Shifter Cone Screw Keeps Loosening, Thread Locker or Worn? Options

[Spoke]

Every 6 months I have to retighten the cone screw on the shifter. This time it came out real quick. I thought it might come out all together. I couldn't get 2nd without hitting reverse. The picture shows how much the screw backed out.

Not sure how much torque I applied but I was bending the allen wrench.

Questions:

Should I have thread locker on this?

What is the torque required for the cone screw?

Possible that the threads have been widened by repeated looseness?

Why didn't they put a bolt through this to really lock the hub onto the shaft?


TIA

(IMG:style_emoticons/default/beerchug.gif)

[brant]

Intended to be one time use

Replace both. And you’ll be done

[Spoke]

The cone screw thread appears to be folded over at the bottom. Really messed up.

[Superhawk996]

Why didn't they put a bolt through this to really lock the hub onto the shaft?

The conical screw provides a positive indexing that couldn’t be obtained by simply matching a flat on the shift rod or using a hole and a through bolt.

The amount of torque that can be used is limited by the material used and the size of the fastener. Again, a bolt of the same size (M6 if I recall) offers no advantage over the conical set screw.

The conical set screw seating into the pocket on the shaft offers positive retention. Should it loosen, the coupler can’t become disconnected from the shaft even though things get terribly sloppy well before the screw could fall out alllowing for a disconnect to occur. This is a very safe failure mode.

[Superhawk996]

The cone screw thread appears to be folded over at the bottom. Really messed up.

Looks like maybe the cone maybe is hitting the top of the pocket in the shaft (rolling the 1st thread).

Hard to say if the cone screw wasn’t machined properly or maybe the pocket in the shaft is getting enlarged by having been loose for too long.

Inspect

Remove 1st thread if needed to allow the set screw to seat fully in the shaft pocket.

[Steve]

Unless their worn or partially stripped, I just put blue loctite on them and reuse them. But yes they are one time use. Some of the new ones i received have a hole in them with a plastic piece to keep it from coming out, but the plastic piece that holds it in, only works once.

[VaccaRabite]

A small amount of blue loctite is all you need.

Though as buggered as those threads are I'd get a new screw.

Zach

[Superhawk996]

A small amount of blue loctite is all you need.

Though as buggered as those threads are I'd get a new screw.

Zach

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Inspect the threads in the coupler carefully. That screw may have torn up the aluminum as it was removed and may necessitate a helicoil repair to the coupling.

[87m491]

The cone screw thread appears to be folded over at the bottom. Really messed up.

Indeed, also the first of your 2 pix shows a void in the threads where a silicone anti vibration, anti backout slug, would be sitting in a new factory screw. Both of those items likely causing you backing out.

[930cabman]

A small amount of blue loctite is all you need.

Though as buggered as those threads are I'd get a new screw.

Zach

(IMG:style_emoticons/default/agree.gif) I have a couple on the shelf for good measure. One time use, but a dab of blue Locktite will do the job

[ejm]

First time I've seen a cone screw facing up. Is there something else going on here?

[rjames]

Not sure how much torque I applied but I was bending the allen wrench.

I don't know what the exact spec is, but it's nowhere near that much.

[GregAmy]

I know it's often said these are one-use items, but there's nothing with the threads that would support that contention, other than new ones come with a dab of loctite (or similar) on them.

In my case I clean the hell out of the threads (usually brake clean) and dab with blue loctite (I use the semi-solid "Quickstix" dispenser version) and - knock on wood - I've never had a problem in either car. And they're part of a standard underside inspection every oil change.

But that one with the buggered threads? Nope. And that may have buggered the aluminum casting in the process.

[Spoke]

I cleaned up the first thread on the cone nut and reinstalled with loctite but there was nothing left of the treads. The threads are stripped. So either heli-coil or new coupler.

[930cabman]

First time I've seen a cone screw facing up. Is there something else going on here?

maybe the OP is in Australia?

[flipb]

If you want to replace the coupler, the part number is 911-424-221-00

My local Porsche dealer obtained it for $56 (plus shipping) a few years ago.

[mb911]

Every 6 months I have to retighten the cone screw on the shifter. This time it came out real quick. I thought it might come out all together. I couldn't get 2nd without hitting reverse. The picture shows how much the screw backed out.

Not sure how much torque I applied but I was bending the allen wrench.

Questions:

Should I have thread locker on this?

What is the torque required for the cone screw?

Possible that the threads have been widened by repeated looseness?

Why didn't they put a bolt through this to really lock the hub onto the shaft?


TIA

(IMG:style_emoticons/default/beerchug.gif)

Man I have seen a lot of 914s and their shift linkages but wondering why the cone screw is at the top versus the bottom like all of the ones I have ever seen seen?

[DC_neun_vierzehn]

This is the cheapest I've found the Genuine Porsche cone screws ($8) and the coupler from the same source at a nice price as well ($61):

https://www.delawareporscheparts.com/oem-pa...nb3J5IFBhZ2U%3D

https://www.delawareporscheparts.com/oem-pa...int-91142422100

[Bartlett 914]

I reuse mine. I use a torch and warm the screw. You will see the plastic ball soften. It will come out easily. I then insert a 1/8" nylon ball n place. A drop of instant adhesive will hold in in place. When inserting the screw, some will be cut off. You may think it all came out but it hasn't. I have done this for yr\ears. McMaster Carr will sell 100 1/8" nylon balls for less than a single cone screw. I have done this for years and no issues!

[brant]

I've salvaged knuckles in the past...
take them apart.
tig weld the alloy housing with the stripped hole.
re-tap.