Hello, I could use a little input on this one.

So less than 11 days to a non-refundable track day at Thunderhill and my tranny won't go into 2nd or 4th. I have disconnected the linkage and cannot engage 2nd or 4th manually. 1st, reverse, 3rd and 5th are fine. It's like there is not enough throw at the side shifter input dongle. It also seems to require a lot of throw to get 3rd/5th engaged to the point that the ball is starting to pull the bushing out of the socket.

Its a 914-6 transmission rebuilt and converted to side shifter by a local Porsche "specialist". About 9 years ago. My tranny has never shifted right since the rebuild and I kept telling myself it was the linkage or something else. Now the problem has presented itself completely! 4th was always "soft" but now its not there at all and 2nd has joined the party. No grinding just no engagement. The car was in project stage for long after the work was done so it tough to try to bring it back to the specialist.

Got any ideas, Is there anything I can adjust with the tranny in the car or should I pull immediately and try to figure it out. I have rebuilt Porsche engines but always stayed out of the transmission world.

thanks Daron

Disconnect the linkage at the tranny and see if you can put it in gear manually at the tranny. That will tell you if it's linkage or tranny. Make sure the arm is not hitting the case on the tranny at the side shift

Uhhhh, you read his post?

He even used the word "manually".


The Cap'n

There's a roll pin in the shift rod going into the tranny. Make sure it's not worn or falling out. Otherwise, it looks like you may have an internal problem. I'm a bit far away, but I'd be happy to help you deal with it. I'm gone on the weekends, though.

The Cap'n

Uhhh, thank you for pointing out that I missed that

Does sound like a pin or wollered out holes in the dongle

many thanks for the replies.

I went back out and checked the roll pin, seemed very likely but no luck. When I try to engage 4th manually i can feel/hear some thing sliding/slipping inside the transmission.

You put pressure on the ball dongle to select 4th and its very free, then it hits something and it slips. "sounds/feels" like a fork slipping on the shift rod. The wierd thing is for this to affect both 2nd and 4th it would have to be both forks loose on their respective rods. Of course when I picked up the tranny many years ago the rebuilder was still putting it together at the last moment. After having it for over 9 months of course. I have had fits getting this tranny to shift nicely over the years.

I dont support you can tighten the forks via the shifter access hole?

If not I guess its pull time

Here is what you have in there......Sounds like it's teardown time. I would first pull the cover\dongle off and take a look through the hole
Click to view attachment

John, go steal Lafluer's differential while he's not looking Isn't Paul Guard still a friend of yours? I know he sold the company but he might have a part or two around???

DONT TEAR IT DOWN!

There is a roll pin on the inside as well. Remove the shift selector console (drain oil, put in neutral, remove two nuts).

The outer roll pin may be fine, but it has an inner one for the shift comb. Easy/fast fix. To do it right, you should replace the O-ring on the console.

There is no other reason for the symptoms that you describe

If that doesn't do it, you might have a problem (broken spring, etc) in the detent circuit... happened to me. Common element.

Good luck.

Broken spring is not common, and would not cause the aft gears to need more pull and the fore gears to be un-engageable, though.

Thanks for all the replies and the great picture. Much appreciated. I will pull the comb as soon as I get home from work today and post results. Dr. Evil your theory sounds promising (I hope) but would that not also affect 1st/reverse? Anyway its time to get extra greasy in a hurry.

Daron

Daron, I'm tied up off and on until the 27th, if that's not too late I can help...

I can take a visual look on the 20th or 21st during the day and most evenings this week if you need some assistance. You can bring it to my shop.

Get a gasket/seal kit ordered.....

My recommendation is purely based on the external cone screws, bushings, adjustments being correct, which you addressed in the first post.

Searching for simple/common failure items is the name of the game. External stuff is first and most common.

Then you get to the selector console which has two roll pins that can fail. Typically they are not spectacular failures, they are insidious like you describe; loss of gears in one direction.

Your question about 1/R is a valid one and when I think about it it does make sense.

1-3-5 are in the same plane and are not impossible to get to.

R-2-4 are in the same plane and 2 & 4 are the ones that are failing. Why not R? Well, R has no synchronization hardware to mess with. It is a straight gear being engaged with a straight gear. No real resistance like 2 and 4. So, it glides right in with little effort. The only resistance you feel is the spring detente.

If it is not the inner roll pin (I will be shocked), you are gonna get into multiple failure points as then you would need two separate bolts to come loose on two different shift rods, and then only shift so that only one way could be selected. Very improbable.

Just pulled the selector console (dongle) and the roll pins are solid. Put it in a vise and could not get either upper or lower to slip/move in either direction. So draining the rest of the fluid to see I I can access the fork/rod bolt(s) via the selector console hole, a very long shot

Wont happen.

Are you SURE that your external linkage was perfect???

cheese and rice,aren't you done yet?

Your pinion shaft bearing is on backwards

So I pulled the gear cluster with the transmission in the car. Only took me about 1.5 hours, not really that bad to do!

Checked console roll pins with a vise, no movement
Checked detent springs and balls, all good,correct order
Checked fork bolt for tightness, does not appear to be any slippage

Paul S is gonna put a 2nd set of eyes on it for me tomorrow night.

Dr. Evil I hear ya and appreciate all input greatly but the thing would not go into 2/4 for anything, even manually with the linkage disconnected. I have done this before in the past so I know what it feels like to get these in gear manually at the tranny.

This is a 914-6 tranny with a side shifter conversion. Is there anything else you have to do to make that correct? Its never been quite right. I have made 3 generations of shift linkages over the years including stock, straight and double u-joint custom. and while each one got better it was never as good or tight as many stock 914-4's I have driven.

all in all a productive night but time for bed, yawnnn

thanks D


Click to view attachment

Click to view attachment

That garage is nicer than my house...

Normally there is no "backwards" on a straight roller bearing as there is no thrust. However there are advantages to locating the weakest part of the roller cage away from severe oil spray

The factory manual shows it is assembled correctly.......
Click to view attachment

Not being able to get it into gear manually at the console is not an indication of issues. That is quite common.

This quote:

"Its never been quite right. I have made 3 generations of shift linkages over the years including stock, straight and double u-joint custom. and while each one got better it was never as good or tight as many stock 914-4's I have driven."

continues to point to your shifter. You can easily see if there is anything obstructing the rods now. Move them with your hand. The only other thing I can think of is that the rods were never adjusted correctly, or that there are broken synchro blocks in 2 and 4. Not probable, but anything is possible.

The factory manual shows it in the orientation see in 912 and 911, or more clearly in the OLD transmissions. By the time they made the 914/901 they flipped them. Yes, it doesnt matter from a straight roller bearing stand point, but when you install the stack into the case and catch that small cover on the bearing and it pops off of your $200+ bearing, you will see whey they switched to facing the cage cover forward (towards the diff). But, what do I know

Can you shift it into 2nd and 4th while its on the bench?
you may see something (like a bearing moving in the intermediate plate) that may be causing this issue.
Neither shaft should move forward and aft....
Rich

From the pic he already removed 1st gear so that shaft can now move.