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I've been running a converted 700R4 w/TCC lock-up for many years and have never been entirely happy with the lock-up function or timing.
I came across Aperions post with a slew of part numbers and wiring diagrams and saw something interesting. That's the GM PN 14014519 which is listed as a vacuum delay switch.
The problem I'm experiencing is the lockup function toggling back and forth right at the vacuum set point under certain driving conditons. This is very aggravating (and don't imagine it does my converter clutch any good).
With a vacuum delay switch, that problem might be eliminated.
Before anyone offers up other suggestions, I've tried both adjustable vacuum switches (1-6" and 6-22") and while I can control the lockup timing I can't eliminate the toggling. I've got the brake switch and a manual operation switch wired in as well. (Wiring isn't an issue. It's what I do for a living so let's not go there.)
The problem arises from the fact that as engine RPMs increase under part throttle acceleration, the vacuum rises and engages the clutch. As soon as the clutch engages, the engine vacuum drops and the clutch disengages. Then the cycle repeats. A delay of the vacuum switch setting (delay on) would allow the engine to build a little vacuum before the switch closes again and engages the clutch.
A switch with an adjustable on and off setting (similar to a pressure switch for a water pump) would be ideal but such a thing doesn't exist in an automotive application (that I'm aware of anyway).
Anyone?
The problem I'm experiencing is the lockup function toggling back and forth right at the vacuum set point under certain driving conditons. This is very aggravating (and don't imagine it does my converter clutch any good). Anyone?
Do you require lockup in the gears ?
The 4th gear switch in the trans would give you lock always but only when 4th gear engaged
No. Just fourth. However I do have it arranged so that I can engage the TCC manually at any time.
Originally Posted by vetteoz
The 4th gear switch in the trans would give you lock always but only when 4th gear engaged
Yes that's true provided that the vacuum switch which is wired in series with the 4th gear switch is also made (enough manifold vacuum to pull in closed).
So what's happening now is that when the trans shifts into 4th and the manifold vacuum is high enough, the I get TCC operation as you would expect.
It's when I accelerate enough to drop the vacuum below the vacuum switch setting ( in 4th ) that it'll drop out of lock-up (which is also expected) but as I gain vacuum, the TCC kicks in. But that drops the vacuum down, so the TCC kicks out. On and on it goes, unless I accelerate harder to keep the vacuum down and the TCC off or I ease up and lug through 4th gear. I have an adjustable switch which I can tune to the point where the lock-up will stay engaged unless I really lean on it but I'd like it to kick out and stay out when I'm passing lightly and want to get into the converter stall a little for additional revs.
If this GM PN 14014519 switch is really a delay vacuum switch, then that delay may prevent the cycling I'm describing. This kind of switch exists in industry where switch on/switch off set points are individually adjustable. Problem with that PN is that it's discontinued and the replacement numbers I've found on-line don't exist (go figure).
Yes that's true provided that the vacuum switch which is wired in series with the 4th gear switch is also made (enough manifold vacuum to pull in closed).
Most don't use a vac switch with the 4th gear switch
full time lockup when in 4th and if you accel hard enough it drops back to 3rd and the convertor unlocks
Ever get this figured out? I had/have the same issue. I got so sick of it I would use a dash mount toggle to keep it locked. Then I finally just bypassed the vacuum switch and always locked in fourth. Three months ago I installed a 5.7 that I rebuilt and installed a new vacuum switch (old one hit the exhaust and burned). Same on/off shuttle issue. I am looking for alternatives again.
Originally Posted by skinny z
No. Just fourth. However I do have it arranged so that I can engage the TCC manually at any time.
Yes that's true provided that the vacuum switch which is wired in series with the 4th gear switch is also made (enough manifold vacuum to pull in closed).
So what's happening now is that when the trans shifts into 4th and the manifold vacuum is high enough, the I get TCC operation as you would expect.
