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How does the 4+3 Manual Transmission Overdrive work?

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Old 05-08-2010, 05:48 PM   #1
bigjohn85
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Default How does the 4+3 Manual Transmission Overdrive work?

I was looking to buy a late 80's corvette with a manual transmission and a seller was telling me that the button isn't in the stick anymore and when he is easy on the car it automatically goes into overdrive and when you are hard on it, it stays in the regular gears. Is this how the transmission suppose to work?
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Old 05-08-2010, 09:36 PM   #2
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Sort of.
The O/d is on every time you turn the key on.
When the right conditions are met ( varies by year ) , speed / engine temp /TPS volts; the O/d will automatically engage.It will also kick out back to direct drive when certain conditions are met ( hard accel, etc)
See
http://www.5speeds.com/43table.htm

The O/d can be turned off by using the button and then manually engaged when ever you want to
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Old 05-12-2010, 01:18 PM   #3
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thanks for the help. Makes a lot more sense now. do you suggest the six speed? I could just go up to a 89.
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Old 05-12-2010, 01:32 PM   #4
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Quote:
Originally Posted by bigjohn85 View Post
thanks for the help. Makes a lot more sense now. do you suggest the six speed? I could just go up to a 89.
6 Speed,89'...Definatly. The early C4 4+3's were not very durable.If you , can..go with at least an 89' and get the ZF 6 Speed.
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Old 05-12-2010, 01:52 PM   #5
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IMO, the 4+3's are fun to play with, but once the novelty wears off and the overdrive unit quits working you will wish you had the (more durable) 6-speed.
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Old 05-12-2010, 07:48 PM   #6
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Originally Posted by Driver84 View Post
IMO, the 4+3's are fun to play with, but once the novelty wears off.
Some owners disagree
http://forums.corvetteforum.com/c4-g...-all-time.html
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Old 05-12-2010, 11:14 PM   #7
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In my early 1985 the O/D is never on automatically when the key is turned on. You must engage or disengage the O/D with a switch on the console. Later on the switch was mounted on top of the gearshifter. Otherwise it's just a T10 4 speed transmission. You can use O/D in 2nd 3rd or 4th gear. Just a note that the early 4+3 transmissions were very durable. Just not many people ever really knew how to use them and wound up damaging them through misuse.
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