Pit26

I want to fit a smaller wheel on a W463a G63 and want to put G550 brakes on the front. Can anyone tell me if this will work? Assuming I would change rotors, calipers, but would I need the brake sensor?

Thanks in advance.

streborx

At last! Someone who wants to downsize his wheel size! (lol)
Without brake pad wear sensors, I think you'll get an instrument panel warning.

Pit26

Yes, agreed but can you use the break pad sensors from the G63amg on G550 Calipers? Can you switch the wear sensors out and have it read correctly?

* Side note rant: The size of the calipers and rotors on the 63 are absolutely stupid and unnecessary. Some of the worlds best setups are small enough to accept 17" wheels.

mercedesmax

Frankly, this is an awful idea.
The brakes on the G 63 were designed for the increased power of the car.
Put smaller brakes on it and you will run out of stopping power sooner or later.
You get into an accident and you leave yourself open to a lawsuit because you tampered with the cars brakes.
Maybe you should just trade for a G 500.

Pit26

Not a concern...stopping power is stopping power meaning a G550 going 100mph vs a G63 at the same rate of speed is the same momentum and rotational force that needs to be brought to a stop. Those brakes are tested at unrealistic speeds and braking for 99% of use. Truck will never see over 90mph. Back to my original Q, if anyone can confirm or deny swapping G550 brakes to a G63 W463a let me know.

streborx

I think the wear sensor on the G550 and G63 is the same p/n, and even if it's not it's cheap ~ $7.
However, the proper analysis is a G63 going 150 mph vs. a G550 going 100 mph. Stopping the G63 from 150 mph is not a concern as you're probably trying to outrun the flashing lights (lol)!

The Butcher

What size wheel are you going with? You going to run Portals on this one?

WillinMA

You could also just cut the sensor right at the brake pad and twist the two wires together. If you ever take your wheels off or just take a peek every so often at your brake pads, you'll know if that are low!!

Pit26

I'd like to run an 18, yes portals

Surge

It’s not a good idea because the G550 brakes are a just a bit underpowered for the car. When I come out of my AMG GTC and into the G550, that’s the first thing you notice, performance wise.
For me, I would want the G63 brakes on the G550, and that’s the only part of the G63 I would want, otherwise I think the G550 is perfect.

streborx

The G63's curb weight is spec'd at 288 lbs heavier than the G550 (5842 lbs. vs. 5554 lbs.), or about 5%. Braking relies on converting kinetic energy of motion (K = 1/2mv^2) into heat via friction by brake pads contacting brake rotors. A G63 versus a G550 (loaded with 288 lbs of compensating ballast so that both vehicles' GVWR are equal), both moving at some velocity "v" require equal amounts of kinetic energy conversion to heat to come to a full stop. Larger pads and rotors on the G63 allow faster energy conversion and thus a shorter stopping distance (and a more aggressive driving style). But to say that the G63's larger brakes are required because of its greater hp rating is inaccurate and misleading.

Surge

Yes, interesting, you are correct!

Well hopefully the G63 brakes feel better than in the G550. They are not terrible, but they could use more stopping power. But the G63 is 5% heavier, as you point out, so the brakes will have to overcome that added weight in order to be stronger than the G550.

084runnerltd

Not to sidetrack this thread, but doesn’t the performance, in this case size, of the brakes have more to do with staying cool and preventing brake fade?

I have a feeling the G550 brakes can lock up the tires as quickly and firmly fitted on a G63, just as well as the original G63 brakes can….?

(Not claiming this as fact, just trying to understand).

If both setup of brakes can lock up (leaving ABS out of this argument to simplify) the tires, what is the difference?

On a track, racing through the mountains, or other high performance situations, the G63 brakes would do better…. But daily driving, I don’t think it matters….?

Also, I would give up some brake size to add portals any day!

streborx

Despite this fractional curb weight difference, both G63 and G550 are rated 5 passenger, 1500 lb payload (passenger + cargo weight), and 7000 lb towing capacity. So it's easy to configure a G550 with substantialy more weight than a G63 that consequently demands more braking performance given equal velocities. Braking performance requires compliance with Federal safety standards, so even a maxed out G550 is going to be able to stop safely under normal conditions.
Larger pads and rotors are ideal for drivers such as a friend of mine who likes to hit 80 mph in his GT3 between stop signs in his neighborhood.

windtendo

As a mechanical engineer, this guy ^^^ gets it. Larger brakes help with brake fade and will dissipate heat quicker than smaller discs.

