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What is the 7-speed manual gearbox?

 
Old 03-21-2013, 05:05 PM
  #31  
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Mike,
I think I have confused you with my casual use of PTV as a general thing. We were caught up in a sort of,"Is it lavendar or is it purple?" confusion. Lavendar is a kind of purple. For clarity, as I understand it:
Ptv= brakes
Ptv+ = brakes & anemic useless LSD

There is no electronic differential adjustment that I have seen. Yes we have had the PDk apart too. There is nothing there either. We have examined every variation there is and none of them have an electronic mechanism whereby the locking factor of the LSD (which by definition must be present for variable locking) can be adjusted.
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Old 03-21-2013, 05:22 PM
  #32  
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Originally Posted by GTgears View Post
Mike,
I think I have confused you with my casual use of PTV as a general thing. We were caught up in a sort of,"Is it lavendar or is it purple?" confusion. Lavendar is a kind of purple. For clarity, as I understand it:
Ptv= brakes
Ptv+ = brakes & anemic useless LSD

There is no electronic differential adjustment that I have seen. Yes we have had the PDk apart too. There is nothing there either. We have examined every variation there is and none of them have an electronic mechanism whereby the locking factor of the LSD (which by definition must be present for variable locking) can be adjusted.
Matt, I'm easily confused.

Actually, as I understand it, and as Porsche describes it :

PTV= brakes & anemic useless mechanical LSD
PTV+= brakes & electronically variable LSD

Based on your definition of PTV+ as having the anemic mechanical LSD, maybe you haven't actually come across a PTV+ PDK gearbox yet. Pure conjecture on my part; maybe you're right and Porsche is just lying. Here again are their lying words from the standard features on the GT3:

Porsche Torque Vectoring Plus (PTV Plus) including electronically controlled rear differential lock with fully variable standard torque split. (Amazing they can do that with just the brakes; wait they're lying...... )

I have a PDF of the Technical Introduction book for the 2009 Carrera which has detailed diagrams of all the new systems for that year. I've been trying to find one for the 2012 991 Carrera which I bet would have great info on PDK+ and the electronic diff in that car but haven't been able to locate it except in hard copy for $75 on ebay. I'll keep looking.

Last edited by Mike in CA; 03-21-2013 at 05:54 PM. Reason: typo
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Old 03-21-2013, 06:04 PM
  #33  
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Hey there Mike,

While I can not confirm this with first hand, hands on data, in doing some research here Porsche did change gearboxes in 2013 forward, in so much as they have a different gearbox model number. In researching the latest papers from Porsche the new differential in the 13+ PDK is indeed electronically actuated, allowing the torque distribution to be infinitely variable.

I have to agree with Matt that while this is the direction that more and more manufacturers are moving toward, it is kind of a bummer for both GBox/OS Giken and GT regarding the new development of PDK differentials that we both spent time, effort and money to design to replace the door stop POS that came with the pre-13 PDK gearboxes.

It will be interesting to see how well the new differential ends up working, as if it is of the design that I know Porsche/ZF are playing around with, there is a good possibility that they might have a new winning combination, which will make aftermarket replacements unnecessary. A great thing for new Porsche owners, but a bit of a bummer for the aftermarket manufactures. Time will tell.

I do have a new 991 gearbox (manual) coming into the shop here for a customer, so in so far as the manual gearbox I will be able to report any new developments regarding fitment. There is some indication that the new differential will fit in this gearbox as well as the pre-13 PDK units. The manual will not have the electronically controlled differential option, at least not yet, but is reported to share 70% of the internals with the PDK version.

Interesting tread, thank for the post.

Erik Johnson
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Old 03-21-2013, 07:10 PM
  #34  
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I just got back from my dealer and he let me have a look at the Technical Data Specs they have on this car. Here is a direct quote from said document:

"Rear Locking Differential - Porsche Torque Vectoring Plus (PTV Plus) with electronically controlled rear differential lock (fully variable locking values)"

Not being a technical/mechanical person, I don't know if this adds any new insight to this discussion but do the words "fully variable locking values" imply it is truly electronic ??


