Not an expert by any means, but coulda swore ya needed more residual for discs than drums becasue you have the adjusters on drums where discs just float.
ANYway,... When I was puttin together my lil beast of a car, I had a similar issue. Turned out my master cyl just didn't have the volume to push the discs, so I never got a proper pedal feel untill I upgraded my M/C to something made for discs. If you were given a M/C with too small a bore that may be the issue.
1956 GMC 370 dump " 'Tater "1970 VW Volksrod "the Black Bomber"
2007 Chevy Avalanche
2020 Jeep Cherokee Trailhawk,
2005 Harley Davidson FLHTCUI
I dig all cars, old and new, whether they were hammered out of American iron, German steel, or Japanese tin cans. Being unable to appreciate them all is missing out on a world of great things.
But thats just MY opinion! :P
