C8 Corvette Transaxle

I'd suspect there are more than a few SL-C that are near 3,000 lbs. Weight is weight, but really if you are not trying to win races on a track, what's the difference between a, 2,700 lb car and a 3,000 lb car?
I guess I was under the impression that a "normal" SL-C build was closer to 2500lbs? The last GTM I ran across the scales was 2520 lbs...and that was with full interior, sound deadening, stereo, AC, fuel....

No doubt that there are great advantages to the dual clutch trans....but what's the difference between a 2500 lb or 2700 lb car vs a 3000 lb car? Well....500 or 300 lbs. All of that weight doesn't only effect acceleration. It also effects cornering, handling, braking. No argument that the SL-C can be whatever you choose to make it.....if you just want it to cruise around and take to car shows.....nothing wrong with that.....but if that's what you're going to do with it....then why do you need 8ms shifts?

In my mind, this sort of comes down to whether you'd rather have a '70 GTO Judge or a 1990 Mazda Miata. The Miata ain't gonna win you any awards at the car show......but the GTO sure isn't going to put a smile on your face while pushing it to the limits on a windy road.
 

Neil

Supporter
Shane:

"......but the GTO sure isn't going to put a smile on your face while pushing it to the limits on a windy road." Don't be too sure of that.

In the fall of 1964, I ordered a new '65 Pontiac GTO coupe with every performance option that they offered- 389 with 3 2-bbl carburetors, a close-ratio 4-speed, heavy-duty suspension with metallic brakes, etc, etc. I was working in Green Bank, WV at that time and drove it to Charlottesville, VA frequently. Route 33 or route 250 ran through the Allegheny Mountains and it was a FUN drive around corners, up hill, down hill, through switchbacks, and with a few short stretches of road. There was very little traffic and no highway patrol. The only things to watch out for were coal & lumber trucks and wet autumn leaves on the pavement. Having a lot of power (torque) on tap (I had my GTO upgraded to a "Royal Bobcat" by Royal Pontiac in Royal Oak, MI) it was easy to swing the rear end around on tight turns.
As much fun as my GTO was, it could not compete with my '63 250GTE Ferrari. It was faster, easier to drive, and the sound of the V12 echoing back through the WV mountains was glorious. Those were epic drives!
 
I could be wrong, but the only sub-2500lb SLCs that I know of are pretty much track cars with license plates. Nothing wrong with that, but not really street cars. As far as the gearbox, the Ricardo in mine weights, like, 200 lb. Strong as an ox, but not Porsche light. Early all aluminum NSXs were 3,200lbs as a reference. Why have the 8ms shifts? Just because your not driving a race car, it would still be fun to shift like you are while blasting down a country road (or track day) :cool:
 
Mine was 2825 with a half tank of fuel.

I could be wrong, but the only sub-2500lb SLCs that I know of are pretty much track cars with license plates. Nothing wrong with that, but not really street cars. As far as the gearbox, the Ricardo in mine weights, like, 200 lb. Strong as an ox, but not Porsche light. Early all aluminum NSXs were 3,200lbs as a reference. Why have the 8ms shifts? Just because your not driving a race car, it would still be fun to shift like you are while blasting down a country road (or track day) :cool:
 

Howard Jones

Supporter
Fast shifting is a advantage in a track car if you need to shift a lot. I can run COTA with only 3,4,5th and only using 5th twice at the end of both straights. Most other track can be run in 3rd & 4th. However I wouldn't give up 500 pounds to save what would really be something in the range of a second or two...……………...maybe. With that additional weight and at a 4 to 1 power to weight ratio, 2500lbs/500hp, it would take another 100hp to make up the acceleration part of the performance envelope and you have still hurt the braking and corner speed. I would guess a lot. Picture a 500 pound passenger in the right seat.

However having said that, the auto downshift would really make the gearbox very reliable verse's heal and toe rev matching not to mention a lot easier. I just don't think it would be faster.
 

Roger Reid

Supporter
A Porsche G96 gearbox weighs approximately 175 lbs according to the CMS website. Does the new Vette twin clutch really weigh in the neighborhood of 675lbs? If the twin clutch came in at 300lbs you would only be gaining 125lbs.
 