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Old 03-21-2013, 07:15 PM
  #35  
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Originally Posted by GBoxguys View Post
Hey there Mike,

While I can not confirm this with first hand, hands on data, in doing some research here Porsche did change gearboxes in 2013 forward, in so much as they have a different gearbox model number. In researching the latest papers from Porsche the new differential in the 13+ PDK is indeed electronically actuated, allowing the torque distribution to be infinitely variable.

I have to agree with Matt that while this is the direction that more and more manufacturers are moving toward, it is kind of a bummer for both GBox/OS Giken and GT regarding the new development of PDK differentials that we both spent time, effort and money to design to replace the door stop POS that came with the pre-13 PDK gearboxes.

It will be interesting to see how well the new differential ends up working, as if it is of the design that I know Porsche/ZF are playing around with, there is a good possibility that they might have a new winning combination, which will make aftermarket replacements unnecessary. A great thing for new Porsche owners, but a bit of a bummer for the aftermarket manufactures. Time will tell.

I do have a new 991 gearbox (manual) coming into the shop here for a customer, so in so far as the manual gearbox I will be able to report any new developments regarding fitment. There is some indication that the new differential will fit in this gearbox as well as the pre-13 PDK units. The manual will not have the electronically controlled differential option, at least not yet, but is reported to share 70% of the internals with the PDK version.

Interesting tread, thank for the post.

Erik Johnson
Hi Erik,

I really appreciate your post. Thanks for the confirmation on the electronically actuated diff. Restores some faith in Porsche for being honest with their claims, on this at least, and also hopefully is a plus for the 991 GT3 and the 991 PDK Carreras.

I can certainly understand the frustration from the aftermarket gearbox guys with regard to Porsche's redesign of their LSD. I hope you can turn it into a positive somehow for your business.

Best,
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Old 03-21-2013, 07:22 PM
  #36  
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Originally Posted by Conekilr View Post
I just got back from my dealer and he let me have a look at the Technical Data Specs they have on this car. Here is a direct quote from said document:

"Rear Locking Differential - Porsche Torque Vectoring Plus (PTV Plus) with electronically controlled rear differential lock (fully variable locking values)"

Not being a technical/mechanical person, I don't know if this adds any new insight to this discussion but do the words "fully variable locking values" imply it is truly electronic ??
Conekilr, I've been using that quote or others similar to it for a while now in this thread. I think the Gboxguys (Erik) post above yours clarifies the issue.....
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Old 03-21-2013, 07:41 PM
  #37  
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Originally Posted by Mike in CA View Post
Matt, I'm easily confused.

Actually, as I understand it, and as Porsche describes it :

PTV= brakes & anemic useless mechanical LSD
PTV+= brakes & electronically variable LSD

Based on your definition of PTV+ as having the anemic mechanical LSD, maybe you haven't actually come across a PTV+ PDK gearbox yet. Pure conjecture on my part; maybe you're right and Porsche is just lying. Here again are their lying words from the standard features on the GT3:

Porsche Torque Vectoring Plus (PTV Plus) including electronically controlled rear differential lock with fully variable standard torque split. (Amazing they can do that with just the brakes; wait they're lying...... )

I have a PDF of the Technical Introduction book for the 2009 Carrera which has detailed diagrams of all the new systems for that year. I've been trying to find one for the 2012 991 Carrera which I bet would have great info on PDK+ and the electronic diff in that car but haven't been able to locate it except in hard copy for $75 on ebay. I'll keep looking.
Mike,

I was thinking about this conversation as I was packing today's shipments. I have come to the conclusion that I am the one who was (is?) confused here. My recollection was incorrect. We never had a 991 Carrera S PDK car that we looked at when we were doing the LSD project. The car that we had was a 997 Carrera S PDK. The only 2 991 cars we have seen so far have been a Carrera 7MT that did not have an LSD and a Carrera S 7MT, which is the one that we didn't think was going to have an LSD, but did.

On re-reading all of this, I am definitely thinking that some of my suppositions are wrong and am now 100% sure that there is a variant that neither myself, nor my development partners have seen, which is this 991 Carrera S with PDK and PTS+ that you are talking about. If you get your hands on that manual I would be very interested to see what it holds. This is one of those situations where I would be happy to be wrong because I personally think the new differential designs that are being used are really neat technology. While I tend to poo poo the electronic nannies, making an LSD into a sharper knife, if you will, is very interesting.

