texasviany

My brother also has a GT4....he has built planes and race cars. This is 2¢ worth

I reviewed images. The issue is "galling". Most likely caused by heat and poor meshing of gears...I still say it's caused by poor shifting techniques and/or relying on auto blip to salvage a miss timed down shift. I rebuild and inspect tranny gears all the time in race car. Some of those images show excessive wear indicating forced or missed shifts. I've got some just like that...lol

You can heel toe and you know how to time a shift...most people cannot do this and 3rd gear is the main one that pays the price.

mooty

^ i agree with the botched shifting and not able to do heel and toe may cause this end result.
not that i shift perfectly but i can do decent heel toe.
about 50000 track miles on GT3/RS chassis and 5000 track mile on 987, they never had this failure on me

on GT4, i dont use auto blip.

i have this failure ;-(

texasviany

That's a bummer. I know that you are a good driver. I don't use the auto-blip either...but I make my wife use it when driving the Spyder. I gave up the H/T lessons with her 25 years ago.

GTgears

This makes absolutely zero sense. What images has he reviewed? The ones in this thread of Sharkwerks good takeout gears with 500 miles on them? Those images show contact on the synchro teeth where the shift sleeve engages it. They do not suggest missed shifts.

This is what buggered synchro teeth look like:


And that's not galling. Galling is adhesive wear of gear teeth. It's not from the impact of banging poorly shifted synchro teeth and shift sleeves together. Galling in a gearbox is always on the gear teeth themselves and usually from poor lubrication, like letting the gearbox run too low or too long without service where the oil breaks down. Galling looks like this:


See how the teeth actually look scratched? That's galling.

texasviany

I will pass it on!

Switchfoot614

Horrible looking welds for sure. Porsche sure needs to step up their supplier surveillance.

MineisanRS

I'm sorry but I feel I need to respond to your comment: I've put 200.000kms on a boxster with one clutch, heel and toeing each time, and have been tracking a 964rs for the past 10 years, adding 50.000kms of track use on it, with more than very decent lap times and have never had to open the gearbox. With the GT4, I've put 7000kms on it mostly of road use. Did few track days, mostly with sport button on, as temp is more stable. I don't think my way of changing gears is the subject here.

Gofishracing

My friend uses the auto blip and had this failure. None of us can heel toe better or quicker. I think it is quite amazing actually. What dates are we hearing about transmission availability right now ? I heard dates being pushed later.

4carl

You know even though a broken weld on third gear is a logical cause.To the best of my knowledge it really hasn't been confirmed on any of the GT4s that have suffered the loss of third gear. its still a theory a logical one but still a theory . i did see a picture of a broken weld but it wasn't 3rd gear from a GT4? I don't know if we will ever know for sure because the factory wont allow the boxes to be opened at the dealer. carl

ExMB

Wait a minute. Is it you or your brother that added $0.02 and made the determination of failure?
Frankly there is nothing worse than speculation, while trying to sound like the expert, without adequate proof, testing, etc, etc, to support ones findings. One maybe a recognized authority in their chosen field but cannot expect that same treatment once stepped out into another arena.

My $0.02

Alan C.

On the bright side they now have a great future in politics.

GTgears

Other than the ones my customers have opened up... but even with the broken gear in hand it is still just a theory.

provoste

Glad a few have chimed in on this redicuousness. Similar story here, heavily tracked 997 whose original clutch lasted 85k, still original tans. '90 964 with God knows how many track miles, I've owned since '07, never replaced clutch, original transmission, never opened up.

I've never driven a car I can't heel/toe in any circumstance (flip flops/dress shoes, etc). GT4 trans failure after 4 track weekends, 4600 miles. Yeah.... not user error!!!

stout

If the gear is failing in that way—where it would (probably?) not were it splined—it seems more like it's a torque overcoming weld issue. In other words, such a failure seems to me like it happened when the 3.8's torque was applied in gear.

Matt, does that make sense?

Wonder if this is also an issue exacerbated by the GT4's stickier tires? The low mileage at failure in reported cases is disturbing.

texasviany

Its no worse that some of the other comments. He took a guess and it was shot down. So he's probably wrong. He knows his stuff....he has built and raced some good cars. I rebuilds his own FE race car transmission himself when the hours are up.

I have my own theory...(probably wrong) I think people are overaggressive with shifting into the auto blip. I see the in-car videos and I see some pretty aggressive downshifting. I plan to continue to not use that function on the track unless I'm driving easy on the road.

My area of expertise was when I was a factory race driver, I tested gearboxes for the one factory until they failed! Its fun trying to break something for once. The engineers would share the failures with us.