My 77 240D has an intermittent problem of one or the other front calipers sticking and dragging. It's not all the time, and it's not the same one every time. When it's dragging really bad the pedal feels really tight and high, and sometimes if you jab it really hard the brakes will return to normal. For these reasons, I decided I would try changing out the master cylinder first, but looking at the cylinder and the VIN, I realized that mine has the extremely expensive pressure sensor model, that is going to cost something like $285, instead of under $100 for the other one.

What exactly does this sensor do, and can I get away with buying the non-sensor MC instead, and just leaving the wire hanging loose? Is it still possible to find rebuild kits for these? Assuming that mine is not horribly pitted inside, I'm perfectly capable of honing mine out and putting new seals in it, for way less than $285.

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1976 Mercedes 240D, unknown mileage
1992 Dodge/Cummins 4WD, 284k