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One of the biggest reasons I am holding off at the moment is the DCT Max Torque value of roughly 900 Nm, or 664lb-two. I like to mod and my last Corvette would have definitely exceeded the capabilities of the base DCT.
So question, do any of the vendors have plans for upgraded clutch packs for the DCT in the Corvette and GT500? I would imagine at the moment vendors may have this in the product pipeline with a general idea of cost, but no direct solution (as they haven’t had the chance to get their hands on the transmission).
One of the biggest reasons I am holding off at the moment is the DCT Max Torque value of roughly 900 Nm, or 664lb-two. I like to mod and my last Corvette would have definitely exceeded the capabilities of the base DCT.
So question, do any of the vendors have plans for upgraded clutch packs for the DCT in the Corvette and GT500? I would imagine at the moment vendors may have this in the product pipeline with a general idea of cost, but no direct solution (as they haven’t had the chance to get their hands on the transmission).
If its 650ft lbs rated that means for the expected lifetime. Probably be able to go over that by 10-20 percent and still get longevity out of it.
So, I was looking for a post about this because I was wondering what the first weak point of building the c8 would be. The DCT is what I some will cause the most issues at first. But, there are people building high power Porsches and other mid engineer cars so there has to be a method to putting power down "reliably."
So, I was looking for a post about this because I was wondering what the first weak point of building the c8 would be. The DCT is what I some will cause the most issues at first. But, there are people building high power Porsches and other mid engineer cars so there has to be a method to putting power down "reliably."
Replacing the clutches in the trans itself seems to be a common upgrade but I do not hear too much about it because either they handle the power or it was retrofitting older DCT's while the newer ones are not an issue.
What will be the tell is the difference in the Z06/ZR1 DCT and the regular C8 DCT.
Replacing the clutches in the trans itself seems to be a common upgrade but I do not hear too much about it because either they handle the power or it was retrofitting older DCT's while the newer ones are not an issue.
What will be the tell is the difference in the Z06/ZR1 DCT and the regular C8 DCT.
That's a good point. I wondered if there were any gear changes that were normal in a DCT like chromoly gear replacements.
One of the biggest reasons I am holding off at the moment is the DCT Max Torque value of roughly 900 Nm, or 664lb-two. I like to mod and my last Corvette would have definitely exceeded the capabilities of the base DCT.
Hmm, if you "moded" a C7 you had a similar issue! particularly folks who had a Z51 with it's 1st gear ratio and added a supercharger! Even the Z06 max torque (with a 1st gear ratio reduced) was a few ft-lbs less max allowed torque than the engine developed. (See chart below.)
In the ZR, that uses the same trans gears as the Z06, they limited the power in first gear electronically so the trans would not be overloaded!
As in all Hot Rod fashion, we have exceeded the manufacturers "calculated" max loads that have a safety factor and are picked so the parts last 100,000+ miles.
I think of the OEM 4:56 gears that came in my first car, a '41 Ford business coupe! It originally has a 136 cid small flathead called the 60 V8, as it had 60 hp. That low dif gear was to go up hills NOT for acceleration! When I put in an Olds engine that I had bored 1/8 inches for 324 cid (big "in-the-day) 1st gear was not needed as it light up the tires starting in 2nd! I can still remember pulling off the rear drums to check the brakes and the keyway in the axle was twisted as was the key! Had to put it back that way! Never had a problem for the same reason you won't with the gears- those tires will not stress them to a point of failure. (now if you had the 16.5 section width (420 metric) I have on my Tubbed Street Rod- that would be an issue!
The clutch won't last the length of time GM planned! That 11 inch clutch wore more that Ford planned in my '41 coupe especially as I had to slip it to get traction!
I wondered if there were any gear changes that were normal in a DCT like chromoly gear replacements.
Heck there are high performance steel gear alloys far belter than simple Chrome Moly! They also contain Nickel, Cobalt with small amounts of Tungsten, Vanadium etc!
Heck there are high performance steel gear alloys far belter than simple Chrome Moly! They also contain Nickel, Cobalt with small amounts of Tungsten, Vanadium etc!
Yeah, we've done alot of gear upgrades for the Lotus. Most manufacturers use case-hardened 8620 or 9310 steel as the hardness can be north of 60 rockwell. This leads to good surface wear and longevity. Additionally, if it doesn't flex too much it resists crack propagation. However, these steels while strong don't have the tensile strength of through hardened 4340 or for really crazy 300M(F-18 tailhooks are made of this stuff).
We've done designs with a lower helix and larger teeth for strength and used either 4340 or 9310. Then shot-peen, then REM. On input shafts, we used 300M. Huge improvement in durability. I expect these options will be available for the vette before too long.....
