Overdrive Trannys

[old51sedan]

Are any of you folks out there running an automatic overdrive such as a 200-4R or a 700-R4 and using a toggle switch to turn the overdrive on and off. If so where did you mount this and how well do you like this method?

[71meangreenc10]

I used a toggle switch to turn on the lock up. I mounted it on the cluster. It has an LED in it that lets me know it is on. I like it, when I hit 50, flip the switch.

Smitty

[pjmoreland]

Personally, I would get tired of constantly flipping a switch and then forgetting to turn it back off. I wanted torque converter clutch lockup to be automatic and natural feeling in my truck, so I designed an Arduino controller that based lockup on manifold vacuum and speed. In my opinion, the best commercially available approach is to go with a speed-based controller such as this one from B&M. The main issue this controller fixes is that you won't want the torque converter clutch to lock when you are driving around town at lower speeds because it will lug the engine.

https://www.summitracing.com/parts/b...44?seid=srese1

A manifold vacuum switch could be wired in series with the speed-based controller to make the torque converter clutch unlock when accelerating at highway speeds.

https://www.summitracing.com/parts/tci-cmp3766b

Here's a thread about how I started with a single vacuum switch and ended up with a custom controller:

https://www.67-72chevytrucks.com/vbo...d.php?t=822382

[Sheepdip]

I've got a 200-4R sitting under my bench that I need to get rebuilt to drop in the 40 Coupe. I've got the switches to make it fully automatic. Just gotta get er done!

[Smitty]

Mounted my switch on the lower lip of the dash. Right by the emergency brake release lever. I drive a ‘71. Using a switch because the majority of my driving is around town. And it would lock up at lower speeds lugging the motor.

[LS short box]

I would check with the aftermarket tranny suppliers to see if they can supply kit to make the lock up/off automatic.
It's been many moons but I believe as soon as you touch the brakes the lock up should drop out.
On my LS/4L60E swaps I have the ECM programmed to lock up and 4th gear not until 50 mph.

[Already Gone]

Am I missing something ? I put a 700R4 in my C10 3/4 years ago and told the installer I just want to drive it and not have to flip a switch on and off and thats what I have. Doesn't lockup till 35/40 MPH and have put 3500 miles or so on since installation and the 700R4 works super.

[pjmoreland]

Originally Posted by Already Gone

Am I missing something ? I put a 700R4 in my C10 3/4 years ago and told the installer I just want to drive it and not have to flip a switch on and off and thats what I have. Doesn't lockup till 35/40 MPH and have put 3500 miles or so on since installation and the 700R4 works super.

If it locks up at that speed, then my guess is the installer wired the TCC to lock when it shifts into 4th.

[old51sedan]

Thanks guys for the replies, I'm at the point where I want to drive it for a while, so I'm going to mount a toggle switch and put a few miles on the old gal. I have a feeling that I too may get tired of flipping the switch. I can at least drive it down to a tranny shop and have someone hook things up for me.Time will tell.

[Rickysnickers]

Here are a couple of other options as well

https://www.classicindustries.com/pr...E&gclsrc=aw.ds

https://www.amazon.com/Painless-6010...2-63e904010ad0

[Mike (Asheville)]

I'm running a 200-4R in my 71 Camaro that will lock up only in 4th, and I wired an inoffensive switch on the console which I use on the highway. If (actually, when) I forget to toggle the switch off after exiting the highway, there's no lock up again until I get into 4th and it's immediately noticeable in town and I flip it off. I like automation but really don't lock up the converter often at all. In town I generally drive with the shifter in 3rd anyway. Just my two cents having driven the car for 9 years like this.

[Myself]

I daily drove my smallblock swapped S10 Blazer for 16 years with the Painless wiring setup. Always worked great. Locked up shortly after 4th gear at around 45mph. The vacuum switch allows unlocking any time you throttle down on it.. And the brake switch unlocks on brake apply no matter what the condition is.

[72c20customcamper]

It’s my understanding that if you put it in 3rd there is no lock up since it’s not in overdrive . I drive the 85 in D around town and 90% of the time on the highway . With the 3.23 gears it seams to hunt (in and out of lockup ) at highway speed which I find very annoying.

