thunk when brake released

'05 PreRunner
Doesn't happen all the time, but after I've come to a stop, when I take my foot off the brake I hear a thump under my feet.
Took a mechanic out, and it didn't happen. (Nothing ever happens when a mechanic's in the driver's seat)
Anyhow, I'd like to go back in to the shop and say that I'd like the U-joints/drive shaft, or something in the brake assembly looked at.
Has anyone had that problem?

 

How long have you come to a stop before releasing the brake?

In other words....If you're stopped sitting at a stop light with brakes on...and then you get the green light, let off the brake...does it still thunk?

Need more information.... Does it do it when you're on/off the brakes fairly quickly?

 

this happened on my last truck when i would either have to slam on my brakes, come to a quick stop, or what janster said when i would be on/off the brakes quickly. I never figured out why, i would be interested in knowing why it was happening.

 

Yup. Your first question describes it just right.
No to your second question.
I notice it most when I've been driving maybe as far as a mile, then come to a stop (at a light). When I take my foot off the brake (to place it on the accelerator) that's when I feel it. It doesn't seem to come from the engine compartment (motor mounts?) but it feels like it's directly under my feet.
That's why I thought u-joint.

 

it's normal.. I can't elaborate but i know somebody else will

 

I'm still confused a bit.... So, you've come to a complete stop. Your foot is still on the brake and remains down fully on the brake for a good 5 minutes - then you take your foot off the brake and it thunks?

I'm trying to tell the difference whether or not you're experiencing axle wrap - or something else.

Axle Wrap occurs when you've got your foot on the brake lightly while the truck slows down. You put the brake on harder as you approach a stop sign. The truck stops......but still has momentum. YOu remove your foot off the brake and the momentum thunks forward (so to speak). The thunk is the suspension coming to its RESTING position after the momentum passes (hard to explain).

 

Thanks, Janster and 619.
So it's 'normal'.
I'll take your word on that, and stop bugging the mechanic, but I've had 4WD trucks for close to 30 years, and never had that kind of sound.
This is the first 2WD I've had and I'm not likin' it.
Good truck, but strange thunks in the night being normal. . . .?
Thanks again, folks.

 

Yep, alot of our Taco's do it.. There was a vid around here somewhere show how loose the cv shaft was closest to the diff. My dads 07 does it also. Ohh you have a Prerunner, well then im not sure. Maybe in the drivshaft?

 

^^ X2 on Axle wrap.

 

mine does the same thing. i can sit at a light for 20 seconds or 2 min, when i let off the brake i get the thunk...'06 2wd.

 

Thanks all. Talked to my mechanic. He explained it in detail, about how there's pressure on the gear inside the axle shaft when it engages other gears in there. Maybe not a good description of what he said, but I understand it. I'm not going to beat a dead horse, just don't understand why I've never felt it on any other truck, (4WD), 3 Dakotas, '83 Nissan and '02 Tacoma - all 4WDs.
Now I'm gonna see how this sucker will hold up going through some washes near Yuma where I've taken my 4WDs in the past. Might be interesting. My son-in-law, (Grand Cherokee) says the only difference between driving a 4WD and mine (locking diff) is that I gotta go faster. That's not my style, but we'll see.
Thanks again.