915 shift issues

[dntlft]

I just figured out (today) the cause for my sloppy shifting tranny... the little cone screw that holds the coupler to the trans shaft was loose. I tightened this up and and I felt very smug and satisfied that I had 'fixed' this problem with no monetary outlay. Guess I shoulda' known better, because at the end of a long drive, low and behold, I couldn't get it to shift into 1st or 2nd again. Got home, screw was loose again. When I went to tighten it again, I felt that familiar, sinking feeling of stripped threads. The cone screw looked like the lower few threads wear worn a bit, so I'm assuming the coupler needs to be replaced.
The question, the coupler looks to have grease all over it, but it is thin fluid that smells like GL5 diff fluid. Might I need to replace a trans seal? It seems like you would want to have a dry coupler and cone screw so it doesn't work its way loose, with all the constant stress of shifting. Should I use locktite on the screw to help hold it in place? What about a standard torque value??

[kodioneill]

Replace the coupler and cone screw don't loctite it.

[911pcars]

Early versions of that cone screw were drilled for a simple retention safety wire. Can upgrade by drilling an equivalent hole. Use Loctite only if you're planning a permanent installation (this isn't one of those)

Sherwood

[dntlft]

OK guys, thx for the tips!

[Walt Fricke]

Blue Loctite can help, and isn't that hard to deal with when next you need to unscrew it.

If the threads in the coupler are stripped, for sure you need a new coupler. While you are at it, replace the oval bushings which come with a new coupler with ones which are round and fit snuggly on the cross pin. You can find new couplers modified in this way for sale - do a search of posts for "915 transmission coupler" for lots of info and recommendations.

For sure there is no good reason for any lubricant anywhere near the coupler. So yes, you ought to follow up to see if you think it is from the shifter seal in the nose piece of the transmission. I don't know of anywhere else oil or grease back there could come from.

That seal can be replaced with the transmission in the car. You ought to do a search for that subject also, but some guys have drilled (carefully) holes in the old seal, and threaded sheet metal screws into it, and pulled on those to get the old one out. A slide hammer in one such hole might do the trick.

I don't know how common it is for this seal to leak, and have never had to replace one. But others might know. And it might be a good idea to check the fluid level in the transmission, lest you have leaked out too much already.

[timmy2]

Walt beat me to it, Blue locktite won't hurt you. Just don't use red.
(And everything else he said)

[ivangene]

I have a couple laying around here that are in bad shape on the cone screw hole - I have been thinking about drilling them out and putting in a heli-coil

heli-coils also come in "locking" form...I like that idea but have yet to experiment with it

McMaster-Carr

[pete3799]

I've got one that is stripped out. Bought a new one to replace it but i think they could be drilled and re-tapped the next size up. Just tapper the new bolt to fit the shift rod.

[ivangene]

one concern about re-tapping it the material is SOOO soft - cast aluminum

it's easy to crack and removing material from that small BOSS where the set screw goes in thins it down even more - of the "junk" couplers I have here - several are cracked right there

I guess if it was for my car - I could accept the risk and manage it - but I cannot try things like this out without some background test results and real world run time to ensure longevity of such a "repair"

[dntlft]

Great suggestions all, guys. I think I'll sleep better at night if I use a spot of blue locktite on the threads. I went ahead and ordered a new oem shift coupler and a couple of cone screws when I noticed both have a small spot of what appears to be white silicon (soft rubbery substance) on the threads, about 3-4mm diameter. Is this on the threads to serve the same purpose as locktite??

[RSTarga]

Most nose seals have a slight oil leakage, I wouldn't worry about it unless oil is pooling in the rubber cup on the shaft. Even then it would have to be a lot. Most times you'll have to drop the engine tranny to do a proper job with an new seal.

[Kidasters]

you ordered the stock coupler? Dang - missed a good op to order the Wevo coupler.

I love my wevo coupler and factory short shift kit

[Walt Fricke]

As to the dot on the screw - yes, that is a friction device, should do the trick for a while anyway.

These screws are a bit tricky to get really tight, as the typical L shaped Allen wrench is not long enough on the short arm to clear the tunnel easily and allow you 360 degree rotation without repositioning and whatnot. Having an aid to add a bit more friction makes sense here.

[dntlft]

Right the f%*$ on!! I appreciate everyones input. I've got a set of allen sockets, I found i had no problem getting to the cone screw and applying enough torque. I think that may have led to my initial problem, hence my question re: factory torque value for the cone screw in the coupler. If the stock part doesn't last or strips, I'll definitely look into the aftermarket/WEVO coupler....