Sudden Brake Shudder / Rapid Pulsing

[HeyBales]

Easily could have had the scenario described prior then with HVB full (EV coach shows that, not the power meter).

But into the pads means full regen happening then.

That means the ICE is going to be used for air braking.
But if ICE was running for heat or required for power used, the generator motor is making changes from gearing needed for required power, to instantly gearing needed to spin the ICE at RPM needed to waste the electrical.
That can be very different RPM, actually opposite direction RPM.

Perfect storm you might say.
The fact it stayed shuddering that way down to 10 mph is different - once GM reverses RPM direction that's done. Once ICE is spinning with no fuel that's done.

This might involve the damper between ICE and eCVT then.
Noticed any shudders when idling in P or D, even N actually?
Might be felt too on accelerations with ICE at just the right power level that allows the vibrations thru.

Next time it happens on coast down - switch to N and be ready for full brake pad engagement with no regen.

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[Kenv24]

These questions from prior post - otherwise I'd say warped rotors if no further details:

Engine on or off (perhaps for heat)?

Do you recall how much into the brake you were digging - like still in Regen mainly or well beyond because it was a fast stop?

Was the shudder closer to the 40 mph side or the 0 side?

Was that 40 mph from coasting or even slight braking to keep it there due to downhill, until you needed to brake for light?

Do you use EV coach to know if you just had an almost full HVB, like full blue bar?

Good points...but I would say it's definitely NOT warped rotors. Not with a bunch of different trucks experiencing this. My truck has done it 3 times....and it has been 4-5 months since I last felt it. It's not the rotors for sure.

 

[HeyBales]

Good points...but I would say it's definitely NOT warped rotors. Not with a bunch of different trucks experiencing this. My truck has done it 3 times....and it has been 4-5 months since I last felt it. It's not the rotors for sure.

Ya - I wouldn't expect that. But if no details were given to include the EV nature of the beast - then back to normal brake shudder reasons. I guess a stuck caliper pin would be in the normal mix of reasons too, should have thrown that in.
But at least details were known and given this time.

 

[wdancer]

I will try neutral next time. The first time I backed off the pedal little and it stopped but started again when I applied pressure again. When I let it all the way off it stopped. The next time, I didn't have the opportunity to let off because the car in front of me was coming up quickly and I had to ride it all the way to stop. It shuddered more the closer I got to stop.

If it happens again, I will try to remember my dashcam footage. It had already over written the day by the time I remembered it.

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