97 explorer - tranny problem?

I'm getting a slight 'bump' fell when cruising along, or under light acceleration. At first it felt like hitting a small bump in the road, but it's definitely in the driveline somwhere. Feels like something in the tranny, but not 100% sure. Hard to make it happen, but seems to be more frequent. Any thoughts on what needs to be checked?
It's a 97, xlt, and haven't changed the tranny fluid since I bought it last year.
What should I check or ask the mechanic to look into?
thanks for any help

I'm getting a slight 'bump' fell when cruising along, or under light acceleration. At first it felt like hitting a small bump in the road, but it's definitely in the driveline somwhere. Feels like something in the tranny, but not 100% sure. Hard to make it happen, but seems to be more frequent. Any thoughts on what needs to be checked?
It's a 97, xlt, and haven't changed the tranny fluid since I bought it last year.
What should I check or ask the mechanic to look into?
thanks for any help

You haven't given us very much info, but here goes....

a slight "bump" at constant speed is PROBABLY not the transmission. Not unless it's happening as a shift occurs, and you didn't say that. It sounds more like a miss in the engine.

What I'm guessing you feel in the driveline is a little play in the u-joints. If that is the case, you should be able to recreate it by taking your foot off the gas suddenly. Or letting off and then back on very quickly. You "feel" the clunk more than hear it.

You may want to consider a transmission fluid change anyway. I have a '96 5.0l that had tranny problems not too long ago. However, my symptoms were really slow (slipping?) shifts, especially 3rd to 4th. I ended up having the fluid and filter changed (actually, they did a "power flush"). It made a HUGE difference. I can't remember where I heard this, but I am under the impression that Explorers "need" transmission fluid changed more than most other vehicles.

Good luck!

You're right in that you feel it rather than hear it... it's quite subtle, but a definite jolt somewhere in the driveline. There's no jump in revs like it's slipping and it's very sudden, like I said.. a bump... almost like the feeling you get when the transmission shifts, but quicker... does feel like a misfire in some way, but can't hear any change in the engine. All in all a bit of a mystery.

I was wondering if it's the transmission 'thinking' about shifting and then changing it's mind, because it often happens under slight acceleration.... (although also noticed at highway speeds on flat surface with no acceleration)... I was wondering if it coiuld be a glitch with the brains that tells it when to shift, the vacumn, or the traction control or whatever.

But I'd heard 97s and earlier had frequent tranny problems and was wondering if anyone else had a similar experience.

Really sounds like a missfire in the engine for one reason or another. Do a big tune-up if you haven't ever done so. See how that does.

Also they seem to run hot in the tranny, so more frequent fluid changes are good. Especially when towing.