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Re: Sudden Silent Transmission failure

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Driving home when I started through the intersection, there was suddenly zero connection between clutch and transmission. Only sound was what was like a bolt falling off. Clutch felt no different from normal. Zero engagement in any gear with no sounds at all. Pushed it to a safe parking and had it towed home.

Did something in the transmission silently let go? Is it related to the clutch?

FYI: 2002 Boxster S
~90,000 miles
@70,000 complete flywheel and clutch replacement at local dealer
No leaks from engine or transmission. (right CV boot needs replacement)
Only sound in garage was in third gear a slight sound when clutch engaged. No sound of any kind in all other gears including reverse.
Completely normal driving experience prior to this.

Baffled... would like to have some idea of how to approach this. Knowing what is most likely causing it will allow me to plan my approach to repair. It gets jacked up and stored in the winter and I can work on it.

Thank you for any time and attention to my issue. I really miss driving it!!!!!
Zero connection between clutch and transmission a possibility, more below, but more likely zero connection between shift lever/linkage and transmission.

Had something similar happen in my Turbo. Went to shift and suddenly the lever had less resistance. I can't be certain now but the lever might have felt a bit loose.

After I had the car flat bedded to dealer tech found one of the cables to the transmission linkage loose. A ball socket at the end of a cable had failed and the ball had come out of the socket.

My advice would be to check the shift lever to transmission linkage very carefully for a broken/loose cable.

With the engine off have someone work the lever from gear to gear and observe the linkage moves and so too do the levers on the transmission. I do not expect any real difficultly in doing this but if for some reason the gear engagement feels like there is some resistance do not force the lever. This suggests there could be something wrong inside the transmission.

If the linkage appears intact and functional then an explanation is the clutch disc is not making contact with the flywheel/pressure plate. The old zero connection between the clutch and transmission. This can be due to a bad release bearing or the pressure plate spring has lost its spring.

At the same time have the helper press then release the clutch pedal to at least ensure the slave is moving the arm that moves pressure plate away from the disc.

You want to be sure you eliminate other possible explanations before you go to the trouble of dropping the transmission.
Well I think we can rule out the linkage. Had the wife go through all the gears while I observed the linkage on the transmission. Everything operated properly. It would seem that things might be narrowed down to something directly related to either the clutch assembly or is there the possibility that a transmission can internal fail without warning and silently. I just can't see that the transmission itself would just cease to engage without announcing its failure with real sounds of metal destroying itself. Even the clutch assembly I would assume that should there be a failure that the spinning flywheel would cause some audible indication of failure. But no.... it just is silent and zero connecting of engine to transmission.
Why weren't you able to drive the car with the just the right half shaft connected? Did the transmission think the left half shaft was spinning that wheel and did not apply torque to the right shaft to allow it to move the car?
The one thing I just couldn't imagine was exactly what it was.

I had the left rear wheel bearing replaced a month ago. It would appear that the mechanic failed to use either a torque wrench or locktite. The half-shaft was disconnected from the transmission and just laying there. Monday morning back to the shop to finish it properly.

Thank you all for your input!!!
Great news!

13 Boxster, Racing Yellow, PDK, SC in yellow, 20" Carrera platinum wheels, sport steering wheel, yellow seat belts, yellow roll bars, 14 way power seats, PDL, sports tailpipe
My experience with half shafts has mostly been good. But there was one exception...

At around 25K miles I had my car in for a new RMS. 'course, the half shafts are unbolted from the transmission to remove the transmission to get at the RMS.

Get the car back and the RMS was leak free from 25K miles to 317K miles when I sold the car. No problem with the new RMS. And no clutch, flywheel or transmission problems.

But oh maybe 50K miles before I sold the car a CV boot split/cracked. Age. Nothing out of the ordinary.

But the tech at the local dealer -- not the same dealer I had replace the RMS -- reported the half shaft bolts were stripped. Not the threads but the heads. It appears the tech who installed the half shafts after the RMS was replaced used the wrong bit and while apparently the bolts were tight enough to remain tight the wrong bit must have spun inside the bolt head damaging this so the right bit would not work any more.

The tech reported he had to hammer a special bit into each bolt to remove it. And of course before he could put the half shafts -- with clean, inspected, and repacked bearings and fitted with new CV boots -- back in the car he had to order a new set of half shaft bolts.
This is why I always start by considering all recent work done to the car before diving in with a more involved / complicated / expensive diagnosis.

Glad it wasn't the transmission.
wow. In many way you were lucky
grant - Sunday at 12:52:28 pm
I had one let go, after track use (long story, cheap replacement, don't go there...) and it flew around like a ball and chain, damaging lots of stuff in its path.

This was partly induced by the LSD I have - you obviously have an open diff. In this case "good thing"

The sound of the car with the LSD trying to apportion torque was awful until i got to the side of the road.

G

Grant gee-lenahan-at-vee-eff-email-dot-net
Without LSD, the disconnected side would just spin while the connected side did nothing (because it has a load - otherwise it would spin slowly).


Grant gee-lenahan-at-vee-eff-email-dot-net
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