Bear with me here while I unload all this information: My 470 engine has a 290-94H cam in it and makes 15 in Hg manifold vacuum at idle. It was rebuilt a couple years ago. I have a 200-4R trans in the car. The torque converter is in the 1800-2400 range. The rear end has 3.55 gears, tires are 245/60/15 or 26.6" diameter. Online calculators tell me the RPM should be about 2100-2200 locked up in fourth at 70 mph. At about 68-70 mph the engine RPM in actuality is about 2500-2600. This tells me the torque converter is not locking up. I honestly don't remember the last time the lockup worked correctly. It may have been before the engine rebuild. Another symptom the car exhibits is that driving around town at about 30 mph, with the shifter in OD, under certain conditions (driving uphill is one of them), the engine RPM will bog down to about 1000 RPM. If I take my foot off the gas or downshift into 3, this problem goes away and the RPM will go back up to something more reasonable and won't bog. I do not know if that bogging issue is a TV cable adjustment issue, or an issue with the torque converter locking up too early, or something else. The lockup kit I'm using is Painless Performance p/n 60110. It operates by having switched 12V first go from the fuse panel, to the cruise control terminals on a new four pin brake switch included in the kit, then to a vacuum switch connected to ported vacuum, then to the four pin connector on the drivers side of the transmission where it goes to the lockup solenoid, and terminates at the fourth gear pressure switch. Painless Performance tech support told me the vacuum switch included in the kit is supposed to be adjustable from 6-22 in Hg and is factory set to 13 in Hg (Superior Transmission p/n K058). The adjustment is done via a set screw that becomes visible inside the vacuum hose nipple where the ported vacuum line connects. The vacuum switch I have has no such adjustment on it. The kit on my car was installed probably 15 years ago. I believe the kit has probably changed over the years to now include the adjustable switch. Some tests and investigation that I have done so far to see why the torque converter is not locking up have yielded the following: 1. With the ignition switch on, I have 12V present at the vacuum switch, so this tells me the power is getting to the vacuum switch from the brake switch just fine. 2. Starting with no vacuum on the vacuum switch and then using my mouth to create a vacuum to test it, and monitoring it with a teed in vacuum gauge, the switch clicks over (closes) and has continuity at 2.5 in Hg. 3. As mentioned above I have 15 in Hg manifold vacuum at idle. 4. I have at least 7 in Hg of ported vacuum and climbing, maybe more. I didn't want to rev my engine much more and aggravate the neighbors to find out where it peaks. My car is loud enough already. 5. I have continuity in the wire from the vacuum switch to the four pin connector on the drivers side of the transmission. Did not see any corrosion at the terminals or connectors at either end of that wire. Painless is telling me I need at least 20-22 in Hg of vacuum at idle for it to work correctly (assuming I have the correct K058 switch, which I don't). However, because my vacuum switch closes and has continuity at 2.5 in Hg, but the torque converter is not locking up, that tells me there is also a problem with either the lockup solenoid and/or the fourth gear pressure switch. I'm currently talking with the guy who built the transmission about all this to see what he thinks. To replace the incorrect/old/wrong vacuum switch I see not only is the the K058 switch adjustable from 6-22 in Hg available: https://superiortransmission.com/product/superior-k058/ but there is also the K052 switch adjustable from 0 to 6 in Hg: https://superiortransmission.com/product/superior-k052/ So my question is which of those two vacuum switches is the smarter choice to get given that I have 15 in Hg manifold vacuum at idle? I really would like to avoid having to rewire the lockup to use a toggle switch in the interior. I would like to keep it as simple to drive as possible. I'm currently talking with the guy who built the transmission about all this to see what he thinks. His last response was that fourth gear pressure switches are easy to test and the lockup solenoids are prone to failure. I'm waiting for him to tell me how to test the pressure switch. I don't have a lift here and his shop is some distance away so I'm trying to do what I can first with what I have before I have to drive there again. Any thoughts are appreciated.
I think my first step would be to run a jumper wire to give the trans 12v at all times. Test drive to see if it locks up. You will feel if it does or not. As it will lock up far too early. Often times you need to keep the trans out of OD in town to keep it from going to 4th and bogging.
I agree - also you should be able to test for 12 volts at the trans by hooking up a voltmeter and drawing a vacuum (as you did in your test) with the ignition on.
I clipped a test light onto the edge of the pan and probed the back of the wire going into the four pin transmission connector. Checked it at idle and with the engine revved up a bit. Nothing. So now I'm on the hunt for an open somewhere. I was on the phone with Painless today and described everything. They recommended the K058 switch so I ordered one. I asked if it would work with engines with hot street cams that generate less vacuum (like the 15 in Hg mine makes) and he said it would work. Fingers crossed. I thought it wasn't supposed to shift into 4th gear until 45 mph or so or faster. Around 30 mph I would have expected it to go no higher than 3rd.
This depends on the TV cable setting there is no MPH limitation or signal to the trans. The 4L60E for example has a low MPH before shift function.
