Thread: 1969 gmc
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Old 03-24-2022, 11:42 AM   #5
Caddylackn
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Join Date: Jun 2016
Location: Bremerton, WA
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Re: 1969 gmc

All 4 drum brakes should have close to the same stopping distance as disc/drums. The big difference between disc and drums is the amount of pedal force required and an increased stopping distance when the drums are wet or very hot (long steep grades). If everything is working correctly, you should not see a decrease in stopping ability in normal conditions.

What commonly happens is old cars that have been sitting awhile with moisture in the brake fluid and both pistons of each wheel cylinder are not moving (one gets frozen) so only one brake shoe is moving and not both. Pretty soon the one shoe starts to wear very quickly and there isn't enough travel left in the linkage to take up for the worn brake shoe. Or the drums have been turned too many times and there isn't enough travel in the brake linkage to engage the drums when the shoes are half worn.
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1969 Custom Camper C20; Factree Air, 350/TH400/Dana 70U with C30 wheel cylinders, Disk brakes, H4 conversion, headlight relay mod, 3G 135 amp alternator. 7500 GVW
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