techrondon

1987 700r4 wont take off in "od",,goes ok in drive and at 50 mph or so put lever in "od" and it shifts,,car slows down and it shifts in and out,,,below 35 mph or so and have to put back into drive to get back up to speed..searched forum and internet and manuals i have and cant find anything about what might cause this prob..fluid and filter change made no diff and fluid looked good..rest of gears work fine and strong,only od slips..any help,places to look,suggestions ,or anything welcome...was pushing it when it started this prob...

mrvette

I"m certainly NO expert, but it sounds like it might be a valve body problem...in that the 4th gear lockup switch with the wire on it...screwed into the end of the valve body might be leaking/broken....allowing 4th gear to slip like crazy...very very bad for the allready weak 3/4 clutch pack....

or maybe the 2-4 band.....if it goes into 2nd and 3rd ok, though...they are proably ok for now.....I wonder about a valve body leak...like gasket failure...

GENE

techrondon

4th gear lockup switch??..wheres that.??..wheres the valve body..???..i need a bit more detail.!..thanks,,frustrated cause i dont know much about trannys..but am mechanical..

mrvette

the Valve body is that large iron plate about 10" square you see that looks sorta like a brain...sometimes called that....on the end of some of the barrell/cylinder shapes in it...are screwed one or two switches...with black wires plugged in...to go to that connector for the lockup converter....well if that 4th gear switch is leaking...apparently it causes a bunch of 4th gear weird symptoms.....

OH...this is inside the pan, same plane as pan...dripping oil forever...whole ton of 10 mm bolts holding it in place....

also the 2-4 band is listed as possible,,...along with 2-4 servo...but if 2nd gear works fine....I personally can't see why it would not work in 4th gear...
but like I said....I"m NO expert....I did have to fix my own 700r4 last spring...and finally did so successfully.....

the switch is a pressure switch run off the oil pressures....and if it leaks the oil is not sufficeint to hold the 4th gear band in application as the valve is not in position al the way....all it does is unscrew from the valve body...one thing you could TRY is just removing it, and taking a 1/8 NPT brass pipe nipple for replecement...and just try it....need rewire the switches so you still get lockup though...but that depends on your installation....

GENE

GENE

techrondon

the switch is a pressure switch run off the oil pressures....and if it leaks the oil is not sufficeint to hold the 4th gear band in application as the valve is not in position al the way....all it does is unscrew from the valve body...one thing you could TRY is just removing it, and taking a 1/8 NPT brass pipe nipple for replecement...and just try it....need rewire the switches so you still get lockup though...but that depends on your installation

hhmmm...interesting..could i try that without wiring to lockup to see if 4th works..??..would only have to try to take off in od.....so far you have more info than two days searching !!..thanks gene..ronco@worldpath.net if you dont want to bother reposting in the forum...

mrvette

The best thing I have found on the web is the ASTG site mentioned above....you need find the 700r4 and then go though all the symptoms, and anything related to 3/4 clutch/2-4 band failure, and so on...servos'c, accumulators...etc....

GENE