Quote:
Originally Posted by OldSD
I have had the same thing happen to me on my 77 300d, 81 300td, and 83 300sd. It appears that when the pads wear down sufficiently, the pad's metal backing plates can come in contact with the leaf spring that pushes the pads in radially and you are trying to compress the leaf width-wise. This results in the load being transfered from one pad through the spring, and into the other pad instead of all of the load going through the disc. I hope I am saying this clearly  . As stated before, I have had this happen numerous times and each time I waited until the pedal effort increased, the pads were in contact with the spring. |
That makes sense. I didn't look closely enough upon disassembly but it seems like the best hypothesis yet. It took some prying with a screwdriver to get that spring out so it was probably right against the backing plates.
It seems like a design flaw.
It would also explain why I thought for a while that perhaps the rear brakes were the only ones working. I had a sense that the car was not 'diving' enough during hard braking, making me suspect the front brakes were the ones not doing their job. The spring limiting the amount that the pads could squeeze would account for that sensation.