Transmission Additives??

[holter95]

Hey all - tech question for you..

Been experiencing a pretty harsh "clunk" in my drivetrain lately... ~55mph, usually under throttle. When I lift off the accelerator suddenly, a loud CLUNK and the whole truck jumps.

Last year about this time I experienced the same thing. Did a trans fluid/filter change and the problem disappeared for several months. Now, about 18K miles later it's back. I have a friend who has a suspicion that it might be in the torque converter, but he is also going on hearsay because I have been unable to replicate the problem when he's riding. He mentioned something about possibly an additive / lubricant that may help the situation, or at least prolong the life of the converter before it could do more serious damage to the trans. Anybody heard of anything? Looking for any suggestions.

More history on the truck - bought at 79K miles immediately following a "trans replacement" courtesy of the previous owner's extended warranty. When I bought it, they said they experienced a clunk at highway speeds, at the time I did not notice, but this may be what they were referring to. I am told (and rebutted per the work order) that the trans was REPLACED, not rebuilt. However, I'm not sure if this includes said torque converter too.

Any help or input on this would be appreciated! Thanks
BTW... 128K miles on the ticker right now.

 

[sholzee]

My 1992 automatic tranny had a hesitation when changing from drive to reverse and got to the point that it took almost 5 -10 seconds to engage. Then one day my wife said it was really bad the thing would shake and shudder and barely move, it had 110k on it.

I figured an additive couldnt hurt, a guy at NAPA suggested "trans tune" made by seafoam. I put half a pint in because my level was at full and it actually worked right away. it started shifting normally. I then change the fluid at filter the fluid was brown and burnt, filter looked ok. Added new fluid 1/2 pint shy and topped off 1/2 pint trans tune. Now have 125K and Knock on wood running good. I'm not endorsing a product just stating what worked for my situtation.

 

[lightning31]

holter95:
I had a shutter in my transmission when shifting under load (E4OD in a 96 Ford F-250 with powerstroke diesel)
The tech at the trans. shop instructed me to visit my local chevrolet dealer and purchase two bottles of GM posi trac additive and put it in the transmission. He said the shudder was the torque convertor clutches and the additive would keep them from chattering. It actually worked!!! He did say to be sure it was GM additive I used.
I'm not pushing a product but this additive worked in my truck and I have put it in my explorer also,sort of a preventative I guess. I hope this helps.

 

[Longs]

It would make me quite nervous to consider pouring posi additive into my transmission!

I've had good experience with a product called TransX in a couple of my cars, and I also know a mechanic that has had good results with it in numerous cars. I have NOT used it in the A4LD in my '93 Limited - haven't needed to.

I'd probably change the fluid and filter again and add the TransX, if it were mine.

Longs

 

[holter95]

Any experience with Slick50 Annual Automatic Transmission Fluid Treatment? I've heard similar thoughts pertaining to the torque converter.

I'll likely try to change the fluid/filter again soon. Worked once, maybe just needs more frequent maintenance to nurse it along. Try to prevent the ultimate KAPUT