Surge

Larger pads and rotors also add more braking force, it's not just about brake fade and heat dissipation.

windtendo

Please, go on.

Surge

Nothing to go on about. I'm also an engineer at worked at Akebono Brake in Japan.
That's why a car with larger pads and rotors stops faster and requires less pedal effort to stop. I think it's obvious?

Fade is another matter, and yes, if you cross-drill and vent you will reduce fade. But larger pads and rotors will do nothing to reduce fade on their own.

streborx

Yes, thanks for getting to the heart of the matter. Brake rotor and pad size is all about increasing the rate of energy transfer and reducing stopping distance and time (checkout the rotor/pad arrangement on commercial aircraft). IMO, if anyone is regularly experiencing brake fade, they either have a serious braking system problem, or they are improperly using their brakes (such as riding them all the way down an 8 mile long hill, or left-footing the brake pedal as a means of trimming their speed). Anyone who schedules brake jobs and oil changes concurrently has a problem.

Surge

Totally agree @streborx .
BTW, it's important to flush the brake fluid every 2 years!

windtendo

If you want to believe big brakes stop quicker, okay. I could tell you I'm an engineer at Brembo or Stoptech too, but it doesn't matter. I'm going to just paste this here and call it a day. No sense in arguing a myth, just Google "big brakes stop faster" and see what comes up. As I said earlier, big brakes dissipate heat better and reduce brake fade.

Surge

No, this is not really correct. I mean, you're right in a sense, but we are talking about the rate of deceleration relative to the pedal input.
"The truth of the matter is that most likely, you already have more stopping friction in your stock brakes that you can use" - this is not the point.

Think about it - larger surface area between pad and rotor = faster deceleration for a given pedal force/input.

Fade is related to heat, which is dissipated by venting and/or cross drilling. Actually, a larger pad and rotor will create more heat, not less, which means fade is more likely to occur with a larger pad/rotor. It's the venting and cross-drilling, and materials of the rotor/pad that reduce heat and therefore fade.

Baltistyle

Hilarious answers to the ops question. Anybody willing to read into the question understands this will be used for overland or off-road duty. The op is not interested in braking design theory, but only if these are a different fit than stock brake calipers and rotors and if so, what brackets need to be made or purchased.

op, yes it’s possible. It is unlikely to find this type of retrofit in this site, imo. This is where you’d get no resistance over going bigger and arguments such as undersized master cylinder or improper abs programming would not matter...cause bigger is bigger.

if you went into any custom off-road store, they would be able to help you out. It’s not as though these rotors are a part of the wheel bearings. And besides you’re changing out the axles so you’ve got some welding ahead for brackets anyway.

sounds fun! Don’t let the engineers steer you. They are supposedly building in tolerances for all these broken parts we see on these boards😂. Just kidding there but an engineer may be a little too technical to simply answer yes or no.

pretty sure we don’t have to look too far back to see smaller brakes on a high powered Amg of any type.

streborx

What I enjoy about this forum is its members' broad knowledge base and the useful and interesting information exchange. I never object to receiving more info than what's being asked for (assuming it's accurate and correct), if/when a thread goes a bit askew. I live on the perimeter of the San Juans in Colorado where some of the best off road driving is found. It's about a 70 mile on road drive to reach the Black Bear Pass turn off, so unless I'm trailering, my truck's on road drivability is as important as its off road. This includes brakes, tires, suspension, etc. Whether or not some part functions correctly in every circumstance is as important as whether or not it simply fits. The OP can pick and choose (or ignore) whatever information he/she wishes in pursuing his/her objective and decision.

Pit26

I greatly appreciate all the back and forth @Baltistyle dialed in the answer quite well as the root of my question was assertaining whether or not the switch would work given all the sensors in these new trucks. It is not a matter of stopping power that will ride the decision. Stand by for final results in the coming weeks.