4x3 Transmission Question
Thread Starter
Burning Brakes
Joined: Feb 2001
Posts: 1,118
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From: West Palm Beach Florida
4x3 Transmission Question
Hey all. I forgot what this was. I guess this was the transmission they used before the 700r4? Why is it called 4x3 - and what year was the last they used it in?
Thanks
Thanks
Team Owner
Joined: Mar 2000
Posts: 83,383
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From: Boston, MA
Re: 4x3 Transmission Question (Sal Collaziano)
The 4+3 was used from 84-88 before the ZF6 6-speed was available in 1989. It is a Borg Warner Super T-10 4-speed manual mated to a 2-speed automatic tranny on the back. You have 7 forward gears to choose from by being able to shift the 2-speed while in 2nd/3rd/4th with the 4-speed.
Team Owner
Joined: Mar 2000
Posts: 83,383
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From: Boston, MA
...They couldn't make replacement parts fast enough... :D
I think it was poor execution of a good idea more than anything. Here are all of the ratios in my particular unit.
Super T-10
2.88 : 1
1.91 : 1
1.34 : 1
1.00 : 1
Two Speed Overdrive Unit
1:00 : 1
0.68 : 1
Combining the available combinations in 2/3/4 you get...
1: 2.88 : 1
2: 1.91 : 1
2*: 1.30 : 1
3: 1.34 : 1
3*: 0.90 : 1
4: 1.00 : 1
4*: 0.68 : 1
* = Overdrive unit engaged.
It is a pretty fun/cool unit. If you are in say 2* puttering along at 35mph and you step on the gas it will downshift to 2 automatically and you're off like a bat outta hell. :) So it has some of the characteristics of an automatic, but the fun of a manual.
There were issues with the 84-86 units that made them a bit more unreliable from the 87/88 units. The 87/88 units are much more durable and with last a long time as long as you change the fluids/filter at regular intervals.
Pro
Joined: Dec 2001
Posts: 715
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From: NYC NY
Re: 4x3 Transmission Question (Sal Collaziano)
I'm sure part of the reason it was discontinued was this (although I like the one about not being able to make parts fast enough for them) .
Look at these ratios again.
1: 2.88 : 1
2: 1.91 : 1
2*: 1.30 : 1
3: 1.34 : 1
3*: 0.90 : 1
4: 1.00 : 1
4*: 0.68 : 1
2nd overdrive is almost the exact same as 3rd gear.
Likewise 3rd overdrive is nearly the same as being in 4th.
Even though this tranny wasn't made to go into 1st overdrive you can do it and basically its like driving around in second.
So esentially the only extra gear worth a crap is 4th overdrive and that's a lot of extra garbage just for one extra gear. In its pure form it is kind of like a 1st to 3rd gear skip I guess, maybe to save gas. Kinda like the later 1st to 4th in the lt1's.
Look at these ratios again.
1: 2.88 : 1
2: 1.91 : 1
2*: 1.30 : 1
3: 1.34 : 1
3*: 0.90 : 1
4: 1.00 : 1
4*: 0.68 : 1
2nd overdrive is almost the exact same as 3rd gear.
Likewise 3rd overdrive is nearly the same as being in 4th.
Even though this tranny wasn't made to go into 1st overdrive you can do it and basically its like driving around in second.
So esentially the only extra gear worth a crap is 4th overdrive and that's a lot of extra garbage just for one extra gear. In its pure form it is kind of like a 1st to 3rd gear skip I guess, maybe to save gas. Kinda like the later 1st to 4th in the lt1's.
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: 4x3 Transmission Question (C4-Wolf)
So esentially the only extra gear worth a crap is 4th overdrive and that's a lot of extra garbage just for one extra gear. In its pure form it is kind of like a 1st to 3rd gear skip I guess, maybe to save gas. Kinda like the later 1st to 4th in the lt1's.
And yes the car does have a version of CAGS in it. When shifting from 1 to 2 it will put you into 2* if you did not go past 70% throttle in 1st gear.
Pro
Joined: Dec 2001
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From: NYC NY
Re: 4x3 Transmission Question (scorp508)
QUOTE
at the time all of Corvette's competitors were using 5-speeds and there was no 5-speed available to GM that would hold up to the torque (supposedly) of the engines at that time that were suitable to fit in Corvette. This is why the 4+3 got designed and used.
That is my point, seems silly to go about making a 5 speed this way.
at the time all of Corvette's competitors were using 5-speeds and there was no 5-speed available to GM that would hold up to the torque (supposedly) of the engines at that time that were suitable to fit in Corvette. This is why the 4+3 got designed and used.
That is my point, seems silly to go about making a 5 speed this way.
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Team Owner
Joined: Mar 2000
Posts: 83,383
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From: Boston, MA
Re: 4x3 Transmission Question (C4-Wolf)
That is my point, seems silly to go about making a 5 speed this way.
Pro
Joined: Dec 2001
Posts: 715
Likes: 0
From: NYC NY
Re: 4x3 Transmission Question (scorp508)
Speaking of the 4+3, have you had to change out your overdrive button? If so how hard is it to get at, I'm going to have to do mine soon? I thought I saw a thread about this but I can't find it now.
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: 4x3 Transmission Question (C4-Wolf)
Speaking of the 4+3, have you had to change out your overdrive button? If so how hard is it to get at, I'm going to have to do mine soon? I thought I saw a thread about this but I can't find it now.
I've replaced the switch two times so far. Which part do you need to replace?
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: 4x3 Transmission Question (C4-Wolf)
I assume the button as I pretty much have too hit it (instead of just push it) to activate/deactive overdrive.
You have two choices...
Buy the switch from GM with the harness for $88.
Buy the switch from Newark Electronics w/o harness for $11.
You can remove the harness from the old switch and solder it onto the new on. Installation is not that hard, but does require a little bit of caution as most of the pieces you will be dealing with are not replaceable anymore.
Lemme know what you decide. :)
Pro
Joined: Dec 2001
Posts: 715
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From: NYC NY
Re: 4x3 Transmission Question (scorp508)
So the button on top actually mechanically triggers a switch below the shift boot? Good to know. I'll have to pull the console up and check it out in the next couple days here. If it is that switch I will probably go with the one with the harness as I haven't had much luck soldering things in the past. Thanks for the help, I couldn't find anything about this in my GM repair manual.
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Yep, the plastic button on top snaps on with 4 small clips that age/crack/break off over time. The front half of the button presses down on a T shaped piece of metal that screws into a nylon block down in the shifter stalk. This nylon sliding block in turn actually presses down and activates the switch.
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: (C4-Wolf)
OK doesn't sound too bad to change out. Man my winter repair list just keeps getting longer... Thanks Scorp.
You'll need....
Phillips Screwdriver
5/16" Open End Wrench
Needlenose Plyers
And also very very small something to use to press out the retaining pin in the nylon block. I use a tiny allen wrench and tap it through gently with a hammer.
