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PDK - any difference between older 987.2 and 981 version?

 
Old 05-13-2019, 03:27 PM
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Raider89
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Default PDK - any difference between older 987.2 and 981 version?

While considering a PDK transmission for possible next car (from my current 987.1 6speed manual), want to understand any mechanical or dependability differences. I intend to use exclusively on track (not racing), just typical 30 minute HPDE track sessions - normally 6-8 weekends per year. I am trying to weigh pros/cons of 987.2 versus new 981 vintage. I have several questions seeking guidance:

1. Is there any difference, same model numbers and manufacturer?
2. For that matter, is PDK different from 911 versions?
3. If coming from donor or older street car, assuming routine street driving, are they pretty robust such that I should not expect any damage?
4. I have read all kinds of stories about PDK replacements, what is realistic? Ignoring core charge, replacements seems to range between $6k and $15k. Dont understand wide variance.
5. Does LSD cause or create more issues with PDK?
6. Seems as though additional cooling is mandatory. Any consensus recommendations?
7. What is recommended maintenance cycle or requirements for PDK for this type of track use only?

Thanks, Dan
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Old 05-15-2019, 02:31 AM
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djm68
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Originally Posted by Raider89 View Post
While considering a PDK transmission for possible next car (from my current 987.1 6speed manual), want to understand any mechanical or dependability differences. I intend to use exclusively on track (not racing), just typical 30 minute HPDE track sessions - normally 6-8 weekends per year. I am trying to weigh pros/cons of 987.2 versus new 981 vintage. I have several questions seeking guidance:

Thanks, Dan
> 1. Is there any difference, same model numbers and manufacturer?
Yes, many differences between the 987.2 and the 981 PDKs, far too many to enumerate here. Honestly, I do not think the there is a big reliability difference between the 987.2 and 981 PDK *IF* the 987.2 PDK has additional cooling added. The 981 came factory equipped with a gear oil cooler that is absent on the 987.2. Most shops I've talked to seem to think the factory 981 cooler is not up to the task of a fast DE driver, hence it will need upgraded cooling as well. The 981 PDK is supposed to be smoother in day-to-day street driven use, which should not be a concern for your application.

I have a 2012 Cayman R PDK, original owner. I added a BGB LSD cooler the first track season, so I've had improved cooling as soon as my driving got faster. My use case is essentially identical to yours: 5 - 7 events a year. I change my clutch/gear oil every season. I've not had a single issue with my PDK, and I know many other who have not. The only person I know personally who has had a failed PDK is a buddy who is not on his *third* PDK for his 997.2 4S...then again the PDK in the 4S is quite different than the 987.2 box

Bottom line is: controlling the heat and changing fluids on a regular cadence is best approach to running a PDK car on the track.

To you other questions:

> 2. For that matter, is PDK different from 911 versions?
Yes, different than the 911 PDK.

> 3. If coming from donor or older street car, assuming routine street driving, are they pretty robust such that I should not expect any damage?
Yes, generally robust, street driving should not impact a PDK.

> 4. I have read all kinds of stories about PDK replacements, what is realistic? Ignoring core charge, replacements seems to range between $6k and $15k. Dont understand wide variance.
A PDK replacement for a for a 987.2 or a 997.2 is $12k - $15k. No idea about the variance, either.

> 5. Does LSD cause or create more issues with PDK?
LSD adds more heat, heat is the bane of the PDK.

> 6. Seems as though additional cooling is mandatory. Any consensus recommendations?
Even 'just' for DE, yes totally mandatory on the 987.2 and, IMO, the 981 also needs additional gear stack cooling.

> 7. What is recommended maintenance cycle or requirements for PDK for this type of track use only?
Change PDK fluid and gear stack fluid every season.
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Old 05-15-2019, 08:00 AM
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Frank 993 C4S
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Originally Posted by djm68
> 1. Is there any difference, same model numbers and manufacturer?
Yes, many differences between the 987.2 and the 981 PDKs, far too many to enumerate here.
Interesting - can you please expand on this and provide a link to the source of this information? I thought they were identical other than the flash and cooler.
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Old 05-15-2019, 03:13 PM
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85Gold
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Originally Posted by Frank 993 C4S View Post
Interesting - can you please expand on this and provide a link to the source of this information? I thought they were identical other than the flash and cooler.
Matt from Guard might chime in. IIRC the 987.2 PDK that doesn’t have factory LSD can’t be upgraded to an LSD. Also if you search you will find several posts on 987.2 PDK failures on heavily track cars. I know one person is on his 3rd and another RL member is also on his 3rd 987.2 PDK. It might behove you to contact BGB and get their input.

Peter
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Old 05-15-2019, 04:48 PM
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Frank 993 C4S
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Originally Posted by 85Gold
Matt from Guard might chime in. IIRC the 987.2 PDK that doesn’t have factory LSD can’t be upgraded to an LSD. Also if you search you will find several posts on 987.2 PDK failures on heavily track cars. I know one person is on his 3rd and another RL member is also on his 3rd 987.2 PDK. It might behove you to contact BGB and get their input.

Peter
Thanks! I'm aware of the posts but was looking for a reliable source as to the exact differences between the the 987 and 981 PDK. Maybe a Porsche publication? I have already been in touch with John from BGB.
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Old 05-15-2019, 08:45 PM
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Either buy a 987.2 that was factory equipped with LSD or go with a 981.

If you buy a 987.2 try and buy one with its original transmission as opposed to one that was replaced with a Porsche reman trans.

In all cases install the BRS PDK cooler as well as the diff cooler.

