Difference in Brake Fluid Reservoirs 68-73

[Coastal220]

Does anyone know what the deal is with the different style of brake fluid reservoirs from the original, more rounded units as seen in the first picture (not my engine compartment) vs the new replacement seen below?





You can see the second one has a visible seam around the side and the form is angular... also note: ATE - "Some models require fluid level sensor modification when installed on early model vehicles still using prior versions of master cylinders."

The sensor terminals look the same to me as on my 1970 220 but it's impossible to tell for sure. Also, the male reservoir plugs that fit into the MC seem to be offset from the center-line of the unit, which I believe the originals are not.

Can anyone shed light on this?

[Coastal220]

Okay, and here's an add-on question:

Does anyone know if a DIFFERENT reservoir also fits this master cylinder? Think later models, 123s...

[JPMOSE]

Unfortunately, the unit that started with the 1968 model year (not sure when it ended), which also has the level sensors, has been replaced with the more square looking version. The unit prior to 1968 model year (w/o sensors) can still be obtained in this original style. I have collected a couple used spares with the rounded look, but they are always badly yellowed (which looks funny with a new washer unit right near it). I guess we will have to live with it until someone develops a reproduction that looks original.

[Coastal220]

Thanks JP. And it looks like the earlier style definitely doesn't fit the 68-73 master cylinders...

I wish there was a way to clean the original yellowed reservoirs.

[Mark DiSilvestro]

Many years ago, I bought a W110 230, where a PO had replaced the ATE master-cylinder. The replacement had an angular, tilted reservoir, making it impossible to completely top-off the brake fluid. At the time, I also owned an early '70s Audi wagon that had an up-angle tilted ATE master-cylinder - with the older round-style reservoir. So I swapped the reserviors between the two cars, which made both reservoirs appearance & angle perfect.