
If it’s loose replace the inspection plate so it doesn’t get loose again.
Bruce

[GH85Carrera]

Likely your shifter bushings are like mine were. There is a cup on the bottom of the shifter itself, and this bushing and then the coupler. Unless you have replaced them before, get a full set of shifer bushings and take a look at the coupler before you order. If the plastic parts in the coupler are shot decide the budget, replace the plastic parts, or replace the coupler with a new one, or a upgraded one. Once you know the bushings are fresh and right, then get the coupler adjusted.

[Reiver]

Replace all of the bushings and/or visually inspect them then reset your rear coupler...it may have come a bit loose and no longer allows the rod to go deep enough to engage the gears.
Failed engine mounts (collapsed) can effect this too by changing the motors orientation in relation to the shifting mechanism.

[kpsoerensen]

Thank you for the replies. I went ahead and ordered new bushings for the shifter assembly and the Wevo PSJ. I’ll first change out the shifter bushings and see if I can reset from there. Hopefully that works so I can confirm it was in fact the bushings, then put on the Wevo.

[Walt Fricke]

The kicker here is no 5th, and no reverse. If the fore and aft adjustment were out of whack, you'd expect one to work, and one not to. As well as issues with 1&3, or 2&4. So the finger would point to the side to side (rotational) indexing being off. 5/R work differently than the rest in terms of how movement of the shift lever creates movement inside the transmission.

My guess is you will find either the plastic cup bushing at the bottom of the shift lever is worn out, or you will find one or both of the bushings in the shift coupler are even looser than they are designed to be, and you weren't able to rotate the transmission shift shaft quite enough in the direction it needs to go for 5/R. It works by a finger on the shift shaft rotating into a slot milled into the shaft the 5/R shift fork is attached to. If the finger doesn't move enough to engage the slot, the shaft can't be pushed/pulled back and forth. I think the tolerance for misalignment is smaller here than for 1-4.

But replacing all the external wear items is the way to start. Keep us posted.

[MichaelSJackson]

kpsoerensen,

There is a bushing inside the coupler too. So you might as well install the Wevo PSJ at the same time. When I pulled my coupler, I was stunned at how deteriorated it was. Hard to believe it shifted at all. Hard to detect without removing. No sense adjusting the coupler twice.

[wjdunham]

Originally Posted by MichaelSJackson

kpsoerensen,

There is a bushing inside the coupler too. So you might as well install the Wevo PSJ at the same time. When I pulled my coupler, I was stunned at how deteriorated it was. Hard to believe it shifted at all. Hard to detect without removing. No sense adjusting the coupler twice.

The WEVO PSJ was some of the best money I spent on my 915 equipped car. My stock coupler wasn't even that badly worn and the improvement in shifting accuracy/feel was very noticeable.

[kpsoerensen]

Well this project begins with a tough choice regarding the carpet.

Curious if there is an easier / less destructive way to pull back the carpet near the shifter. I suppose I can either do two short slices perpendicular to the shifter:
(Firewall) - | - (Rear seats)

Or peal back the carpet which was replaced in the ‘90s and glued down very securely. Is eels like it will take a lot of force to pull it back and I likely won’t put it back better than I found it. .

Any alternatives? Any preference between these two methods?

[MichaelSJackson]

Remove both seats. Pull up the floor carpets at the center enough to pull up the carpet at the hump.

A little more detail than that (undo the gas pedal, remove shift boot, etc.) But no need to cut the carpet and you can glue it back in place.

[kpsoerensen]

@Michael - thank you for the tip. I’ll give it a shot tomorrow. Still a bit nervous to pull the carpet back - it’s glued down very securely.

I did order the Wevo PSJ and worked on installing that today. Good news is I was able to get into both 5-R, in exchange for 1-2 lol. So I’m bouncing between having either or right now. More adjustment needed but I’m glad to have isolated the problem to the shift coupler. the stock one was super sloppy upon inspection.

I’ve read a bunch about the adjustment process for the Wevo on this forum which has been helpful. In order to get the 5-R gears I turned the shift rod itself toward the passenger side, holding the coupler/transmission in neutral.

[Walt Fricke]

Sounds like you will find one or both of the bushings up by the shifter have gone bad, which would explain the loss of a couple of degrees of shift shaft rotation. So however much work it is to get to the shift tower, it will be effort well spent.

I don't recall having to do a lot of removal to pull my tower, but I can't just go look because the car is now track only and doesn't have carpet.

[kpsoerensen]

Was asked by another user to keep everything about this job in this thread.

I am installing the Wevo PSJ and I am having a heck of a time getting it adjusted. Right now the best I can do is either 1-4 or 3-R. I have done a lot of reading on this forum and have tried various suggestions

e.g.
- keep shifter in neutral and centered and move coupler toward passenger
- hold shifter in the 1-2 plane (still in neutral) and move coupler toward passenger side.
- I was able to get R by holding the coupler and actually moving the shift rod itself toward the passenger side.

