Tadge Juechter: The C8 Corvette Reduces Torque During Drivetrain Break-In

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Tadge Juechter: The C8 Corvette Reduces Torque During Drivetrain Break-In


the Corvette Forum runs a series called “Ask Tadge” where regular forum members and Corvette enthusiasts post questions aimed at the Chief Engineer of America’s Sports Car, Tadge Juechter, and he periodically chooses some of the more thoughtful or common questions and writes up an answer to them.

One of the most recent ones comes from just before Christmas when forum member, JVP posed the following, multifaceted question to Mr. Juechter regarding his new baby, the 2020 Corvette Stingray, being in reduced torque output mode during the initial break-in period of 500 miles, “…Can you elaborate on the purpose for [reduced torque mode], 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?”

One of the coolest things about “Ask Tadge” is that the busy Chief Engineer of the Chevrolet Corvette does it out of his passion for the cars and a desire to ensure that owners are as educated about them as possible and as usual, Tadge brought his A-game when he responded to this edition of the series that bears his name.

Tadge Juechter: The C8 Corvette Reduces Torque During Drivetrain Break-In


He starts by mentioning that General Motors recommends a 500-mile break-in period on all of their cars, not just the fast ones. Next, he gets awesomely engineer-y about the importance of this preparation period:

“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.”

He then continues to talk about how they implemented the reconfigurable redline when the C7 first came to market and discusses how using full power right out of the gate can be harmful to a vehicle:

“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 do 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.”

Finally, he answers the limiting of torque in the C8 question:

“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.”

We don’t know about you, but we feel all warm and fuzzy inside after reading that, as commenter, mammoth713 puts it “As an engineer myself, I love reading his detailed responses to technical questions. Stuff like this makes me have a better appreciation of the corvette brand.”

The thread doesn’t cease being interesting there, either. A short scroll down the page reveals a comment from an astute new member who asks, “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 (would this still be recommended if I were to drive my new C8 900 miles home from the dealer)?”

Tadge didn’t need to field this question because the forum’s greatest strength is the vast wealth of knowledge brought there every day by its members. A senior member by the name of Ragtop 99 proceeded with this reply, “The varying speed requirement was in the C7 owner’s manual and I would expect it to be the same for the c8. Take some back roads on your trip home the first day. If you have to be on the highway for a long stretch, use the paddle shifters to alternate between 5, 6, 7, and 8th gears so that you don’t stay in 8th for long periods of time.”

This is some good stuff, thank you to all who contributed and we hope that as many new C8 owners, especially the large number of them who will be piloting their first ‘Vette will take it all to heart! Ease into your new mid-engine marvel for 500-1,000 miles and it will be a reliable friend to you for years to come!


Source:
CorvetteForum.com

Related:
[VIDEO] Corvette Chief Engineer Tadge Juechter Talks C8 Corvette on Autoline After Hours
Corvette Chief Engineer Tadge Juechter is No. 4 on MotorTrend’s Power List for 2020
[VIDEO] Tadge Juechter and the 2020 Corvette Stingray Convertible Visit Jay Leno’s Garage

 

2 COMMENTS

  1. I’ve owned Corvette’s, Plymouth Cuda’s, a Mercury Cougar 428cu, TransAms, and have always observed a break in period. It sure saves a lot of headaches later down the road. I knew a guy who had early or mid 60’s vette with a 409. I’m not sure if it was the original engine, but he really rung it out and blew the engine, had the engine rebuilt and promptly blew it again and couldn’t understand why it went to pieces again.
    I think his middle name was ‘ stupid ‘.

  2. The people who don’t know or understand engine break-in periods are the younger set; those with more horsepower than brains. Hit the start button and off they go. They do it in every car they own.
    For the most part, us ‘older car guys’ have this minds eye mental image as we ‘insert and turn the key’ or ‘hit the start button’ of our cars, regardless if it is our daily driver or our beloved Corvette[s]…..
    power from the battery going to the starter motor;
    bendix clutch engages starter motor gear to fly wheel gear;
    engine turns…..dry….o-m-g, watch oil pressure gage as oil pump gets the life’s blood of an engine to its wearing parts as pressure rises;
    fresh fuel/air mixture being drawn into enters cylinders thru the carburetor….[I’m 73, my ’80 has its original Rochester!]; or, injectors squirting fresh fuel into the intake air stream [my ’13 manual trans GS];
    spark plug ignites fuel/air mixture, ignition;
    watch all the gages – oil pressure-’80&’13, & coolant temp/oil temp-’13.
    That’s what we do, us older guys, who have an appreciate for all things mechanical.
    Tell me you old guys, like me, don’t go thru that mind’s eye mental thought process each and every time?
    You know you do!

    Mike 8TY4SPD & MNL13GS

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