All those machine tools you bought and you're not even going to just manufacture your own pin?
Photography by Tom Suddard
Remember that broken 981-chassis Porsche Cayman I picked up for $15,000–or less than half price–then drove cross-country with its four working gears? After tearing out its transmission, it was finally time for the moment of truth: cracking it open and figuring out what really went wrong. Finally, I’d learn why fifth and sixth gear were missing.
Remember, this car fell into my lap after the Porsche dealer quoted this car’s previous owner $15,000 for the repair. Porsche treats these transmissions as a nonserviceable item, which means internal parts and diagrams aren’t available, and dealers won’t open them up. When a car has an internal problem, like mine does, the only remedy is replacement with a new transmission.
But I’m not Porsche, and I’ve never let a lack of parts and diagrams stand in the way of a cool project before. So I loosened every bolt that seemed important, split the transmission in half, and braced for the consequences.
Would a pile of shredded gears tumble out all over the floor? Would everything look perfect, meaning I’d disassembled the transmission for nothing? Or, perhaps worst case, would a single, simple problem be evident, but be rendered unfixable by a lack of parts? Or, on the funnier side of the spectrum, maybe I’d disassemble the transmission incorrectly, resulting in an unsolvable puzzle of parts that I’d never be able to reassemble.
As it turns out, none of those bad things happened. In fact, the transmission looked absolutely perfect inside–save for one missing piece: the dowel pin that secures the fifth- and sixth-gear shift fork to its rail. After a little digging, I found the missing pin safely attached to the magnet in the bottom of the transmission’s sump. I measured the pin at 5.8mm in diameter, which explains why it fell out of the 6mm hole. And after I reinserted the pin, the transmission shifted perfectly on the bench.
That’s right: My educated guess of this transmission’s failure mode turned out to be correct, and this car doesn’t actually need a $15,000 transmission. Instead, it needs a properly sized dowel pin, which I ordered in a pack of 25 for $12.90.
My Cayman isn’t fixed yet, but it’s far, far closer. I’ll attempt reassembly in the next update.
All those machine tools you bought and you're not even going to just manufacture your own pin?
Woohoo! Score!
are you sure you dont want to buy a new $15,000 trans just to be sure?
Everyone loves a happy ending 
So now what are the plans for the Cayman? A potential keeper for future upgrades to produce content or a quick flip that produced a cool road trip and a few repair stories? It seems like either could be succesful but the quick flip has to be enticing .
wae said:All those machine tools you bought and you're not even going to just manufacture your own pin?
I know, I know. But it's cheaper to buy the pin than to buy the stock to make one.
Tom Suddard said:wae said:All those machine tools you bought and you're not even going to just manufacture your own pin?
I know, I know. But it's cheaper to buy the pin than to buy the stock to make one.
Plus you can sell the other 24 for $250 apiece as a specialty part that solves a known Porsche transmission weakness. Think of the dinners you could buy your mom with the profits! (I'm kidding except for the part about taking your mom out to dinner.)
Margie
Hell ya! Major score!
Was the missing .2 mm wear or just like that from the factory?
Stampie said:Was the missing .2 mm wear or just like that from the factory?
i would guess that the hole got wallered out as the pin made its exit
Gotta love that outcome. Nice!
If the 6 mm dowel is a bit loose just hammer in a 1/4", I'm sure that would be fine! Glad you found the problem, good luck with the reassembly.
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