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Manuel locking of transmission convertor

3K views 30 replies 10 participants last post by  dodgedawg 
#1 ·
I have a 1997 Dodge Ram 3500 with the Banks Brake system, SmartLock, and a 47re automatic transmission. I pull a trailer that is around 14000lbs. The Banks Brake works great, but when I drive down a 6% or steeper mountain grade, I'm into the brakes alot because the torque convertor ONLY will lock up in 3rd and 4th gears. I need to be in 2nd gear for the engine RPMS to be high enough to slow down the vehicle. I only want to be traveling about 40MPH or less on those hills.

Currently, the SmartLock controls the torque convertor. I was thinking of wiring a toggle switch to the torque convertor switch and manually locking the convertor while driving down a hill in 2nd gear. That way the engine brake would slow down the truck and trailer. When I get to the bottom of the hill, I'd turn off the switch, shift into 3rd, and let the tranmission run like normal.

Does anyone out there think this solution will work out ok? Is this transmission tough enough to handle coasting down a hill without burning up the clutches in the convertor? Anyone know someone who has done this? any input would be nice....
 
#2 ·
I think a manual lockup would solve the problem. Not sure about the tranny holding it though.
 
#3 ·
I think it'll hold. There isnt an extreme load when coasting....but what do I know I drive a stick shift
 
#4 ·
With my new trans I can lock all forward gears and it works great to slow the truck down, But I think the valve body needs to be set up to allow 1st or 2nd gear lockups. Maybe the smartlock will allow it worth a try not 100% sure though somebody else with more experience what to chime in?
 
#5 ·
me too

I've had my '97 3500 for close to a year now and I too want to setup my TQ to lock with a toggle switch if it isn't already. The truck came with a Pacbrake exhaust brake and came with a bunch of toggles a few of which I haven't figured out yet; where do I look or what do I test to tell how the previous owner locked the TQ so the Pacbrake will work? None of the toggles do it. That engine brake is worthless in it's current configuration (other than warming the engine up faster).
 
#6 ·
The way I was told to do it by the guy who built my trans was to run a wire down to the 8 pin plug on the trans tap the orange wire with black tracer hook up to toggle switch. Take another wire attach to the other side of the switch and solder in a 33 ohm resister in line and attach to a good ground. There is nothing else needed it has worked flawlessly since I installed it. Or there is another way directions here.

http://www.tstproducts.com/Torque Converter Lockup Switch.pdf
 
#8 ·
I followed the instructions but nothing happens. Only difference the way I did it was to connect my wire coming off the orange with black striped wire directly to a ground in the cab instead of through a switch to a ground.

One major concern I have is when I have the jumper wire in place of the trans relay and I turn the key on I hear whining and crackling coming from what sounds like the torque converter solenoid...yikes. I took it all back apart for the moment.

I'm electrically illiterate but what do I need to do to make this work? I really want to use my exhaust brake. Thanks!
 
#9 ·
If you go buy a 33 ohms resistor from radio shack and a toggle switch it will work with out removing the relay. By just sending the wire from the trans straight to ground it will do nothing as you have found out, actually you probably will not even have overdrive working as the trans will more than likely gone into limp mode.This is the way I did mine and have had zero problems. Take the wire from one pin on the switch and run it to the orange wire with black tracer on the transmission. Solder the resistor into the wire that you will be using as a ground attach one end to the other pin on the switch and then ground the other end to a chassis point. This way the ECM will still lock and unlock the converter when the switch is off, But when you flick the switch it's like driving a standard transmission turn it off or it will stall. I hope this will work for you. I looked at the tst website and did not like the idea of using a jumper wire on the relay.
 
#10 ·
thanks

Sounds good, I'm glad to hear I can still make it work, I'll do that Friday. I was about ready to just snatch that exhaust brake off when I straight pipe it this weekend but if I can lockup my tc I'll keep the pacbrake on there.

How do I manage my lockup switch? From what I understand you just have to unlock before you get down to a certain speed or it wears out the converter and stalls? Once you get up to fourth it will just hold that gear?
 
#11 ·
What I like about it the most is once you flip the switch its locked and you let off the throttle it won't unlock like if the ecm is controlling it. When coming to a stop I just turn it off I did forget once and it made a ton of noise and stalled.

