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My 2007 w221 has always had that issue with "warping" the front rotors. I.e., pulsation in the brake pedal.
I have resurfaced the rotors a couple of times as well as installed new rotors a couple of times.
The issue always comes back in a couple of years.
Even with new or resurfaced rotors, I'll end up with a lateral runout between 0.001" to 0.002".
That tells me the hubs are not true. This ends up causing thickness variations in the disks.
It gets annoying around 0.004 and above. Last time I had left: 0.005" and right 0.013"
I would like to try to use rotor shims but I have not been able to find any for w221.
Does anyone know who sells these shims?
I would likely need 0.001 and 0.002 to eliminate lateral runout after I resurface the rotors the next time.
Once I achieve a lateral runout of 0.000 then it will be interesting to see whether the issue goes away for good.
Edit: Here's a video to explain what i am talking about:
My 2007 w221 has always had that issue with "warping" the front rotors. I.e., pulsation in the brake pedal.
I have resurfaced the rotors a couple of times as well as installed new rotors a couple of times.
The issue always comes back in a couple of years.
Even with new or resurfaced rotors, I'll end up with a lateral runout between 0.001" to 0.002".
That tells me the hubs are not true. This ends up causing thickness variations in the disks.
It gets annoying around 0.004 and above. Last time I had left: 0.005" and right 0.013"
I would like to try to use rotor shims but I have not been able to find any for w221.
Does anyone know who sells these shims?
I would likely need 0.001 and 0.002 to eliminate lateral runout after I resurface the rotors the next time.
Once I achieve a lateral runout of 0.000 then it will be interesting to see whether the issue goes away for good.
You say "The issue always comes back in a couple of years". This means the runout does not exist when you have new or re-surfaced rotors and the problem develops over time. If you measure 0.001"-0.002" it is nothing. And the brake caliper "floats"... These shims would not help.
I think you have warping rotors. How do they measure when bad? You say 0.005" is bad but is it that this is only in one spot around the rotor?
OP are you a savage with the brakes? If so you are doing great at just having them warp every couple years.
Seek out rotors on hats. Brembo makes them. Then the rotor is on pins/sliders. Helps. I warped those over and over too. I’m a savage with the brakes. I solved that with Carbon Ceramic brakes in the 222 car. Never warped brakes that last and last.
rotors fall off helicopters - they are brake Discs
never heard shut drivel as shims... what condition are the wheel bearing and suspension bushes in ?
do you think Mo55ad had a party ? (The CEO of the Spanish branch of Siemens and his family died on Thursday. Agustín Escobar, who was President of Siemens Spain, his partner and their three children were declared dead shortly after the Bell 206 aircraft careered into the Hudson River)
This shim things - well never heard of the and from an engineering sense - better to fix issue.
I mean how do they make this work?
How much along hub surface needs how thick a shim ?? I mean way too many variables so shim I bet is just one thickness thru-out.... which well then does nothing but push everything outboard more..
I don't believe rotors "warp". I drive like a granny and my other three MBs have no such issue.
My w221 brake calipers are not floating. They are fixed with four pistons.
From my research, if the hub is not 100% true, it will result in lateral runout of the disk.
Typically between 0.001" to 0.002" for a new rotor, per my measurements.
Now, that small lateral runout will touch the brake pad every rotation as the disk is now wobbling.
Over time, this will cause the rotor to wear a little more in that spot. This makes a surface indentation,
which in turn makes a thickness variation of the rotor. This can be felt as pedal pulsation.
This is the theory that I want to test with the shims.
I don't want to buy new hubs since expensive.
I don't want to keep turning the rotors, since work and annoying.
These shims seem to be available for some cars but I have not seen them for Mercedes.
I'll keep looking. Perhaps I can find some with matching hole pattern.
I experienced perpetual rotor runout on a '91 BMW 3-series that I owned many years ago. Only the front rotors would warp, and every 12K to 15K miles, I would have them machined, and I had to replace the rotors every 25K - 30K miles. Went through 3 or 4 sets of rotors. I thought the problem could have been braking system imbalance or inadequate rotors for the braking load, resulting in excessive heat that the rotors couldn't dissipate. Guess I'll never know, but this alternate possibility is interesting.
