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From the early AP vids, the GT4 has a torque limiter. You would have to imagine it is intended to prevent just this sort of problem occurring. My guess is that Porsche knew it was a weak link, but thought they had done enough.
Yeah, the mysterious "torque peak limiter" that AP mentioned. From searching around, the most common belief seems to be that that's a "clutch delay valve" that will smooth out clutch engagement if someone dumps their clutch. I don't think that was specifically intended to avoid this scenario, but yes it does suggest that the engineers felt that some extra safety measures needed to be placed around the gearbox as a result of pairing it with the 3.8 -- although considering all of their other models with the most power and enthusiast appeal are now PDK-only, I wonder if they might have done the same on those cars as well. I wonder if the 911R and upcoming GT3 will have such a limiter.
But the counterargument to that position is that GTGears and BGB have both said that they've used these gearboxes successfully under brutal conditions and, in some BGB cases, even with 3.8 motors without seeing issues like this, although those probably used the spline 3rd gear, so maybe the box would have been just fine had it not been for the switch to EBW?
Does anybody have a picture of a 981 splined 3rd gear? If in fact they used it in the 981 gear boxes. Or is it pure conjecture that they changed the 981 third gear to the EBW design?
Does anybody have a picture of a 981 splined 3rd gear? If in fact they used it in the 981 gear boxes. Or is it pure conjecture that they changed the 981 third gear to the EBW design?
I believe the EB design was confirmed in a failed gearbox torn down, with a photo posted in the other thread on the topic.
Does anybody have a picture of a 981 splined 3rd gear? If in fact they used it in the 981 gear boxes. Or is it pure conjecture that they changed the 981 third gear to the EBW design?
No pic, but there is this post from GTGears, emphasis mine:
Originally Posted by GTgears
Anyway, here's the rub. I've been saying that these gearboxes are a decade old and even the 3rd gear ratio is the same. But there is a change. Below is the current gt4 gear. This came out of Sharkwerks mule with less than 1000 miles on it. See the welds?
Memory suggested that only 5&6 were welded in the 987 and 3&4 were splined like 915 or gt3 gears. So I rang John Teece and asked him to check. He confirmed for me.
So what's causing the failures? The welds are breaking and the ring is spinning right off the gear.