[Accelo]

I am assuming you didn't mean "using a toggle switch to turn the overdrive on and off". But the lock up feature of the torque converter.
Others have given you some options for wiring.
Doing nothing is another option. It will just work like the early transmissions.
Highway RPM will be a nominal 200 rpm higher.
I ran a 4L60 like this for years behind a BBC in my 1971 C20.
Some believe they will overheat when ran this way.
Mine had a transmission temp gauge and I never had this issue.
It would not go over 100mph in overdrive, it would shift back to third at 100mph.
I had zero transmission issues.
I like to see lock-ups working but it's not required.

One issue when using a switch method is it will extend your emergency stopping distance.
It's the equivalent of stopping, with a manual transmission, a leaving it in gear with the clutch out.

[leddzepp]

I had a 700R4 in my first 72 many years ago. It had no wiring, no toggle switch, etc. just had the TV cable attached to the carb linkage in the same spot as a kickdown cable for a TH350. It worked great for years, no issues. I only put it in D on the freeway at higher speeds, mostly kept it in third. I plan on swapping in another 700R4 in my 68 when I get the time.

[LS short box]

As I understand one more reason to use the the lock up is if you have a stall converter the lock up will stop any slippage and reduce heat in the trans.

[Accelo]

Originally Posted by LS short box

As I understand one more reason to use the the lock up is if you have a stall converter the lock up will stop any slippage and reduce heat in the trans.

You are absolutely correct. If it's not slipping it's not making any heat.
However, for decades converters lacked any lock up feature.
The coolers were designed for such slippage.
The newer transmission unlock when floored and this is when they make the most heat. And they still make heat when pulling, especially when stuck.
So even now with less heat, under normal conditions, the high heat scenarios still exist and have to be compensated for.
I have not even mentioned the slipping that occurs when the newer transmission slip the clutch inside the converter purposely using Pulse width technology.
Or the lock and unlocking that sometimes takes place, on some models, during a shift.

All of this makes a compelling argument to transplant an "Electronic" shifted transmission as the computer takes care of all these functions seamlessly.
It makes sense at least when you have to have an ECM for the motor functions anyway.
Cheers

[pjmoreland]

Originally Posted by Accelo

You are absolutely correct. If it's not slipping it's not making any heat.
However, for decades converters lacked any lock up feature.
The coolers were designed for such slippage.
The newer transmission unlock when floored and this is when they make the most heat. And they still make heat when pulling, especially when stuck.
So even now with less heat, under normal conditions, the high heat scenarios still exist and have to be compensated for.
I have not even mentioned the slipping that occurs when the newer transmission slip the clutch inside the converter purposely using Pulse width technology.
Or the lock and unlocking that sometimes takes place, on some models, during a shift.

All of this makes a compelling argument to transplant an "Electronic" shifted transmission as the computer takes care of all these functions seamlessly.
It makes sense at least when you have to have an ECM for the motor functions anyway.
Cheers

One thing about overdrive transmissions like the 700R4 is that its planetary gears are spinning when in the overdrive gear. This produces heat compared to a TH350 or TH400 that has none of its planetary gears spinning in third gear.

[davischevy]

We have six 700R's behind big blocks and small blocks, one has been in service for 10 or 12 years. None of them have manual switches. One of the oldest ones is in a SS 454 El Camino that I have put over 40,000 miles on and my son in law has made countless passes down the 1/4 mile. I have one in my Longhorn behind a 454. I put it in drive when towing and it has towed a lot.

If it's going to see heavy use, I would install a trans cooler.

[LS short box]

So one more thing trans cooling wise. My hot rods aren't driven in the winter. I run a large stacked plate tranny cooler. Typically a B&M. Pic of my current 80 Camaro project. Some would say it's a bit much size wise and could "over cool" but my local trans builder says it's fine. I'm running a electric fan so at low speeds the fan pulls air thru the radiator and trans cooler.
So maybe off topic but maybe a 4L60E with an aftermarket controller you adjust many things trans wise? Shift points. Lock up.