Then the other variable is length. I'm not sure how that factors into finding all the gears, or if that's more static once you are able to catch gears, and the main variable being the twisting of the coupler.

Any tips are appreciated.

@Walt I think you’re right, and perhaps since the shifter bushings are in such bad shape perhaps that’s what’s making the PSJ adjustment so difficult.

[Reiver]

The length is important...adjusting for and aft. You want the same depth of engagement in 1st as in second. If there is lateral resistance in 1/2 from any spring load you should hold it 'centered' by hand while you adjust laterally.
It really takes some practice and feel once all bushings are replaced.
Finally....how are your engine/tranny mounts? When they deteriorate/collapse/settle they change the angle of the input shaft and can allow movement when driving that will change and mess with your adjustment.

[Kidasters]

When I re-did mine, I added the wevo coupler, the factory short shift kit as well as this:

Seine Systems > Gate Shift Kit

I'm not using the "gate" part of the seine kit - as I didn't weld the tab to the shifter. But - the springs do a great job of centering on the 3/4 plane.

Adjust as per Wayne's "Projects" tutorial. I've never had a problem since I did the mods.

[kpsoerensen]

@Reiver - wanted to clarify with you: hold the shifter in the 1-2 plane, keeping it centered, and then adjust the shift rod left right? There is no spring load when moving into the 1-2 plane. Also, the shift rod is the piece that moves left right - the coupler only has a few mm of travel left right. Correct?

Apologies in advance I’ve been working on this for 2 hours and just want to drive the car! Haha

[Reiver]

I have a spring load on both sides but always adjusted in the 1/2 plane and it was essential to keep the shifter stalk 'centered' as it will fall to one side or the other.
It has been a long time since I've done this so I am trying to remember what I do with this.
I first 'feel' the engagement of depth....between 1/2 or 3/4...you should have the same 'throw' for and aft...if not you will need to adjust the forward/rearward position of the coupler.
Then I check the lateral by going into 1st gear...holding the shifter in the middle of it's 'play' left right and check going laterally to 3 or 5th....if it will not go to 5th then some lateral adjustment is in order (mark your for /aft position as that will be easy to lose when you loosen the coupler).
You are searching for the sweet spot and it takes some attempts.
I also would drive a bit when it would shift into all gears...if I get too much 'noise' from the box then I adjust for and aft a bit.....it is usually a depth issue then.

As to your question...I put it into 1st gear and 'center' the shifter in whatever 'play' there is in that gear....does that make sense? Visualize what is taking place. The shaft into the tranny only has so much movement. When in first gear center the shifter when tightening the coupler...then try 5th/r...if it won't go into those gears then loosen the coupler and give it a bit more movement/engagement in the direction of 5th/r. Keep doing this until you can engage all.
If your depth...for and aft, is off you will often hear too much mechanical noise from the box as the gears are not totally meshed....then you adjust for or aft until you have a similar sound form 2 and 3rd....

Welcome to the intricacies of the 915....you'll get it...the more you try the more you get the feel of what is taking place.

At one time early on I thought this kind of thing a pita....it is a bit but it is also 'personality' and when you figure your 911 out you get this connectivity.
I've had my SC for 10 years now, rebuilt numerous systems myself and 'know' the car like no other...the damn thing talks to me when I drive it...swear.

[Walt Fricke]

Kid - the Seine weld tab performs the same function for 1/2 that the stock tabs perform for 5/R. When you spring load a gear selection, something limits the spring's compression. Without the tab system, that something is the ball on the end of the dongle pressing against the edge of the slot in one of the steel slots on a shift rail, which translates into pressure on the brass shift fork involved. This could lead to decelerated wear on the fork, which normally has no pressure on it once a gear is engaged and the engagement teeth and synchro ring do their job of holding the teeth together. The noticeable effect of this unwanted pressure, however, is some noise when in 1st or 2d

The predecessor to Seine was Robotek, and I installed one. Still have it, works fine. But I noticed the extra sound in 1/2. So I fabricated a hook and tab system, and it went away. Once a gear is engaged there is no residual pressure.

The original WEVO shifter did not incorporate any mechanism to deal with this residual loading in 1/2. I asked Hayden about it, but he felt it was not of consequence. He is a smart and knowledgeable mechanical type, but I wouldn't use a shifter system which didn't take up the spring pressure up front in the shift tower.

Porsche saw this as useful for 5/R. To be sure, 5 may be the gear which gets the most mileage, but around town you are in 1/2 quite a bit. The hook and tab system is a lot like the accelerator pedal stop, or the clutch pedal stop - keeps the forces where they belong.

This is off the topic of adjusting the shifter, though, and in no way related to the problems Mr. Soerensen has.