S-Prihadi

Sharing..............

I been annoyed if I can hear even the slightest sound of brake pad touching the rotor when I spin the wheel by hand.
This is not rubbing kind of issue, this is feather "touch" kind of contact.

I never work on my brakes until after I over heated the brake pad at the track, back in 2020. Usually I get my indie to do my brakes.

Back in Dec 2021, I replaced new rotor FRONT and I still can't constantly get zero touching of brake pad to rotor.
The test is to spin the wheel by hand and apply the brake and see if the brake pad float up properly or not.
I use marker pen to detect brake pad "feather touch".

Example is below. This annoys me.



The "feather touch" can occur at the outer side or inner side. In this case, it is the outer side.
Inner side was OK,




I had the opportunity to overhaul the front Brembo caliper, so it is then a good time to make sure I can achieve zero touch , consistently at all times. The rotor and brake pad ( front) is under 2,000KM old, a good timing indeed.
Brembo overhaul is here : https://mbworld.org/forums/e-class-w...-overhaul.html

For a piston to retract on its own, it is the square piston seal duty. The seal "hugging" quality is so good, pressing in the piston with new seal is NOT EASY.... that much resistance !!!
Source of image : https://ricksfreeautorepairadvice.co...caliper-works/




Piston self retract feature from the square seal design is one thing, but how does the piston SUCK the brake pad in , so that brake pad will float above rotor ?
The Brembo on my E400 uses double side tape from 3M, to make sure the brake pad stick well to caliper piston and retract along with piston.



This double side tape is this one : 3M 468MP - 200MP adhesive https://www.3m.com/3M/en_US/p/d/b40071697/


Example anti-squel layer taped using this 3M: https://www.partsformercedes-benz.co...oducts_id=2621


Since I have removed the brake pad so many times, I need to replace the 3M.
In fact, once removed, replace it as it will no more stick well or it will add THICKNESS to the piston-to-pad interface when old layer curled up like mine.

The smartphone repair industry is using this super thin double side tape too, thats how I managed to get it locally and in small 1 meter length x 25cm wide. This is expensive to buy in 1 big roll.
2 inch x 60 yards is US$45ish. 100 year supply... LOL https://www.hisco.com/Product/00021200193385-31196 minimum 24 rolls, yikes !!.
Rip off seller :
The rear brake pad on mine, single piston ATE, one of the brake pad , the inner one is using sort of a clip (A), not double side tape.
The other pad, uses a spring (B), which some people call that B item as anti-rattle spring.




Aside from the 3M double side tape, lubrication at the correct spots is important to allow smooth retraction of the brake pad.


Zone A is a high maintenance zone. By gravity the brake dust wil collect there and with brake caliper grease = PUTTY like.
Rust also collect there at Zone A, because its shape can store water, a bit.


Now the fun part.
How many millimeters does the square seal allows a piston to move outwards while square seal maintaining grip/hug and not creep or loose grip ?
I don't know, but I been testing and it seems, setting brake pad clearance to rotor at 0.20mm is best, 0.15mm decent, 0.25mm you are lucky. This I speak of my Brembo.


LEFT FRONT CALIPER - Inner Side Pad - Before fine adjustment at 0.15mm. Already floating good no touching to pad, but I want to make it near equal to the OUTER pad, which is 0.25mm





LEFT FRONT CALIPER - Inner Side Pad - After adjustment. 0.20mm achieved.




Above is after fine tuning.
Fine tuning is totally MANUAL, open bleeder port a tiny bit, squeeze brake pad to push piston a bit in. Lock bleeder port.
Spin rotor, press brake ( 2nd person ) and do this 5 times and measure clearance.


Outer side is good. All at 0.25mm




A zero touch pad to rotor is nice and smooth rotation by hand, noiseless.


I been observing , the TOUCHING ( I dont call it rubbing, not at this feather touch ) , is almost always the inner diameter of the rotor.
That is where the brake pad is least supported.

A are the push pins supported.
B are doubel side tape supported.
C is lonely , and that is where the feather touch happen

Above is the overheated brake pad I speak of.




WILL CONTINUE...........................

S-Prihadi

REAR BRAKE SYSTEM.
I can't find the ATE genuine seal kit, so I can only clean it to my best ability and re-lubricate and test to achieve zero touch brake pad to rotor.

I can't achieve zero touch with old piston seal and this single piston caliper is a pain in the azz to fine tune.
Single piston retraction value is 1/2 per side of the brake pad. Maybe this is also why its tough.

The touch is feather-touch only, at inner side, where the piston is at.
Always at the inner diameter of the rotor.



Zoomed




The outer side was feather-touching too before adjustment, now OK after adjustment, only the inner side I failed




I will need to replace my hand-brake/parking-brake pads. Already ordered, need 45 days special order, bloody hell.
This parking brake pad been this bad since I bought the car. in 2018 1st owner's driver must have washed the car and car kept un-used for a week or more. Rust will develop that way and pad will have bad surface.
Also this freakin jurrasic parking brake design is King Of Dust Collector. Must clean it often too...yep, lots of work.







