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I like this. Very neat, the twin disc clutch is pretty beefy but it looks like it can be made to fit. The clutch without the alloy flywheel is exactly 13 kgs. So with the flywheel and ring gear I suspect it is about the same as the Porsche factory clutch. I can't remember but I think that is around 20 kgs? <br/><br/>I think the best way to adapt the front part of the conversion is to make a custom bell housing with custom inspection cover along with custom flywheel. <br/><br/>
Does anyone have an automatic torque tube out of a four speed car and out of the car also that they can measure? I tried measuring in the car but it not very accurate. I got 1300 mm. Thanks in advance.
You are tempting me. I have been wanting to do a Corvette transmission swap since Dinsdale put his first conversion out.... albeit I would prefer to do a C5 Auto so my wife can drive it later. Nothing like a 928 S4 with 3.73 or 3.90 gears I bet...
Good luck on your project. This will be a fun one to watch!
Very nice! Interesting that they added the heat shield material on the torque tube. Previous models did not have that. How long is that torque tube?
Cheers!
Carl
Hi Carl,
The tube from flange to flange is 1365 mm. I believe and my best measurement is somewhat rough, that the Porsche 928 auto tube is 1300 mm. At the front of the conversion this may be perfect, a little bonus is that the spigot bearing is the same id as the 928 spigot but it does appear at the other end I have some issues with length. The TR6070 appears to be about 30 to 35 mm longer than the 928 auto.
So that is a bummer as I don't want to have to shorten the tube. The reason for the heat material is because the tube is made from carbon fibre
Last edited by slate blue; 11-25-2015 at 07:02 AM.
The tube from flange to flange is 1365 mm. I believe and my best measurement is somewhat rough, that the Porsche 928 auto tube is 1300 mm. At the front of the conversion this may be perfect, a little bonus is that the spigot bearing is the same id as the 928 spigot but it does appear at the other end I have some issues with length. The TR6070 appears to be about 30 to 35 mm longer than the 928 auto.
So that is a bummer as I don't want to have to shorten the tube. The reason for the heat material is because the tube is made from carbon fibre.
Well I will have to edit the above post as I have just pulled apart the torque tube, the driveshaft is aluminium as such easy to alter. I won't go into where my confusion stems from but the Driveshaft Shop makes custom shafts for $1400. This conversion then becomes a bit easier.
However any alterations cost money, I will have to see if I can move the transmission forward about 30 mm and that way the original plan of using the factory diff mounts will work and the space between the diff housing and the battery box is retained for large exhaust systems. In my case it is 3 1/2".
The driveshaft weighs 9 kgs with all its attachments. From what I see on their website the CF shaft saves about 6 kgs but if I went that route I am retaining the rubber isolators. I have heard without them it is a nightmare. So I just rang a local driveshaft specialist, it is about $200 to shorten and rebalance the inner shaft.
Z06 tube disassembled
Last edited by slate blue; 11-25-2015 at 07:03 AM.
Investigations have continued and it appears the only way forward in a very integrated way is to make the rear section of the TR6070 in billet and that piece will also be the adaptation piece. So the differential housing will bolt directly to the redesigned rear section which is about 190 mm long and wide. This will also make it very sturdy.
I have to consult with the gear maker before going down this route as they had some concerns about the output shaft moving for and aft. Just quickly about the shaft it is just a touch bigger in diameter than the Porsche output shaft in the automatic. In fact if the heat treat could be dealt with you could just machine the existing Tremec shaft.
Tremec TR6070
I don't think there will be any for or aft movement but I must be sure. It will really cause trouble if we have to deal with that. Although I suppose one solution might a tapered roller bearing instead of the straight roller bearing in situ now.
The other issue I must address is the length, I need to save some length, (again if anybody has the length of the 4 speed torque tube please advise) I need to make the parts very compact. I think I can save 15 to 20 mm by intergrating the adaptor and hopefully the remaining 15 to 20 mm can be saved in the custom bell housing.
I have my machinist coming to the house on the weekend to give me an opinion about the required pieces. The issue is he is working full time and only uses his spare time on my project. However he tells me he likes challenges. He certainly has one here.
Last edited by slate blue; 11-28-2015 at 05:38 AM.
So by rough measurement, pretty accurate, enough to get an idea, it appears we need to shorten the torque tube by 37 mm which is close to the amount that the seven TR6070 is longer than the TR6060 (42 mm longer) again from rough measurements, the TR6070 is 35 mm longer than the automatic Benz 4 speed. So we need to push that tranny further forward so that we can use the factory mounts. This will leave around 130 mm of clearance space for the exhaust. My exhaust being 90 mm in diameter leaves only 20 mm around the pipe for clearance when perfectly positioned.
On a different topic, people have said here and to me personally that this is a bastardisation of the car. Well, it certainly isn't a standard resto, however, if you think about what Porsche did. They took another's transmission in the case of Mercedes Benz and adapted it. They purchased a transmission from ZF for the manual option also.
So given this, I am actually just doing the same as Porsche. The differential is retained completely including the PSD. The parts will be bolt in with no adapters. I am just changing out the parts that are the weak link in terms of strength and adding extra features like more ratios and the speed and precision of the billet shifter with active rev match. I think swaps like this should be judged on intergration and functionality.
I prefer the 6 spd manual in Corvettes vs. the 7 spd. With hundreds of thousands of miles on the 6 spd and tens of thousands on the 7, I can say if given a choice...
I prefer the 6 spd manual in Corvettes vs. the 7 spd. With hundreds of thousands of miles on the 6 spd and tens of thousands on the 7, I can say if given a choice...
It's basically the same box, just an extra gear added. Have a look at the ratios, mine are basically the same as the ZR1 except for the top gear for economy. The TR6070 has extra sensors and uses the carbon blocker rings which was a aftermarket upgrade to the TR6060.
The machinist thinks it will take two days to machine the billet rear housing which is ok. I now have to check with the gear maker my design is an appropriate approach to finding a solution to fit the new transmission.
Originally Posted by slate blue
Investigations have continued and it appears the only way forward in a very integrated way is to make the rear section of the TR6070 in billet and that piece will also be the adaptation piece. So the differential housing will bolt directly to the redesigned rear section which is about 190 mm long and wide. This will also make it very sturdy.
I have to consult with the gear maker before going down this route as they had some concerns about the output shaft moving for and aft. Just quickly about the shaft it is just a touch bigger in diameter than the Porsche output shaft in the automatic. In fact if the heat treat could be dealt with you could just machine the existing Tremec shaft.
Tremec TR6070
I don't think there will be any for or aft movement but I must be sure. It will really cause trouble if we have to deal with that. Although I suppose one solution might a tapered roller bearing instead of the straight roller bearing in situ now.
The other issue I must address is the length, I need to save some length, (again if anybody has the length of the 4 speed torque tube please advise) I need to make the parts very compact. I think I can save 15 to 20 mm by intergrating the adaptor and hopefully the remaining 15 to 20 mm can be saved in the custom bell housing.
I have my machinist coming to the house on the weekend to give me an opinion about the required pieces. The issue is he is working full time and only uses his spare time on my project. However he tells me he likes challenges. He certainly has one here.
Just thought I would share a comparison of the Porsche double disc clutch vs the Corvette double disc. There is a big difference in price with the Vette clutch costing $350. It also weighs approx 13 kgs not counting the flywheel.
Comparison of the clutch plates.
Comparison of the pressure plates
The Porsche clutch sitting on top of the Vette clutch.
11-23-2015, 06:52 AM
