requesting real life experience with 904 lock-up with manual switch

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str12-340

str12-340

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I'm building a Dart for long distance travel and am considering using an electric trigger lock-up 904 with the wider spaced gears ( 2.74, 1.54, 1.00) and a lock up converter. To make things simple I was just going to install a manual switch to activate the lock up on the open road. Is anybody out there doing this? What are your experiences and what pitfalls have you encountered?

thanks for the help!!!
 
A member here did it and his ride has been a champ, from all the posts I've read.

@TrailBeast ?
 
The A999 (32RH) is a hydraulically-activated (thus the H in 32RH) lockup convertor. No switch needed to function. However, a "Tow/Haul" switch was used in the truck versions to lock out the lockup ability when pulling loads.
Pretty much a bolt in for '67 and later A bodies, but the restrictive tunnel in early As requires a bunch of grinding on the 32RH "reinforcement" ribs on the tailshaft (not present on regular 904s) for clearance of the crossmember.
The 999/32RH also was bumped up to 3/8' cooler lines from the 904's 5/16".
Overall length and output spline is the same as a standard 904.
 
I like the switch idea, might way to tie it to the brake pedal so if you hit the brake the converter disengages.

maybe even make a relay to controle it so touching the brake disengages it till you turn it on again, not a super complex cir.

16275981636406761997512961476584.jpg
 
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STR, I drove a turbo 2.2 Dodge Spirit that for several years that I installed a turbo lockup A-470 FWD automatic in. I used a manual switch on it. Worked great but I needed to be sure to unlock it when slowing down. I was not excited about cutting into the OEM brake switch circuit wiring as I was too lazy at the time so i just controlled it manually. Dana's idea is safer. :):)
 
LOL. The old gas 2500 ram I had had switches on the 46RE. Couple times I forgot to flip them coming to a light on the highway, and was real suprised when the thing quit runnin'
 
Wonder if you could use a 700r4 type lockup switch. Uses a vacuum reference, and brake light tap to know when to engage and not.
 
I like the brake release suggestion. I'm installing an aftermarket speed control that needs a release using the brake light circuit anyway, so using the same added circuit should be a breeze. I got what I was really concerned about - whether using a switch would somehow bollix up the overall transmission function or compromise its longevity and what I am hearing is that it's just not a problem.

I am looking at sourcing the transmission and converter from a Portland, OR based rebuilder. Does anybody have a source that they would recommend instead? It doesn't seem that any of the usual sources for non-lock-up transmissions (TCI, Performance Automatic, etc.) offer a heavy duty (or any) version of this transmission.
 
Call Milt at Precision of New Hampton converter company in Iowa. He has been very helpful to me and their converters work very well.
 
Just out of curiosity...

Why do you want a lock up converter?

If it is for MPG you may never make your investment back in savings in your life time. Just my 2 cents
 
Dana67Dart said:
Why do you want a lock up converter?
Click to expand...
It is my understanding that to get the wider spaced gearing, the only option is to get a lock-up transmission. Since the trans is set up for it anyway it doesn't seem that big a leap to just use it that way - am I missing another alternative? I want to use relatively high (numerically low) gears for gas mileage, without having the car be a dog around town (thus the desire for lower 1st and second gears)
 
VOETOM said:
Call Milt at Precision of New Hampton converter company in Iowa. He has been very helpful to me and their converters work very well.
Click to expand...
Exactly!
@lkopaska buys a ton of convertors from Precision. He also knows a lot about O/D 904's. (sorry Lon, I had to. LOL)
 
No problem Mike.
@str12-340
I am running exactly what you are talking about in my 67 barracuda convertible,
273 commando , lock up A998 mid 70's non electric controlled with wide ratio gear set and a 2.94 rear gears.
Pulls out with same low final ratio as 3.23,
Has a slightly longer tack drop between gears but is hardly notable, high gear still 1-1 ratio but lock up drops rpm approx 200 rpm at a 50 mph apply and drops out on its own when road speed drops or if kick it .down.
Whats not to like? Works great but didn't plan on building a drag car, mileage and cruiser.
Lon.
Pm me if you have questions.
 
