C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

warning: trailing throttle oversteer

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Old Jul 28, 2018 | 01:49 PM
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Default warning: trailing throttle oversteer

I dont drive my vette much so its hard to get a real feel for the car. I noticed when bombing on an on ramp I abruptly lifted in a near straight line at about 83mph that the rear slid and started to come around on me. Im an automatic with a 2:58 rear end so that might have something to do with it.. but just warning you guys who dont drive it much and is just a weekend toy to be careful. Ive got super sticky continentals on too.

With as much meat as I have in the rear I just wasnt expecting that. Ive got many hours of racing experience on road courses and I know this is a no no but as we ahem get older we forget

Edit: I did program my torque converter not to let go at high speeds so that might have something to do with it too...

Last edited by barchetta1; Jul 28, 2018 at 01:50 PM.
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Old Jul 28, 2018 | 02:11 PM
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throttle off weight transfer is a bitch... A viper wrecked at a runway event here in dallas after he lifted going through the line at ~200mph... car was totaled. Had a chute too which is what he should have used.
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Old Jul 28, 2018 | 02:15 PM
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I would be having a very close look at alignment and suspension condition. Car shouldn't be doing that behavior.
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Old Jul 28, 2018 | 02:46 PM
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Originally Posted by Tom400CFI
I would be having a very close look at alignment and suspension condition. Car shouldn't be doing that behavior.
Could be, but doubt it.. just vehicle dynamics in play. Once you get weight moving it does not want to stop.

EDIT: I also daily drive a 2017 bmw 330 and it basically drives itself.. you lose your skills in modern cars.

Last edited by barchetta1; Jul 28, 2018 at 02:48 PM.
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Old Jul 28, 2018 | 02:46 PM
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Originally Posted by rjacobs
throttle off weight transfer is a bitch... A viper wrecked at a runway event here in dallas after he lifted going through the line at ~200mph... car was totaled. Had a chute too which is what he should have used.

What is a runway event? Closed airport?
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Old Jul 28, 2018 | 02:58 PM
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Originally Posted by barchetta1
Could be, but doubt it.. just vehicle dynamics in play. Once you get weight moving it does not want to stop.
What has to happen to cause trailing throttle over steer?
1. you're rear tires need to lose traction.
2. you have a rear steer from alignment change

1. No car should be breaking the tires loose from chopping the throttle at 83 mph...unless you slammed the shifter into "1/lo" at the same time, or you grabbed a fist full of Parking brake. Did you? Then the rear tires shouldn't be breaking traction from that type of event. Especially with your 2.58 rear, which reduces the tq to the wheel both accelerating and decelerating.

2. This is not an uncommon issue with older C4's; the toe rod ends are worn, car "steers" in the rear on throttle vs. off. 25+ year old rubber bushings are hard, cracked, beat, missing....you lose directional control over the wheel.


I have a '92 6 speed with a 3.45 gear and I could chop the throttle at 83 mph in a straight line with no adverse effects at all. Car should not be "getting sideways" from chopping the throttle in a straight line at that speed.
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Old Jul 28, 2018 | 03:05 PM
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Originally Posted by Tom400CFI
What has to happen to cause trailing throttle over steer?
1. you're rear tires need to lose traction.
2. you have a rear steer from alignment change

1. No car should be breaking the tires loose from chopping the throttle at 83 mph...unless you slammed the shifter into "1/lo" at the same time, or you grabbed a fist full of Parking brake. Did you? Then the rear tires shouldn't be breaking traction from that type of event. Especially with your 2.58 rear, which reduces the tq to the wheel both accelerating and decelerating.

2. This is not an uncommon issue with older C4's; the toe rod ends are worn, car "steers" in the rear on throttle vs. off. 25+ year old rubber bushings are hard, cracked, beat, missing....you lose directional control over the wheel.


I have a '92 6 speed with a 3.45 gear and I could chop the throttle at 83 mph in a straight line with no adverse effects at all. Car should not be "getting sideways" from chopping the throttle in a straight line at that speed.
Im going to bring my car in and have all the tie rods and bushings replaced. thanks.
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Old Jul 28, 2018 | 03:48 PM
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Historically it takes either a lot of rear brake and a lot of overhung rear weight think Porsche 911 sort of thing. A bunch of rear bump steer and rear toe out can get real busy too. It makes it turn in very nice but a handful going straight fast, definitely the no snooze zone. I am with Tom new rear suspension parts and a good alignment.
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Old Jul 28, 2018 | 04:13 PM
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Originally Posted by ddahlgren
Historically it takes either a lot of rear brake and a lot of overhung rear weight think Porsche 911 sort of thing. A bunch of rear bump steer and rear toe out can get real busy too. It makes it turn in very nice but a handful going straight fast, definitely the no snooze zone. I am with Tom new rear suspension parts and a good alignment.
I would venture to guess that 95.7% of the corvettes driven in this forum are in the state/condition mine is in. Thus the warning. I shouldnt have used the word virtually, I was on a 2-5 degree turning radius.

I would disagree that a rear engine sports car is the only type susceptible. Ive had this happen to me in my SCCA ITB rabbit. It depends on conditions, road surface and how quickly the lift was done. A slight "bump" on the surface at the right time can cause this in almost any car.

Also if you have just completed a maneuver and the suspension is still loaded it can happen very easily. All while driving in a straight line.

Didnt mean for this to be a debate, I believe its a valid and helpful warning for those of us who have 22 yr old plus corvettes and drive them on weekends.

Disregard it and blame it on broken suspension if you like, that is your prerogative.. maybe I save some fiberglass of those who heed my warning and dont pull a dumb *** move like lifting abruptly at high speeds.

EDIT: when thinking back to racing, one mistake I commonly made was to assume just because the car was driving straight for even .025 seconds doesnt mean the suspension is done dealing with lateral G's. Its an oopps moment you dont forget.

Last edited by barchetta1; Jul 28, 2018 at 04:17 PM.
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Old Jul 28, 2018 | 05:20 PM
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^All good points. Thanks for posting.
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