Starting from a stop issue

Hey everyone!

so I’ve been trying to research anyone whose feeling the same way I am and haven’t found any other threads so deceived to start my own.

I have a 2019 tundra with almost 8000 miles and I noticed a strange feeling the second I give it gas after coming to a complete stop. For example if I’m driving down a highway road then come to a light and come to a complete stop, when I let off the brake it rolls forward but the second I give it gas it almost feels like a split second of disconnect like something may be not correct. Almost like a bump/ hesitation feeling that only I notice. I don’t feel it every time and there are no noises or clunks or anything associated with it but it’s enough of a feeling to notice. I looked at different drive shaft components and nothing looks loose or off.

I am very picky when it comes to things so I don’t know if I’m over reacting or if it’s normal or if anyone else’s feels the same little hesitation type thing that I’m feeling. I want to mention it at my next oil change but if others feel the same and it’s normal I’ll be at ease and it’s not enough to bother me. Thanks!

 

It's probably the rear driveshaft slip yoke, especially if it's a 4x4. Spicer coats the splines and it's permanently greased but it still sticks a bit. The tolerances have to be tight because that shaft spins 3000+ rpm. Some driveshafts will have a zerk to squeeze fresh grease onto the splines every now and again to stop the sticking. Not ours.

You can feel it because of the rear axle wrapping a bit. Braking force pushes the pinion down a bit and extends the driveshaft. Before the truck stops the driveline spins slow enough for the engine to start pushing forward again and it puts a little torque on the splines, which can make them stick. This holds the pinion slightly down because the driveshaft is still extended. Sometimes it'll unstick right as you stop and you'll feel a slight thud. Other times the additional torque when taking off pushes hard enough to lift the pinion and overcome the sticking yoke and you feel it then. The truck accelerates when the axle torque pushes against resistance from the leaf pack so the more angle the pinion can move up, the greater the hesitation feeling as well.

Tacoma guys have fretted about the phenomenon for years. In that lighter truck with the older 3-leaf pack it would feel like getting rear-ended. Disassembling the driveshaft and regreasing stops it from happening, for a few thousand miles anyways. But it always comes back. An annoyance for sure, but not really a mechanical problem to worry about.

The only ways I know of that might cure it are a super stiff leaf pack or a frame-connected traction bar to stop the pinion from rotating around the axle so much.

 

Do a rolling stop on a hill it happens in the 4runner as well. Almost feels like its hunting gears. Feels like trying to down shift but you have the foot on the hammer!!!

 

I appreciate your lengthy response! Im a machinist not an auto mechanic but I completely understand what you’re saying and that would make sense that the splines in the slip yoke sticking after coming to a stop. Now I see other threads regarding the slip yoke as well. It’s truly a very small thing I noticed and after reading what it probably is I’m not worried and I’ll just let it not bother me. Absolutely love my tundra otherwise!