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So my last issue was the crossover seal. Brembo DOES NOT sell them, nor anyone.
Finally I got it from Ebay in June 2022 from someone/store with very positive review. I bought both types related to Brembo as I do not yet know if my seal is mushroom type of flat type.
When it arrived, the result was kinda dissapointing and I wrote to complain, but I still keep them seals, too cheap to refund anyway.
MUSHROOM SEAL
=====================
FLAT SEAL
I work on the FRONT right caliper yesterday.
So I can verify which type of seal is being used by Brembo.
It was the mushroom ones, exactly as what I seen on youtube :
Close up, Ebay one vs Brembo original. Crude texture vs smooth.
Will the Ebay one worked ? Well it should, because this is a static seal non moving ...unlike piston seal.
The seller claimed he done hundreds of Brembo overhaul. Well assume he is 50% honest, still a lot of Brembos there ha ha ha.
NOPE, I did not replace the Brembo mushroom seal as it is still nice soft and assuring.
I will keep the Ebay one for emergency only.
PISTON SEAL
Damn this piston fits so tight on the seal !!!
I wanna share, on how piston retract itself after we let go of brake pedal. It is the special square seal above, is the reason why. I never knew this
Messing with the Ebay one. Fitting is okey, but its poor texture unlike smooth Brembo one is what I do not like.
Since 4 pistons do not pop out together. I use DIY polyturathane sheet 1mm thick as gasket to shut down airflow to section without pistons.
The bite of the seal to the piston is very strong. Yes, I use compressed air only, none of the crude screwdriver as crow bar to lift up piston.
This hydraulic gallery/hole is the lowest and furthest away from purge/bleed valve, it is the only one I see has rust stain.
This is quite logical. I have my old Toyota 1.5L which its manual clutch uses hydraulic too and is sharing with brake fluid circuit and it is located low and has no bleed port, as such water damage
can occur there after 10 years.
In the Brembo caliper case it wont happen so bad to seize lower piston. If there are two bleeder/purge port, one at bottom can be a totally drain port and one more at usual on top as air/fluid bleed.
The Nissan kit has a nice rubber plug with retainer....yipeee !!! MB one only a rubber cap and one can loose it easy.
So, dust boot is I am sure silicone. The strecht, feel and strength of it is silicone territory....not to mention heat resistance.
Your 8-pistons front brakes are going to feel crisp like new again
rusted conduit
Bleed screws being at the highest point of calipers, there is really no way to bleed the heavy moisture out of neither front or rear brakes... The only way is your solution
I am still hunting for the rear repair/seal kit, it is by ATE. Still have not found them yet.
Funny, the LEFT caliper lowest fluid gallery/hole does not rust so bad, only minor very minor.
I wonder, when we bleed + flush a caliper as big as this 4 pistons Brembo, how many % old fluid stil stay ?
There is no way 100% of the brake fluid can be replaced, no way.
Well I can cheat a bit actually, loosen the big torx bolt x 2 per caliper side and let it leak to bleed .
If I have spare original mushroom crossover seal, I will bleed this way.
I forgot to add :
I do not have a vice and I have to start loosening the 4 big torx bolts on the caliper while the caliper is still on the wheel knuckle.
Otherwise its going to be a challenge to loosen 4 big torx bolts and they have some rust too at the thread.
Liner for the piston. Very nice, very smooth.
I can't clean all the stain, I also do not want to even use Scotch Brite or any abressive for that matter.
Degreaser a few times and soap. That's it.
344 means 344mm my rotor is, for this 344mm caliper.
Surya says: "I wonder, when we bleed + flush a caliper as big as this 4 pistons Brembo, how many % old fluid stil stay ? There is no way 100% of the brake fluid can be replaced, no way."
Great question... and thank you for bringing us to see the answer!
The only DOT-3\4 that gets flushed is from the MC + brake lines, not the calipers!
The air buble near the top screw comes out of the caliper but none of the liquid.
To flush the calipers... you have to push back pistons with bleeder opened. Then 90% of the liquid behind the pistons is forced out minus the heaviest stuff that's trapped in grooves.
You have the best timing to rebuild calipers before they have a chance to get wasted. Too bad Brembo doesn't distribute necessary seal kits with recommended schedule
Steel vs aluminum oxidation:
-- The pistons are steel and the calipers halves are aluminum that can both oxidize just as well with pitted surface.
-- Aluminum has no anti-rust properties.
