77 International Drum brake Issue

xjdrew

xjdrew

Well-Known Member
Joined
Apr 19, 2010
Location
Goldsboro, NC
I have 1977 Loadstar 1600 International, that I'm having some brake problems with. When I go to pump the brake, the first pump is good, but if I keep holding it down or go to pump it again, it gets hard as rock. If I wait a good 20 seconds or so and go to pump it again it's fine, but just on the first pump. The truck has no problem stopping on the first pump, all the brakes are grabbing like they should. I've already replaced the brake booster, I replaced that twice thinking the first one was a dud, I also replaced the master cylinder, and wheel cylinders. I was thinking maybe the springs?? Just to clarify, it does have drum brakes all the way around. Anyone have any advice??
 
Well, I adjusted all the brakes again and still no difference, I disconnected the vacuum from the booster and it acts the same way, whether it connected or not
 
does the brake pedal go down too far on the first pump? Is that why you are going for the second pump? Usually if the booster is good you push the pedal once and hold it. No need to pump the brakes (unless you are skidding).
 
No the pedal does not go down all the way, it feels good on the first pump, it'll stop the truck, no skidding. Its always made me feel a little safer by pumping to slow it down a bit before making a full stop, but not always necessary . The problem is when I need that second pump or hold it down on the first pump it just goes hard. I'm on my second booster, and no change. I followed all the vacuum lines to make sure none are clogged, or had any leaks, and it's holding good vacuum. I've bled the system, but either way it does not feel like it has air. We have 4 more Internationals and we have always had brake issues, but nothing like this.
 
I'd say it's operation normally. Ever try to pump the brakes on something newer? Second pump the pedal gets hard as a rock since you've moved as much fluid as you can with the first pump. There's no room for any more fluid.
 
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