C43 Amg 334mm Brake Weights

[Pagz]

One of my favorite past times is weighing parts and seeing if saving can be made with minimal compromise(each to there own =P) As most would know weight saving can be one of the best performance upgrades.

As I've found with the C43 there is very few lite weight parts if any,though it looks like they did attempt it on the brake rotors.

The stock 334mm C43(210/208) rotors are a two-piece with alloy hat,there a nice looking rotor especially with the cast AMG logo.

For comparison I have a 332mm stoptech kit lying around, the rotor are the same thickness as the AMG however the depth of the contact surface on the AMG pad to rotor is much more.

Results:

AMG 2-pot cast Iron Caliper w/pads 8.5kg(18.7lbs),(Pads ~0.7kg each)
AMG Rotor w/slight wear 9.65kg(21.23lbs) (would be closer to 10kg when new)

Stoptech 4-pot Alloy Caliper w/pads 5.25kg(11.55lbs)(pads 0.5kg ea)
Stoptech Rotor new 7.65kg(16.83lbs)

To summarise, The AMG brakes weigh 5.6kg(12.32lbs) more per side than the Stoptech's, - thats a fair amount!

Imo the greatest benefit would be in the lighter stoptech rotors due to the rolling mass,with secondary benefit being the un-sprung reduction ,One compromise is the Stoptech tend to squeal when cold. As far as life of the rotor I would imagine the stoptech rotors wouldn't last as long as the AMG's Larger contact surface and pads but I could be wrong.

Would I swap out the AMG for stoptech's? Tempting in most aspects!.

[SLAMMED_C]

I say swap em out Paul!!
Might as well save weight where you can. And plus they look nicer than the stock 43 brakes!

[dokotela]

I'm with Ross on this one....besides 4 pots gotta give you better braking as well.
Do it.

[kowalski]

do you have to put left side stoptech caliper on right side on your c43 as with the c55 calipers conversion, to get the bleeders pointing up?

[Pagz]

I say swap em out Paul!!
Might as well save weight where you can. And plus they look nicer than the stock 43 brakes!

I'm with Ross on this one....besides 4 pots gotta give you better braking as well.
Do it.

I agree on the weight saving,look and performance...temptation would be to repaint them in the new look gunmetal and add AMG to match

There are two more comprimises I forgot to mention, while the stoptech rotors are only 332 instead of the AMG's 334, the caliper is both much taller and wider.

What this means is stones tend to get trapped between the caliper and the rim which causes a fair amount of damage,so these should really only be run with 18".

In summery, the AMG's are better suited to my 17" wheel with the benefit of being able to run a much flatter spoke(disk) wheel which could in some situations look better than the stoptech brakes!.

[Pagz]

do you have to put left side stoptech caliper on right side on your c43 as with the c55 calipers conversion, to get the bleeders pointing up?

The stoptech's were fitted to my C230k in the correct orientation with bleeders upwards, However I will trial fit them tonight whilst I have the C43 brakes off to make sure all alighn correctly.

[Dearlove]

i have 356mm fronts im ftting to my c36, ill let you know the weight of them soon

[dokotela]

I agree on the weight saving,look and performance...temptation would be to repaint them in the new look gunmetal and add AMG to match

There are two more comprimises I forgot to mention, while the stoptech rotors are only 332 instead of the AMG's 334, the caliper is both much taller and wider.

What this means is stones tend to get trapped between the caliper and the rim which causes a fair amount of damage,so these should really only be run with 18".

In summery, the AMG's are better suited to a 17" wheel with the benifit of being able to run a much flatter spoke(disk) wheel which could in some situations look better than the stoptech brakes!.

And you have 18" lightweight wheels...so it a no brainer. The car won't be aesthetically proportional with 17's IMO.

[Pagz]

And you have 18" lightweight wheels...so it a no brainer. The car won't be aesthetically proportional with 17's IMO.

That's where the conflict is,The Enkies are 17" ...And if I go 18" I would want a flat spoke so the stoptech's may not clear!.

