I have a really steep driveway with no turnaround space, so I back down it. Oftentimes when doing so, my brakes behave oddly: they jerk sort of rhythmically and I can feel it through the brake pedal. It's hard to describe, but it sounds and feels like a very mechanical kind of a pulsing and scraping thing.

Anyone know what this is? Should I be worried?

Thanks.

 

Is your steering wheel in a full lock position ?

 

Not sure exactly what you mean. I'm actively steering back down the steep and curved drive. . . .

 

Are you turning the steering wheel all the way to the left or right while you were braking ?

 

No, I'm not. The steering is more subtle than that.

 

Are you going over a bump at an angle? If so it's the unloading of one wheel and causes the pulsating described when braking.

 

Nope. The drive was recently paved. It's happening on steep and smooth ground. Is that unloading possible just because, say, one side of the car may be lower on the incline, since I'm backing down at an angle?

It seems worse if I'm taking the steepest approach.

 

Is this a base Carrera?


If so I'm Almost certain my car used to behave this way at times on steep inclines while braking.

I have upgraded to Turbo/GT3 6piston front/4piston rear and 350mm rotors all around .

The car no longer has that problem .

 

It is a base Carrera. (Still a high-end enough car that I wouldn't think I'd need to upgrade the brakes just to back down a driveway, though.)

I don't mind it too much, but for the concern that I may be doing some kind of damage . . .

 

My thoughts were that since it gets worse on the steepest part of the incline then it has to be related to weight transfer. As you back down on a steep incline the front will get lighter, there's a possibility of the ABS pulsating due to less weight to the front wheels. I'm insinuating what you are hearing/feeling is the ABS and the skipping of the front tires as the calipers open/close.

My car does this when I leave my underground parking, so I'm going up a steep driveway over a sidewalk hump at an angle under braking. I get the noises that you describe.

 

is it all wheel drive

 

It is not all-wheel drive.

This sounds pretty reasonable. Is it causing any harm?

 

No harm...

 

Thanks, all.

 

+1

I also back down my steep driveway and this happens to me. There's little weight in the front so when backing up and braking, you're shifting weight even further to the rear, causing the abs to pulse.