No, it is not. You are misunderstanding the function of these devices, both the brake switch, and the lockup clutch. The vast majority of what I have installed to lock up converters in GM automatics involved no brake switch. By your explanation, this should not work. No brake light switch is required. Almost every setup I have installed simply used a pressure switch on 4th gear (and occasionally 3rd, as well). By function, the converter is not ever locked (nor should it ever be) in 1st, or 2nd. Since it is virtually impossible to be in anything but 1st, or coming down from second, at a stop light, or stop sign, the converter will not ever be locked under those conditions. The brake switch is there to unlock the converter if you get on the brakes, on the freeway, or otherwise at speed, not at traffic lights. The converter clutch on a 700R4/2004R is a single friction disc, with no more friction material on it than a single automatic clutch, it is just larger in diameter. Having it engaged at low speeds will destroy it, in short order. It's purpose is to maximize efficiency, by eliminating parasitic loss, when in top gear(s), to increase freeway fuel mileage. It is not intended to have any function at lower speeds.
Hey @gimpyshotrods , All you state is true and correct. I could have perhaps been clearer. It is not the slow speed coming in to an intersection I was refering to. It is the highway speed 4th gear panic braking situation that concerns me. I would always incorporate a brake switch to disengage the lockup immediately in this situation. A locked converter will affect braking capacity and distance until a downshift happens, right at the time you need all the help you can get. In my mind it is just something that costs little, but may help lots.
I drove a setup like gimpy described. In 100k miles, about 80% highway never had a problem with lockup. Sometimes the simple setup works fine. Phil
I agree totally with keeping things simple. These transmissions work fine with the basic setup gimpy does. I have too much respect for gimpy's qualifications and experience to question his input on this subject. As stated earlier in this thread, I once set one up with no computer that had a mul***ude of ****ogue sensors/switches to make it do everything a computer controlled one would do. I never said that I recommended doing it this way. It was total overkill, but a fun challenge at the time that taught me a lot about the function of the 700r4 lockup system. The next one I set up was as per the gimpy method plus the brake switch and a dash-mounted kill switch. Works fine. I must admit that I did stretch things a little by having a dash led red/yellow/green light system to indicate off/on/converter engaged respectively. What can I say, I don't sleep much.
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