Shift knob breaking when installing

[Roby466]

So is it just me or the new Porsche shift knobs are made of cheap plastic?

I have broken two while installing them. They are about $100 each so I don’t want to do this too often. I’m tempted to go to a wooden one now as I feel it is futile to dump money buying another!

Anybody else has this issue with new ones? Maybe I should look for an old one on eBay!

First I e broke inside (as if the crush ring pushed the plastic stop in and it cracked. Second one cracked around the ring when the crush sleeve goes in. There is a metal ring and the plastic around that cracked.

It’s a 930 4-speed knob with crush sleeve.


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[john walker's workshop]

how are you installing them? Try pushing the sleeve in all the way, put the knob on straight and bonk it a few times.

[Roby466]

Hi John’. Long time no see, you used to work on my car for the previous owner and I visited your shop when I bought it almost 11 years ago.
That’s how I think I do it…. Not sure what mistake I make but it’s an expensive one…
I’ll keep my cracked one a few more months and try again


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[RSTarga]

push the crush ring past the ridge on the inside, otherwise it will crack.

[911pcars]

There's gotta be a better way to attach (or remove) a $100 plastic shift knob so it doesn't break. The factory crush ring or sleeve assumes a standard clearance between the lever and knob. In reality, not so. Thus, there's often less than wiggle room to attach the knob without inordinate force.

The crush sleeve is a sheet of steel (stainless perhaps) formed into a circle with a series of raised bumps on it that provide an interference fit.



I might suggest a little trial and error by trimming the circular length of the crush sleeve, then trial fit the knob at a certain depth. If you trim too much, the clearance will grow, but you can close it up by wrapping some electrical tape around the sleeve. There are probably other, more effective options.

Hope that helps,
Sherwood

[RWebb]

MOMO has a better way to attach (or remove) a shift knob so it doesn't break...

[911pcars]

Originally Posted by RWebb

MOMO has a better way to attach (or remove) a shift knob so it doesn't break...

Most shift knob manufacturers have an R&R system without destroying their product.

[panzerfaust]

it would be nice if someone can come up with a treaded insert placed in the knob and thread the shifter rod. just a thought

[SWS911]

My '67 912 had a threaded shift rod. I think the SWB cars all had one as did the 356.

[911pcars]

Originally Posted by panzerfaust

it would be nice if someone can come up with a treaded insert placed in the knob and thread the shifter rod. just a thought

See post #9.

Here’s a thought. Buy a threaded knob and install a threaded male insert into your shift lever. A stud with the correct thread can work. Machine one end to fit into lever and install (epoxy). Install threaded knob. Done.

[panzerfaust]

Originally Posted by 911pcars

See post #9.

Here’s a thought. Buy a threaded knob and install a threaded male insert into your shift lever. A stud with the correct thread can work. Machine one end to fit into lever and install (epoxy). Install threaded knob. Done.

That’s the kicker, there isn’t a stock looking 915 or 930 knob with female threads to the best of my knowledge. It would have to modified.

If one didnt cared about stock looks, just buy a momo knob with a lock collar and set a screw…. Done, no gluing, machining etc, they are universally adaptable.

[panzerfaust]

Originally Posted by SWS911

My '67 912 had a threaded shift rod. I think the SWB cars all had one as did the 356.

It’s unfortunate they went to the interference fit crush collar. Cost cutting measures I presume…

[Fleming]

A crushed sleeve allows the knob to be correctly rotated once it is on.

Threaded knobs have to have perfect alignment to the shaft threads or the shift pattern is not aligned when tight. The 356 and 911/912 didn't have the shift pattern on them early on. Had a threaded one that was screwed on and glued to have correct alignment. (Yes a prior owner read a manual and tried to hammer it off).

As two others have said - is there a cavity in that replacement knob's shaft that accepts the crushed sleeve?

Look into the shaft is it the same diameter it's full length or is there a pocket at the top?
If it has a pocket will that pocket accept the length of the sleeve?

When installing the next knob - measure the crushed sleeve inside diameter after it is in the knob and compare to the shaft diameter, how much does it have to flatten to fit?
If it needs more space, can the plastic knobs inside shaft be enlarged (sand out) to allow the compression/expansion space it needs?

[911pcars]

Originally Posted by panzerfaust

That’s the kicker, there isn’t a stock looking 915 or 930 knob with female threads to the best of my knowledge. It would have to modified.

If one didnt cared about stock looks, just buy a momo knob with a lock collar and set a screw…. Done, no gluing, machining etc, they are universally adaptable.

The desired 915/930 shift knob can be drilled/bored to accept a Rivnut of the right thread size (glue it in). A jam nut underneath could lock the knob in any desired position (given a threaded stud at the top of the lever).

[Roby466]

There is not a “ridge” per say to accept the crush sleeve. There is a steel sleeve inside the knob that provides the force to hold the crush sleeve tight. That steel sleeve is about 1/4 in inside the knob. Two issues I think:
-Maybe the shift lever is not clean enough: Next time I’ll give it a slight sanding to remove any leftover glue residues from the PO’s previous leather knob install
-as it requires very high force to go in, maybe there is a tendency for the knob to become slightly angled applying pressure on the plastic portion the protrudes past the metal sleeve, that would initiate the crack that propagates itself past the steel sleeve, so the knob can move on the tightly held sleeve.
So I’ll wait until my pride has recovered and try another knob. Or I’m tempted to go to the wood type one but I kind of like the stock look…


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[hart930]

I have also gone through two plastic early turbo knobs with cracked plastic. One cracked on install at the shop and the other while driving. I ended up ordering a basswood knob from aase sales and so far no issues other than the look. I prefer the older style.

Some additional information. The early turbos through 79 install with the crush ring. My 87 has the bolt that goes through the knob with threads that are inside the shifter barrel. I swapped to a wevo shifter and the barrel is slighting larger in diameter and no threads. That may be my problem but share your pain with broken cheap plastic. Reach out to Brian Farmer at Einmalig. He may have some old shift knobs.

[Roby466]

Originally Posted by hart930

I have also gone through two plastic early turbo knobs with cracked plastic. One cracked on install at the shop and the other while driving. I ended up ordering a basswood knob from aase sales and so far no issues other than the look. I prefer the older style.

Some additional information. The early turbos through 79 install with the crush ring. My 87 has the bolt that goes through the knob with threads that are inside the shifter barrel. I swapped to a wevo shifter and the barrel is slighting larger in diameter and no threads. That may be my problem but share your pain with broken cheap plastic. Reach out to Brian Farmer at Einmalig. He may have some old shift knobs.

Thanks! I’ll contact him and see what he has. I wonder if Porsche has shifted to a new supplier a few years back and the plastic is more brittle. Or maybe we are just less skilled at installing them


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[911pcars]

Neanderthal installation and removal process. With all due respects to Porsche engineers, it appears the knob wasn't designed to be removed and replaced.