jmcghee

Does any know of a source for these new? Are the backing plates the same for a 7.5 differential and an 8.5 ?

joe_padavano

Which brakes do you have, the 9.5" drums or the 11" drums? The 1977-1985 Delta 88 could have come with either, depending on whether or not you have the HD suspension and brakes.

jmcghee

car has 9.5 brakes

joe_padavano

The original part number is 18014440. Goggle that and you'll find new ones, even from GM. Note that despite the fact that some vendors call these LH or RH, the B-body cars used the same backing plates on both sides. The e-brake cable on the RH side actually exits out the rear and loops around to join the cable from the LH side.

https://www.gmpartsonline.net/oem-pa...Y2LWdhcw%3D%3D

jmcghee

Thabks Joe!!!! Have you put the 11' rear brakes on any of your 88 s? Are those backing plates available? I think........ uh oh, there I go again. Gm used same calipers, on both systems 11" and 9,5". That the only difference is the prop valve? I see" large piston" calipers advertised , Can not find specs, of " large piston" calipers If they, really are larger maybe prop valve change not needed That could be done latter if needed. Running 225/ 70/15 tires . I think , the tires would allow more braking, before they would lock, versus stock 205s There goes that " thinkin" again.

joe_padavano

The 11" rear drums were used with the larger 12" front rotors on wagons, Ninety Eights, and D88s with the HD suspension and brakes. These also use a 5 x 5" wheel bolt circle, not the 5 x 4.75" pattern. Note that unlike the one-size-fits-none combo valves that are sold by the aftermarket brake companies, GM tuned the spring in the proportioning section of the combo valve for each specific application. Wagons got different combo valves than sedans, for example.