^^
Been out of the Industrial Gas business for some years so checked the web to see if Cryo Treating has any quantitative performance data available.
Some websites from Treaters make it sound like it will cure the common cold including for use on any car part!
It does transform some retained austenite to martensite etc and this is what one company said re gears: "Treating rear ends will reduce wear and improve crack resistance. Your ring and pinion gears will be less susceptible to chipped teeth and fatigue failures."
Had a good friend from my old company who was still in R&D and a few years ago he said they have shown improvent in performace with liquid Nitrogen treatment. However when I left I went from managing an R&D lab to director of welding market development. My counterpart had the same job for the "gas applications business." We were the largest Indusrrial Gas company at the time and were great at selling Ovygen, which left a lot or liquid Nitrogen that had to be vented- no market!
His 30 person group was always looking for ways to sell Nitrogen so I wonder about how effective some of these teartments really are! Guess it can't hurt!
Hmm, if you "moded" a C7 you had a similar issue! particularly folks who had a Z51 with it's 1st gear ratio and added a supercharger! Even the Z06 max torque (with a 1st gear ratio reduced) was a few ft-lbs less max allowed torque than the engine developed.
Correct! Hence why I upgraded my C5Z from a T-56 to a TR-6060 with a McLeod RXT Clutch. Problem solved
Hmm, if you "moded" a C7 you had a similar issue! particularly folks who had a Z51 with it's 1st gear ratio and added a supercharger! Even the Z06 max torque (with a 1st gear ratio reduced) was a few ft-lbs less max allowed torque than the engine developed. (See chart below.)
In the ZR, that uses the same trans gears as the Z06, they limited the power in first gear electronically so the trans would not be overloaded!
As in all Hot Rod fashion, we have exceeded the manufacturers "calculated" max loads that have a safety factor and are picked so the parts last 100,000+ miles.
I think of the OEM 4:56 gears that came in my first car, a '41 Ford business coupe! It originally has a 136 cid small flathead called the 60 V8, as it had 60 hp. That low dif gear was to go up hills NOT for acceleration! When I put in an Olds engine that I had bored 1/8 inches for 324 cid (big "in-the-day) 1st gear was not needed as it light up the tires starting in 2nd! I can still remember pulling off the rear drums to check the brakes and the keyway in the axle was twisted as was the key! Had to put it back that way! Never had a problem for the same reason you won't with the gears- those tires will not stress them to a point of failure. (now if you had the 16.5 section width (420 metric) I have on my Tubbed Street Rod- that would be an issue!
The clutch won't last the length of time GM planned! That 11 inch clutch wore more that Ford planned in my '41 coupe especially as I had to slip it to get traction!
Never heard they limited 1st gear torque for the sake of the trans, could see it being for the sake of the tires and traction if that was actually the case. The numerically smaller gears handle more torque because they have less teeth therefore are stronger was my understanding of the different ratings of the 3 trans and the engine produced more torque ahead of each trans which made torque multiplication from gearing less needed as well.
^^
Torque multiplication is dependent on the gear ratio. May be multiple parts of the trans that can be an issue but 1st gear being the most toque multiplication will govern the max loads on all parts, case distortion etc.
One reason straight cut gears are used in racing transmission (where the excess noise they generate is a none issue) is unlike helical cut gears that load the ends of the case, straight cut gears create no loads on the gear shaft direction! In fact, helical gears have more of the tooth in contact for the same size gear.
1st gear in a LT1 Z51 will provide 460 ft-lbs X 2.97 = 1366 ft-lbs of torque output.
1st gear in the LT4 Z06 will provide 650 ft-lbs X 2.29 = 1488 ft-lbs, similar output
Of interest, Tremic says the max torque for the Z06 gearing is limited to 635 ft-lbs which is 1454 ft-lbs - closer.
I would not want a high boost application.. I would be very happy with a simple, low cost kit making 5-8psi with 150hp. Just enough to take out the z06 c8 and 99% of the other cars and not blow rods and parts.
That’s the same torque rating of the 8spd auto in the current C7 ZR1, and look at the power some folks are putting through those nowadays. BTW:That’s the highest rating for any stock GM transmission.
Here’s how the entire slate of Chevrolet Performance transmissions compare: https://www.chevrolet.com/performance/transmissions
08-24-2019, 01:00 PM
Transmission upgrades
Never had a problem for the same reason you won't with the gears- those tires will not stress them to a point of failure. (now if you had the 16.5 section width (420 metric) I have on my Tubbed Street Rod- that would be an issue!
