6-spd. Speeders Help Me.
Thread Starter
Drifting
Joined: Jan 2002
Posts: 1,731
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From: Bay Area CA
6-spd. Speeders Help Me.
Last night I was driving at about 150mph in 5th gear. I wasn't on it very hard. I have never put it into 6th at such a speed so I wanted to try it out. My RPM were somewhere around 4500 - 5000, I dumped it into 6th, and floored it immediately. It seemed and looke dlike the clutch was slipping. The RPM's stayed high and the engine sounded like it was bogging down. I let off the gas and it started to catch, RPM's dropped to about 3000. Is there something wrong with my C5, or is 6th gear not inteded for high speeds? TIA.
Burning Brakes
Joined: May 2001
Posts: 1,188
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From: Dallas TX
Re: 6-spd. Speeders Help Me. (PeterC)
:eek: :eek: :eek:
I've taken mine up to 135 in 5th when street racing, and then put her in 6th to cruise. No problems, but I didn't try accelerating in 6th at that speed.
I've taken mine up to 135 in 5th when street racing, and then put her in 6th to cruise. No problems, but I didn't try accelerating in 6th at that speed.
Le Mans Master
Joined: Sep 1999
Posts: 7,393
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From: Los Angeles CA
Re: 6-spd. Speeders Help Me. (PeterC)
Last night I was driving at about 150mph in 5th gear. I wasn't on it very hard. I have never put it into 6th at such a speed so I wanted to try it out. My RPM were somewhere around 4500 - 5000, I dumped it into 6th, and floored it immediately. It seemed and looke dlike the clutch was slipping. The RPM's stayed high and the engine sounded like it was bogging down. I let off the gas and it started to catch, RPM's dropped to about 3000. Is there something wrong with my C5, or is 6th gear not inteded for high speeds? TIA.
Thread Starter
Drifting
Joined: Jan 2002
Posts: 1,731
Likes: 1
From: Bay Area CA
Re: 6-spd. Speeders Help Me. (allanlaw)
I was definately in 6th, I let off the gas and the rpm dropped. I left it in 6th for a while and drove it at about 90mph. I'll test it tonight after work. I've driven the car at 120mph or so in 6th. Usually I shift from 5th to 6th at about 75 - 80 and it does well, not as well as leaving it in 5th, but pulls without a problem.
Intermediate
Joined: Nov 2001
Posts: 42
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From: Oshawa Ontario
Re: 6-spd. Speeders Help Me. (PeterC)
Hello, I can tell you right now your clutch WAS slipping. These car's had REALLY week clutch's up until 2001 and there still week but, much better ever since they upgraded all c5 to a Z06 clutch in2001. Sorry but, it will only get worse from now on. Depending on how much you beat on your car you might need one fairly soon. Hope this help's, just my .02 cent's. STEF
Le Mans Master
Joined: Nov 2000
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From: Galloway Twp. NJ
Cruise-In VII Veteran
Re: 6-spd. Speeders Help Me. (C5Noir)
Sixth gear is not intended for top speed. Fifth gear is your top speed gear :)
[Modified by RPOZ4Z, 6:25 PM 1/28/2002]
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6th Gear
Joined: Sep 2000
Posts: 6
Likes: 0
From: San Antonio, TX
Re: 6-spd. Speeders Help Me. (PeterC)
The reason that your Vette does not accelerate at 150 MPH in sixth gear is threefold. First of all, sixth gear is an extremely tall gear (0.50:1), even in comparison to fifth (0.74:1) All other things being equal, torque multiplication drops by almost a third when you shift from fifth to sixth. Secondly, when you are traveling at 150 in fifth, the engine is turning somewhere in the neighborhood of 4500 RPM (I don't have a calculator in front of me), which puts the engine at or near the peak of its torque curve. When you shift into sixth, the engine is turning somewhere in the neighborhood of 3000 RPM, which puts the engine way below its peak torque. Because (a) the gearing is producing less torque multiplication, (b) the engine is producing less torque, and (c) aerodynamic drag is a huge obstacle at such high speeds, it is pretty much impossible for a stock 6-speed Corvette to accelerate in sixth gear at 150+ MPH. Sixth is meant only for highway fuel economy.
Hope this helps. :)
[Modified by Blue Streak, 6:18 PM 1/28/2002]
Hope this helps. :)
[Modified by Blue Streak, 6:18 PM 1/28/2002]
Le Mans Master
Joined: Sep 1999
Posts: 7,393
Likes: 7
From: Los Angeles CA
Re: 6-spd. Speeders Help Me. (Blue Streak)
The reason that your Vette does not accelerate at 150 MPH in sixth gear is threefold. ........
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
Re: 6-spd. Speeders Help Me. (pkmoose)
Blue Streak hit the nail on the head. I used to run these calcs for the Army when I worked for them and top speed is a function of drag, torque and gearing. It sounds like your clutch is slipping, and I don't think you should "check it out" as further damage will occur. I would go easy on it until you can change it, my $0.02.
Race Director
Joined: Jan 2000
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From: Lynnfield MA
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Re: 6-spd. Speeders Help Me. (PeterC)
Welcome to the forum BTW... At that speed your clutch, IMHO, was slipping as others have stated. Fifth gear is the gear of choice with high speed runs.
Nick
Nick
Safety Car
Joined: Mar 2001
Posts: 4,174
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From: Parker Colorado
Re: 6-spd. Speeders Help Me. (PeterC)
Last night I was driving at about 150mph in 5th gear. I wasn't on it very hard.
I hate to see what you mean by "hard driving!" :D
[Modified by RUGBY, 5:56 AM 1/29/2002]
Le Mans Master
Joined: Dec 2000
Posts: 6,312
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From: North Haven, CT
Re: 6-spd. Speeders Help Me. (PeterC)
Sounds like your clutch was slipping to me. Mine had similar symptons before it went. I replaced it with the '02 Z06 clutch and am very happy with it.
Thread Starter
Drifting
Joined: Jan 2002
Posts: 1,731
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From: Bay Area CA
Re: 6-spd. Speeders Help Me. (BillY2KFRC)
It definately felt like it was slipping. The RPM's stayed high until I let off and it caught. Than the engine bogged down. Too much rain last night to even thinkabout speed. Guess I'll see what happens. Got some good advice though, thanks.