I don't believe rotors "warp". I drive like a granny and my other three MBs have no such issue.
My w221 brake calipers are not floating. They are fixed with four pistons.
From my research, if the hub is not 100% true, it will result in lateral runout of the disk.
Typically between 0.001" to 0.002" for a new rotor, per my measurements.
Now, that small lateral runout will touch the brake pad every rotation as the disk is now wobbling.
Over time, this will cause the rotor to wear a little more in that spot. This makes a surface indentation,
which in turn makes a thickness variation of the rotor. This can be felt as pedal pulsation.
This is the theory that I want to test with the shims.
I don't want to buy new hubs since expensive.
I don't want to keep turning the rotors, since work and annoying.
These shims seem to be available for some cars but I have not seen them for Mercedes.
I'll keep looking. Perhaps I can find some with matching hole pattern.
Thanks.
The rotors absolutely can warp. There is plenty writing about this in the forum and the quality off the part seems to be the issue.
Your brakes are floating. It just is that the pistons on both sides if the disk do it and not the calipers.
The video shows how the runout is measured from the brake disk itself so this shim corrects a bad disk out of the box. I don’t think you would find hardly any runout if you measured the hub.
If I had the tool for rotating the disk and measuring it before installation I would just return the disk that is bad as new. Why use shims to fix a bad part you bought?
The rotors absolutely can warp. There is plenty writing about this in the forum and the quality off the part seems to be the issue.
Your brakes are floating. It just is that the pistons on both sides if the disk do it and not the calipers.
The video shows how the runout is measured from the brake disk itself so this shim corrects a bad disk out of the box. I don’t think you would find hardly any runout if you measured the hub.
If I had the tool for rotating the disk and measuring it before installation I would just return the disk that is bad as new. Why use shims to fix a bad part you bought?
Agree -- rotors do warp, and it would seem they could wear unevenly also under some circumstances. The two would seem to be interactive with each worsening the effect of the other.
I disagree with the rotors "warp"...Mostly it is uneven pad deposits from the pads. Fix is to re-bed the pads. Brembo indicates this on their website and tells you how to do it.. So do other pad manufacturers. Google search will confirm this for you.
I have posted this before on MBworld. It is very rare to have the rotors "warp". In the rare case the rotors are defective, it is from a very hard spot on the rotor formed during the casting process...."cutting or truing" the rotor wont fix that and the vibration is quite severe.
But then again that is my knowledge from 50 years of experience including track experience and crewing on SCCA S2000 cars in the 2000's.....As always, this is "IMHO"
I disagree with the rotors "warp"...Mostly it is uneven pad deposits from the pads. Fix is to re-bed the pads. Brembo indicates this on their website and tells you how to do it.. So do other pad manufacturers. Google search will confirm this for you.
I have posted this before on MBworld. It is very rare to have the rotors "warp". In the rare case the rotors are defective, it is from a very hard spot on the rotor formed during the casting process...."cutting or truing" the rotor wont fix that and the vibration is quite severe.
But then again that is my knowledge from 50 years of experience including track experience and crewing on SCCA S2000 cars in the 2000's.....As always, this is "IMHO"
Can you post a photo of what pad deposits on a rotor look like?
That’s all. Anything further is operator (mis)use.
What is known in this forum about the S600 disk brake rotors is not to get them turned. The result is shorter life and the warping returns earlier than the first time.
Experience dictates to always replace the pads and rotors together. Best result one can hope for.
The brakes will have a long life and perform well if driven moderately with an occasional spirited driving.
What is known the pads/disks are under designed by being the incorrect materials, when matched up on this very heavy luxo barge.
JR
Last edited by johnnyrocket52; Apr 16, 2025 at 01:22 AM.
met a bloke yesterday that’s bought the Lotus electric monster truck - for a company founded on "adding lightness", Colin would be having kittens this thing is 2910kg
here is a pic of uneven pad deposits on a rotor.
the colour should be even all around the rotor and if not the deposits are uneven. Many new pads have a selfbedding layer facing the rotor that cleans off the old deposits and allows the new pad to deposit new material consistently around the whole braking surface of the rotor. New pads MUST be bedded in properly to acheive that even layer and avoid buliding up uneven layers that feel like the rotor is "warped".
