Bump when down shifting 5 to 4

Truck is relativiley new to me. 43k miles. I'm not sure if I'm going crazy or it's another characteristic of these 5 speed auto transmissions. But sometimes there will be a bump down shifting from 5 to 4 coming to a stop or turn or whatever. Is this the torque converter unlocking/gear downshift or an abnormality? It will normally be a smooth downshift or an engine break downshift going down hill but every so often I get a bump or a knocking feeling coming out of 5th around 35mph coming off the highway or slowing down from traveling.

 

Mine has done it. It doesn’t do it regularly. Maybe a few times a year?
And just like you, it’s usually when coming to a stop from higher speed.

And yes. Before someone suggested I check my fluid level, it is full.
Typically if the fluid is low, it will jerk into gear all the time, or most of the time.

BTW, mines done it since I’ve owned it. 13 years now.

 

Thanks for the reply. I just took the truck out and drove for about an hour and it didn't do it the entire time. I'm getting a friend of mine who works at Toyota parts to get me some ATF fluid cheap and I'm gonna do a drain and fill and check the fluid. It seems like if I've been driving the truck for a while I'll get smoother shifts all around. It hasn't been really cold or anything. Mid 50s and 60s. Idk perhaps I'm a hypochondriac. I'll notice something and keep focusing on it. Just want my truck to last as long as my dad's previous Toyota trucks. 400k miles and he's never changed the damn tranny fluid.

 

I did a drain and fill at 100k.
It wouldn’t be a bad idea to do it every 50k.

Some guys drop the pan and change the filter, I didn’t and have not yet.

 

I did one about 5000 miles ago but this time around I'm gonna do it myself and check the fluid level. You never know what you get at a dealership

 

Funny mine just started doing that but from 4th to 5th.

 

the 4 to 5 and 5 to 4 shift under just the right circumstances can be uh... odd. Just a characteristic of the stock tuning of the truck.

New to you truck, I dont care how many miles it does or doesnt have, or what maintenance records show. But change all the fluids properly (theres a special procedure for the trans fluid fill level). Front diff, tcase, trans, rear diff, engine oil, brake fluid, radiator fluid etc.

 

Yea I'm aware of the procedure with the ATF fluid. Everything else was done the first 2 months I had it. Coolant flush, PS fluid, diffs and transfer case, plugs, oil twice now, greased the drive shaft u joints, trans drain and fill, now I'm about to do the drain and fill again.

 

Mine was doing it up shifting at first now it does it down shifting under the right circumstances. My wife thinks I'm crazy. She's probably right.

 

I noticed my truck doing it when the u-joints/carrier bearing were going bad. Now that I’ve changed all that out, I have to pay attention to notice it.