[ANSWERED] C8: Reduced Torque During Drivetrain Break-In
12-18-2019, 12:21 PM
#1
Tech Contributor
Thread Starter
Member Since: Mar 1999
Location: Northern VA
Posts: 10,066
Received 3,805 Likes
on
1,145 Posts
"Ask Tadge" Producer
[ANSWERED] C8: Reduced Torque During Drivetrain Break-In
The original question is here.
jvp asked:
During your recent interview with Jay Leno on his Garage show, you mentioned that the new car will be in a reduced torque output mode during the car's initial break-in period. Can you elaborate on the purpose for that, and explain to folks what happens at 500 miles? Does the engine's full output happen automatically due to programming or is it something that will require a maintenance visit?
During your recent interview with Jay Leno on his Garage show, you mentioned that the new car will be in a reduced torque output mode during the car's initial break-in period. Can you elaborate on the purpose for that, and explain to folks what happens at 500 miles? Does the engine's full output happen automatically due to programming or is it something that will require a maintenance visit?
Tadge answered:
Thanks for the question JVP. This is a good opportunity to clear a few things up. For as long as I can remember we have recommended a 500 mile break in period for new cars. Not just Corvette, all cars. It has been emphasized in the owner’s materials with further definition around brakes and driveline.
Why is this important? Any machinery that has moving parts, whether they have point contact, a rotational interface or slide against each other will “bed-in” over time. What that means is, no matter the manufacturing process, two interfacing parts will find their own equilibrium. You can think of it as mutually refining each other’s surface texture until they reach a steady state. This steady state condition generally minimizes noise, vibration and wear. Although manufacturing has improved to a point where break in effects are minimized, they are still at play despite claims to the contrary. And the truth is, there may be additional minor benefits to a longer break in period. If it was my car, I would try to be patient for 1,000 miles.
Starting with the 7th generation Corvette we established a variable red line on the tach to give drivers a visual indication on when it would be advisable to take it easy on the car. We used it for the first 500 miles of driving and when the engine was coming up to operating temperature after break in was complete. Our reconfigurable display enabled us to to that. We didn’t actually limit torque, horse power or RPM, it was just a visual indication. Despite the tach and owner’s instructions, some customers use the full capability of the car immediately. We have too many videos of people doing burn-outs off the dealer lot or showing up to a track (both road course and drag strip) with near zero miles. Taking any green and cold engine to max torque and speed can cause undesirable wear patterns that could affect engine operation over the long term. Running full torque through the trans under the same conditions can score gears, especially those in the differential after the engine torque has been multiplied. We have had examples of customers not observing the break in guidelines and then returning the car to the dealer with complaints of gear noise or differential whine.
For the 8th generation Corvette, we have taken it a step farther. With more weight on the rear, the car has more traction and we take advantage of that with more aggressive gearing. That translates into more torque multiplication and more loads in the driveline. We decided for the first 500 miles to limit maximum torque in first and second gears. The torque reduction is roughly 25 to 30% depending on which transaxle (standard or Z51) and which gear. That may sound like a big reduction, but in reality the car is still really fast. In fact, you could easily spin the tires on some surfaces. Engine speed is not limited at all – it will wind out to redline. So the torque reduction limits the worse of potential break in wear, but is not a panacea. We will still be asking customers to stay well off max torque and speed for the first 500 miles. We know it is hard to stay patient when such performance is available, but it will pay off in the long run.
Thanks for the question JVP. This is a good opportunity to clear a few things up. For as long as I can remember we have recommended a 500 mile break in period for new cars. Not just Corvette, all cars. It has been emphasized in the owner’s materials with further definition around brakes and driveline.
Why is this important? Any machinery that has moving parts, whether they have point contact, a rotational interface or slide against each other will “bed-in” over time. What that means is, no matter the manufacturing process, two interfacing parts will find their own equilibrium. You can think of it as mutually refining each other’s surface texture until they reach a steady state. This steady state condition generally minimizes noise, vibration and wear. Although manufacturing has improved to a point where break in effects are minimized, they are still at play despite claims to the contrary. And the truth is, there may be additional minor benefits to a longer break in period. If it was my car, I would try to be patient for 1,000 miles.
Starting with the 7th generation Corvette we established a variable red line on the tach to give drivers a visual indication on when it would be advisable to take it easy on the car. We used it for the first 500 miles of driving and when the engine was coming up to operating temperature after break in was complete. Our reconfigurable display enabled us to to that. We didn’t actually limit torque, horse power or RPM, it was just a visual indication. Despite the tach and owner’s instructions, some customers use the full capability of the car immediately. We have too many videos of people doing burn-outs off the dealer lot or showing up to a track (both road course and drag strip) with near zero miles. Taking any green and cold engine to max torque and speed can cause undesirable wear patterns that could affect engine operation over the long term. Running full torque through the trans under the same conditions can score gears, especially those in the differential after the engine torque has been multiplied. We have had examples of customers not observing the break in guidelines and then returning the car to the dealer with complaints of gear noise or differential whine.
