GTSEdition1

Hi,

The brake light just came on with check brake message, so I started looking into replacement. I think I will have to check the rotors to see if they need replaced but what is the general consensus on 30k mile car?

Another strange fact i came across is the pricing.....on anyother car I have owned has had higher cost on front (being larger) than the rears. All the quotes I have received for OeM and non-Oem including Brembo has been double the price on rears than the fronts. Is that a norm on these cars?

Appreciate any feedback.

Thanks

user33

Search the forum and you'll find multiple postings where I've included a picture of the wear-indicator divots on the rotors and stated that AMG rotors are normally good for 2-3 brake-pad sets ... assuming there's been no deep-groove scoring and/or excessive radial-cracking by the vent holes.

Most dealers/shops will always replace the (rather expensive) rotors with any brake-pad swap, which works out to "most of the time, unnecessarily."

GTSEdition1

Thank you user33. I appreciate the advise and will look for your threads on this. Just looked externally on the pads and fronts still look over half life left but rears look low. So I'll probably just slap pads in the rear and check for the condition of the rotor




.

user33

Sounds like a good plan. FYI, I use one of these to check pad wear (there are also others that are less expensive):

Pads are relatively easy to replace as long as you don't remove the hydraulic brake lines and just hang the calipers after they're unbolted. Remember to use new bolts that attach the calipers to the suspension as they're "1-time use" bolts (applies to fronts when doing pads).

The pad-wear sensors will contact/alert at about 3 MM thickness ... unless you're on the track, there they're unlikely to work at all (heat destroys plastic wire carrier and the sensor's embedded wire is not worn/cut by the rotor until it's too late). After the low-pad warning and under normal street-driving scenarios, the pads will likely have a thousand miles of wear before hitting the pad backing.

Note that inside pads can wear differently from the outside pads (often more) and that, under some scenarios (e.g., track running) there can be a significant top-to-bottom wear-difference skew as the pads wear (I've seen up to 5 MM difference/wear-skew on my tracked GTR Pro's front pads).

G. P

Here is a simple way to determine when you need new rotors (non-ceramic, iron rotors):

Depending on the year and model, most front GTS, GTC, and GTR rotors are slotted and have a diameter of 390 mm. When new, they are 36 mm thick with a slot depth of 1 mm. The recommended minimum thickness is 34 mm. Therefore, when the slots start to disappear, it indicates that you have lost 1 mm on each side of the rotor, resulting in a total reduction of 2 mm in thickness, reaching the minimum of 34 mm.

The same principle applies to the rear 360 mm rotors (the GT may have this size on both the front and rear). When new, these rotors are 26 mm thick, with a minimum thickness of 24 mm.

Please note that the inside of a rotor may degrade faster than the outside, so when the outside slots are nearly gone, the inside may already be worn out.

I based this information on the GTR and GTC models, so please check if your 2016 GTS has the same specifications.

If you want to increase the longevity of your rotors, consider changing the brake pads when they reach between one-half to one-third of their original pad material thickness (excluding the metal backing plate). For example, the GTC/GTR rear pads (MB OEM is TEXTAR p/n 2516302) have an overall thickness of 19 mm, with the pad material itself being 12 mm thick. A good time to change them would be when the overall thickness is between 10-11 mm, or when the pad material thickness is down to 3-4 mm.

When installing new pads, follow the manufacturer's recommended bedding-in procedure. This process ensures that the pad surface is mechanically aligned with the disc surface for full contact, maximizing brake performance. During bedding-in, the pad's friction material is transferred and evenly distributed onto the rotor.

GTSEdition1

Thank you so much user33. I looked at the divots you mentioned on the front rotors and they are still pretty visibile, so hopefully front rotors are good and the pads so far.

For the rears I picked up the new pads and sensor for the rear but didn't get the bolts. Though I will get the new bolts as well.

Again, thanks for all your help!

GTSEdition1

Thank you G.P.
This is very helpful and great information. I will measure the rotors and pads as you suggested to figure out where I stand with them. At this time looking to do rears. Just by looking at the outer pad by flashing light. It seems it might still have about 2mm. Will have to check as you mentioned the backside pads might be worn a bit more.

Appreciate your write-up and help.

user33

Normally, you don't need to remove the calipers from the suspension mounting on the rears ... you only remove the bolts the hold the movable portion and these are OK to reuse (and they have a fairly low torque spec, compared to the mounting bolts).

G. P

You are absolutely right. There is no need to remove the caliper support (8) from the wheel carrier to replace the rear pads.

GTSEdition1, you will need two open-end wrenches to release each of the two bolt sets (4 & 6) that hold the floating caliper to the caliper support frame. When reinstalling the calipers, ensure that bolts 4 and 6 move freely inside cylinder 8 (see picture). Torque bolts 4 and 6 to 35 Nm (26 lb-ft).



(This Pic is just for reference. Taken from C190 with Ceramic Brakes. Code B07)

GTSEdition1

This is a great step by step. Thanks user33 and G.P. So I won't need the new bolts if I only do 4&6 and don't remove the caliper?

I will also look at what needs to be done to release the handbrake. I am sure there are bunch of discussions on that.

Appreciate it.

I wish the Lexus forum was this helpful where I am trying to figure out how to change the fusible link on a 2004 lx470

G. P

That is correct