-- Stainless steel pistons would be nice to prevent dissimilar metal interaction 😊
Last edited by CaliBenzDriver; 09-19-2022 at 02:22 PM.
I was parked next to a newish Corvette this morning with awesome brakes... check this out: slotted rotors 6 pistons... powder coated caliper
The pads are half-way worned out but the discs surface are still wearing super smooth, shiny like new besides an outer lip showing wear.
This looks like serious brakes quality
NAspirated V8, tranny all the way at the rear! One thing I noted is the liquid A/C line is factory insulated with a rubber pipe to keep engine heat out.
Multi-grooved serpentine is groved on both sides... it has no smooth side like our belt does.
Last edited by CaliBenzDriver; 09-19-2022 at 09:30 PM.
So that is how it looks like.
I guess engineers wants more traction on where previously the device get belt's smooth side, example on M276 will be the water pump pulley and tensioner pulley....better alignment too perhaps ?
Cali wrote : One thing I noted is the liquid A/C line is factory insulated with a rubber pipe to keep engine heat out. They saw your post
DAMN !!!
The RIGHT front caliper, bottom seal ( crossover seal), inner side is leaking !!!
I took a quick look and the seal is fine.
Maybe some small dirt got stuck ?
Too late already tonite, I am so tired today afternoon doing the LEFT front wheel bearing freeplay adjustment.
I found out about the leak only tonite as I was filling fluid to the brake system and purging the air.
Had another one unlucky event last nite, the plug for the oil pipe fell off and I lost lots of fluid. I did not position the plug correctly, below is the correct position to place such a plug shape I am using.
Fluid loss is okey, it will be replaced anyway, but the air bubbles now so much........
Anyway, need to fix the crossover seal region leak first.
by the time you're done tomorrow, your calipers will work better than today
What do think happened ...
the old seal you reused moved during assembly?
What's your favorite bleed method of choice to extract air bubbles? low pressure on MC cap to prevent blowing through seals
Xentry has a helper mode to move fluid through the ABS/ESP module, right?
Last edited by CaliBenzDriver; 09-20-2022 at 03:27 PM.
I don't know what exactly happen... its part of Uncle Murphy magic hahahah.
Maybe this is what happened.
RIGHT side caliper, I did not realized when installing the piston, I did not bottom it out enough the piston. Its still 2mm more to go to bottom.
My brake pad is 1,200KM old only and is so thick, so I can't install it with the piston protrusion.
Lazy to remove the caliper assy from wheel knuckle, I loosen the 2 big torx bolts of inner side and also outer side, in order to make space for the brake pad.
And then, when braek pad goes in, I tightened slowly the 2 torx bolts per side and slowly it compresses the brake pad and the piston too
Maybe when I loosen the 2 big torx bolts per side, automatically the Alu part of the caliper get lifted up or move away from the middle steel/iron frame where the crossover seal is at.
Perhaps there is some minor misalignment of the seal on its cavity. Actually the positioning and the design of the musrhroon crossover seal is so good, it will auto align itself in the cavity..... if it is facing the sky or 12 o-clock.
While caliper already mounted on wheel knuckle, the mushroom seal is facing 3 o'clock, maybe that is how things went wrong when I loosen the torx bolt.
Funny, there is no sign of "squeezed" /damage mushroom seal, if indeed it came off its cavity and got squeezed by the Alu caliper part ( piston liner side ).
Anyway, I managed to buy a spare W124 brake hose to use it as a troubleshooting tool.
So far so good, been 3 hours. No leak.
The caliper 4 torx bolts is not torqued yet for the test. I only tightened enough but the surface machining is so good on the alu part and also the steel/iron part, no leak.
Senior moment: Lazy to remove the caliper assy from wheel knuckle, I loosen the 2 big torx bolts of inner side and also outer side, in order to make space for the brake pad.
Lesson learned:
don't split calipers halves during install.
You're careful enough that your left brain watches your right hand and your right brain the opposite hand - You always overcome challenges and make it home safely 👏
My Benz has the basic slide pins single piston just no rear drums!
Last edited by CaliBenzDriver; 09-21-2022 at 02:46 PM.
Senecat,
I dont think it is torque to yield for my car. Because this 3 piece Brembo is unique that the bolt thread is into the middle part which is cast iron or steel.
While the caliper piston liner is aluminum.
The two piece Brembo probably is torque to yield as they are aluminum all the way. Same as our tranny oil pan baby torx bolts, aluminum bolts and torque to yield 4Nm and 180 degrees ...one time use only.
