Difficulty shifting / getting into gear

[Jascha]

I would really appreciate some creative / collective thinking on this shifting puzzlement.

Quick background:

My new p-drive is a well-cared for 85 Targa with ~120K miles that had a good lineage of owners including a fully documented and professionally 915 rebuild with new clutch (~ 8K miles old).

I have developed an intermittent problem shifting into any gear. After I realigned the shift-rod coupling the shifting got considerably better. Without warring or progressive deterioration I lost the ability of selecting any gear (without the risk of girding if forced) but could get going by turning the engine off and so I went for few more weeks

I did a complete changeover of every bushing in the linkage (shift lever-->shift rod coupler).

After a nice round of congratulatory kudos from the good wife for a job well done and trouble free driving for ~3-weeks I am back at "zero". As of last week I was not able (again!) to shift but could get into gear with engine off and continue shifting trouble free until I got home (~20 miles).

I read all the archives and drained the trany oil (Swepco 201), took off the shift cover and found no loose parts, fork looks perfect and not loose…


Any and all suggestions as to where I might look next (e.g. set screw on shift-rod coupler…?)

Thanks!

Jascha

85 Targa
96 993

[Bones]

Have you investigated the clutch and it's adjustment yet?

[Jascha]

yes... did that by the 101 P-book (replaced cable) as per specs

[Bones]

Can you select all gears with the engine turned off?

[Jascha]

That seems to be the only way I can get going when I am in traffic and have to respond to a harried horn-blowing mate...

Once I am in motion "things" seem to get realigned (cosmic forces at play?) and I am good to go for a while


Thanks for the good observations!

[B D]

Any signs of an oil leak by the clutch?

[Jascha]

Good thought B D

Have the p-car on ramps so down under I go to see...

BTW, I had the typical leak from the oil pressure sender (darn rear location) replaced it some months back

[Bones]

Just a thought if you're under there check that the clutch actuating rod isn't bent and also that the gearbox mounts are tight.

[Jascha]

... the clutch housing area is impressively dry. I too was thinking about the mounts and therefore re-torqued them while on the lift.

Bones, are you referring to the clutch release lever or the cross--shaft itself (inside the protective tube?).

My sense is that the clutch engagement is fine since I can uncouple (unload) the engine from the transmission when in motion (in all gears) and no slippage is detected

[djmcmath]

Stupid thought, just to check -- if you don't fully tighten the screws in the shift coupler linkage, they come loose and end up horribly maladjusted (if even connected). Then you won't be able to shift into any gear. Chances are excellent you're way smarter than me, and didn't make that mistake though, which is too bad, 'coz it's really easy to fix when you figure it out.

Dan

[Bones]

The release lever Jascha, but following on from what Dan said if you have a working clutch and box then something isn't connecting when you move the lever or it's just way out of alignment or the coupling has undone itself. Try readjusting the coupling and have a good look in there to see the bolt is firmly clamping the coupling onto the splines where you wnat it to be. Iknow you've been through all tyhis but it's worth a look. BUMP this thread a few times later it's not getting enough attention.

[Early_S_Man]

What is the current freeplay measurement at the clutch pedal?

Not being able to get into gear without grinding is indicative of a dragging [not disengaging] clutch disk. Easiest to fix is the freeplay. Fractured/broken throwout bearing lever or rusted/siezed pilot bearing require pulling engine and transaxle.

There aren't many other things to check at this point ...

[Jascha]

Warren, thanks for chiming in...


At our last p-car pow-wow Tech session the experts in the tent decided we can take-up some of the extra gap (now ~0..6 mm) but that did not cure this intermittent shifting problem.

I will take the coupler off (new bushings installed) and see if clamp is fractured or the set-screw in the shift rod coupler is not seated and holding.

I dread thinking that it could be the dragging disk (original suspicion although the adjustment of shift-rod-coupler fixed it for few months) it happens even when the Traga is sitting overnight.

More to the issue at hand, I have to take the p-car for much awaited F1- tires and do not have a spare paper gasket for the guide-fork cover plate. Do you think I can get away with a liquid gasket (copper RTV silicon type ...??) maker


Cheers,

Jascha

[Jascha]

I put all the pieces back together, refilled the 915 with new gear oil (no Swepco on hand) and shifting I went. So far, no difficulty whatsoever…

I used the 1-part (Valvoline straight)+ 2-part (Valvoline blend) gear oil.


I appreciate all the help with the 915-diagnosis. In my other life to find a root cause we often use a similar differential diagnosis technique to rundown the possibilities....

Perhaps we did not identify the single root-cause but I enjoyed the electronic pow-wow.

Cheers,
Jascha

[911mot]

Sounds like the cable is stretching. That would give clutch drag like symptoms and wouldn't affect free play measurement

[Jascha]

Irrespective of the cable length wouldn’t the clutch release specification distance (25.0 mm) setting take care of that (…)

If this measurement proves to be out of tolerance the way to rectify it is to adjust the clutch pedal stop.

Might be worth disturbing the neighbor to help push the pedal

Later,

Jascha

[Jascha]

Problem Resolution:

For purposes of archiving the shifting problem resolution here is the update:

Excluding systematically the likely possibilities (drive train drop being the exception) as a last attempt at minimal invasiveness I decided to realign the shift linkage using a modified method.

1. Loosened the coupler in the tunnel
1. Engaged the trany into 1st
2. Advanced the shift lever to "far left" position (left-most corner of H)
3. Locked-in place

Have been shifting problem free ever since…