Girodisc brakes
Member
Joined: Jun 2012
Posts: 80
Likes: 6
From: Perth Australia
2013 ML 350 Bluetec
I purchased these myself from Tal at ACG with a set of MX72 pads. Fitted them up in the garage without too many issues. They were significantly lighter than the std discs, so a significant weight saving over 4 discs, I honestly feel that I could feel a difference through the seat of the pants. The car felt like it accelerated and turned in with a little more vigour, so smiles all round. ACG were great to deal with, many thanks Tal! Minor issues, braking the calliper mounting bolts, you will need to have the front end raised so you can turn the wheels to give clearance for the breaker bar, and you will need a 300mm breaker (or similar). The only other issue was that the fixing screw hole did not line up with the hub thread but not a big deal as they are tight on the hub centric spigot. My advice is go for it, no downside that I am aware of.
Junior Member
Joined: Mar 2014
Posts: 39
Likes: 0
Jeep Grand Cherokee
One thing no one has mentioned yet on the weight savings is that you are saving weight on rotating mass. I am pulling this number out of memory, so it may be inaccurate, but it's something like 1 lb saved in rotating mass =100 lbs saved in stationary mass.
When the motor drives the wheels it is also having to spin the brake discs. Saving weight on them makes it easier for the motor to drive the wheels. The discs are smaller in diameter than wheels and tires are so lightweight wheels and tires make a bigger difference.
The improvements are so minor they likely cant be felt on the butt dyno but they are there.
When the motor drives the wheels it is also having to spin the brake discs. Saving weight on them makes it easier for the motor to drive the wheels. The discs are smaller in diameter than wheels and tires are so lightweight wheels and tires make a bigger difference.
The improvements are so minor they likely cant be felt on the butt dyno but they are there.
MBWorld Fanatic!
Joined: Jan 2013
Posts: 3,745
Likes: 811
From: The Great White North
W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, Taycan GTS Sport Turismo, C5 Z06 & IS300 race cars
One thing no one has mentioned yet on the weight savings is that you are saving weight on rotating mass. I am pulling this number out of memory, so it may be inaccurate, but it's something like 1 lb saved in rotating mass =100 lbs saved in stationary mass.
When the motor drives the wheels it is also having to spin the brake discs. Saving weight on them makes it easier for the motor to drive the wheels. The discs are smaller in diameter than wheels and tires are so lightweight wheels and tires make a bigger difference.
The improvements are so minor they likely cant be felt on the butt dyno but they are there.
When the motor drives the wheels it is also having to spin the brake discs. Saving weight on them makes it easier for the motor to drive the wheels. The discs are smaller in diameter than wheels and tires are so lightweight wheels and tires make a bigger difference.
The improvements are so minor they likely cant be felt on the butt dyno but they are there.
Your argument about the motor having to drive the wheels is somewhat misleading, as it ultimately has to drive the entire car, not just the wheels, so in a straight line the weight savings (and thus performance increase) are exactly what you would get by removing the mass that you'd measure on the scale, let's say 26 lbs over the P31 rotors, which is not very significant.
During cornering however (and especially on a bumpy track), you would indeed get better grip and thus the results would be akin to removing more weight from the car as you suggested, although IMHO the ratio is a lot closer to 10:1 instead of 100:1. So yeah, during hard cornering, the resulting level of extra grip you would get as a result of reducing the unsprung weight by 26 lbs would be closer to shaving off 260 lbs from the sprung mass of the vehicle. Your "butt dyno" can definitely feel this - you'll even feel it in the steering response right away.
Last edited by Diabolis; Mar 19, 2014 at 02:14 PM.
Super Member
Joined: Nov 2013
Posts: 579
Likes: 41
S63
I got mine from Tal too (great to work with) and replaced the cals with freshly painted cals thru his exchange program while I was at it. I appearntly had the 2 piece fronts, so the weight savings wasn't as much for me. Though I did need new rotors, so it all worked out fine anyways.
Banned
Joined: Apr 2010
Posts: 2,914
Likes: 8
From: San Diego, CA
a car
I got mine from Tal too (great to work with) and replaced the cals with freshly painted cals thru his exchange program while I was at it. I appearntly had the 2 piece fronts, so the weight savings wasn't as much for me. Though I did need new rotors, so it all worked out fine anyways.
Thank you again for all the kind words
Banned
Joined: Apr 2010
Posts: 2,914
Likes: 8
From: San Diego, CA
a car
I purchased these myself from Tal at ACG with a set of MX72 pads. Fitted them up in the garage without too many issues. They were significantly lighter than the std discs, so a significant weight saving over 4 discs, I honestly feel that I could feel a difference through the seat of the pants. The car felt like it accelerated and turned in with a little more vigour, so smiles all round. ACG were great to deal with, many thanks Tal! Minor issues, braking the calliper mounting bolts, you will need to have the front end raised so you can turn the wheels to give clearance for the breaker bar, and you will need a 300mm breaker (or similar). The only other issue was that the fixing screw hole did not line up with the hub thread but not a big deal as they are tight on the hub centric spigot. My advice is go for it, no downside that I am aware of.
The performance gains on these rotors are significant in every way:
- Less weight: Almost 7 pounds per corner of unsprung mass
- Directional: Meaning they vent properly, versus the OEM AMG which do not
- Serviceable: Discs can be replaced
- Less expensive option for PP owners
Let me know if you guys have any questions. I personally run these on my E55 and will install a set on my C63 this coming weekend.
MBWorld Fanatic!
Joined: Dec 2008
Posts: 2,169
Likes: 75
From: San Diego
Hyperion's Candy-Coated 4 x 4
Thank you for the kind words sir! I'm glad you are enjoying the new brakes
The performance gains on these rotors are significant in every way:
- Less weight: Almost 7 pounds per corner of unsprung mass
- Directional: Meaning they vent properly, versus the OEM AMG which do not
- Serviceable: Discs can be replaced
- Less expensive option for PP owners
Let me know if you guys have any questions. I personally run these on my E55 and will install a set on my C63 this coming weekend.
The performance gains on these rotors are significant in every way:
- Less weight: Almost 7 pounds per corner of unsprung mass
- Directional: Meaning they vent properly, versus the OEM AMG which do not
- Serviceable: Discs can be replaced
- Less expensive option for PP owners
Let me know if you guys have any questions. I personally run these on my E55 and will install a set on my C63 this coming weekend.
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Banned
Joined: Apr 2010
Posts: 2,914
Likes: 8
From: San Diego, CA
a car
MBWorld Fanatic!
Joined: Dec 2008
Posts: 2,169
Likes: 75
From: San Diego
Hyperion's Candy-Coated 4 x 4
Super Member
Joined: Oct 2007
Posts: 730
Likes: 9
From: The Beach
2012 C63 Purpose built race car, 2015 CLS 63 S, 2016 GLA45, 2017 GTS
This is my set up and I love it. The rotors are for the E55 but work perfect on my 2012 C63 Coupe.
Last edited by freefall; Mar 20, 2014 at 11:38 PM.
