power disc brakes for early 110?

[woodrat]

is it possible to convert a 62 190D over to disc brakes by using the parts from a 66-67 200D?

[Tristar1959]

Not a lot of difference between the near-contemporary W111 swing-axle rear brakes and the W115's, so that might work - but suspect the front end might have to be W111, also a kingpin front end. Would also look at pedal/booster from a 111. Is there adequate vacuum to suck a booster, in a 190D (even with a 200D engine)...?

[300SDog]

The general rule is that upgrades within the same chassis series will bolt right in. The front hubs, spindles and hydraulic lines going from drums to discs will be different. Also the w110 200D disc brake Master Cylinder will have diagonally coupled hydraulic lines, meaning the master cylinder pushes a dual piston assembly that activates left front and right rear OR right front and left rear indepedently of each other. A safety feature in case you break a hydraulic line or loose all the fluid from one system.

Swapping from early drum brake w110 to later disc brake w110 will no doubt involve swapping the kingpin assemblies to accomodate spindles, rotors and callipers. It will probly be a difficult conversion to make but not impossible if the 2 cars are side by side.

Ask Mark Desilvestro on this board. He owns a 1962 220Sb with drums, has probly thought about the same conversion and can answer better than I can.

[Mark DiSilvestro]

The 200D's front disc spindles and calipers should just bolt right on to the 190. Biggest hassle in the conversion is that the early drum-brake Fintails used a single circuit master cylinder on the firewall, The early power-brake, standard on 220S and SE but optional on other models, used a separate ATE power-brake servo, mounted next to the radiator.
When front discs were phased in on the 220S and SE Fintails between '62 and '63, they still retained the single circuit master cylinder and separate power-brake servo setup from the drum-brake cars.
Finally in 1964, all Fintails got a modern dual-circuit front disc brake, with a firewall-mounted master cylinder/booster assembly. Unfortunately, I don't believe that unit will simply bolt up to the firewall of the earlier cars.

Swapping in the 200D's master cylinder/booster unit may involve some firewall modifications to your 190. Also, if your 190 is a manual-shift, the 200D's vacuum booster will interfere with the 190's underhood clutch master cylinder, so you will need to swap in the later brake/clutch pedal unit, which relocates the clutch master cylinder under the dash.

In the case of my all-drum '60 220S, I have a spare front disc-brake axle from a '64. If I decide to do the conversion, I'll retain my existing ATE power assist servo unit, but will probably have to remove the residual pressure valve from my original master cylinder and install one, in-line, for the rear drums. If the conversion is successful, I'll worry about the dual-circuit master cylinder/booster conversion later.
Happy Motoring, Mark