For the 8th generation Corvette, we have taken it a step farther. With more weight on the rear, the car has more traction and we take advantage of that with more aggressive gearing. That translates into more torque multiplication and more loads in the driveline. We decided for the first 500 miles to limit maximum torque in first and second gears. The torque reduction is roughly 25 to 30% depending on which transaxle (standard or Z51) and which gear. That may sound like a big reduction, but in reality the car is still really fast. In fact, you could easily spin the tires on some surfaces. Engine speed is not limited at all – it will wind out to redline. So the torque reduction limits the worse of potential break in wear, but is not a panacea. We will still be asking customers to stay well off max torque and speed for the first 500 miles. We know it is hard to stay patient when such performance is available, but it will pay off in the long run.
The following 35 users liked this post by jvp:
427bob (01-13-2020),
88flyer (12-21-2019),
Archways C7 (01-03-2020),
burtonbl103 (01-01-2020),
Bvvet (12-19-2019),
and 30 others liked this post.
Popular Reply
12-19-2019, 12:56 PM
Racer
I am totally fine with this. Very smart on GM’s part. Great response by Tadge. I really like how he is very in depth with his answers.
The following 9 users liked this post by Jeffro19:
396tears (01-07-2020),
427bob (01-13-2020),
Bvvet (12-19-2019),
Bwright (07-02-2020),
CorvetteBrent (12-23-2019),
and 4 others liked this post.
12-19-2019, 04:44 PM
#3
He is the best ambassador for the Corvette brand, and has done some great U Tube interviews. I like the way he dispels the rumors.
He took my question at Carlisle about engine cover lighting even though I was not part of the Press Q&A
Keep it up Tadge
He took my question at Carlisle about engine cover lighting even though I was not part of the Press Q&A
Keep it up Tadge
The following 8 users liked this post by Bvvet:
burtonbl103 (01-01-2020),
Bwright (07-02-2020),
CorvetteBrent (12-23-2019),
FrankLP (01-07-2020),
GSVette19 (12-28-2019),
and 3 others liked this post.
The following users liked this post:
JLSuperfly (12-20-2019)
12-21-2019, 09:52 PM
#7
Hopefully Mr. Tadge can advise on this: I may drive my new C8 900 miles from the dealer to my home. Back in the 60's and 70's the best break-in was varying speeds, rpm, loads, temperatures, etc, over a period of time. Is wide variation still recommended during the first 500 miles? Am I treating it properly by driving it moderately 900 miles over 2-3 days, where variation may be minimal ?
12-21-2019, 10:40 PM
#8
Safety Car
Hopefully Mr. Tadge can advise on this: I may drive my new C8 900 miles from the dealer to my home. Back in the 60's and 70's the best break-in was varying speeds, rpm, loads, temperatures, etc, over a period of time. Is wide variation still recommended during the first 500 miles? Am I treating it properly by driving it moderately 900 miles over 2-3 days, where variation may be minimal ?
The following 4 users liked this post by Ragtop 99:
Corvette310 (01-26-2020),
CorvetteBrent (12-23-2019),
Ed Bard (01-13-2020),
lusluckylad (12-27-2019)
The following users liked this post:
Bwright (07-02-2020)
01-08-2020, 08:35 AM
#11
Race Director
Member Since: Jan 2014
Location: Huskerland
Posts: 10,532
Received 2,834 Likes
on
1,970 Posts
2021 C6 of the Year Finalist - Modified
So I guess that puts to rest the old muscle car strategy, if you break it in hard it will run hard...... another old school theorem bites the dust...... 
01-11-2020, 04:05 PM
#12
Pretty much anything in a new car, including the driver, needs a break in procedure. No different than a horse or a girlfriend. Break in process is a fun time.
01-11-2020, 10:40 PM
#14
It's possible a bunch of folks here are idolizing a few senior members who post dubious things about break-ins, dealer allotments,etc, etc. Everyone posting here has owned serious cars prior to the C8, and should not abandon what they have learned over many years. There is nothing different about the C8 drive line from a Camaro or a pickup truck, no matter what the "experts" want you to think.
01-13-2020, 02:51 AM
#15
It's possible a bunch of folks here are idolizing a few senior members who post dubious things about break-ins, dealer allotments,etc, etc. Everyone posting here has owned serious cars prior to the C8, and should not abandon what they have learned over many years. There is nothing different about the C8 drive line from a Camaro or a pickup truck, no matter what the "experts" want you to think.
01-14-2020, 06:23 AM
#17
Melting Slicks
Interesting, I know a few Ferrari guys who took their car to the track with only a 100 miles on them.
Do you think the C8’s that will be used for the press launch will be broken in over 500 miles before they hand them over to the media?
Do you think the C8’s that will be used for the press launch will be broken in over 500 miles before they hand them over to the media?
Last edited by fasttoys; 01-14-2020 at 06:25 AM.
01-14-2020, 09:24 AM
#18
Tech Contributor
Thread Starter
Member Since: Mar 1999
Location: Northern VA
Posts: 10,066
Received 3,805 Likes
on
1,145 Posts
"Ask Tadge" Producer
01-14-2020, 01:46 PM
#20
Team Owner
Member Since: Sep 2005
Location: Big Bend Country, TX
Posts: 29,114
Received 2,186 Likes
on
1,337 Posts
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15- '16-'17-‘18-‘19-'20-'21
NCM Lifetime Member
.......... 