4L60E bizarre problem.

[arcticryder85]

hello folks,
i have a '94 chevy silverado 2wd and have been having a strange problem with it. the transmission works great except when in OD and at slower speeds (1500ish rpm, around 50-55mph) the trans will slightly pulse (minor consistant jerking). if i speed up and bring the rpm's up to 2000 or so it works good. it only happens in overdrive. downshift to another gear and it works fine. Fluid does not stink or have discoloration, when drained i found nothing out of the ordinary. i replaced the fluid and fliter and it didnt seem to help. theres about 120000 miles on the truck and about 50000 since i had the transmission rebuilt 2 years ago.
Thank you!

 

[6chevy9]

check out your u joints and rear axle. that would be my next step. then go from there. in the axle look for missing or chipped teeth on the ring gear. feel around on the pinion as best you can for the same. look for chunks of steel in the diff. if everything if fine change the fluid and keep looking into other things.

 

[Butch]

I would have the system completly flushed, my sister blazer was doing the same thing, same tranny, it fixed its problem.

 

[6chevy9]

but it also sounds like the ring gear is missing a tooth. because when your on the throttle its got the pressure on the fronts of the teeth where you would notice it and when off the throttle its on the back side where you wouldnt notice it. although just thinking of it now i bet your TC is locking in and out. try getting into over drive, once it starts to do it again put a little more load on it by riding the brake why still on the throttle. if it goes away i can almost gaurentee its the TC! let me know if im right good luck!

 

[Butch]

it only happens at a certain rpm range, it would have to be missing a few teeth and be a hard jerk through out acceleration and cruising. I say its a TC if its more of a surge then a jerk.

 

[Hodges87]

Does it jerk when slightly accelerating from 55 or when you hold the petal steady at 55? Its sounds like the converter is locking to early then unlocking to maintain the speed.

 

[6chevy9]

yeah i had totally forgot about that because i have had it happen too lol. obviously not on my 97 but on another truck.

 

[arcticryder85]

it is not any problems in the differental or driveline, that has been ruled out. It could be the TC locking in and out improperly . that was one thing i was thinking of myself too. it will mainly jerk under constant speed. upon accelertion is pulls smooth. what would cause a TC to act this way?

thanks,
Russ

 

[6chevy9]

not sure what causes it but i belive it needs to just simply be replaced. try holding your brake like i mentioned to confirm that is the problem.

 

[arcticryder85]

okay i have tried the brake thing numerous times and as soon as i tap the brake (enough brake sensor touches on) the tourque converter unlockes and the pulsing goes away. so i now know i have a tourque converter problem, but it seems it shouldn't be locking when it does? IMO it shouldnt lock at slower speeds or when climbing a grade, which it does. what controls the tourque converter as far as locking and unlocking? ? or do i simply just have to replace tourque converters?
thanks!!