When changing pads, especially when going from organic /ceramic to semi sintered or full sintered for track days, that bedding in process is critical for acheiving full stopping power.
For street use only, most bedding in instructions follow something like this: 4-5 stops at ~ 70% braking power followed by 5 minutes cooling down while driving slowly then 4-5- stops at 80% followed by cooling down while driving gently. Cool the brakes down fully overnight.
Enjoy your fully bedded much better stopping brakes.
PS the proper way to brake is to initate the brake pedal then press harder and harder and harder. You would be amazed by the much shorter stopping distance and what you brakes can really do. Pressing gently all the time just glazes the pads and reduces the available braking power.
You guys and ‘uneven distribution of pad material,’. LOL.
My rotors always ended up blue in color. Yup, they warp just fine when you are a savage!
Try harder! Uneven pad material burns off just fine when the car is driven hard.
What most folks report about the S600 brakes, if driven like a wild man, they warp.
I just replaced my warped front rotors/pads as received from the previous owner, with, OEM Mercedes parts. The pads had a lot of meat left on them, but out they went. Read to change them as a set. I performed a “bedding in” recipe similar to the one quoted here. Bled the brakes. They worked perfectly right out of the gate.
In the forum, it says-ah, let’s all hold hands and say together, if I don’t like warp, brake smooth and occasionally short spirited wild braking maneuvers.
You can’t make ice cream out of poop.
The S65 AMG rotors/pads is the answer to the question for the young savage driver on the go.
I like the forum because I get to learn from other folk’s experiences including successes and failures.
JR
Last edited by johnnyrocket52; Apr 18, 2025 at 04:01 PM.
JR.... Mine was a 221 S-65. Big rotors with the embarrassing pair of heavy sliding calipers for each wheel in the front. Warped them repeatedly and mostly just put up with it as pads and rotors wore quickly. Found a Brembo big brake kit for it with bigger rotors on hats and large six piston solid calipers. This shed 15-20lbs per front corner (unsprung weight bad!). Warped them as well. The big brakes looked great.
The 222 S-65 has just under 135,000 on it. Carbon Ceramic brakes. Original rotors. Second set of pads have 45,000 miles on them. Pads still look as new. Never warped brakes. When they get noisy a few firm applications of brakes from three digits burns off whatever made the noise.
JR.... Mine was a 221 S-65. Big rotors with the embarrassing pair of heavy sliding calipers for each wheel in the front. Warped them repeatedly and mostly just put up with it as pads and rotors wore quickly. Found a Brembo big brake kit for it with bigger rotors on hats and large six piston solid calipers. This shed 15-20lbs per front corner (unsprung weight bad!). Warped them as well. The big brakes looked great.
The 222 S-65 has just under 135,000 on it. Carbon Ceramic brakes. Original rotors. Second set of pads have 45,000 miles on them. Pads still look as new. Never warped brakes. When they get noisy a few firm applications of brakes from three digits burns off whatever made the noise.
Your post was the last I read on the W222, how much more robust the AMG brakes perform and last.
I didn’t realize the W221 missed the boat on the brakes.
It sounds like the W222 S-65 got a lot of things re-engineered, making it the one to get next.
Still out of my budget.
For now, dreaming is still free.
JR
Last edited by johnnyrocket52; Apr 20, 2025 at 01:47 PM.
JR the 221 that is not an AMG car has same brakes as 221 S-550. Small for a 5200lb car. I wrecked the AMG brakes repeatedly. But I’m a savage.
The 222 car is where MB got as much of things right as it got as far as I’m concerned. Current cars with huge screens and the pig nose just don’t do it for me.
petrol costs so much here you can afford to touch the brakes....
I must share with you’all as written by our President, Elon Musk; What makes America Great:
1. Very inexpensive gasoline.
2. The availability of guns.
3. Large breasts!
I think I will look into replacing the hub itself as after-market is not too expensive, between $70 and $100 on Rockauto. That includes the bearing.
The next time I get the S550 into the garage for service, I will measure the lateral runout on the hub itself to confirm whether excessive.
I'll check WIS to see whether they have a spec on this.
I once tried to "bed in" the brakes to get rid of the brake shudder. It did nothing to improve the situation in my case.
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