I have a transmission shudder. It seems to only occur in overdrive. It seems to occur primarily when I am going up a hill at approx. 50 mph and I lean on the accelerator and approach the point of downshift. It is a brief shudder and does downshift ok. Otherwise the transmission seems to operate ok in all gears and doesn't appear to slip when I "get on it". I was told it could be the torque-converter. I was also told that the overdrive uses a small clutch and that it might be the culprit. Small clutch??? Could the computer be getting bad information from road speed sensors and thus cause incorrect response. The engine feels like it starts to falter and buck slightly when I cruise at approx. 50 mph on flat or hilly road surface. Can't really tell if it's the engine or the transmission. I'm not getting any codes, so I'm kinda lost. Everything seems to go to hell around 50 mph. By the way, the tach is at 1,500 rpm in overdrive at 50 mph. Does this sound correct?
I'm trying to sell this truck and I tell all prospective buyers about this problem. As you can imagine, nobody wants to touch it. I refuse to be dishonest and not tell them about it. Any help would be much appreciated.
Thanks,
Mark

It is most likely tcc chatter. Have the trans serviced and add a bottle of lubeguard or Lucas. These are the ONLY additives to ever put in a trans. The converter may already be too damaged for this to fix.

I've always thought that it was the torque converter trying to lock and then unlocking - essentially bad programming.

Health's blog has a how to on manually controlling the lockup. I'll be doing that shortly.

Personal update. I was full of crap! My chuggle was caused not by the transmission but the EGR. Before, it seemed that the torque converter wasn't staying locked around 48mph. Well, after I blocked the EGR that chuggle disappeared and I tried HARD to get it to do it again.

I believe what was happening is that when the truck would go into overdrive the EGR was popping open and closed under the low vacuum/rpm. Whatever it stopped chuggling.

Personal update. I was full of crap! My chuggle was caused not by the transmission but the EGR. Before, it seemed that the torque converter wasn't staying locked around 48mph. Well, after I blocked the EGR that chuggle disappeared and I tried HARD to get it to do it again.

I believe what was happening is that when the truck would go into overdrive the EGR was popping open and closed under the low vacuum/rpm. Whatever it stopped chuggling.
mine's been doing that since the tranny was new, right around 80 kph, it feels like its jumping in and out of lock, its been doing that for 5 years, i have a vin F engine so its cant be EGR in my case.. i think its bad programming..

Vin