700r4 lock up
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Thread: 700r4 lock up

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    700r4 lock up

    hello

    anyone explain this in the most basic of forms.

    have a 700r4 with a vacuum swich that you power via a toggle switch ,but for the life of me cant understand what it does and why you would need to switch between lock up and non lock up.

    read a few things where they say you should flick the switch when motorway driving,but what a pain in the arse that would be.are you flicking it to turn it on or off

    for normal everday use,should it be in lock up or non lock up mode

    thanks
    wayne
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    Off the Xmas card list kapri's Avatar
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    It reduces friction losses . A normal spec torque convertor is ( say ) 85% efficient , with alock up it behaves as a solid coupling and power transmission is 100%.
    On normall cars the lock up is automatic poswered by a vacuum switch that switches on at a set vacuum. Vacuum can vary depending on weight of new vehicle , type of carb , and cam spec.

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    Administrator blackpopracing's Avatar
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    On my Camaro it was automatic, you reached 44mph & it locked up.
    Dropped the revs about 400rpm so definitely worth doing as it saves a lot of fuel. Think there are kits out there that make it automatic?

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    Off the Xmas card list kapri's Avatar
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    You can buy adjustable vacuum switches to make it automatic but you possibly need a better understanding of vacuum and what affects the readings than many non mechanically minded rodders may have. So instead they just make it a flick switch as most of their journeys would be freeway.

    You can make it auto switch off by using a relay powered from the brake light switch same as cruise control.

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    It's a new TCI box. With a vacuum switch fitted but just can't understand the instructions as it says it should do it automatically but then goes on to say you can switch it on or off.

    It kinda contradicts itself
    Rod/custom/drag build profiles:
    Mini | Pop | Porker | Trike | Morris 8

    | 48 chevy coupe | ford f100 | tube chassis,d pop

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    Is it a standalone vacuum switch or do you mean the electrical fitting on the actual box?

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    ill have to relook tommorow.its bolted onto the side of the box.it came with it.think i looked at the instructions for too long and confused myself
    Rod/custom/drag build profiles:
    Mini | Pop | Porker | Trike | Morris 8

    | 48 chevy coupe | ford f100 | tube chassis,d pop

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    vacuum needs to be on to activate lock up BUT does that happen when power at switch is on or off?

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    Off the Xmas card list kapri's Avatar
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    On my A4ld it would switch power ON to activate and then drop at if vacuum dropped below 15" .I tested its operation by rigging a vaccum gauge and an idiot light to show when it was energised.

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    Got salt Briz's Avatar
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    If you wire it +12v without a switch, it locks up in 2nd, 3rd & 4th. Makes the car a bit sluggish once out of 1st. A bit un-nerving when it shifts down as well, you're waiting for it to go into 1st before it stalls!
    You really only want it in 4th.
    If you screw a harley hydraulic brake light switch into the right port, that will activate it in 4th, Later ones dont have the port and you have to drill & tap the servo cover 1/8npt for it.
    The vacuum switch is so it disengages on acceleration, not really needed as it'll downshift anyway.

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