how do i tell if i have a lockup torque converter???

[jbs68]

Hi ,
i have an '87 blazer,350, 700r tranny. How do i know or tell if i have a lock up converter or not? anyone?
thanks,
james

 

[Jonny-K5]

all 700s come from the factory w/ lock up converters. to test if yours still works, drive down the freeway, get the truck up to around 65. stay at a steady cruise,with your left foot barely push the brake. you should feel the rpms jump up by about 200. there is a unlocking circuit that engages when the brake lights come on. my trucks converter wasnt locking when i bought it. fairly common.

 

[jbs68]

lockup tq conv.

well, kewl. thanks. how did you fix yours? new converter? i notice my tranny drops down to third when going up slight grades. does the torque converter just work in OD?

 

[Jonny-K5]

it is normal for it to downshift into third up inclines, since you are probly losing momentum and pushing the gas more.
the way i fixed mine was a whole new tranny and converter from bowtie overdrives(performance 700r4 rebuilder). very pleased. my tranny went out soon after the torque converter stopped locking up. when it doesnt lock up, its generating alot of heat, and heat is the #1 killer of auto trannys.



700s only lock up in overdrive. ive heard from one person from here claim his truck locks up in 2nd and 3rd as well, but i dont think its true. my truck is rigged with a manual lock switch, so i can lock it in 2nd or 3rd,for towing purposes. but to shift from 2nd to 3rd, or 3rd to 4th with the converter locked is very harsh. so i dont see how it could come from the factory that way. unless it unlocks between shifts. according to the only factory setup was locking in OD.



if you want to learn more about how a 700 works, or to look into replacement performace 700s, check out www.700r4.com

 

[jbs68]

thanks again, Jon. i will go get ed-u-macated over at that site! Actually, a manual lock up switch sounds like a good idea.
james

 

[Jonny-K5]

thanks again, Jon. i will go get ed-u-macated over at that site! Actually, a manual lock up switch sounds like a good idea.
james

it is, especially for long steep grades where your in third or second for along time. another good thing to have is a temp gauge. must have for a 700 in my opinion.