A Porsche G96 gearbox weighs approximately 175 lbs according to the CMS website. Does the new Vette twin clutch really weigh in the neighborhood of 675lbs? If the twin clutch came in at 300lbs you would only be gaining 125lbs.
It only weighs in at 341lbs according to the leaked engineering document. It’s not that heavy for carrying 8 gears, and electronic LSD that also has built in clutches. Now you may need additional coolers for track usage and electronics to run it. Nevertheless it’s a very compact unit for what it offers
 

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It only weighs in at 341lbs according to the leaked engineering document. It’s not that heavy for carrying 8 gears, and electronic LSD that also has built in clutches. Now you may need additional coolers for track usage and electronics to run it. Nevertheless it’s a very compact unit for what it offers
DCT would probably save 10-20 pounds vs the clutch/flywheel setup in a traditional gearbox. From the DL800, but the clutch size and weight in the Corvette DCT's should be basically the same.

There won't be 8 gear pairs, by the way - the layout in the DCT is different. In a 7 speed DCT, for example, there are a total of 11 gears that give it 7 speeds.
 

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Shane:

"......but the GTO sure isn't going to put a smile on your face while pushing it to the limits on a windy road." Don't be too sure of that.

In the fall of 1964, I ordered a new '65 Pontiac GTO coupe with every performance option that they offered- 389 with 3 2-bbl carburetors, a close-ratio 4-speed, heavy-duty suspension with metallic brakes, etc, etc. I was working in Green Bank, WV at that time and drove it to Charlottesville, VA frequently. Route 33 or route 250 ran through the Allegheny Mountains and it was a FUN drive around corners, up hill, down hill, through switchbacks, and with a few short stretches of road. There was very little traffic and no highway patrol. The only things to watch out for were coal & lumber trucks and wet autumn leaves on the pavement. Having a lot of power (torque) on tap (I had my GTO upgraded to a "Royal Bobcat" by Royal Pontiac in Royal Oak, MI) it was easy to swing the rear end around on tight turns.
As much fun as my GTO was, it could not compete with my '63 250GTE Ferrari. It was faster, easier to drive, and the sound of the V12 echoing back through the WV mountains was glorious. Those were epic drives!
A quick google search indicates that your '65 GTO weighed in at 3478.....while the '70 GTO that I mentioned weighed in at 3781.....a 303 pound difference. And what did your 250GTE weigh?...google search shows 2820.....which sort of makes my point....right.....?

Again...it matters not one bit to me how people choose to build their cars....building them exactly the way YOU want them is what these cars are all about! My only point is that sometimes it's worth while to take a step back and really think about what you want and if what you're installing in your car is going to get you closer to what you want or get you farther away from what you want. I see the same thing with people building their own AR-15's. "I'm going to build the ultimate "do everything" AR-15!". My first thought is, "no...you're not. You're going to end up with an AR-15 that really isn't good for anything at all."
 

Neil

Supporter
Shane, I was just taking issue with your "......but the GTO sure isn't going to put a smile on your face while pushing it to the limits on a windy road." It did put a smile on my face... :)
 
Understood! And 5 and a half decades ago.....that GTO would have been seen as one of the top performing "American performance cars" available.....and I'm sure that 55 years ago, it probably delivered on that promise. Fast forward to today and almost every single aspect of that "performance" can be outdone by new 4cyl Toyota Camry. Times change....along with what we expect from a "performance car".
 

Neil

Supporter
True, but I'd still rather still have that GTO than a Camry... I wish I still had that Ferrari, too. ;)
 

Howard Jones

Supporter
It looks like a G50 like mine weights 146 pounds. That's still a couple of hundred pounds more for the C8 @ 341. That's quite a lot of weight difference and all on the rear axle centerline. I think I would rather have the Porsche even with the high tech shifting. But I'm old and the tech stuff really doesn't impress me all that much.
 
It looks like a G50 like mine weights 146 pounds. That's still a couple of hundred pounds more for the C8 @ 341. That's quite a lot of weight difference and all on the rear axle centerline. I think I would rather have the Porsche even with the high tech shifting. But I'm old and the tech stuff really doesn't impress me all that much.
What’s the overall G50 weight with engine adapter plate, flywheel, clutch, disc, throw out bearing, linkages, and fluids? Ya, the whole package.. and the graziano total?
 
Now that the C8 Corvette numbers are out, it’s unbelievable how fast the transaxle really is. It can launch a 3,600lbs car from 0-60mph in only 2.8 seconds , and send it down the 1/4 in 11.1 @ 123mph.. with only 500hp. I think the same engine/trans combo into an SLC should be able to hit around 9.8 sec or so in 1/4, or maybe low 10s.
 

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