It's when I accelerate enough to drop the vacuum below the vacuum switch setting ( in 4th ) that it'll drop out of lock-up (which is also expected) but as I gain vacuum, the TCC kicks in. But that drops the vacuum down, so the TCC kicks out. On and on it goes, unless I accelerate harder to keep the vacuum down and the TCC off or I ease up and lug through 4th gear. I have an adjustable switch which I can tune to the point where the lock-up will stay engaged unless I really lean on it but I'd like it to kick out and stay out when I'm passing lightly and want to get into the converter stall a little for additional revs.
If this GM PN 14014519 switch is really a delay vacuum switch, then that delay may prevent the cycling I'm describing. This kind of switch exists in industry where switch on/switch off set points are individually adjustable. Problem with that PN is that it's discontinued and the replacement numbers I've found on-line don't exist (go figure).
I never found the PN in question and I ultimately went with the OEM switch that came standard on non-computer equipped 700R4 installations. I don't have a number handy but could probably dig it up.
Interestingly, since that post I've replaced the transmission and the new unit tends to downshift out of OD a little sooner than the previous unit. The toggling in and out of TCC lock-up occurs much less often as it drops out of fourth. I too have a dash mounted switch which I use. It sort of turns the transmission into a 5 speed as I apply the TCC after having accelerated through 4th/OD gear.
I did not know they had an OEM version until yesterday. The PN I found (14020691) is no longer available. I have been dealing with this for 8 years. PITA! If you have a chance to post up the OEM P/N you found that would be great. I am currently looking at "on delay timer" products as an alternative.
Originally Posted by skinny z
I never found the PN in question and I ultimately went with the OEM switch that came standard on non-computer equipped 700R4 installations. I don't have a number handy but could probably dig it up.
Interestingly, since that post I've replaced the transmission and the new unit tends to downshift out of OD a little sooner than the previous unit. The toggling in and out of TCC lock-up occurs much less often as it drops out of fourth. I too have a dash mounted switch which I use. It sort of turns the transmission into a 5 speed as I apply the TCC after having accelerated through 4th/OD gear.
I thought I might have the PN stashed in my "as built" parts list but that's not the case. I'm working out of town for the next couple of weeks but will look to see if there's a number stamped on the part itself when I get back.
For the record, my vacuum switch looks like the image below. And that's what comes up when I searched GM PN 14014519. Whether mine and that one are functionally the same, I can't say.
I thought I might have the PN stashed in my "as built" parts list but that's not the case. I'm working out of town for the next couple of weeks but will look to see if there's a number stamped on the part itself when I get back.
For the record, my vacuum switch looks like the image below. And that's what comes up when I searched GM PN 14014519. Whether mine and that one are functionally the same, I can't say.
Most 80s C series trucks and G series vans had that exact switch as well as a blue/black two port vacuum delay check valve in the vacuum hose connected to the switch. They also had a thermal vacuum valve in the vacuum hose between the port on the carburetor for it. Connection on the carb was ported vacuum. If I looked around I probably still have both hanging around the shop from when I went to ECM controlled lockup on my old 700R4 in my 1983 G20.
They are no longer available new for sure. I tried eBay without luck.
I ended up ordering a delay relay board. It will create a user adjustable delay from the time the vacuum switch actuates until the TCC ground circuit is made. This should help, if not eliminate, the cycling issue. It's more complicated than the factory stuff for sure. It costs about $15 for the board and a case to put it in.
I thought about going back to computer control, but I would have to rewire the trans internals plus provide a forced lockup circuit. Easier to do the above.
Originally Posted by Fast355
Most 80s C series trucks and G series vans had that exact switch as well as a blue/black two port vacuum delay check valve in the vacuum hose connected to the switch. They also had a thermal vacuum valve in the vacuum hose between the port on the carburetor for it. Connection on the carb was ported vacuum. If I looked around I probably still have both hanging around the shop from when I went to ECM controlled lockup on my old 700R4 in my 1983 G20.
