W108/109/111/113 brakes upgrade with 560 parts

[GGR]

Hi all,

I did a mock-up install of a W126 560 front caliper and rotor on my W111 Coupe. The caliper is a straight bolt-on, and by using the wheel lug holes to fix the rotor it appears that the offset is also correct.

The problem is that the center hole on the 560 rotor is too big and the rotor fixation holes pitch is of a bigger diameter. The solution would be to find some "blank" 560 rotors where the front face of the hat hasn't been drilled yet. Then the same pattern as the original rotor could be duplicated.

I wasn't able to find such "blank" rotors anywhere. If someone knows of a way to get some, please let me know.

[DieselPaul]

Could you use hub centric rings to make up the difference?

[GGR]

I have thought about that, but this would then require re-drilling and taping the hubs according to the 560 rotor fixing point pitch, as the original holes would then be partially covered by the rings. This may also weaken the hubs.

I've also thought of using the wheel lug holes to fix the rotors to the hub with long bolts that would then come out the other side allowing to tight the wheel on them with nuts. However, the shape of the hub is such that part of these holes are in the conic shape of the hub's periphery (one could see the bolt in between the hub and the rotor when looking from the top) and I'm not sure such an arrangement would be satisfactory. Finally, strength of the hub/rotor assembly depends on the contact surface in between the two parts, and it would be too small.

The easiest would really be to find "blank" 560 rotors and drill them as per the original rotors. I think it will be easier, stronger and safer.

[dirtyharry]

Is it just more caliper piston area you are looking for? or more rotor surface to dissipate the heat better? I think the stock stuff is mostly fine. I run Girling 17/3 calipers on the front of my coupe. they have 40mm more caliper piston then the stock 2 piston ATE. I'm mostly sure they are even bigger then the 560 caliper. they bite and lock the wheels up very easily.

Here is what I actually think. the combination of W108 wheels with the fins, girling 17/3 calipers and vented rotors up front would be more the adequate with a better compound pad. the W108 wheels in particular are very good at keeping everything cool. also you could removed the dust shields or drill them for better airflow.

if you run larger rotors it will only lock up easier, I think reducing the rotating mass is more important. if you have less mass it is easier to start and stop anything moving.

[GGR]

I agree with you that the stock brakes are very powerful. However, they are prone to fade after a few aggressive laps on a track. The are also a bit lacking if you need to come to an emergency stop from high speed (from above 100/120 mph). This can be improved with higher boiling point brake fluid and carbon/Kevlar pads. The downside is less bite on the road especially when the pads are cold.

I Have some 15x7 wheels on my Coupe so I have space for 560 300mm rotors and calipers. I realize I will be increasing the unsprung mass and rotating mass, but I will have usable and more durable brakes even under abusive conditions. It's a compromise.

[dirtyharry]

these are 17/3's pictured, you can see my drilled upper control arm on my coupe as well. I'm saying that the W108 wheels on the front in combination with a larger caliper will prevent fade. however, are the 560 calipers cast iron or aluminum? the cast iron will retain more heat , but be less prone to warping under hard braking. another option would be like the Porsche 924 turbo caliper, which is 4 piston I believe, and should more or less bolt up I think. but the calipers are hard to come by. depends on the budget.

[GGR]

Porsche 924/944 seem to have 282mm diameter rotors, when the stock W108/111 rotor is 273mm. So I'm not sure it would match well. Later 944 used 300mm rotors, so the calipers, if they fit the MB, may be a nice upgrade over the 560 cast iron calipers. But I would still need to get a 300mm rotor to fit.

[Raffaelli]

I had the same problem when I put lexus ls400 brake on my 82 Toyota truck. The Lexus rotors center hole was too small and lug bolt holes were to big. Iirc I centered it best I could and bolted it to the hub. Then mounted the hub in a brake lathe and trued it out.

I'll post pics if you'd like.

[GGR]

Looks like I have the opposite problem: the center hole on the rotors I want to use is too big.

[Tony H]

You might be able to get the holes welded and re machined-just a thought. It's done with cams and cranks all the time.

[Raffaelli]

Can u use the 560 hubs and larger bearings/w some bearing spacers?