With out a billet input I wouldn't want to leave it locked up while shifting it's a heavy load on the input. I lock mine in third and when it shifts to overdrive it's fine as long as there is some rpm and the engine is not lugging(billet input).

Today I managed to figure out how to make the led light in the switch light up with a relay when the TC is locked. I will try to make a wiring diagram of what I did tonight at work and post tomorrow.
 
#12 ·
Hey thanks for this info, trial and error could have been very costly! So I shouldn't lockup until I'm in 4th (or 3rd w/od off)? Then on a long grade I would throw the switch to lockup, throw the switch to the exhaust brake, and I should get some stopping power from it?

I look forward to your lighted switch schematic. I wired a lighted switch into my rear auxillary lights day after I got a ticket for forgetting I had left them on. Had 'em pointed right at the sheriff's eye level!!
:pointlaugh
 
#14 ·
Only in 4th gear IMO.....you can leave it locked to slow down but you'll trash a stock converter and tranny (input shaft) in no time flat if you leave it locked and have the trans shift through the gears....basically it should only be used as the "poor man's" exhaust brake.
 
#15 ·
Thanks for the schematic TB1.

I'm heading out this evening to try to wire this all up!
 
#17 ·
I'll try to attach.
 

Attachments

#19 ·
finally

I'm proud to report that after hours of consult, diagrams and photos with/from TB1 I was finally able to tap a single wire onto a single wire, lol! Didn't want to show my face on here again until I did...geeez. I had soldered onto the gummy ends of the resistor (from packaging) alas no ground.
:poke:
Took it out for one test drive since and I love the brake savings even alittle engine braking pays. Makes my exhaust brake work well too. Not just because I'm a hijacker but was curious if dodgenewbee got it hooked in yet? If so, how's that working out for 1st and 2nd?

Conrol of the RPMs is what I miss the most about a stick. Holding a coffee, plugging in my bluetooth and holding those duallies in a lane with my knee is what I like about automatic though, j/k.
:sly:
 
#20 ·
Sorry for the delay in response. I'm on the road and Internet sites aren't always there.

I appreciate everyone's input and the directions on connecting the toggle switch. I am looking into whether the tansmission can handle a heavy load going downhill locked in 2nd. A mechanic I ran into thought everything would work, but was worried about low oil pressure in the lines since they are driven straight from the throttle position. Think I might just install the switch and see what happens. I will be doing this in the next 5 days, so I'll return and tell you folks what happens.

Thanks again.
 
#21 ·
I'm really liking the switch and in the process realized what it even feels like for the torque converter to lockup. Before changing my filthy tranny oil and installing the switch I don't think the TC was locking up at all. Meanwhile I had gotten down to 10 mpg with lousy power (compared to now).

Let us know how it goes:Thumbup:
 
#22 ·
Just got a scare from a mechanic I trust. He was cautioning me NOT to install the switch for use in 2nd or 1st gears because he believes it with tear up my tranny....especially if I stop with it locked up (which I don't plan to do). I will look for another opinion now before I install it. I already have it locking up in 3rd and 4th...but haven't found anyone trying it in 2nd gear yet. If anyone out there has it installed, and has engaged it in 2nd gear..please let me know what you experianced.
 
#23 ·
I'm not sure if I would use it in first either, there just isn't usually a lot of line pressure......
 
#25 ·
I mean that I know the engine will be spinning at about 2100RPM with no throttle input, but the engine brake will be on and doesn't that mean the engine will be bearing the brunt of the pressure of slowing the vehicle down...not the transmission?

I viewed an old discussion from another forum, and yet I don't know if it answers my question, maybe someone else maybe able to make sense of it on how it applies to this issue. http://www.dieseltrans.com/phpBB/viewtopic.php?t=51
 
#26 ·
TB1 and DodgeDawg...I had an additional question for you two since you have installed the toggle switch already for your tranny. Have you downshifted to 2nd gear on a hill, manually locked your tranny, and turned on your exaust brake? Did the engine keep the truck going slow? Did your tranny temps increase much? Any funny noises?

A mechanic I spoke wasn't sure if the clutch packs could handle the load...but I don't know how you would gauge that???
 
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