Jason987.2

Hello all,

I have an 09 Boxster S with PDK and Sport Plus, <30 k miles. PDK clutches seem to slip when hot, on a 3->4 and 4->5 WOT upshift done at ~5000 RPM.

What happens is that on a full-throttle manual upshift without lifting the gas, the RPMs drop "lazily" instead of snappily like usual.

It happened on the track towards the end of the 20 minute session at the end of the day. Ambient was only 80°F and I was short shifting so I wouldn't catch up to the car in front. I noticed it and so I started lifting before a manual upshift so as not to burn the clutches. I was in Sport Plus Automatic mode, but I would sometimes do a manual upshift.

A few days later it happened on a 3->4 upshift on a mountain road. It was 85°F out. I was in Sport Plus manual mode. I have not tested if it would do it in Normal or Sport mode.

I don't know if it will slip upshifting at redline. Maybe only at ~5000 RPM because there's more engine torque there.

Car has a 3rd radiator in the nose from the factory.

I had an independent check for PDK codes, and there were none. I later found out the clutch fluid was never changed and is due for a change at 6 years.

Here are the possibilities I heard:
- clutch fluid got hot - but I never saw a temperature or limp mode warning; temp gauge was centered (yes I know it's not very accurate), and it was only 80+*F
- clutch fluid low from the factory (will be solved by clutch fluid change)
- software update will fix it - however from everything I've heard software only addresses low speed driveability issues - the dealer also says the car had no pending required software updates
- clutches are bad and require replacement

Can the clutch fluid level be checked before replacement?

I heard that on Audis and BMWs the "grabbiness" of their DCT's are adjustable in the software... anyone heard of this?

Anyone else heard of this problem?

extanker

no WOT issues of any kind on my 09 30k .

HoBoJoe

Contact BGB, they make a PDK cooler to help keep temps down.

Jason987.2

^ Thing is, it's not normal for a stock car to slip clutches at 85°F ambient on a mountain road.

HoBoJoe

They may be able to shed some light on whether or not your track condition caused another issue that needs to be corrected.

caymannyc

Seems like a clutch/transmission fluid issue to me. The third radiator would have no affect on that because the radiator deals with keeping the engine cool.

No matter what people tell you, these cars are not meant to be driven long and hard on the track or mountain roads in stock condition. Same goes for the M3 or any other comparable car.

Besides pads, suspension and tires, cooling and fluids are really the biggest changes you should be making to your car before you seriously track your car. Don't go based on what your local shop says, since they often don't have experience dealing with track cars. Go to a proper race-oriented shop. They'll swap out your tranny fluid with a better (and more expensive) synthetic and can install a separate tranny cooler.

One thing to note: manual transmission cars don't have this "tranny overheating" issue nearly as much as PDK, tiptronic or other paddle-shift cars.

See if there is any "lag" when you drive normally. If there isn't, and the problem only pops up after a long hard ride, you have your solution.

Jason987.2

Update. I had the clutch fluid changed out. Was about a half quart low. All is well now. No problem with 20 minute track sessions in 85*F weather.

Note that before the change I could feel the issue on the street in 90*F weather. No issues now on the street even in 105*F heat.

maplefrm

Thanks for updating the thread.

terbiumactivated

Jason just curious what were the charges for a fluid change?

Moochier

[QUOTE=Jason987.2;13754846]
What happens is that on a full-throttle manual upshift without lifting the gas, the RPMs drop "lazily" instead of snappily like usual.[Quote]

I have a 2011 Cayman R PDK and have been experiencing the same 'lazy' changes from 3-4 and 4-5 only on track, under WOT on manual shifts.

Seems perfectly ok even when hot between 1-2, 2-3 and sometimes 3-4, 4-5 is snappy.... but sometimes not.

If it's just fluids that cause this then that's great... I've asked by local Porsche dealer about changing tranny fluid for a while now and they seem to fob me off, saying it's not needed... maybe it's time to force them to do it along with clutch fluid.

Anything else that should be looked at for a car that's tracked reasonably regularly?

Cheers

Dr.Bill

If I remember right, the service guidelines call for a PDK fluid change at 6 years during the annual service. So, on the 2009 in question, that was overdue. Probably should be done more often on a tracked car.

BGB Motorsports

When the PDK acts up and behaves as described we usually service the ATF fluid in the PDK and then recalibrate the PDK AND run the car through an adaptation cycle. The dealership should have no problem doing this. If you're in Florida and have this happen, call us. The PDK is rather robust and can handle the abuse of the race track. Like anything else, they just require attention every now and again. 981 PDKs seem to be even more reliable than 987s but much has been improved in the valve body of the PDK gearbox since 2009.