So I took the new truck on a road trip to St. Louis today, and was able to get a definite behavior on a shudder I have. Whenever I'm braking, there is a very fast shudder that starts at 21mph and stops at 19mph? This only happens on braking. I thought it might be the tranny shifting, but I manually shifted down to 2nd, and it still did it. The truck has 800mi on it, and has done it since new, but I just finally discovered the behavior. Truck is FX4 crew with 5.0.

Any ideas?

 

Could be a warpped brake rotor.

 

X2 on the warped rotors. Could also be brake pad material transfer to the rotor. Only other thing could be a front wheel just ever so slightly out of balance.

 

A warped brake rotor can cause this at only a certain speed? This is a new one on me. I should mention the shudder is neither worse or better the harder I brake. The pedal doesn't shudder at all, only the truck?

 

My last truck, a Dodge, was horrible about warping rotors, and it did exactly what you are describing. Just a little shimmy when slowing down between certain speeds. It's called harmonics.

Let it go for a while, and it will get worse, causing a shake at different speeds, as the harmonics change with the increase in the warp of that rotor.

I had two rotors warp once on the opposite corners of the truck, and it caused it to have the death shakes at exactly 50 mph, then it would smooth out at 55, then vibrate again at 70, but only a little.

Each time, I would take off the rotors, have them turned, and it would go away.

With these new brake by wire abs systems, you don't get feedback unless it the abs system kicking in.

 

That's currently my issue. . .the tires just about need to be replaced anyway, so I'll deal with it for another 6000 miles. . .whenever the bad tire is on the front I get the truck shudder when braking. The harder I brake, the harder it shudders.