700R manual convertor lockup...

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woody

woody

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been doing a pile of searching and reading on this, and can't seem to get a straight answer on it....

A few people I know have put a manual lockup switch on their 700R's to lock up the torque convertor in lower gears....

reading on one site says the 700R is designed to now allow lock operation in 1st gear, no matter what...

reading on another site says it's only allowed in 3rd or 4th and that the vehicle must have sufficient hydraulic pressure going for it to work, like 30mph or something on a street ride...

so, is this a worthwhile mod? Seems to me having the lockup switch available in 1st gear during steep downhills would help with engine braking, but I don't wanna waste my wire-time to do it if there is no gain....
 
lol from what i know, your a bit late. This mod needed to happen when you were in the trans.

3 and 4 lockup? thought it is 4th only stock, dont play with these enough.

depends on which manual valve body you have? wether or not you can do engine braking.

BTW i did ask before it was built.

TCI # 376010 376015 wbrake use these here to see what is done http://tciauto.com/instructions.htm under transmission/converter
 
Why do you want this? When I talked to the tranny guy that worked on mine, he said comming to a stop with it locked would be bad a thing.

Mine has a lot of engine braking, but I'm at 148:1. Maybe you need more gear.
 
Last edited:
warpdriv said:
Why do you want this? When I talked to the tranny guy that worked on mine, he said comming to a stop with it locked would be bad a thing.

Mine has a lot of engine braking, but I'm at 148:1. Maybe you need more gear.
Click to expand...

With the converter locked it is just like having a manual trans down hilling, engine brakes instead of foot brakes. Much more control!
 
also, most of the switching setups are designed so the lockup shuts off when you activate the brakes....a nice "bad thing prevention" feature...

I'll see how I like it this weekend, the trans IS set up for it, wondered if it was really worth it....

no one seems to know if it'll work in 1st tho.....
 
"no one seems to know if it'll work in 1st tho....."

if it has the mods like the above TCI 376015 it will, here is the warning from the instructions

"Understand that operating the TCC in first gear at very low vehicle speeds can stall the engine much like a manual transmission equipped vehicle will"

manual lockup, and manual lockup with braking is different and requires different mods to be able to do the manual braking. (from what i have gathered). VB could be the same, just the other componets/mods required to do the braking might be different???

Anyone here know?
 
sorry i have'nt replied earlier. you can use the TCI kit to lock up the trans in first, but it's pretty rough on them, especially on the converter itself.
in stock form, th700s are designed to lock up in 3rd and 4th gear. lockup will only occur under the following circumstances:
3rd or 4th gear
above 42mph
brake pedal can not be depressed
can not be at full throttle
vacuum has to be at a certain level; will not go into lockup under too much load

basically, anytime you're cruising along at roughly 45mph or more it'll go into lockup and stay there unless oyu hit the brakes or accelerate fast.

most people who want to modify the th700 to lock up in the lower gears do so to achieve more compression breaking. in theory this works very well, but like i said earlier, it's pretty rough on the trans and i personally would'nt do it. if you're geared low enough like nolan, you'll have enough compression breaking as it is.
 
excellent.

I think everyone will just have to figure if the like or dislike the amount of CB based on the way the wheel and the different setups.

buddy runs 142:1 and felt he need a bit more on some obstacles. (th350)

those that run a small stall might have even a bit more trouble with braking without lockup.
 
had a good chance to test it in current config this weekend on some long downhills, loose rock, etc....no complaints....IMO, no need for the lockup switch, so it's off my mod list...

Did get the furthest up a few nasty loose rock/sand ledges....with luck, pics later tonite or tomorrow....

oh, and my cryo'd rear pinion finally died.....time to do the fine spline!!
 
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