And unlike Erik, I don't think any of this means any of my efforts have been for naught. You know what my best selling LSD is? 915. That's a gearbox that hasn't been made in over 25 years. In just the last 12 months the 997 LSD market has exploded in its own right. What is brand new right now today has never been what pays our bills. Club racers rarely take brand new cars and convert them to racecars. They wait 3-5 years for depreciation and salvage auctions. And then they build racecars. I could have made a PDK LSD 3 years ago but the market hadn't matured yet. No matter what they do with the 991 Carrera S PDK and 991 GT3 PDK, we can make a product for it. We make a dynamic LSD for the Subaru STi center differential to replace Subaru's DCCD. There's no reason we can't make one for a Porsche too if Porsche gets on that bus. We've just got to see a demand for it before we'll make it. We don't grow markets, we harvest them.

Regards,

Matt
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Old 03-21-2013, 07:50 PM
  #38  
Mike in CA
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Originally Posted by GTgears View Post
Mike,

I was thinking about this conversation as I was packing today's shipments. I have come to the conclusion that I am the one who was (is?) confused here. My recollection was incorrect. We never had a 991 Carrera S PDK car that we looked at when we were doing the LSD project. The car that we had was a 997 Carrera S PDK. The only 2 991 cars we have seen so far have been a Carrera 7MT that did not have an LSD and a Carrera S 7MT, which is the one that we didn't think was going to have an LSD, but did.

On re-reading all of this, I am definitely thinking that some of my suppositions are wrong and am now 100% sure that there is a variant that neither myself, nor my development partners have seen, which is this 991 Carrera S with PDK and PTS+ that you are talking about. If you get your hands on that manual I would be very interested to see what it holds. This is one of those situations where I would be happy to be wrong because I personally think the new differential designs that are being used are really neat technology. While I tend to poo poo the electronic nannies, making an LSD into a sharper knife, if you will, is very interesting.

And unlike Erik, I don't think any of this means any of my efforts have been for naught. You know what my best selling LSD is? 915. That's a gearbox that hasn't been made in over 25 years. In just the last 12 months the 997 LSD market has exploded in its own right. What is brand new right now today has never been what pays our bills. Club racers rarely take brand new cars and convert them to racecars. They wait 3-5 years for depreciation and salvage auctions. And then they build racecars. I could have made a PDK LSD 3 years ago but the market hadn't matured yet. No matter what they do with the 991 Carrera S PDK and 991 GT3 PDK, we can make a product for it. We make a dynamic LSD for the Subaru STi center differential to replace Subaru's DCCD. There's no reason we can't make one for a Porsche too if Porsche gets on that bus. We've just got to see a demand for it before we'll make it. We don't grow markets, we harvest them.

Regards,

Matt
Matt, thank you for that. You are obviously a stand-up guy! If I find that technical info I will definitely share it. Nothing but the best,
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Old 03-21-2013, 08:09 PM
  #39  
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Originally Posted by Mike in CA View Post
Matt, thank you for that. You are obviously a stand-up guy! If I find that technical info I will definitely share it. Nothing but the best,
Mike,
You're welcome. For years I used to have a signature that said,"I don't care who is right, I just want to figure out what the right answer is." I'm not always right even though I am an "expert" in certain things. And I will be the first to admit that I haven't spent a whole lot of time examining the 47 different models of 911s today and the mind boggling myriad of options and option packages that they offer on them. This is definitely an instance where I misunderstood what Porsche was saying, probably because long ago they stopped being innocent until proven gulty in my eyes. Maybe it is time to revisit that bias.

Regards,

Matt
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Old 03-21-2013, 11:13 PM
  #40  
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Originally Posted by GTgears View Post
,"I don't care who is right, I just want to figure out what the right answer is." ...probably because long ago they stopped being innocent until proven gulty in my eyes.
Erik, thank you for taking the time to add to the conversation, much appreciated.

And I share Matt's thoughts above. If it is a true electronically controlled diff I will gladly retract my comments in this thread.

Follow-up edit- I edited my two previous scathing posts.