Only want cake if I can eat too

[Pagz]

i have 356mm fronts im ftting to my c36, ill let you know the weight of them soon

Ok sure, are they also stoptech's?

[Pagz]

@ kowalski,

I test fitted the Stoptech's and they fit perfect on the C43 with bleed screws up, no mods needed!.

[Vetruck]

11.3 lbs per wheel unsprung weight is not just a fair amount, it is HUGE. The corner weight on the front end is about 850 and the unsprung is about 120 lbs- so loosing 11 lbs is pretty major for the ride ratio. Most brake setups will generally only go about 2-3lbs savings. Those calipers are heavy. Most of the weight savings on upgraded larger brake setups is generally in using Aluminum hats with 2pc rotors.

The rotor face of on a rotor like the Stoptech allows for a more even heat range of the pad because the actual pad contact surface on the rotor is in the narrower band width of iron further away in radius. example- take a 13" rotor with the pad contact in the 5-6.5" radius band, as opposed to another one in the 4.5-6.5" band width. The first example uses genrally a longer narrower radius width pad as oppsed to the second using a shorter wider pad/both the same Sq inch volume for example sake. The heat range stays more predicable and even with the narrower band and all of the pad volume has more leverage in the higher radius. Weight and design of the rotor is what cools it and disapates heat away from the pad, but when the pad is spead out in a wider range rather than taller range it will not hotspot a rotor as easy and keeps a more even heat diapation accross the entire face of the pad.

ps- I am not a liberty to reveal any exact info, but Dearlove has something a bit more special than average in the works- I am sure he will show some nice pics and info in due time.

[Pagz]

@ Vetruck,
Thanks for that input!,Originally when I changed from the stock ~280mm C230k brakes to the 332 stoptechs I noticed a difference in the steering and how the front end felt over bumps,i never wieghed the 280mm rotors/calipers but I would assume they were lighter than the stoptech's as the front tended to jump over bumps more after the install. The difference in steering feel may have been due to the thicker alloy hat(+2mm to offset) and maybe the gyro effect of the larger rotor ?.

I did wonder about the effects of having a pad that is spread accross a larger variance in rotor speed vs one aimed more towards the high speed area, would this make the AMG brakes more linear in function and the stoptechs more abrupt?

Cant wait to see what Dearlove is working on, could it be brakes from a much newer AMG? =)

[popcorn smiley]

[Pagz]

Update,
I got confused with a CLK550 and CLK55 on stoptechs site along with the fact they dont list BBK for C43,After speaking with Stoptech it turns out they do list the C43 but the ST40 calipers I have don't have the correct pistons sizes ie I have the 36/40 for the smaller brakes on C230/280 etc. The CLK55/E55/C43 are 44/44.

[Pagz]

Update,
While on vacation in California I picked up a set of STR40 calipers and stoptech street pads to suit my older stoptech ST40/332mm setup,stoptech have changed there forgings since I purchased many years ago, the finish and design looks much better.

The STR series is all CNC and slightly lighter than regular ST's, if you love machined stuff you just have to go with it.

The original reason to swap these out was weight savings,but also hoping for an improvement in pedal feel. the results for this setup vs OE are:

Stoptech
STR40 Caliper 44/44 pistons w/ mounting bracket - 3.7Kg
332mm rotor - 7.65Kg(near new)
Pads - 1Kg
Total per corner 12.35Kg

OE C43
ATe/AMG Caliper - 7.25Kg
AMG rotors - ~10kg(heavy wear at 9.65kg)
MB Pads - 1.35kg
Total per corner 18.6Kg

So all up a saving of 12.5Kg(27.5lbs) unsprung/rotating...pretty happy with that.

I'm still installing so haven't had the new pads out for a spin yet,the original Axis ultimates worked well but tended to squeal when used lightly for extended periods,stoptech say there street pads are an improvement over this,we will see.

[anf6789]

i love race car parts

[John Jones Jr.]

Lovely stuff there Pagz and a very nice weight saving too. Sadly, I'd say the cost of those is out of my league. Looking forward to updates.

[Pagz]

Thanks guys!

