In what way is a GT3's Transmission different than a 997?
07-23-2012, 02:07 PM
#31
Nordschleife Master
This all sounds very authoritative. However, check back on Porsche's original press release about the 'PDK'. It was lifted verbatim from that of Ricardo 2 days previously and VW the previous day. You could say that a Ricardo PR flack wrote the substantive parts of both VAG's and PAG's press releases. This ought to tell folk something (About the same time a US manufacturer also rehacked the same release).
Generalising, Japanese drivers are quite abusive of gearboxes, hence their manufacturers have developed pretty tough manual transmissions and have removed some of the slush from the automatics. It seems sensible to make use of this technology. On the other hand, many Germans understand far too much about how fragile gearboxes can be and to this day handle their transmissions with a level of care and consideration not encounted in many other places. This is good for Hansel und Gretel, but not so not for those whose sporting driving is limited to accelerating away from the lights at T-junctions. Hence the interest in Japanese transmissions.
I have driven, and tested the GT3 box inverted and installed in a mid engined configuration. With one caveat, I'd say it works pretty well. The problem, which is not entirely resolved owing to a shortage of demand, is the need to ensure that there is an extra series of oil pick-ups to maintain adequate lubrication when operated in this configuration.
R+C
Generalising, Japanese drivers are quite abusive of gearboxes, hence their manufacturers have developed pretty tough manual transmissions and have removed some of the slush from the automatics. It seems sensible to make use of this technology. On the other hand, many Germans understand far too much about how fragile gearboxes can be and to this day handle their transmissions with a level of care and consideration not encounted in many other places. This is good for Hansel und Gretel, but not so not for those whose sporting driving is limited to accelerating away from the lights at T-junctions. Hence the interest in Japanese transmissions.
I have driven, and tested the GT3 box inverted and installed in a mid engined configuration. With one caveat, I'd say it works pretty well. The problem, which is not entirely resolved owing to a shortage of demand, is the need to ensure that there is an extra series of oil pick-ups to maintain adequate lubrication when operated in this configuration.
R+C
As for flipping a GT3 gearbox and making it reliable, it is pretty straight forward. It requires about 12" of tubing to move the oil pump pick up and filter from the stock location to the other side of the box so that lubrication properly flows. And a little machine work to encourage flow between the cases, and other than moving the breather and drain, it's pretty much done. We did dozens of them when we were the OEM supplier for Mosler for the MT900.
As in synchros for the 997 Aisin box cost about twice as much as GT3 synchros. At the same time they released the parts, they pretty much doubled the price of the crate gearbox overnight. It's typical Porsche. They don't release service parts for the gearboxes for 4-5 year after a new one comes out. They offer what I call "goodwill" pricing on replacement boxes during that window so anyone who needs one that isn't warranty doesn't get too pissed off. Then when they release the service parts, they take away the goodwill pricing and reduce the amount of inventory they hold of remanufactured gearboxes. They do the same thing with engines too.
07-23-2012, 02:26 PM
#32
Race Director
Ultimately, the most satisfying automated manual transmissions (flappy paddles to most of us), are those with a single clutch. Many purist engineers find the double clutch offensive in that it is inherently wasteful and heavy - would Colin Chapman have tolerated one?
As for Colin Chapman, having owned from new a real Chapman designed Lotus (1973 Europa Twin Cam Special) I can attest that his design philosophy of "simplify, then add lightness" had both advantages and disadvantages. That Chapman might not have tolerated a dual clutch transmission like PDK in a road car is not necessarily a bad sign....
Last edited by Mike in CA; 07-23-2012 at 05:13 PM.
07-23-2012, 03:43 PM
#33
Rennlist Member
As in synchros for the 997 Aisin box cost about twice as much as GT3 synchros. At the same time they released the parts, they pretty much doubled the price of the crate gearbox overnight. It's typical Porsche. They don't release service parts for the gearboxes for 4-5 year after a new one comes out. They offer what I call "goodwill" pricing on replacement boxes during that window so anyone who needs one that isn't warranty doesn't get too pissed off. Then when they release the service parts, they take away the goodwill pricing and reduce the amount of inventory they hold of remanufactured gearboxes. They do the same thing with engines too.
i am just getting a feeling that in a long run it may be cheaper to ditch both M96 and aisin from my car and put in older rebuilt 996/997.1 gt3 3.6l with a gearbox rather than try to rebuild M96/tranny. will see.
07-23-2012, 04:15 PM
#34
Nordschleife Master
so, if you have new info - how much exactly will a replacement aisin box cost compared to gt3 one now?
i am just getting a feeling that in a long run it may be cheaper to ditch both M96 and aisin from my car and put in older rebuilt 996/997.1 gt3 3.6l with a gearbox rather than try to rebuild M96/tranny. will see.
i am just getting a feeling that in a long run it may be cheaper to ditch both M96 and aisin from my car and put in older rebuilt 996/997.1 gt3 3.6l with a gearbox rather than try to rebuild M96/tranny. will see.
As for the cost of a replacement boxes? A GT3 crate gearbox is still a fair bit more expensive than a 997 crate Aisin gearbox. How big the difference is I don't know without calling the dealer. But keep in mind, they won't take your Aisin core and give you back a GT3 Getrag crate gearbox. They only trade like cores for like replacements. That's what Mobonic had to do. He had to find a gearbox and engine on the open market because under no circumstances do you want to pay the core charge on top of the actual cost of the replacement unit.