The switch from Jegs is the one I am actually using. The one from Speedway seems like a good, but expensive kit with the same surging problem the TCI kit has. The included PDF recommends using the GM vacuum delay valve that is no longer made.
Good finds! the 214-479 is a vacuum delay valve. While looking for it I found a reference to the switch for a different trans that is still available and might work. I don't know what the set point is though.
Good finds! the 214-479 is a vacuum delay valve. While looking for it I found a reference to the switch for a different trans that is still available and might work. I don't know what the set point is though.
It is supposed to be used in conjunction with 214-479.
The 214-331 is the same switch I posted earlier. GM 14014519. Set point is about 4-6" vacuum if it's anything like the one I have. It certainly looks the same.
Interestingly, the 81 Monte Carlo, which I modeled my TCC lock-up after has the vacuum delay valve in the circuit too. This is OEM. At the time I didn't know what the valve was. Now I can see that with it installed, the toggling issue is likely to go away. The Monte Carlo has no issues with the TCC.
For what it's worth, the Superior Transmission adjustable vacuum switch (6-22" or 0-6")
combined with the vacuum delay valve listed above would be the ticket. I think it would be safe to say that this combination would solve the problem and provide a level of adjustability as well.
I think I just might try and find that vacuum delay pod and work with the adjustable switches I have already. I could fine tune the TCC off function which would make passing simpler. Now I typically switch off the lock-up manually.
Thanks for the part numbers.
Last week I received a time delay relay from amazon along with an ABS box for it. I wired it through my vacuum switch and adjusted the delay circuit for 5 seconds. Works perfectly. No more torque converter cycling. Total cost of the box and relay was about $15.
Well done.
Since I've installed the new transmission, I haven't noticed the TCC dropping out and in. I think that now that I have the correct governor and related bits to ensure the right gear at the right speed, the factory vacuum switch arrangement is performing much better. At the very least, rather than just the TCC dropping out at reduced vacuum, the trans drops out of OD altogether.
I'll certainly keep that delay switch option open though. Again, well done.
I know this is an older thread but I'm dealing with something similar and came across this solution from Monster Transmission. It appears very simple and utilizes a pressure switch on the 4 gear valve to lock the TC. No vacuum lines and super easy install without dropping the pan. Hopefully this will help someone else searching for a solution as I was.
The 700R4 External Lock-up Kit
This kit will enable the driver to control the operation of the torque converter Lock-up. The switch will allow driver to turn the lock-up function off during in-town driving and on during high speed/highway driving. When switch is on the transmission will not engage into lock-up until transmission is in 4th gear. Transmission will automatically disengage lock-up switch when it down shifts to 3rd gear and re-engage when transmission shifts back to 4th gear. This kit is an external wired kit, no need to drop pan for installation.
The electrical bits looks to offer the same functionality as the manual switch I have installed on the dash. While the TCC is less of an issue now than it was, I still turn the TCC off altogether when cruising around town.
I don't quite understand what the brass plumbing parts are for though.
The electrical bits looks to offer the same functionality as the manual switch I have installed on the dash. While the TCC is less of an issue now than it was, I still turn the TCC off altogether when cruising around town.
I don't quite understand what the brass plumbing parts are for though.
The brass pieces are for connecting a pressure switch to the external port for fourth gear. When that switch is activated from pressure in the fourth gear line it closes the circuit causing the selenoid to lock the convertor.
Figured it was something along those lines.
I've got that 4th gear applied switch as part of the valvebody although I understand that obviously some do not.
What I've learned is that compared to a transmission that I did the usual upgrades to myself like the Vette servo, .500" boost valve, TransGo shift kit, etc, there's no substitute for having one professionally built from top to bottom. The shifting characteristics of this new trans are superb and the TCC toggling became a non-issue. Drop down to 3rd gear is quick and precise whereas my old trans tended to hang on in OD causing the problem.