I have been dealing with my own 987.2 PDK trans woes and the advice above is distilled from probably 100 hours of research and direct conversations with BGB, LN Engineering, and Guard Trans.
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Old 05-15-2019, 08:49 PM
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Thanks for all responses and recommendations.
Dan
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Old 05-15-2019, 09:09 PM
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981 PDKs have two oil to water heat exchangers on them. 987.2 may only have one. CG2.25 and CG2.40 (718S) have 3.62:1 FDR; CG2.05 have a 3.73:1 FDR. Not sure about 987.2 FDRs.

1. All 9x1 PDKs are made by ZF.
2. Due to rear vs mid engine the engine and transmission rotate in opposite directions, so the differential is on different sides. So a 991 trans cannot be used on a 98x.
- Turbo 991s have a bigger clutch, so larger bellhousing and CV flanges on them. If you need a new clutch, Dodson Motorsports (New Zealand) has an 8 disc clutch available ($10K)
3. Depends on mileage and if the car was abused. Change gear and clutch oil first. Get a guarantee on a used one.
4. Labor is probably $3k. Porsche refurb is about $14K plus core charge. If the core is toast, then don't expect much, if anything back.
5. Not heard much on this. Compared to aftermarket LSDs, the factory units are weaker and have less amount of lock (22%)
6. Newer PDKs with two heat exchangers have fewer heat problems. Add third center radiator and insulate exhaust to keep trans cool. Run in Sport or Sport plus mode so coolant is regulated at a lower temperature and increases heat transfer via the heat exchangers.
7 Clutch fluid changes color quickly under track use. Sample frequently and change when it turns dark.

I tried to post this last night but the site went down.

V6 (Owner of CG2.05, CG2.25, and CG2.40 transmissions for experimentation)

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Old 05-16-2019, 05:37 PM
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g
Originally Posted by 85Gold View Post
987.2 PDK that doesn’t have factory LSD can’t be upgraded to an LSD. Also if you search you will find several posts on 987.2 PDK failures on heavily track cars. I know one person is on his 3rd and another RL member is also on his 3rd 987.2 PDK. It might behove you to contact BGB and get their input.

Peter
Any shop who works with these track/race cars can support them

two diff 987.2 PDKs “baby” and “big”

“big” had the factory diff (cayman R)

in my 987.2 R I added guard LSD tpc pdk cooler kit and Spencers OUTSTANDING diff cooler kit.

all PDKs need a cooler on the trans side (bgb,brs,tpc,speedsport, bodymotion) all builts basically the same. mocal rad and some fittings and lines. w the guard diff - temps still got too high - so we added spencer’s kit (speedsport) and have a pump switch that runs the diff cooler

the big thing w pdk in my experience is that they are temperamental. have a shop w a piwis calibrate if you make any changes. i recalibrate before every race weekend, and change trans and diff oil every other race weekend (not needed in a de car really)
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Old 05-16-2019, 11:02 PM
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I read that the 987.1 transmission isn’t compatible with the 987.2 engine, yet here everyone is talking about both 987.2 and 981 for a 987.1 application. Can you mix and match?
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Old 05-16-2019, 11:13 PM
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Raider89
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Thread only intended to address differences in 987.2 and 981. I am looking to upgrade from my current 987.1, and considering all options.
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Old 05-17-2019, 07:34 AM
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Originally Posted by Raider89 View Post
Thread only intended to address differences in 987.2 and 981. I am looking to upgrade from my current 987.1, and considering all options.
Right, I don’t mean to derail the thread, but how will you use either if they are not compatible with your car? Or more to my interest, if the conventional wisdom says they are not compatible, and you are able to use them, I’d be very interested in learning how. I’ve been looking into the opposite (upgrading the M97 engine to a 9A1 without also having to replace the trans).
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Old 05-17-2019, 08:49 AM
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Frank 993 C4S
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Originally Posted by Raider89 View Post
Thread only intended to address differences in 987.2 and 981. I am looking to upgrade from my current 987.1, and considering all options.
Still interested in this as well. Other than the cooling the “many” differences seem to be a well kept secret.

Originally Posted by Difool View Post
I’ve been looking into the opposite (upgrading the M97 engine to a 9A1 without also having to replace the trans).
That’s not possible. You have to go with a 987.2 trans.
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Old 05-17-2019, 05:42 PM
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Originally Posted by badabing View Post
Either buy a 987.2 that was factory equipped with LSD or go with a 981.

If you buy a 987.2 try and buy one with its original transmission as opposed to one that was replaced with a Porsche reman trans.

In all cases install the BRS PDK cooler as well as the diff cooler.

I have been dealing with my own 987.2 PDK trans woes and the advice above is distilled from probably 100 hours of research and direct conversations with BGB, LN Engineering, and Guard Trans.
What woes have you been experiencing with your PDK? Has installing the BRS clutch oil cooler and diff cooler addressed your issues?

DJM
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Old 05-17-2019, 05:51 PM
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Originally Posted by Frank 993 C4S View Post
Interesting - can you please expand on this and provide a link to the source of this information? I thought they were identical other than the flash and cooler.
I do not have a link that details the differences between the 987.2 and the 981 PDKs, sorry. I have spoke to the guy who is responsible for the PDK programming at COBB and he gave me a fairly detailed explanation of why certain features off their flash programming are only supported on 981 and new PDKs. The Transmission Control Unit on the 987.2 PDK has much less flash space hence is not capable of supporting more sophisticated programming. Two examples: reverse shifting pattern (push lever forward for downshift) and 'open clutch mode' -- pull both paddles back simultaneously, and the clutch disengages.

I would assume Matt at Guard and John at BGB would know quite about about the differences between the gear boxes. FWIW, I gave up trying to find out more details about the differences as it is hard to get definitive answers. I'd like to swap a 981 PDK into my 987.2 Cayman R, but I can not find sufficient information to determine if such a swap is feasible.

DJM
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