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str12-340 said:
It is my understanding that to get the wider spaced gearing, the only option is to get a lock-up transmission. Since the trans is set up for it anyway it doesn't seem that big a leap to just use it that way - am I missing another alternative?
Click to expand...

You can get the wide (low - reverse) gears from a 904 /6 trans or some later year trans and direct swap them into a V8 904.
Next time I pull the trans they are going in.

I bought mine from a local Mopar guy who builds trans on the side.

Converting 904 transmission to 2.74 low gear set
 
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Dana67Dart said:
Just out of curiosity...

Why do you want a lock up converter?

If it is for MPG you may never make your investment back in savings in your life time. Just my 2 cents
Click to expand...

What's the disadvantage? It's not just the MPG, but less wear and tear, less noise.....what's not to like? Plenty of companies offer high performance lockup converters. If the transmission has that feature, why not use it?
 
RustyRatRod said:
If the transmission has that feature, why not use it?
Click to expand...
Not saying don't use it but it seems like more work than a gear swap at a trans rebuild. Just want the OP to know he has options.

As for less wear and tear, not sure that will pan out. You have added more parts to get the lockup, and as my dad said... "The parts you don't add, don't cause you no trouble"
 
Dana67Dart said:
Not saying don't use it but it seems like more work than a gear swap at a trans rebuild. Just want the OP to know he has options.

As for less wear and tear, not sure that will pan out. You have added more parts to get the lockup, and as my dad said... "The parts you don't add, don't cause you no trouble"
Click to expand...

I go along with that a little bit. But if it's a GOOD quality converter, unless you get a somehow defective one, I think you'd be ok. "everything else" is valve body related and they seldom malfunction.
 
Dana67Dart said:
I like the switch idea, might way to tie it to the brake pedal so if you hit the brake the converter disengages.

maybe even make a relay to controle it so touching the brake disengages it till you turn it on again, not a super complex cir.

View attachment 1715773108
Click to expand...

Dana - an electrical engineer I'm not, but I am good at following directions! What is an N.O. relay, an N.C. relay and an N.O momentary? Where might I acquire these items???
 
Amazon.

Basically the same relays you would use for an electric fan should work.

If the relay is single pole double through it will work for the NO and for the NC relay ( you need 2 separate relays. The push button switch can be any type of momentary NO momentary switch. ( It can be a push switch or a toggle switch your choice.

This relay should work for both relays.
Screenshot_20210803-203002.png

For a momentary switch, if it can handle 1A that should be enough.

As for the reallys only one of the relays needs to carry any current (unknown till you can measure the current draw by the lockup converter, then double it. If it draws 5 amps be sure your relay can handle at least 10 amps)

But for simplicity use the same relay for each.

For wires I would suspect that 18awg would be fine.

Be sure to fuse the 12v source
 
Just noticed I missed a wire on my drawing, the power to the TC. (by the way I am assuming the TC needs 12v to engage)

16280456742225528902303734288513.jpg
 
Dana - just for my education, what do N.O. and N.C. stand for?
 
Dana - just for my education, what do N.O. and N.C. stand for?
 
Sorry.

N.O. is normally open
N.C. is normally closed.
16280475325174575155664784978878.jpg


A momentary switch can be N.C. till you push it then it will be open
16280478580189205471099524748100.jpg



OR
it can be N.O. till you push it then it will be closed.


16280478489758988670167545744326.jpg
 
Dana67Dart said:
Just noticed I missed a wire on my drawing, the power to the TC. (by the way I am assuming the TC needs 12v to engage)

View attachment 1715775479
Click to expand...
On the a999/32RH (the OP's "904 with lock up), the TC engages and disengages solely by hydraulics (speed/load)- no external electrical source needed. The only time an external switch is used is on some truck models with a tow/haul lockout, where a simple 12v source is used to disable the lockup feature. Pass car and light van transmissions that I have seen don't even have that, only trucks.
 
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Professor Fate said:
the TC engages and disengages solely by hydraulics (speed/load)- no external electrical source needed. The only time an external switch is used is on some truck models with a tow/haul lockout, where a simple 12v source is used to disable the lockup feature. Pass car and light van transmissions that I have seen don't even have that, only trucks
Click to expand...
That simplifies things!
 
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