Watching Endurance, a documentary by Porsche, around the 1:06:36 mark they have the car pull into the pits after a rear right puncture. The tire is completely gone and the team is faced with the issue of a "completely destroyed differential".

How exactly could the (quite extreme case) of a puncture destroy the differential?

Now, I understand a puncture causes a massive loss of grip on the wheel. In an open diff this would basically make the car impossible to drive (all power would go the the freely-spinning rim) but in GT3 it's definitely some sort of LSD. How would driving 20km with an LSD that is constantly "locked" (at the maximum of how much slip it will allow) affect it so much that it could be "destroyed"?

Any input appreciated!

  • 1
    Googling "LSD differential" brings up Limited Slip differential, not locking. Even if the wheel with the bad tire doesn't spin on the pavement, the effective differences in radius of the wheel would cause the side with the flat tire to spin faster than the other side, and whatever mechanism tries to equalize that could overheat and cause damage. Dec 28 '20 at 18:05
  • I was not precise enough. "locked" was in quotes because I meant the diff is at the limit of how much slip it allows. As locked as an LSD gets.
    – maligree
    Dec 28 '20 at 18:13
  • hitting the curb sideways in a racecar can harm the structural integrity of not only the diff but the rest of the car too :) Dec 29 '20 at 8:27

Why are you assuming it was "locked"?

If it was controlling the slip between sides then the diameteral difference would cause the lsd to work at max for much longer than it was probably designed to do. Probably only designed for so many seconds at max in a period of a minute or some such.

4X4 that are designed for off-road have locking diffs that lock for a reason as the slip required causes rapid failure, so they put in locking diffs.

  • I was thinking it is 4x2 with dif lock. not 4x4. Dec 28 '20 at 16:36
  • @XCSource did I say the Porsche was 4x4?
    – Solar Mike
    Dec 28 '20 at 16:38
  • This is the right answer. A lap of the Nürburgring Nordschleife is more than 20km and a significant portion of a lap with a flat rear tire at even 50% of racing speed would put a great deal of stress on the differential.
    – Edward
    Apr 26 at 12:41

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