Something else.
Using feeler gauge to test brake pad to rotor clearance is only possible on new or still very new rotor.
MB's rotor wear is never till the outer most perimeter. So my rear brake rotor, since it is used 36,00KM ish, the feeler gauge get stuck at the "lip" of the rotor outer edge.



Single piston ATE, without holder/slider bracket.



Slider/Holder. Lubrication points






If I ever am able to source genuine or very good seal kit for the ATE rear caliper, I still want to try for zero touch, while doing preventive maintenance.



Unique INFO
I was cleaning the wheel speed sensor and I realized MB inserted a foam between the brake dust cover plate to the knuckle



Okey dokey...end of report.

CaliBenzDriver

I am with you on getting the pads to back off the rotor so friction stops after braking and less heat is transfered into calipers.

Half the battle with floating calipers is with the slide pins. This type is more simple than fixed calipers where both pads are directly actuated by pistons.

I have a hands-on tip for your sliding calipers.

Have you noticed that when you disassemble or reassemble brake calipers without changing the pads, it takes a while for pads to brake well again??
Used pads need to wear out a bit to perfectly match discs... you noticed that before, right?

Actually to some extent this is also applicable to new pads as well but less so because new pads surface are perfectly neutral.

This is where a hidden PIN issue comes in !
The bracket machinings that host the pins IS TOO BIG AND IMPRECISE.
Every time you tighten the pins, they get in a slightly different geometric position because of this oversized looseness.

I have a simple workaround solution to correct that !

When you reassemble floating calipers (new/used pads alike): apply brake pedal pressure before tightening the pins, so they are biased to be in the precise location that is exactly matched to the stack of [caliper + pads + disc].

The difference this procedure delivers is a fraction of degree to ensure the pin geometry is super matched to disc.... extremely smooth sliding from a perfect alignment... strong velvet brakes.


pin alignment has a lot of leeway to work with any calipers

The minimal pin friction helps unload the pads pressure the way we like it!!

S-Prihadi

Cali,

My floating caliper is totally a slide in design , no tightening necessary.
By shape and position, it will stay put once it receives the 2 sliding pin as you marked orange.
That sliding pin has no bolt end, it is just a sliding pin.

Male stainless steel Sliding pin is item 110.



Rubber female bushing to take in sliding pin is 100 and its plastic cap.

Item 100



Sliding pin when removed from holder/slider.

CaliBenzDriver

Indeed your sliding pins are removable and are screwed in place.



each time you screw the pins back on, they land in a different spot that sets the caliper in a different geometry with disc ...
try solution on one wheel only to compare the difference, you'll be amazed!
✌️

S-Prihadi

The sliding pin is removeable but not for when doing brake pad replacement.
I can slide out entire holder assy once it is no more on rotor.

The rubber bushing is very forgiving and super slippery, it won't hold geometry like say a metal bushing.
Your suggestion probably work with metal bushing but not on my current unit.

I have applied 3M double side tape ( LEFT REAR only for now ) to the brake pad at the inner/piston side, now it can properly retract the pad and float off the rotor.



No touching at inner side brake pad now



The outer brake pad probably will benefit from the 3M too, but I have not tried it yet.
I do not see any "suction" mechanism for outer brake pad.
The spring is noise control only, does not help with retraction.

I still have minor scrubbing on the outer brake pad, but this brake pad and rotor is not new like front ones.
The rotor is 36,000Km and the pad is approx 15,000KM old.



By using screwdriver to push out the brake pad ( OUTER ONE ), I can achieve zero touch, but probably when on the road I applied brakes many times and hard, the brake pad will move closer to rotor again and
can't float itself out enough. Its is very crude the way the outer pad is to be self retracting, which is like NONE

This is after I use screwdriver to push out the brake pad ( OUTER ONE ), I only need to push out brake pad at the top bottom end only, its sliding/grease point.


Since we are looking at 0.15mm to 0.20mm movement to float brake pad away from caliper, I probably can hone/polish down all friction surfaces of outer brake pad towards holder/slider assy and
use the 3M double side tape too.

Let me use the car for 1,000+ KM first and I shall re-visit this matter.
I may want to drive to Bali this year, that is 3,000 ish KM already .

Thomas1953#

I have my front calipers sticking on my 1999 C$# AMG. The car does not get driven much. I did swap out the brake booster, install new rotors, and bleed several times. It still will lock down both front wheels. The only way to get it to release the brakes is manually pull up on the brake pedal.about half an inch. Is the rod in the master cylinder adjustable?

Thomas1953#

I didn't state clearly that the car is a 1999 C43 AMG with 171,000 miles. BTW, the car is for sale in Georgia. I will post it tomorrow.

Left Coast Geek

I don't believe that car is a W212, which are 2010-2016 E class. you probably want to find the appropriate C class fsection of this site.