When I press the brakes to slow down, my car jerks or stutters forward. Not sure if it’s the brakes or something else. It’s kind of like when you ride a bike and keep pressing and releasing the brakes and it jerks you. Any ideas?
Warped brake rotors.
That won’t show up on a diagnostic scanner will it?
Ok, last question, how do I know if it’s the front or back rotors? Thanks for your help
What kind of vehicle?
2001 Porsche boxster s
Nine times out of ten the front rotors cause this problem.
But to find out for sure, a dial indicator is used to check the run-out of the rotors.
I’ll just buy new rotors and replace them, Thank you for all your help
Buy new brake pads, too.
If you have a parking brake that you can apply and release with one hand - like the between the seats lever with a release button on its end - that works only the rear brakes. You can apply/release it while driving and see if the rear brakes are working smoothly or not.
It is typical with modern cars that they have disc brakes all around, but that they have a tiny set of brake shoes (i.e. drum brakes) inside a hat-shaped mechanism attached to the rear rotor. If this Porsche has rear discs with a separate drum brake mechanism inside a “hat”, your suggestion will not produce any valuable results.
Does the OP know whether his Porsche uses the disc brake mechanism for the parking brake function, or if it uses a separate set of brake shoes for the parking/e-brake function?
Yeah, you’re right. I was thinking of the rear drum brakes on my Honda and even older cars.