W123 dual brake system explained
 

Is the dual brake-circuit configuration on the W123 (without ABS) a TT configuration (front-axle rear-axle split). If so, does the rear chamber of the brake expansion tank power the front brakes and the front chamber power the rear brakes?

Does the W201 190E 2.3-16 have three chambers in the brake expansion tank?

the portion of the master cyl next to the booster is for the rear brakes and the end of it is for the front.

i have no answer for the reservoir. good luck, chuck.

Thank you.

This weekend my son and I renewed the brake fluid in his 1981 280E, a recent acquisition. I was able to suck out the fluid from the rear chamber of the brake expansion tank, but not able to do so for the front chamber. The 123 Service Manual says to remove the brake fluid "pump out brake fluid via an open bleeder plug of the front axle and rear axle circuit."

Are there bleeder plugs for the front & rear axles respectively or do I simply open caliper bleeder plugs? When I did my daughter's W123, I removed the expansion tank and let the fluid run out the pipe of the front chamber.

no, just at the calipers. i always pull the tank and let it drain. good luck, chuck.

Chuck

Okay, thanks! I should have just followed the lines to see where they went. And of course, my son left the pressure bleeder at his 3-hour distant home.

yes the system is split front to back, the markings are on the master cylinder as V and H

V = front
H = rear

use a flashlight to see fluid in the master cylinder container when bleeding the brakes, the dividing wall is pretty tall inside and you may pump air into the system.

Robby,

If you need a pressure bleeder setup, I've got one.

Jim

Hi Jim

Maybe Hans will share the one I gave him with me, ha.

Good to hear from you, and nice cars!

Robby

Thanks for everyone's help with my question.

Bottom line -- A single brake line comes off the front of the master cylinder (marked H), is fed from the front chamber of the brake expansion tank and powers both rear brakes. Two separate lines come of the rear of the master cylinder (marked V and closest to the brake booster) and are fed from the rear chamber of the brake expansion tank. This rear chamber powers the front calipers with one line going to the right front caliper and a separate line going to the left front caliper.