72 K5 Brakes (HARD)
 

So, I've been working on my brakes on my Blazer(DRUM&DISC) on and off for about 2 years now and still have a hard pedal. The break pedal is hard. I hit the brakes and it stops, but it still continues to roll a bit.
I have checked the brake lines and they are good. I then replaced the brake booster and master cylinder and the pedal is still hard.
I just replaced the calipers and the pedal is still hard.
Could it be the perportioning valve? That is what I may replace next.
I have talked to other friends with first gen blazers and they say that the brakes on their blazer are okay, but not great.
Anyone have any suggestions?
How do your guys blazers stop? Do the brakes lock up the tires?

Re: 72 K5 Brakes (HARD)
 

How much manifold vacuum are you pulling?

Re: 72 K5 Brakes (HARD)
 

Mine sounds just like yours. If I have to stop quickly they will go to the floor but never lock up and the truck keeps rolling. I was going to get rear discs this spring.

Re: 72 K5 Brakes (HARD)
 

You might want to look into the 3/4 ton mastercylinder swap.

Re: 72 K5 Brakes (HARD)
 

In good working order these brakes work great, lock up when called on to do so. They have plenty of stopping power and should have a firm pedal but not hard. Keep trouble shooting you will find your issue. Good luck!!

Re: 72 K5 Brakes (HARD)
 

Be sure to bench bleed the master cylinder before installing?

Re: 72 K5 Brakes (HARD)
 

a collapsed rear hose will cause the rears to not engage fully. jack the rear up have someone start to slowly apply the brakes while you manually turn the wheel. if it takes a while for them to stop then you may have a bad rear hose it will also cause a hard pedal due to the restriction.

Re: 72 K5 Brakes (HARD)
 

Check your manifold vacuum (should be at least 15), the line going to the booster, and the check valve.

I just got my Jimmy back on the road after sitting for 20 years. I reused the steel brake lines, replaced all the rubber lines, wheel cylinders, calipers and master cylinder. I reused the brake booster and proportioning valve. My brakes are very sensitive and work great.

Also, are your drums adjusted correctly? Just curious.