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lock up torque converter

ciffer

ciffer

1/2 ton status
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Feb 27, 2008
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Southeast MN
how do i tell if the 85 k10 in my signature has a lock-up torque converter or not? i put a late-87 700r4 into it yesterday to replace the dead original 700r4.

i want to make sure i didn't over look a detail with the torque converter.
 
All factory 700R4's have a lock-up convertor unless the trans was rebuilt and was set-up for a non lock-up convertor.
 
is there anything special that needed to be done to make the torque converter work correctly with the newer transmission? as best i could tell, there was only one way to put the torque converter on. i had it as far on the imput shaft as it would go when i installed the transmission. when i installed the bolts from the flexplate to the torque converter it came probably about 1/4 inch towards the engine to meet the flexplate.

this is my first time installing a transmission so i am a little paranoid about getting something wrong. it is not helping that the truck belongs to a friend and i am not 100% sure about the condition of the transmission.
 
Did the truck originally have a 700R4 in it? If it did do you have the square plug on the driverside hooked up?
 
yep, it was a 700r4, nothing fancy in the replacement, just bad part out good(hopefully) part in. i assume you mean the 4 pin connector, it is hooked up, i have the locking piece of the male end over the notch on the female side.
 
Ok, since the truck was an original 700R4 and the connector is hooked up you just need to test if the convertor is actually locking up as it should. There are a couple different wiring configurations for the connector though so you might need to drop the trans pan and talk with your local trans shop IF the convertor isn't locking up.

Drive down the road and get up to at least 50-55mph and ever so gently rest your left foot on the brake pedal and the engine rpm should come up about 300rpm or so, if it does this then the convertor is locking up properly.
 
thanks for the info, i'll check that if the truck moves when i put it in gear.
 
crazy question. you arnt reusing the dead tranny convertor ? your question sounds a bit funny just checking.
 
i am reusing the torque converter but it has been flushed out. i also hooked up the line from trans to cooler and put a hose on the return line to a bucket, filled the trans, started engine, pumped out the pan, repeated until the fluid came out clean.

truck runs and shifts great, the old cooler lines were damaged and i tried to cobble something together, which kind of worked but leaks. i'll buy some new cooler lines and fix them correctly.
 
ciffer said:
i am reusing the torque converter but it has been flushed out. i also hooked up the line from trans to cooler and put a hose on the return line to a bucket, filled the trans, started engine, pumped out the pan, repeated until the fluid came out clean.

truck runs and shifts great, the old cooler lines were damaged and i tried to cobble something together, which kind of worked but leaks. i'll buy some new cooler lines and fix them correctly.
Click to expand...

NEVER reuse a convertor from a failed trans, it's just asking for major trouble. You CANNOT flush all the metal and crap out of a convertor that came from a bad trrans.
 
i have a bit of a problem then, everything is back together and the truck has been driven, although only about 4 miles. i kind of wish i had known this prior to putting everthing back together. regardless, i'll take it back apart, should be easier this time considering that all the bolts were recently loose and i know more about the process.

napa lists this torque converter
http://www.napaonline.com/MasterPag...PartNumber=GM18A&Description=Torque+Converter

is that the correct one?

i didn't count the splines, but i do know there are 3 bolts holding the torque converter to the flex plate.

my other problem is the cooling lines. i can't find any parts stores that sell pre-bent cooler lines, LMC also does not offer them for 700r4. are there any sources for pre-bent lines besides a salvage yard?
 
you've already run it, ran all the dirty fluid through the system, i'd just change out the filter and fluid again, and hope it holds up, otherwise i would be willing to bet people are gonna say it needs a complete rebuild again. :crazy:
 
if it makes things any better, prior to running the vehicle, the engine was started and let run in park with the return line disconnected, put quite a bit of fluid through that way until it came out bright red. there as some dark fluid that was spit out the return line. all that was pulled from the pan was fresh clean fluid.

what exactly is left in the torque converter that is cause for concern? i am not trying to be cynical, just trying to learn more. the transmission never completely failed, but it did lose everything except first gear and reverse. the old pan had quite a bit of wear metal in it, like what is typically cleaned off the magnet during fluid and filter change, but there was a lot more.
 
The convertor holds about 9 quarts of fluid, once that fluid leaves the convertor it goes through the whole trans before leaving the output cooler line to the cooler. Like was already said, if damage is going to be done, it's already done. Just pray the trans continues to work and let this be a lesson about torque convertors and the reuse (or lack in this case) of them with a new/different trans.
 
:doah::doah::doah:well crap. what do you think the best route to take for fluid/filter changes? i am thinking of driving around for a few days then dropping the pan to change the fluild/filter then again in a few thousand miles. i have a pile of rare earth magnets sitting around, i am thinking of putting a few of them in the pan on the reasoning that they will do a better job of pulling wear metals out of the oil than the weak stock magnet.
 
You've got a filter, IMO changing fluid does nothing when you are talking about junk in the transmission. The fluid/crud gets embedded in all the clutches, so nothing short of a complete rebuild will remove junk from the internals of a transmission. When you pull a pan after 50-100,00 miles, you'll see the pan coated in grit, it's not like that keeps going through the system. Once it hits the pan it stays there, but the damage has already been done. No reason to worry about whats in the pan at that point.

As mentioned, consider it a learning lesson. Long story short, converter in one of my cars wasn't machined correctly, and ground off part of the pump tangs. Didn't do anything but shim the converter a bit and run it, and didn't have any problems afterwards. But I considered that lucky, and why I don't run auto's when I have a choice. :)
 
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