6 speed 4L80E

SY2455

SY2455

70's Veteran
Re: 6 speed 4L80E

The spare Turbo 400 that I have in the garage has the following gear ratios.

1st = 4.96 2nd = 2.96 3rd = 2.48 4th = 2.00 5th = 1.48 6th = 1.00

The trans would shift so hard on the 1st and 2nd shift that it twisted a driveshaft in half in the middle when I was running a 3.91 gear in the rear. I had to get a heavy wall driveshaft to keep the trans. The next time I used it I will be running a 2.56 rear gear.
 
ty166

ty166

Donating Member
Re: 6 speed 4L80E

SY2455 said:
The spare Turbo 400 that I have in the garage has the following gear ratios.

1st = 4.96 2nd = 2.96 3rd = 2.48 4th = 2.00 5th = 1.48 6th = 1.00
Click to expand...


ar eyoy running the overdrive/underdrive unit ?
 
sy#2716

sy#2716

SyTy 4 Life
Re: 6 speed 4L80E

I bet he has a gear venders overdrive unit attached to it becasue the th400 is just a 3 speed tranny.
 
H

hrodgmc

New member
Re: 6 speed 4L80E

Jet had the same thing out years ago. It was a weird looking valve body and alot cheaper.

TCI what a great company.......:D
 
vanillagorilla

vanillagorilla

Member
Re: 6 speed 4L80E

The 4L80E is actually capable of 8 forward speeds since it has 3 separate planetary gear sets. Jet was doing this back in the 90's but it didn't become popular because you had to shift it manually.

The only way to do this is to have at least two dual event shifts, which might affect the way it shifts since the 4L80E normally doesn't have any dual event shifts.

I'd like to hear about a 6 speed TH400 though. I've never heard of anyone doing that without an under/overdrive unit.
 
SY2455

SY2455

70's Veteran
Re: 6 speed 4L80E

Sorry for the long post, but I hope this will answer your questions. So in a nutshell as there is alot more to it.

The transmission is turbo 400 that came in the 1966 and 1967 Olds 442. It is more commonly known as a switch pitch turbo 400. What is different about it is the pump and a special torque-converter that had the capability of changing from a high stall to a low stall. The transmission when it was stock was control by a rheostat that would vary the stall anywhere from 1200 rpm to 2800 rpm with the stock 1966 or 1967 Olds 442 torque-converter . But if you bypass the rheostat and just put in a toggle switch you would just get the 1200 rpm low stall or the 2800 rpm high stall.

For my transmission when I went though it, I had a spare switch pitch torque-converter from a 1965 Olds 442 Jetaway transmission (which was like a powerglide transmission but because it had the special pump and torque-converter it was more like a 4 speed automatic because of the high -low torque-converter.) So I use the torque-converter from the 65 442 which turn out is the same one as the 1967 Olds W-30 cars. This torque-converter had the 2 stall speeds of 1400 rpm low stall and a high stall of 3200 rpm when used with a toggle switch :tup:. By the way if you use the special pump and torque-converter you can do the same thing for a Chevy turbo 400.

The only thing that I left out in the 1st posting was the fact that you get 2 gears in reverse too, which would help if you were towing something or had to move a heavy trailer around :tup:.
I was thinking about using this transmission in the 1970 Indy Pace Car that I have. There is no gear venders overdrive unit on this tranmission.
 
vanillagorilla

vanillagorilla

Member
Re: 6 speed 4L80E

SY2455 said:
What is different about it is the pump and a special torque-converter that had the capability of changing from a high stall to a low stall. The transmission when it was stock was control by a rheostat that would vary the stall anywhere from 1200 rpm to 2800 rpm with the stock 1966 or 1967 Olds 442 torque-converter .
Click to expand...

That's pretty bad ass. I've never knew what the switch pitch meant. I've seen switch pitch converters in catalogs, but I never looked into what it meant.

What I don't understand is how varying stall speed translates into specific gear ratios. Do you start out it 1st with high stall, then switch the pitch, then shift into 2nd and go back to the high stall, then switch the pitch and so on? It's still slipping somewhat though, so it's not like you can pin point an exact gear ratio.
 