Yes unfortunately this stuff doesn't come free =), and since the MB performance market here is non existent there worth very little used.

I still have the old ST40 calipers for the non-amg models, however anyone wanting to use them would need to purchase the rotors,mounting brackets and maybe lines from stoptech so the calipers would have to be a give away,hence my excuse to buy new calipers to use the old gear with.

[dokotela]

Wow. That saving is huge Paul. Gonna be a different car now for sure. Cant wait to hear abt it.

[Pagz]

Hey!

Mixed feelings at the moment - the car feels MUCH more nimble on the front axle and suspension/ride is much more accommodating,its a clear difference and I'm really happy with that aspect.

however,after bedding them in they hardly feel different from stock in terms of braking force which is fine,if anything they are slightly more linear but not by much. I was hoping the braided lines would remove a little pedal travel but its really the same as stock atm. still need to re-bleed though.

Weird things that happened when completing the 10x 100 - 10kmh stops the ESP/BAS light came on and when I stopped to turn the car off and reset the trans decided to play up, when i restarted it gave a couple of really rough shifts, just what i wanted haha,honestly i'm not so sure about MB trans/control of this era anymore.

[John Jones Jr.]

Are using the standard brake master cylinder?

[Vetruck]

You are having different brake forces then what the traction control coputer is designed for and monitors. The ESP (Electronic Stability Control) and the BAS (Braking Assist System) work alot like ABS does in terms of they count the teeth on the reluctor wheels. When the system applies the brake force it thinks it needs, the car is doing otherwise becasue fot the change in caliper force.

You are experiencing about the same feeling of OEM braking becasue this system is on. However, the system will not stay on long when you start to push the car and get heat into the brakes. Best to disable it if youa re going to tailor a new brake setup and balance things with a Wilwood prop valve (or such) to the rears.

Very nice weight savings. That will definately show in ride quality, as well as play a tremendous part in handling over rough surfaces. Are those calipers fitting onto OEM spindles or did you have to custom machine brackets for them? I debated at first when I got this car on changing brakes etc when I was looking to start building this car-only because my experience with American cars is they most always have poor brakes (never owned a Euro car, just a few Toyotas and VW's.) I have to say that in a year of driving this car I am quite pleased with the OEM brake setup on my car. It is plenty adequate for street use, however, I do not plan to ever track this car not even autox type stuff. I am sure if I raise the temps I would have trouble with heat, so I can see why you are looking for a change if performance minded. My car is mainly for looks and just built suspension for high speed safety. The brakes will never get hot with repeditve stops.

Dean

[Pagz]

Guys,
Yep using the standard master cylinder, The C43 Stoptech kit w 44/44 piston setup is designed to be used with the factory system so comes with brackets and bolts up perfect , its' not a bespoke setup.

I forgot to mention the ESP only came on on the 10 or 11th stop in a row from 100-20kmph of which they were smoking by this time, it felt like front wheels let go for a second but the ABS didnt kick in,that's when I got the ESP light,so you could be right on the money there as fade would have caused it to fall outside the ESP's control window.Surely I don't think this will be an issue on the street in future=).

I notice when I press the brake pedal I can hear air bubbles around the ABS unit,I have never bled the ABS unit before but if i recall an MBstar is needed to crank it over while bleeding,In the past I have found a slippery surface to test the abs on then re-bled afterwards,im not sure if this is the most effective way to go about it.

I agree - the factory MB brakes are plenty for everyday use!. My goal with the C43 is to loose some of the heavy feeling without too much compromise,changing out the heavy brakes has made a really positive improvement towards that, the real surprise was the pedal travel staying the same, which I'm starting to think is existing air in the system.

[Pagz]

Including the enkie wheels its a saving of around 32Kg's rotating/unsprung over the stock AMG gear!,it really helps a lot towards making it more nimble and responsive.

[Pagz]

Looking at the WIS, this is a note there to cycle the ABS unit with the hand held controller if air has been allowed to enter from work on the master cylinder or lines to the ABS only, It does not recommend this for general flushing of the system.