Rusty Transmission shift rod - Is it difficult to replace?

[gssereik]

I have the transmission pulled from my 83 SC due to necessary engine repairs (broken head studs). I knew the tranny was leaking at the front seal where the shift rod exits the front of the tranny. I’ve had the new seal in hand for a while now but as I more closely inspect the old seal I am worried that the shift rod is significantly rusted/pitted in the area near this seal. See pics... Have any of you encountered this before? I am not sure how bad the rust is at the contact surface for the front seal but I imagine this shift rod might never seal properly. Some of the pitting is rather deep. Any advice? How difficult would it be to install a good new/used shift rod? Obviously I need to remove the nose cone and the square shift rod access cover near the bottom of the tranny. But would it then be as simple as disconnecting a couple of bolts inside to disconnect the shift rod? Or might it be more complicated? Thanks, George

[john walker's workshop]

The shift rod is installed along with the center section, so that has to be R&R'd.

[911pcars]

The shift rod might be worn beyond repair, but that's only the section exposed to the elements. Before diving into a gearbox rebuild, I'd remove the seal and inspect the sealing section. If it looks serviceable, install a new seal, then pour some heated lube inside with about the same viscosity, maybe rotate it using a large drill motor and see if it leaks. If it doesn't, you might be okay. How did it shift before you yanked it? If okay, you can decide whether to reinstall or have the shaft replaced and the while-you're-in-there - rebuild (maybe needed or not).

A commercial repair shop might lean toward replacing shaft and rebuild, but it's your call. The front seal is a buck, maybe two.

Sherwood

[gssereik]

Thank you John and Sherwood for your feedback which is very helpful. I was hoping that the shift rod might be an easy swap out but realize now that getting it out will require almost complete tranny disassembly. This transmission has never been apart and has 127k miles on it and is working good so my current plan will be to swap out the seal and do exactly what Sherwood suggested to test it for leaks and hope for the best.

[991gts6s]

dont worry it leaks inside the tunnel.....lol

[Walt Fricke]

The only area which counts for the seal is the cylindrical band swept by the seal lip as you move the shift lever forward or backward. If that area is pitted, it may be hard to stop the leaking. The pits will move oil outward, and they will wear the seal prematurely as well, most likely.

Porsche has a rubber boot system to prevent water from getting on this end of the shifter rod - looks like that got torn and not replaced at some point in this transmission's life.

Here is one possibility if there is pitting where you don't want it (not that you like the other pitting, but cleaning it up to stop the rust is all that is needed for function): you could see if you can sleeve it.

A sleeve is a tight fitting very thin steel tube which slips over a shaft with a damaged seal surface. You can purchase these for the engine flywheel seal area of the crank shaft. You might be able to find just the right super thin tube which maybe you have to heat to put in place, or use green Loctite sleeve retainer. Unlike the crank sleeve, this one has to deal with back and forth motion, and only limited rotation. The seal will be a bit tighter, but you can remove the garter spring and stretch it a bit if that seems to be a problem.

Just a thought. I don't think you will find a sleeve made for this application, unlike the crank sleeve. But about anything can be created if you try hard enough.

[gssereik]

Thanks Walt! After I pull the old seal I will have a careful look at the sealing surface of the rod and am hoping it is clean. The rubber boot was present but not attached properly by previous owner and so the rod was attached by the elements. If I see pitting in wrong area then I will look into sleeving. Great idea! Thanks, George

[yelcab1]

Drive it until it bothers you enough to replace the rod during a gearbox rebuild. I doubt you can find a sleeve for that.

[911pcars]

Originally Posted by yelcab1

Drive it until it bothers you enough to replace the rod during a gearbox rebuild. I doubt you can find a sleeve for that.

PAG engineers are pretty sharp. They engineered a shaft that uses existing seals and bearings to fit. Seal manufacturers have various seals up the ying-yang.

Measure the shaft, then do some research for off-the-shelf sleeves or bushings that might possibly work (steel, bronze, brass, aluminum, plastic), preferably thin. The spec book has the dimensions and wear limits for that shaft. Suggest researching bushings and oil seals offered by manufacturing sources. You might find a compatible bushing/seal combo that fits into the end housing - maybe even a double-lip seal. If the bushing is slightly oversize for the shaft but fits otherwise, there are Loctite or equiv. products designed to fill that gap until gearbox rebuild is due. This application only involves a short axial motion with slight rotation, a relatively low load oil seal. Confirm the gearbox vent is clear and faces the correct direction.

Sherwood

[pmax]

Corrosion due to salt ?

How far does the rust extend into the tranny ? Does the rod seal leak ?

[Trackrash]

What does the input spline look like?

[gssereik]

Answering recent questions from Gordon and pmax... The input spline looks normal and the original seal on that end is still working. There is some light surface corrosion on the spline but no pitting. Corrosion at the shift rod could be salt damage as this car has some history in upstate New York and could have seen some road salts, possibly. Also, the rubber boot at front of tranny was installed improperly by the previous owner and the shift rod was exposed to the elements. The shift rod seal definitely leaks and will be replaced. Once I have the old seal out I will inspect carefully to see how far the rust pitting extends. I am hopeful that the sealing surface of the shift rod will be ok. I just don’t know yet. Rust is definitely in close proximity to the sealing surface. I’ll dig into this issue further soon enough. But at this time I am focusing more energy on my engine which is up on the engine stand and has just received new lower head studs

[proporsche]

.... just install the seal a little deeper-away from the rust part ..whatever you do, do not touch the rod with a send paper...also


Ivan

[proporsche]

There is a trick how to make the new seal work even a little better.My mentor showed me in the 1980`s

remove the spring from the seal ,than unscrew it from each end where the meet.Cut of about 2 mm of it and screw it back together.Each end twist the opposite way on disassembly and assembly..

[proporsche]

i forgot to add the pick when the spring is all together..here

[gssereik]

That is a pretty neat trick to adjust the seal spring! I never thought of that but can see that it might help to "tighten" the seal around the sealing surface. I will definitely keep this idea in mind.