I know for a fact I would not like the TC to always be locked in OD. Even 50 or 100 rpm makes a difference when needing a little extra acceleration, but not enough to downshift. I messed with my vacuum switch and never could stop it shuttling on and off at a certain throttle position. I have a switch on my dash to force it on or off, but when forced locked that ends up in me needing more throttle and more downshifts. I drive a 5,000 lb barn door so that makes a difference I'm sure. I ended up adding a 15 second delay circuit that does a wonderful job.
Always liked the idea of the vacuum delay. The early stages of this thread were directed that way although at that time there wasn't anything definitive being posted until your solution came along. Nice job.
I have come up with a solution to the vacuum operated TCC (torque converter clutch) lockup problem where it pulsates or oscillates on and off. This occurs when vacuum is just barely at the threshold of engagement, it will go in and out of lockup because the vacuum switch pulses on and off.
The idea of my design is to have a "high" vacuum setting for engagement. And a "low" vacuum setting to disengage.
All we need are the following:
Two adjustable vacuum switches (Lockup kits only come with one)
Bosch 12v relay (I only use quality relays like Bosch)
Diode (part # 1N4001)
Here's my circuit:
How this circuit works....
The "low" vacuum switch is set to at a lower vacuum and will engage first to provide ground on pin 30 of the relay. Because the relay's coil isn't trigger yet, pin 87 is still open and nothing has happened.
The "high" vacuum switch will engage when the engine vacuum is higher than the "low" switch. Now you have ground on pin 86. This triggers the relay coil and pin 87 will be connected to pin 30. This provides ground to the TCC solenoid. Lockup is now engaged.
Here's the special part that prevents the pulsing... when the "high" vacuum switch disengages, the diode keeps flowing ground from pin 87 to pin 86, which keeps the relay engaged. If the "high" vacuum switch oscillates on/off quickly, the TCC solenoid will stay engaged thus preventing the pulsating problem.
Only if the "low" vacuum switch disengages, will ground be removed from the entire circuit, allowing it to reset. Note, if the "low" switch oscillates, no big deal. Since the circuit will not engage until the "high" switch tells it to.
You will need to adjust the vacuum switch settings. The TCI ones can be very sensitive to the slightest adjustment. The "low" switch obviously needs set lower than the "high" switch. If it isn't, the circuit won't work correctly and you'll have the same issue you're trying to fix. I started with a spread of 2 inches vacuum. What I mean is, the "low" switch triggers at 2 inches of vacuum less than the "high" switch. I used a Mityvac vacuum pump and a continuity tester to set the vacuum switches one at a time. In my example, the "low" switch engaged at 13 inches vacuum, and the "high" engaged at 15. Every engine is different so you may not even have enough vacuum for these settings if you have an aggressive camshaft. Connect a vacuum gauge and go for a drive. During highway cruise, measure your vacuum and set the switches at least a couple inches below that setting.
If your vacuum settings cause the TCC not to engage, they are too high. Lower them.
If the TCC still pulses, try widening the vacuum gap between the "high" and "low" switches. Also, check your diode, it could be backwards. My thoughts are make the gap just enough to prevent oscillation and not much more.
When you're cruising and you moderately accelerate to pass someone, it should disengage. If it doesn't disengage before you go into passing gear, or If moderate throttle doesn't disengage it, the settings are too low. Or your transmissiong goes into passing gear very easily.
It is possible to wire the diode backwards. This won't hurt anything but the circuit won't operate correctly. Just reverse it if that happens.
Vacuum can be connected to ported or manifold vacuum. Personally, I used ported so when I let off the throttle, vacuum goes away and disengages the circuit. If you use manifold vacuum, it is recommend to wire in another relay to interrupt the ground to this circuit when the brake lights go on. That way it disengages the lockup when you hit the brakes.
A diode operates by allowing current flow in only one direction. They have a white stripe on one end to show their orientation. In this circuit, the white stripe goes towards pin 87 on the relay.
We are switching the ground side of the lockup circuit on & off with this design. This is because the TCC solenoid is setup to be triggered via ground.
If you want/need to understand relays, check out this video:
02-10-2014, 08:38 AM