Last edited by savyboy; 03-22-2013 at 07:34 PM. Reason: note my edits. good day sir!
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Old 03-22-2013, 05:23 AM
  #41  
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OT but related - Chris Harris describes the electronic variable diff in SLS Black Series. Skip to 3:40.



I believe the new M5 also uses a similar system where an electric motor is used to change the locking factor -

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Old 03-22-2013, 03:03 PM
  #42  
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OK, I did my homework and have the factory tech documents. This adjustable LSD is a reality. I have seen the skematics. Here's an exerpt of their description of actuation of the LSD:

"Depending on the pressure applied in the pressure duct, the thrust washer is pressed onto the disk pack via 8 pressure pins and in this way achieve a locking value dependent on the pressure. This value is absolutely variable from 0 to 100%"

And

"An additional hydraulic control block is installed in the transmission for supplying oil pressure to the controlled rear differential lock..."

Furthermore, I have found reference to suggest that in addition to the 991 Carrera S PDK, this system is already in use on the turbo PDK vehicles.

Regards,

Matt
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Old 03-22-2013, 03:15 PM
  #43  
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Originally Posted by GTgears View Post
OK, I did my homework and have the factory tech documents. This adjustable LSD is a reality. I have seen the skematics. Here's an exerpt of their description of actuation of the LSD:

"Depending on the pressure applied in the pressure duct, the thrust washer is pressed onto the disk pack via 8 pressure pins and in this way achieve a locking value dependent on the pressure. This value is absolutely variable from 0 to 100%"

And

"An additional hydraulic control block is installed in the transmission for supplying oil pressure to the controlled rear differential lock..."

Furthermore, I have found reference to suggest that in addition to the 991 Carrera S PDK, this system is already in use on the turbo PDK vehicles.

Regards,

Matt
Fascinating. I'm not clear on what "pressure duct" might mean. I assume it's an electric motor pushing a thrust plate, which in turn pushes the 8 pins into the diff clutch plates. I can't imagine it's hydraulically actuated, so I assume the reference is to using the trans cooler to squirt oil on the diff and keep it cool. That's nice.

That's a tech doc with a schematic for the 991 Carrera S. Is this all model years or something introduced for 2013?

Any chance of a part number of the tech docs, please?

By "in use" you mean the 997.2 Turbo with PDK has this electronically controlled diff in its PTV (or is that PTV+) system?
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Old 03-22-2013, 03:31 PM
  #44  
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Originally Posted by Carrera GT View Post
Fascinating. I'm not clear on what "pressure duct" might mean. I assume it's an electric motor pushing a thrust plate, which in turn pushes the 8 pins into the diff clutch plates. I can't imagine it's hydraulically actuated, so I assume the reference is to using the trans cooler to squirt oil on the diff and keep it cool. That's nice.

That's a tech doc with a schematic for the 991 Carrera S. Is this all model years or something introduced for 2013?

Any chance of a part number of the tech docs, please?

By "in use" you mean the 997.2 Turbo with PDK has this electronically controlled diff in its PTV (or is that PTV+) system?
It is hydraulically actuated. There's very clear pictures and I have just posted a partial of the written description. It is section 3, titled Power Transmission from the 991 Carrera/CarreraS technical documents. They go into some detail about how it is actuated and about the sensor that feeds back to the TCU telling the Electronic Pressure Adjuster (aka EDS7) when to apply force.

It is not an electric motor. It is actually a line that pressurizes the Cup Spring and pushes it inboard toward the 8 pins, which in turn clamp down on the clutch pack. There is even a thrust washer between the Cup Spring and 8 pins to deal with the fact that the LSD assembly is spinning, but the Cup Spring is not.

By "in use" I mean that I found a reference to PTV+ that said it was new for the 991 Carrera but was previously employed on the previous (997.2) turbo models.
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Old 03-22-2013, 03:35 PM
  #45  
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Same diff BMW has been using since 2001 in the M3, and same diff Fiat has been using since 2004. It is long lasting (by its pressurized lubrication, a by product of the oil lines applying pressure to the clutch pack to close the diff, and release pressure to open the diff and reduce friction to near Zero). Best feature in my Scuderia, 2nd best feature in the 458 Italia too (the 1st being the gear-ratios chosen for the 458), the SLS shares the e-diff with Fiat (and also the DCT Getrag trans).
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