Sullyvette

I recently had my transmission replaced with a newer designed version. After they punctured a hole in the new transmission, They had to order a new gasket and pan. The pan they received didn't fit the new transmission. Had to order a new style pan and gasket??? Anyone hear of a design change for the C8? Mine is a 2021 Z51.

RKCRLR

I had heard there was a casting redesign in the works to address the porosity issue but I hadn't I heard it went that far.

Newdude

There is a 1st design and a 2nd design pan and case.

All of 2020 and some 2021 have the 1st design pan/case. 1st design pan has 13 bolts and 2 studs holding it on and has some sort of reinforcement plates on it.

The rest of 2021+onwards are 2nd design pan/case. 2nd design pan use 17 bots and 2 studs to hold it on and no longer uses the reinforcement plates.

1st/2nd for 2021 cars is identified from a 4 digit code on the trans broadcast label but the more obvious method would be counting the # of bolts and studs present.

Greg G

Any idea of the vin number or date when they made the switch?

Kracka

1st design: stamped steel
2nd design: cast aluminum

I too would like to learn the VIN or date cutoff for the change!

JVi

Mine is the new design for 2021 with a VIN ending in 17848 built July 1.

Phil1098

No, there is is no VIN cut off, it's a visual verification on what a particular car has. The new pan is cast aluminum and has more bolts holding it in place. The old style is a stamped steel pan with a gasket and reinforcement plates (like they used to use on old stamped steel valves covers) so the bolts don't bend the steel pan. The aluminum pan also has an integrated reusable O-ring type seal instead of a separate gasket. Because there are more bolts holding it on, that means the main case casting changed with more threaded holes for the additional bolts.

Kracka

Good to know! We were built the same day: VIN 17787

RKCRLR

Interesting. So if you go into the parts department to buy a transmission pan gasket they can't look up the correct part number by VIN? They'll tell you to go pull your bottom cover and tell them which one you need?

Phil1098

Yes, I have gone to the parts counter and looked at the parts screen. For 2021 it has two part numbers for pans and the description says, with reinforcement or without reinforcement. When a technician is at the parts counter he already has a car in the air and sees the car has a pan leak so he can also see what pan is on the car.

frankjr

Have a late 2021 build of August 26, 2021. No problems and car is awesome, best corvette I have owned and really enjoyed my 2019 GS.

Avanti

It's a shame GM didn't go with an established manufacture of a similar part, and not be Tremec's beta-tester.

Phil1098

I don't think that's entirely accurate, they acquired HOERBIGER Drivetrain Mechatronics BVBA located in Loppem, Belgium in 2012, almost a decade ago. Those folks did the DCT controls in Ferrari Italia 485, AMG SLS and McLaren MP4-12C, not exactly substandard cars. This isn't the first transmission Tremec has made, the TR6060 is a beast of a manual transmission. I have yet to see an actual transmission failure like bent shift forks, stripped splines, etc.

rjsmith169

According to chief engineer Jordan Lee they tried to use an existing European design ― he specifically mentioned Porsche's PDK ― but none, including Ferrari's Magneti Marelli F1 system, could handle the torque output of the engine. Although I'm certain he was referring to the LS6 engine in the 2023 Z06. But for commonality, and economies of scale, they use the current box for all C8s.

Someone sent me a link to the SAE white paper discussing this. I will search for that link. You can download the PDF file because it's easier to read than the online version.

Ray

rjsmith169

Courtesy of RKCRLR (Sterling Rorden):

https://secure.viewer.zmags.com/publ...9#/9455a1b9/22

Ray

Undy

LT2 torque is > then the LT6, 470 vs 460'

diehrd

You are spot on , But take the LT2 to 670 Hp and the torque that comes with that HP will wipe out the clutches in the DCT. I am an American purest when it comes to engines. And bottom end torque has a feel these high revving flat planes don't have. I wish GM simply super charged the LT2 while beefing up the DCT to deal with the torque.

Rapid Z

I do believe the entire transmission housing including the pan was changed sometime during the middle of the 2021 model year.

wsrc6

For street driving I would rather have low end torque than 900 HP @ 9000 but that would sound so Gooood!!!!

rjsmith169

You have it backwards. HP is a function of torque and RPM. The function is HP = (torque(rpm))/5252. Where 5252 is a proportionality constant.

That equation says that there are two ways to make horsepower. You can increase torque, or you can increase rpm. European engines produce less torque (by virtue of their smaller displacement). To get the horsepower, they need to rev higher. American muscle is more displacement, but lower rpm unless overhead cams are used to eliminate much of the reciprocating mass. The LT2 is an OHV, two valves per cylinder, cam-in-block engine with a CPC and a 5,600 rpm redline ― i'e' a Chevy small block. The LS6 is a four valves per cylinder, DOHC engine with a FPC and a redline of 8,600 rpm. It can produce less torque and by revving much higher can produce more horsepower. Much as the Ferrari F430 can produce 495 HP from only 4.3 liters

And good luck getting an LT2 to produce 670HP.

Ray