help me understand the "self-adjusting" feature of the handbrake

[pkennethv]

Hi all,

I understand the handbrake in these cars can be manually adjusted in 2 ways:

1) Turning the star adjuster wheel at the drums (either shrinking or enlarging the diameter of the drum brake pads)

2) Adjusting the slack/tension of the handbrake lever cable by removing a couple trim pieces along the center console.

My question is regarding the “self-adjusting” functionality.

If during the installation of new rear brake rotors the drum brakes were manually adjusted to their smallest diameter setting, but the star adjuster wheel was never readjusted after installing the new rotors (leading to the hand brake lever needing to be pulled up really high in order to engage the drum brakes), the car was driven like this extensively, leading to the self-adjusting feature “tightening” things up over time…

…does the self-adjusting feature accomplish this via method 1 (expand the diameter of the drum brake pads), or 2 (tightening the handbrake lever cable)?

I’m willing to share the backstory / why I want to know this if it helps you answer this question (or are just curious), but I thought I’d keep the post more concise to respect everyone’s time.

Thank you!

[Spuds]

I believe it is #1.

[soundman98]

method 1. the parking brake drums are just simple drum brakes

method 2 is for further personal adjustment.

[marco_mc22]

Install new hardware, engage handbrake a couple times, done.

[pkennethv]

Originally Posted by marco_mc22

Install new hardware, engage handbrake a couple times, done.

I wish that was the case with my car😔

A mechanic was troubleshooting fitment of a new brake rotor (turns out, EBC Brakes' compatibility list was wrong & the rotor does not actually fit my car), and in doing so, intentionally shrank the diameter of the drum brake pads to their smallest sitting (turns out the rotor was physically interfering with the dust shield but he didn't catch that, and thought the resistance felt might have been the result of the handbrake dragging).

So the mechanic threw the old (stock PP Brembo) rotor back on so I can drive the car until I get a new, properly sized rotor replacement.

Centric has a 4 month wait to ship out the new rotors to the shop I'm ordering from, so I've been driving the car around like this for the past >3 months and the hand brake still engages super high (though a bit tighter/lower than when I first drove it out from the mechanic's).

I didn't adjust the star adjuster myself later at home because it turns out the mechanic didn't align the hole in the rotor to access the star adjuster with the star adjuster itself (I only found out after removing the wheel myself), and I don't want to deal with removing the entire rotor myself to realign them.

[pope]

Originally Posted by pkennethv

I didn't adjust the star adjuster myself later at home because it turns out the mechanic didn't align the hole in the rotor to access the star adjuster with the star adjuster itself (I only found out after removing the wheel myself), and I don't want to deal with removing the entire rotor myself to realign them.

Uhh… the rotor spins…

[pkennethv]

Originally Posted by pope

Uhh… the rotor spins…

Oh! I somehow either assumed or got the incorrect impression that the star adjuster will rotate together with the rotor & never gave it a try / didn't accidentally find out because the handbrake was engaged when I jacked up the car, so nothing was able to spin.

Thank you for letting me know! I will give it a try next week when I do my winter tire swap

[Tcoat]

Originally Posted by pkennethv

Oh! I somehow either assumed or got the incorrect impression that the star adjuster will rotate together with the rotor & never gave it a try / didn't accidentally find out because the handbrake was engaged when I jacked up the car, so nothing was able to spin.

Thank you for letting me know! I will give it a try next week when I do my winter tire swap

If the handbrake was on and unable to spin what are you trying to adjust?

[pkennethv]

Originally Posted by Tcoat

If the handbrake was on and unable to spin what are you trying to adjust?

I was trying to adjust (expand) the diameter of the drum brake pads inside the rotor using the star adjuster – which I am aware needs to be done with the handbrake disengaged.

This is the order of operations as I had laid out in my head:
1) park the car with the handbrake engaged because I am working on a sloped driveway
2) put on gloves
3) jack up the car
4) remove rear wheels
5) remove the rubber plug on the two rear rotor that covers up the hole used to reach the star adjuster
6) remove gloves (I am a stickler for clean interiors)
7) disengage the handbrake
8) adjust the star adjuster

Due to me not being aware that I may need to / could spin the rotor for the access hole to line up with the star adjuster, once I completed step 5 and saw the hole not being lined up with the star adjuster, I just went “argh, fuck.” and put the wheels back on without fiddling any further. So the thought of touching (releasing) the handbrake didn't even cross my mind as I still had my dirty gloves on.

I had the incorrect impression the star adjuster would be spinning in tandem with the rotor and whether the holes in the rotor lined up with the star adjuster or not was determined by the orientation of the rotor when sliding them onto the studs.

[Turdinator]

So just to be clear OP, are you wanting to adjust the handbrake because you know the mechanic adjusted them smaller or because the handbrake isn't engaging enough to stop your car or even that the handbrake lever now pulls way too high?

[pkennethv]

Originally Posted by Turdinator

So just to be clear OP, are you wanting to adjust the handbrake because 1) you know the mechanic adjusted them smaller or 2) because the handbrake isn't engaging enough to stop your car or 3) even that the handbrake lever now pulls way too high?

All of the above.

I have fixed the issue now by rotating the rear disc so that the access hole lines up with the star adjuster when I did my winter tire swap last week.


but to answer your question:

1) When troubleshooting fitment of a new brake rotor (later confirmed by EBC themselves they made an error in their fitment database & that the rotor will not fit on my car), the mechanic adjusted the rear drums to their minimum diameter.

After bailing on the new (improperly fitting) rotor, the mechanic put my old rotors back on the car so I could drive home, but did not take the time to readjust the drums back to an appropriate setting.

The mechanic explicitly made me aware / warned me of this (the handbrake not engaging well / stick goes really high up / not full holding strength), and said they'll adjust it properly when I come back to get the (properly fitting) replacement rotor installed.

I have not gone back with a new rotor.


2) If I pull the handbrake lever to its maximum travel, it will hold my car on my medium-sloped driveway, but judging by the amount (lack) of resistance in the lever, I'm fairly certain there's a lot of braking force left on the table, and it potentially will not hold the car on a steeper slope.


3) as stated above, I am (was) able to pull the handbrake lever to its maximum height.