I cant figure out whats wrong with my truck can someone help?

(2010-05-30 19:59:51)

1. dmac Says: Okay so i have a 1999 GMC Sierra 1500 with a 5.3l v8 engine and everythings in real good shape runs fine and everything but the only problem i have is when im traveling about 30 mph+ and start pressing the brakes to slow down or stop the truck starts bouncing up and down as if it were going over intense bumps or had hydraulics. The front rotors and brakes have all been replaced and are brand new and the wheels have been aligned. I cant figure out what would cause it to bounce like this. please help...

2. Blackcat Says: sounds to me like a bad torque converter lockup solenoid.

3. 89 z71 step side 6'' lif Says: maybe a wheel is loose or bearing is very very bad, broken sway bar matched with worn shocks?

4. Desert Dust Says: Sounds like a warped disk brake rotor. Take it to your favorite mechanic guy.

5. cyclebri Says: If it's all brand new it sounds like someone installed a caliper wrong or maybe one of the pistons in the caliper is gummed up or something like that.

6. bandit_60 Says: bad shocks or struts will do that and also make the front end nose dive too.