Pulsating brake pedal

[Delp]

Hi all brake issue every time I press the brake pedal I get a pulsating and grinding at the brake pedal and feel it on the foot🤔Work already carried out new front discs and pads, calipers good so my mechanic tells me. Any ideas I did read that the rear axel carrier bush could need replacing, any ideas.

[Lwerewolf]

Car model?

Have they measured runout on the rotor and on the hub? Have they matched them for minimum runout? Is the mating surface clean?

[Delp]

Hi

GS430 sport. No runouts at all. Excuse my ignorance what is a runout and is it essential, were can this be done..

[steve2006]

Disc “run out” is basically wobble of the disc caused by either warping of the disc or not being mounted true to the hub.

The fault you have sounds very much like an ABS problem, there is a toothed wheel behind each hub and a pick up sensor which detects rotation of the wheel. This is how the ABS detects a wheel locking up and corrects the problem.

It sounds like you either have a damaged toothed ring or a faulty sensor on one of the wheels.

You may also find that during the brake work some crud has broken away and clogged the sensor (they are magnetic so attract particles).

I would first perform a diagnostic code check to see if anything is stored relating to the ABS as this may assist you by pointing out which wheel is causing the problem, even if the warning light is not illuminated there may still be a stored fault code in the ECU.

If that shows nothing a careful inspection and clean of the sensors and toothed rings may sort the problem, the toothed wheels can also crack so make sure this has not happened and they are all firmly attached to the hub.

The picture below shows the basics of the system in a simple form but shows the components I have referred to.

[The-Acre]

Was this wobble there before the new discs were fitted or after?

[Delp]

Thankx fir the replies. The pulsating pedal was always there and not as bad since new front discs and pads are done. I will get a run out of all discs,  and get plugged in and get the teeth on the rings.. are they also called the reluctor ring?

 

[Delp]

9 hours ago, steve2006 said:

Disc “run out” is basically wobble of the disc caused by either warping of the disc or not being mounted true to the hub.

The fault you have sounds very much like an ABS problem, there is a toothed wheel behind each hub and a pick up sensor which detects rotation of the wheel. This is how the ABS detects a wheel locking up and corrects the problem.

It sounds like you either have a damaged toothed ring or a faulty sensor on one of the wheels.

You may also find that during the brake work some crud has broken away and clogged the sensor (they are magnetic so attract particles).

I would first perform a diagnostic code check to see if anything is stored relating to the ABS as this may assist you by pointing out which wheel is causing the problem, even if the warning light is not illuminated there may still be a stored fault code in the ECU.

If that shows nothing a careful inspection and clean of the sensors and toothed rings may sort the problem, the toothed wheels can also crack so make sure this has not happened and they are all firmly attached to the hub.

The picture below shows the basics of the system in a simple form but shows the components I have referred to.

Would it be ABS Speed sensor rotor you referring to..

[steve2006]

18 hours ago, Delp said:

Thankx fir the replies. The pulsating pedal was always there and not as bad since new front discs and pads are done. I will get a run out of all discs,  and get plugged in and get the teeth on the rings.. are they also called the reluctor ring?

 

Yep,  also called reluctor rings, the rears are more susceptible as they collect more crud around them.

[Delp]

Hi if the ring/rings are bad are they easily replaced if so we're can you can get replacement..

58 minutes ago, steve2006 said:

Yep,  also called reluctor rings, the rears are more susceptible as they collect more crud around them.

 

[Delp]

Hi if the ring/rings are bad are they easily replaced if so we're can you can get replacement..

2 hours ago, steve2006 said:

Yep,  also called reluctor rings, the rears are more susceptible as they collect more crud around them..

www.reluctorrings.com

Found this site anyone else used them before, looks as though it's there speciality.

[steve2006]

Yes, several members have used them, no bad feedback.

[Delp]

26 minutes ago, steve2006 said:

Yes, several members have used them, no bad feedback.

What's the best way to inspect the rings. Is it a case of taking drive shaft off or is there an easier way😁