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Brakes feel underwhelming, anyone else?

Saksak said:
I’m thinking the amount of brake pressure to reach a given deceleration rate varies with the amount of regen, making the brakes feel different at the different regen settings. I agree - it takes a surprising amount of force on the brake pedal to slow down with no regen, but the Gravity is a heavy vehicle.

I’m reading that the brakes are fly-by-wire with a hydraulic backup. I doubt the brake springs plus hydraulic back-pressure is tunable.
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The only thing guaranteed here is that brake behavior is not going to get changed for a single person after a full year of sales. They had professionals tune the system. So it’s either broken or back to stock. Not sure why any senior Lucid people need to get involved, they got a company to save.
 
037 said:
The only thing guaranteed here is that brake behavior is not going to get changed for a single person after a full year of sales. They had professionals tune the system. So it’s either broken or back to stock. Not sure why any senior Lucid people need to get involved, they got a company to save.
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I agree - there doesn’t seem to be anything wrong with the brakes given the OP’s braking test. Both the brake and accelerator pedal require slightly more force than most vehicles, but there is nothing wrong with that. It does reinforce that the Gravity is heavy, so maybe it’s intentional.

The difference in brake pressure with varying regen is also expected. With less regen, it’s intuitive that you’d have to apply more brake pressure.
 
Brake Graph.webp


Ok maybe a graph might help illustrate my issue and perhaps why Lucid can't fix my complaint.

Yellow Line = Regen Standard
Red Line = Regen High
Blue Line = Physical Pedal Stroke

Braking force is on the left Y axis
Time elapsed is the bottom X axis
Pedal stroke is on the right Y axis

Red and Yellow represent to regen curves created by Lucid's team. The blue line, shows pedal stroke required to exceed the braking force currently provided by brake regen at an specific moment in time. In this case, it is at the end of the time because I am trying to illustrate the requirement for a sudden increase in braking force.

All I'm saying is that I feel like the requirement for additional braking force above the red curve requires an amount of pedal stroke that is uncharacteriscally high.

Also, I realize that there is a potential issue with this graph and my initial hypothesis. The blue line should probably be additive to either the standard or high regen curve. I think, but I'm not sure.

Possible solutions to fix this issue:
#1 - Redo the red curve and bring it down so pedal stroke is less. But then overall braking force is also less.
#2 - If the braking system is electronic, perhaps there is a way to tune the pedal stroke relative to the braking force. Different pedal stroke to braking force ratios for different regen profiles.

And if the two things above are possible, then I'm certain Lucid is already playing with these tunables.
 
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NoseyReporter said:
View attachment 39584

Ok maybe a graph might help illustrate my issue and perhaps why Lucid can't fix my complaint.

Yellow Line = Regen Standard
Red Line = Regen High
Blue Line = Physical Pedal Stroke

Braking force is on the left Y axis
Time elapsed is the bottom X axis
Pedal stroke is on the right Y axis

Red and Yellow represent to regen curves created by Lucid's team. The blue line, shows pedal stroke required to exceed the braking force currently provided by brake regen at an specific moment in time. In this case, it is at the end of the time because I am trying to illustrate the requirement for a sudden increase in braking force.

All I'm saying is that I feel like the requirement for additional braking force above the red curve requires an amount of pedal stroke that is uncharacteriscally high.

Also, I realize that there is a potential issue with this graph and my initial hypothesis. The blue line should probably be additive to either the standard or high regen curve. I think, but I'm not sure.

Possible solutions to fix this issue:
#1 - Redo the red curve and bring it down so pedal stroke is less. But then overall braking force is also less.
#2 - If the braking system is electronic, perhaps there is a way to tune the pedal stroke relative to the braking force. Different pedal stroke to braking force ratios for different regen profiles.

And if the two things above are possible, then I'm certain Lucid is already playing with these tunables.
Click to expand...
I don’t think the graph is accurate. Applying brakes would just shift all the curves up by the same amount for a given amount of brake pressure.

Let’s assume the following (all units are in ft/s^2):
  • A pedal stroke decelerates at 5.
  • Zero regen decelerates at 1 (wind and rolling resistance)
  • Low regen decelerates at 5
  • High regen decelerates at 10
Applying brakes at the same pedal stroke, the resulting deceleration:
  • Zero regen: 6 (1+5)
  • Low regen: 10 (5+5)
  • High regen: 15 (10+5)
Brake pressure just adds to the regen and it’s smooth based on how hard you press. There is no blending.
 
