Comparing 6 speed to 4+3 manual.

[BADRACR]

I've learned to manipulate my shifts at the right rpm's so that I can leave mine on and get it to kick in in third and fourth when I shift into these gears. First & second I still drive like normal, but if I wind second & third just right, shift & hold the clutch in a second or so extra the trans will engage the od and give no shift shock. I also engage the clutch when turning the od on. It feels hard sometimes otherwise.

 

[vdogamr]

As I think I have stated in other threads, I believe whatever logic my cars uses to switch gears is broken. I have had my car tell me to upshift when I was in 3rd at about 1200 RPM. But the reason I post now is because I actually had my car in 1st the other day with the OD on. That is supposed to be impossible if everything is working correctly right? And the other day I could not back my car up without revving the engine. My guess is that I turned the car off with the OD engaged and so I was trying to back up in the equivalent 2nd gear. But all this said, if I just us OD as 5th gear then everything works fine.

 

[larry bud]

Having the original 4+3 in my '86, then replacing it with a Richmond 6 speed after the 2nd time it died, the 6 speed is WAAYY more fun, and the car is much faster. I always thought that 3rd gear in the 4+3 was anemic.

Corvette Richmond 6-Speed Transmission Installation

In addition, it's easier to do a clutch job with the Richmond. It's a smaller transmission and much easier to get the "C" bracket off.

 

[vetteoz]

Someone above said that this is a Borg Warner T-10 with an OD unit -is that correct?

Borg Warner Super T-10 2.88 1st gear
All internals are identical but the rear of the trans case is reinforced to mount the DNE O/d unit.
A special short output shaft is used to connect to the O/d in place of the long stock shaft that extends through the tailshaft housing

 

[jerrywagner]

I just bought an 87 Vette with the 4+3 and my stick shift has no switch in the stick shift, I took off the top of the stick shift and it was an empty cavity, is there suppose to be an overdrive switch there on the stick shift for a 1987 model year ?

 

[vetteoz]

I just bought an 87 Vette with the 4+3 and my stick shift has no switch in the stick shift, I took off the top of the stick shift and it was an empty cavity, is there suppose to be an overdrive switch there on the stick shift for a 1987 model year ?

Top of shifter knob has a hinged flap that works as a button for the O/d switch mounted at base of shifter
The button pushes on a shaft that runs down the shifter and operates the switch at base.
If you can't work switch , by default you get automatic O/d engagement as soon as engine is up to required operating temp

 

[CharlesBrown]

If you get the 4+3, or have one now, It's not a bad idea to use the clutch for the changes in and out of the OD. No, of course you don't have to... but it "don't hurt."

 

[jerrywagner]

there is not a hinged button on the shifter and no switch under the current button, could some models not have this ? I suspect a previous owner did not like the function of the overdrive and removed this, in any event it will not engage on the freeway

 

[WhalePirot]

I disagree with the 4+3 bashing and am surprised at the source of some of it. Using that logic, the '90 ZR-1 is inferior to the C6 version. Does that make the '90 less of a car?

In any design there are compromises and often refinements. We all have our preferences and certainly, opinions. I've long appreciated the kick-down of the 4+3 which is nothing like an 'early Chevy 4-speed'. It has the quickness of an automatic with the control of a manual; down shifting much faster than any manual. The O/D allows for better acceleration from starts, and darn good fuel economy on the highway., also unlike and old 4-speed.

As too-often stated, much of the denigration of the Doug Nash O/D was due to misunderstanding of its operation and/or inferior maintenance. The O/D portion of mine was fine when I chose to rebuild it at 100k+. The gears in the T-10 were surprisingly worn, however, particularly 2nd. When I researched changing to the 6-speed, I found it could not handle the power of my re-engined monster. My "inferior" 4+3 still works fine behind that engine.

I'd also considered the Ritchie 6-er versus the overhaul of my stock units. One installer told me that he had removed more than one from a customers' cars due to the noise of the straight-cut gears.

In the end, I am quite satisfied with the unique 4+3.

 

[vetteoz]

no switch under the current button,

Switch is at base of shifter; not visible unless everything dismantled
Possibly someone fitted a early 4+3 shifter with no button .Early cars had the button on the console

in any event it will not engage on the freeway

As I have stated previously ; by default the O/d will automatically engage when the right conditions are met without any input from the driver
If not , then you have problems. Most current problems with these are centered around the control side ; bad wiring / connections / faulty relay / etc.
Rare to be a computer problem

I suspect a previous owner did not like the function of the overdrive

Would make no difference;
O/d is automatically on The button just gives the driver manual control