4r70w o/d shudder / clunk

[ultraclyde]

Okay guys and gals, here's the problem...

1997 5.0 2wd w/tow package, 154k miles, occaisionally tow a 2k lb camper, always with o/d off.

it recently started hitting very hard going into / out of o/d at 40-50 mph, and sometimes shudders going into o/d.
If you are under hard accel, it's not noticeable. Other gears are fine. seems worse when cold. fluid is correct level and clean, doesn't smell burnt. Fluid has never been changed that I know of. No DTC codes or flashing o/d lights.

Any ideas as to cause? Am I about to have to rebuild this trans??
Thanks for your help!

 

[rizzjc]

I have similar symptoms, shifts fine while accelerating. Haven't found the cause yet, but I have changed my fluid regularly. I'm under it right now changing the filter. Fluid looks new (synthetic ATF with about 20-40k on it). Not sure how long the filter has been there, as I had most services done by a shop, who SHOULD HAVE changed the filter, but who knows.

 

[sportbikes]

This sounds very similar to what mine is doing aswell only mine is a 97' 4.0 xlt 4x4. It seems to shudder while driving regularly and it seems more abrupt when driving up hill. Especially in 3rd gear trying to go into overdrive.

 

[rizzjc]

Well, we have a different tranny than you sportbikes. For mine a fluid and filter change has solved bad shifting. It has worked for 140k miles, so hopefully that trend continues.

 

[97BlackX5.0]

I know ford had a tsb out for something like this. It had to do with the fluid type. I remember they updated it to mercon v instead of mercon III and that solved some issuses but they also had a new pressure control valve spec. too. I dont know the tsb # though maybe someone else here can point it out. There is also a additive that you can add called lubeguard (napa carries it) that is supposed to make mercon III into mercon V (or at least act like it) that is supposed to help with shudder. If you have not changed your fluid though I would have the pan dropped and a new filter/fluid put in....It might just be the pump starving for fluid at low rpms from a clogged filter.

There is a rebuild diary up near the top of the page that might show you some different things about this trans.