For the last yea or so I've had a shimmy under braking in the Ram (2011). I just replaced the front brake pads & rotors at 183,000 and rear brake pads at 184,000 and it didn't go away. Can't feel it in the brake pedal with shoes on, but driving shoeless I can feel a faint pulsation - but nothing like how the entire truck is shaking. Can feel it a bit in the steering wheel, but again, it's mostly in the butt and pretty much the rest of the truck. Like it's more chassis induced than brake induced.

The only thing I can think to do is replace the front hubs? I don't remember if they are the original hubs or not. They aren't grinding or making noise, and the tire spins free on the jack. So i'm genuinely confused.

Any other thoughts?

 

Might be worn steering parts, bad shocks, or even a tire going bad..... If you only feel it when stepping on the brakes though... That does imply a brake problem. Did you turn the rotors when you replaced them?? Just because they are new, doesn't necessarily imply they are true.... I got into the habit of taking a couple thousandths off the new ones, just because I didn't like come-backs for brake pulsation....

 

No, I did not have them turned and we don't have a lathe. I'm tempted to grab the dial indicator from the gear setup kit and see if I can check them on the jackstand though.

I'm almost certain the shocks are the factory ones, as is most of the suspension. I'm putting ~1800-2000 miles per month on the truck; The first 100,000 were predominantly highway miles but the more recent 84,000 have been mixed city and highway. The lifter/cam failure was at 160,000 last May and now I'm at 184,000.

 

Most of the brake shops around here don't have a lathe any more either...... Which strikes me as rather strange...... I tried to buy one from my buddy when he retired, and closed his shop, but, day late, and a dollar short. He had already sold both of his.

 

OK, so I had the right front rotor turned (left front was new on the brake change) and it didn't go away.

We put the truck on jackstands and ran it to 55mph . As soon as you lightly tap the brakes, it started shaking. So we know it's driveline. The transmission tailhousing was bouncing up and down violently, so put a new Anchor brand transmission mount on.

It still shakes under braking. Towing makes it dramatically worse.

My next move it to get both rear rotors turned, but there's no faith in it - you don't feel any pulsing in the pedal, it's all Seat Of The Butt.

That leaves us with transmission or rear gear. Sure hope not, neither is cheap.

Thoughts?

 

Rear disc?? Yeah, turn the rotors, see if the problem goes away.

I would also do up the remaining front rotor. Just because its new, does not imply it doesn't have some excessive runout. When I was doing this for a livin', I would turn new rotors/drums 'just because'.... I hated doing jobs twice, and spending a few minutes on the lathe made sure I didn't have to.

 

Usually a front brake rotor that is not running true will also cause a wiggle in the steering wheel under braking. Since you're really only noticing this in the brake pedal (slightly) and in the seat under braking, I would COMPLETELY recommend starting with the rear brake rotors. Also make real sure there is no debris between the rotor and the hub when re-installing, especially if you choose to machine the rotors rather than replace. It's pretty easy for rust to fall out of the vents during the installation process.

-Rod

 

update: it was indeed the rear rotors. So wierd, dad's never seen rear rotors cause a tranmission tailhousing to bounce around, and have no feeling in the pedal.

 

Thanks for the update. Goes to show that one is never too old to learn something new.

-Rod