Don't you have to have the pressure switch closed to get a reading at the pin? Are you sure it was closed? Also, your rear end ratio will cause some hunting at low speeds, depending on the govenor used by your builder. Some folks will shave a little on the weights to make the 2004r shift later. Otherwise you should keep it in 3rd/D instead of OD, as Sean said..
The vacuum switch I have closes at 2.5 in Hg, thats why I revved the engine up a bit to generate a ported vacuum signal that would close the switch. 2.5 in is relatively low, it shouldn't take much RPM to generate that kind of vacuum to close it.
I ran a 700R4 in my 72 C-10 for 7 years with the following set-up: Switched 12V going to the normally closed (with brake pedal up) cruise control side of the brake light switch, to the 4 pin connector of the trans. Inside the trans the 12V (from the brake light switch) wire went directly to the 2 terminal pressure switch, the other side pressure switch goes to the solenoid, the other side of the solenoid goes to ground. I never ran a vacuum switch, but I did have a toggle switch on my dash to turn off the lock-up when towing. If your vacuum switch is switching at 2 to 3 " hg, it will be closed all the time so, that's like not having a switch at all, you can by-pass it for trouble shooting just to be sure. Be sure you connect the wires to the normally open side of the vacuum switch. If the switch has an adjustment, it's an Allen screw inside the port. With the cam you're running, I would set the switch to about 8"hg. If you drop the pan and check the continuity of the solenoid, it should read 21 to 25 ohms. To check the pressure switch, you'll need to remove it and use brass fittings to attach it to an air line to check the terminals with and ohm meter , should read near zero ohms. If your trans is shifting into OD at 30 MPH, either your TV cable is way too loose, the governor is incorrect for the gear ratio and tire size or the governor is sticking.
My vacuum switch has no adjustment to it and has only two terminals. I've got a replacement adjustable switch on order. I will install that when it shows up and go from there. If you go to the Summit website and download the installation instructions for 60110, they are an older version of what is on the Painless Performance website for that same part number now. The older ones show the two pin non adjustable switch with a plastic connector that I have now as opposed to the NO/NC/COM three terminal adjustable switch with spade connectors you get now: https://www.summitracing.com/parts/prf-60110 If dropping the pan is needed I'm not doing it, I'll bring it back to my transmission guy. He built it to be like a takeout from a Grand National. I don't know what it came from originally but it wasn't that, it was one of the other G bodies. Right now I hope and suspect it's a TV cable adjustment. I will go over that with him also.
The tv cable controls the pressure inside the trans, not the shift points. If it's loose you can burn up the clutches quick. Your tranny guy can put guages on the pressure ports and check to be sure the cable is set correctly.
I bought a new K058 switch and put it in, didn't fix the problem. I adjusted the switch all the way down to about 6 in Hg from the factory set 13 in Hg. I temporarily hooked up the switch to manifold vacuum just to see if it works correctly and it does, I've got power on both sides with a test light. Right now I'm waiting for when the transmission guy can look at it. I'm figuring TCC or 4th gear pressure switch at this point.
You need to drop the pan and follow the circuit. You could have a bad pressure switch, bad TCC solenoid or even just a connector that's fallen off. Easy too ring the circuit out with a meter. Generally if you hotwire the tcc solenoid and it clicks its good. Pressure switches can be checked with compressed air and a meter. Make sure replacement pressure switches are correct, I was just burned on this as I trusted that the trans supply guy knew what he was doing. Also, be prepared, you need to plan ahead on parts as unless you have a transmission parts house nearby, your local parts stores probably won't have anything on the shelf.
Brought it to the transmission guy this past Saturday. He changed the switch from ported to manifold vacuum and changed the way the switch was wired from NO to NC, both of which go against the instructions for the lockup kit as written by Painless but the way he did it makes more sense. He found that the vacuum switch is working but is not getting consistent 12V. He found the brake switch IS consistently outputting 12V. There wasn't time to fix it that day, so now it's up to me to replace the wire between the brake and vac switches. Contorting myself under the dash to see how that wire is routed from the brake switch has been fun. It disappears into the rats nest of wiring under there. Someone suggested cutting the wire and pulling it out from both ends. I may do something like that but I have to figure out where it's routed first so I don't pull on one wire and damage six others with the amount of zip ties under there. To test the lockup he wired a temporary toggle switch from the battery to the transmission connector. We took it for a test drive and I hit the switch and the lockup worked correctly, so the fourth gear pressure switch and the lockup solenoid are fine. So now it should just be a matter of replacing the power wire to the vac switch and then tuning the switch, if need be.
I ran a new wire from the brake switch to the vacuum switch. I put a new crimp on the other wire to the vacuum switch since the connection was loose. I also adjusted the brake switch. It was real loose and wobbly in the bracket that holds it. The switch plunger was basically all the way out without pressing down on the pedal at all. Seems to be working better after doing all the above. At 70-72 mph, tach is showing 2200-2300 RPM. Better than the 2500-2600 RPM it was reading before.