07-24-2012, 12:20 PM
#35
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.... The point of my comments was that Porsche has historically been very protective of their proprietary technologies and I just find interesting that they seem to have changed their perspective on such things and have partnered with Aisin on the 7MT instead of continuing to work with ZF.
As for flipping a GT3 gearbox and making it reliable, it is pretty straight forward. It requires about 12" of tubing to move the oil pump pick up and filter from the stock location to the other side of the box so that lubrication properly flows. And a little machine work to encourage flow between the cases, and other than moving the breather and drain, it's pretty much done. We did dozens of them when we were the OEM Porshe supplier for Mosler for the MT900.
As for flipping a GT3 gearbox and making it reliable, it is pretty straight forward. It requires about 12" of tubing to move the oil pump pick up and filter from the stock location to the other side of the box so that lubrication properly flows. And a little machine work to encourage flow between the cases, and other than moving the breather and drain, it's pretty much done. We did dozens of them when we were the OEM Porshe supplier for Mosler for the MT900.
As far as your method of modifying the gearbox is concerned, it has the merit of being very straightforward and elegant in design. However, endurance racing at the Nürburgring showed that rather more work was required, it was a shame because everything else was pretty fine, only the gearbox and rear suspension requiring additional development. If it had been up to me, I would have popped in a transverse unit from xtrac.
R+C
07-24-2012, 12:27 PM
#36
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For track applications you have a point, but for a car that will also be driven on the street the dual clutch transmission is superior and, taking all driving conditions into account, more satisfying to drive. That's why manufacturers from Porsche to BMW to Ferrari are going that route.
As for Colin Chapman, having owned from new a real Chapman designed Lotus (1973 Europa Twin Cam Special) I can attest that his design philosophy of "simplify, then add lightness" had both advantages and disadvantages. That Chapman might not have tolerated a dual clutch transmission like PDK in a road car is not necessarily a bad sign....
As for Colin Chapman, having owned from new a real Chapman designed Lotus (1973 Europa Twin Cam Special) I can attest that his design philosophy of "simplify, then add lightness" had both advantages and disadvantages. That Chapman might not have tolerated a dual clutch transmission like PDK in a road car is not necessarily a bad sign....
R+C
07-24-2012, 12:41 PM
#37
Rennlist Member
^I love puttering around in my Smart car. Best city car I've owned so far. The scion Iq doesn't look bad on paper either with 2 rear seats in the back but damn where is the space for legs. Mike
07-24-2012, 06:16 PM
#38
Nordschleife Master
What is PAG IP, VAG IP, Getrag, ZFFAG or Ricardo intellectual property is a moot point. I was pointing out that what many folk assume is PAG technology is often developed elsewhere. VAG is a huge supplier of technology to PAG. Very often tech contracts are covered by NDAs, which allow fairly boastful claims to be made which are difficult to refute.
As far as your method of modifying the gearbox is concerned, it has the merit of being very straightforward and elegant in design. However, endurance racing at the Nürburgring showed that rather more work was required, it was a shame because everything else was pretty fine, only the gearbox and rear suspension requiring additional development. If it had been up to me, I would have popped in a transverse unit from xtrac.
R+C
As far as your method of modifying the gearbox is concerned, it has the merit of being very straightforward and elegant in design. However, endurance racing at the Nürburgring showed that rather more work was required, it was a shame because everything else was pretty fine, only the gearbox and rear suspension requiring additional development. If it had been up to me, I would have popped in a transverse unit from xtrac.
R+C
Do you mind telling me what the point of failure was on the inverted Nurburgring box? Was this the Alzen Cayman, or some other car? If I am prying just say so and I'll respect that you don't want to discuss it further.
07-25-2012, 03:04 AM
#39
Pro
One data point here. Tracked my 06 997s probably 20 times. Not one issue with the tranny or anything else. Road atl, barber, cmp, t-hill, laguna, button willow. Pretty hot places.
07-26-2012, 08:08 AM
#40
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It wasn't the Alzen one......
But I really really like driving the GT3 when its supercharged and dropped into the Cayman chassis on the street, possibly the best forced induction implementation I've encountered, from a purist pilot's viewpoint; not much lag at all.
Notice how I have avoided your question!
R+C
07-26-2012, 03:59 PM
#42
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Failing either of those possibilities, Alois Ruf would probably expand further on the subject.
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07-28-2012, 12:56 PM
#43
Rennlist Member
Rad... Is it the quality of the transmission in your cayman, or the fact that you "no lift shift" it around the track at 7k+rpm. I would tend to believe it's the latter. Something tells me the boys in germany didn't intend for you to row through the gears at WOT.
07-30-2012, 04:38 PM
#44
Nordschleife Master
Sorry, I think the team regards it as 'propriety information', they know what broke, and are holding this close to their chests in case they revive the project. As you know your way about this world, you will find the team in Aachen, alternatively the driver with the initials MS who was in the car at the time, rebuilds gearboxes for stress relief, he could discuss the specifics.
Failing either of those possibilities, Alois Ruf would probably expand further on the subject.
R+C
Failing either of those possibilities, Alois Ruf would probably expand further on the subject.
R+C
02-24-2020, 02:18 AM
#45