Saksak said:
I don’t think the graph is accurate. Applying brakes would just shift all the curves up by the same amount for a given amount of brake pressure.

Let’s assume the following (all units are in ft/s^2):
  • A pedal stroke decelerates at 5.
  • Zero regen decelerates at 1 (wind and rolling resistance)
  • Low regen decelerates at 5
  • High regen decelerates at 10
Applying brakes at the same pedal stroke, the resulting deceleration:
  • Zero regen: 6 (1+5)
  • Low regen: 10 (5+5)
  • High regen: 15 (10+5)
Brake pressure just adds to the regen and it’s smooth based on how hard you press. There is no blending.
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Agreed. I think I mentioned that after thinking about it more it should be additive.

But by blending, I'm really talking about how you tune pedal stroke such that it feels additive in a expected manner. Not necessarily some type of automated blend of regen and physical brakes by the software. Not sure if that makes sense.
 
So I played with the car today with no regen. My god the pads have zero bite to them. It's sad. I genuinely think the pad compound isn't aggressive enough.

Just being back the high regen from prior to 3.6. Hell give me max regen, and let me deal with controlling it via the accelerator position. 😅
 
I think of the regen settings as emulations of engine drag deceleration in a manual transmission vehicle -- but with the bonus of stuffing electrons back into the battery.

No regen is clutch to floor, gliding ("wind & rolling resistance")
Low regen is 4th gear deceleration
High regen is same speed but downshift to 2nd

To increase stopping power / deceleration with any of the above, hit the brake pedal. Your clutch-foot does the "blending."

I think the major factor causing anyone to get flummoxed by the Gravity's braking sensation is how astonishingly & deceptively nimble this thing feels for a 3 ton vehicle -- in all axes of driving dynamics: absurd acceleration, lateral tossing with minimal body roll, and composed braking, assisted by the magic of regen.

For someone coming from ICE vehicles / sports cars (esp. those that weigh literally half as much as a GGT) maybe what's required is not any "tuning" of the brakes.

It's tuning yourself: getting to know the car and attaining some necessary re-mapping of kinesthetic habits to adapt to a big-ass heavy electric vehicle that (mostly) feels like a sports car.

To reality-check the brake pedal-feel issue here, maybe hop in a ICE Range Rover P530 SE LWB (curb weight 6025 lbs) and see what kind of pedal stroke it takes to go 60-0.
 
nelslens said:
I think of the regen settings as emulations of engine drag deceleration in a manual transmission vehicle -- but with the bonus of stuffing electrons back into the battery.

No regen is clutch to floor, gliding ("wind & rolling resistance")
Low regen is 4th gear deceleration
High regen is same speed but downshift to 2nd

To increase stopping power / deceleration with any of the above, hit the brake pedal. Your clutch-foot does the "blending."

I think the major factor causing anyone to get flummoxed by the Gravity's braking sensation is how astonishingly & deceptively nimble this thing feels for a 3 ton vehicle -- in all axes of driving dynamics: absurd acceleration, lateral tossing with minimal body roll, and composed braking, assisted by the magic of regen.

For someone coming from ICE vehicles / sports cars (esp. those that weigh literally half as much as a GGT) maybe what's required is not any "tuning" of the brakes.

It's tuning yourself: getting to know the car and attaining some necessary re-mapping of kinesthetic habits to adapt to a big-ass heavy electric vehicle that (mostly) feels like a sports car.

To reality-check the brake pedal-feel issue here, maybe hop in a ICE Range Rover P530 SE LWB (curb weight 6025 lbs) and see what kind of pedal stroke it takes to go 60-0.
Click to expand...
I still own my 6speed stickshift Subaru and can thus readily, as you say, "hop in a(n) ICE" car to compare.
I couldn't agree more that Regen on High is like more aggressive downshifting to control speed into curves for instance, where as Regen on Standard is more like a simple lesser one gear downshift. I don't really enjoy or want to feel a 6000lb car going into a curve on brake pads alone w/o Regen as you definitely lose the precise control of the vehicle that High Regen gives you ...so for me there's only one good option here.
I am aware there's more heat loss with Regen set on High than Standard but would be willing to bet that the additional friction braking necessary causes way more heat to escape and thus loses even more efficiency.
 
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