This is probably why my torx bolts are so big but only 2 per side, more surface area I think but not much torque required. I use 90 Nm ( no data ).
The middle part (cast iron or steel ) of the caliper to the wheel knuckle is 115Nm ( as per MB ).
UPDATE :
The leak still there when I use brake booster. Very very mild leak, but leak it is
I read brake fluid pressure at normal braking is 500 psi and at panic braking can be 2,000 psi.
I replaced the seal for experiment sake with the Ebay flat seal, worse leak ha ha ha ha.
I need the brake because I am in the middle of tranny oil change. I can't engage gear ( for 1st time ) when I do not use brake.
Today tranny oil change done, including torque converter drained.
So tomorrow try again on the caliper and this time using the Ebay mushroom seal.
I had a hard time finding the crossover seal for a couple of Brembo Cadillac calipers that I was refinishing/powdercoating for another project car of mine but I did find them. This was a while ago so I don't remember where I found them but I haven't used them or completed that project yet so I'm not sure if they would have worked either. But you are right, dealers don't want people disassembling/servicing a lot of their calipers like you are doing so they don't offer that seal. I was actually going to leave the halves together and bake them with the seal installed and pray it didn't melt Lol
I'm not sure where your leak would be coming from still?
Looking at the seal design, this mushroom shape serves a single purpose.
It is a precision F-U DIY kind of seal.... that means we DIY-er get screwed big time when cracking open such caliper
The one on Nissan 350Z by brembo or STI, is less evil.
The cavity for the seal is o-ring typical channeling, so it is easy to source such common shape and the o-ring works as an o-ring should.
The one on mine is weird and super fragile, beacuse its cavity is THE booby trap and totally against what I read on o-ring handbook.
Anyway, the Ebay mushroom seal passed brake pedal test.
Let see on the road and with ABS activated and some heat, how will it do.
Can't do high speed , high heat test yet.
35 minutes drive to a friend's place. Nice slow drive.
So far no leak.
Thermocouple D is the Brake Caliper inner side ( Aluminum piston liner housing ) temperature.
It is slow to get hot, because brake rotor friction heat to brake pad is isolated by a floating aluminum piston 44mm x 2 of the Brembo.
The piston does not physically touch any metal parts of the caliper. So piston will warm the brake fluid and brake fluid then warm the entire caliper assy.
Sure, wheel knuckle will transfer heat to the caliper middle/iron frame, but I guess that is more the case if I drive many many hours.
The VACUUM pressure of the brake booster is below.
It is in ABSOLUTE SCALE which means perfect vacuum if PSI shows ZERO.
If PSI shows 14.5, that is ambient pressure or no vacuum at all.
So spike up 2 - 7 PSI means I am using the brake booster, hence vacuum is being "consumed"
The more I use the brake booster or brake pedal pressed down fast and repetitive pumping in a short say 10 seconds time span, the more vacuum will be lost.
Learned a lot here on how the ABS/ESP module contributed to the introduction to fine air bubbles when I accidentally lost too much brake fluid. Also MB's ESP-ABS intervention is not as simple as I once imagined.
Learned a lot too on why Brembo/MB uses the adhesive on the brake pad to caliper piston mating surface and yada yada.
Wil discuss it in another thread.
I shall update this thread when I have done successful ABS activation ( on the road, in real time, not Xentry test ) a few times and raise caliper metal skin temperature to at least 120 C.
My thermocouple sensor is on the skin of the caliper.
I did 2 ABS actuation, but not super aggressive. The 2nd one I get the ABS to fully engaged. 1st one it is engaged but very subtle.
I feel kinda embarassed, I mean I do not want people to think there is a NUT-CASE on a white W212 or else I would do more.
In a log view , the 2 test as per the video above. Vehicle speed is KM/H
I can't get the caliper to any HOT temperature , car move above 60-120KM/H on average , the wind cooling is so good.....caliper is so cool.
So the caliper will only get hot if driven slow, below 25KM/H and also heat radiation from engine bay can warm the caliper. 24,500 ish data points at 5HZ. This is an approx 80 minutes test drive.
I am kind of lazy to go faster and stay longer at high speed tonite. The road was not as empty as I wished to "look stupid doing brake test"... LOL
The test is good enough as per brake fluid : NO LEAK and no trapped air bubble....yipee.
09-19-2022, 02:36 AM