SY2455

SY2455

70's Veteran
Re: 6 speed 4L80E

vanillagorilla said:
That's pretty bad ass. I've never knew what the switch pitch meant. I've seen switch pitch converters in catalogs, but I never looked into what it meant.

What I don't understand is how varying stall speed translates into specific gear ratios. Do you start out it 1st with high stall, then switch the pitch, then shift into 2nd and go back to the high stall, then switch the pitch and so on? It's still slipping somewhat though, so it's not like you can pin point an exact gear ratio.
Click to expand...

You will see a theroretical gear ratio change because of the 2 different stall speeds that the torque converter has. Back in the day if you had a car that use this transmission, you could use a bigger cam and still get away with it, because you had in real simple terms two completely different transmissions in one. The switch pitch (SWP) THM400 and 425 of 65-67 had a torque converter 3rd element (stator) with VARIABLE VANE angle, changeable between performance and economy (instead of a compromise) as you drive. This gave 2.5 times torque multiplication, a 25% increase.

The switch pitch converter has a stator with variable stator vanes whose pitch (angle) can be changed by hydraulic pressure. Conventional stator vane angles are set to about 23 degrees. The TH-400 switch pitch converter vanes can be set to 18 or 26 degrees. An electric switch is used to send a 12-volt signal to an electric solenoid in the transmission (a switch was originally connected to the throttle linkage on factory applications.) The solenoid directs oil pressure to the stator clutch assembly, causing it to "switch" the stator vane positions.

When you change the the position on the torque converter from high to low or low to high, it doesn't matter what gear you are in YOU will feel it and if you are watching the tach, you will see the drop or rise of the engine rpm because you are changing the load on the engine. If George Blake was around I know that he could explain it alot better then I could or can. We lost alot when he left :rant:. With the transmission that I have in the garage I was able to run a mid 12 at 112 with a mild 455 in a 1965 442 and get 20.5 mpg on the HWY.
 
It's just a six

It's just a six

Super Member
Re: 6 speed 4L80E

I thought there are only three gears in a switch pitch TH 400.

Same as a standard TH400????

I would like to see some literature or a link to this trans.
 
SY2455

SY2455

70's Veteran
Re: 6 speed 4L80E

There is only 3 gears, you get the other three from the change in the stall speed of the switch pitch torque converter.
 
SY2455

SY2455

70's Veteran
Re: 6 speed 4L80E

It's just a six said:
I would like to see some literature or a link to this trans.
Click to expand...

If you want to do some reading here you go. The 1st two links have to do with the GMC Motorhome.

http://users.california.com/~eagle/SWITCH.html

http://www.bdub.net/tranny/index.html

For the normal Turbo 400 used in cars. Here you go.

http://www.442.com/oldsfaq/oftsp.htm

http://buickperformance.com/switchpitch.htm

http://pw1.netcom.com/~gnenad/switchpitch.html




It's just a six said:
Ok,
so if we have a stall on our 700R4's plus we have lock up,,,,how many gear ratios do we have :)
Click to expand...

You only have 4 because of the design. You only have the rated stall of your torque converter. The switch pitch has 2 complete stalls in 1 torque converter and depending on how you hook it up you can have two completely different transmissions. When I set mine up I had a switch on the factory dual gate shifter that everyone thought was a NOS set up button. When I operated the switch it would change between the 2 different stall speeds in the torque converter at any speed and any time.
 
A

Andre Twin

Andre Twin
Re: 6 speed 4L80E

It's just a six said:
Just wondering if any of you guys are considering one of these?

http://www.tciauto.com/Products/6x/photos/trans.png

http://www.tciauto.com/

Gear spacing is nice.:tup:
Click to expand...
I am considering running a TCI 6 speed with pedal shifter in my Syclone. The whole purpose is to get better gear range while taking it to the track or canyon runs. I am building my Syclone for the same reason Adam from High Performance Trucks was building his before he went all out with Time Attack truck. And I wouldn't be surprised If Adam went with it as well or if he didn't already.:myclone:
 
You must log in or register to reply here.
Top