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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: mats1985gmc on August 27, 2011, 08:24:01 pm

Title: Brakes
Post by: mats1985gmc on August 27, 2011, 08:24:01 pm
I cant post anywhere else.
My brakes feel very weak. Do I need a new master cylinder or it there an easy upgrade. In the future I would like to some bigger brakes on the front and get rid of the drums in the rear. any ideas. thanks
Title: Re: Brakes
Post by: txchainsawgogi on August 27, 2011, 08:46:20 pm
how's the fluid level in the master cylinder? You probably just need new pads or at worst, new rotors. Also, you'd be surprised how well fully functioning drums would feel.
Title: Re: Brakes
Post by: beastie_3 on August 27, 2011, 09:50:54 pm
bleed the brakes first to see if there is any air. that is free
Title: Re: Brakes
Post by: Irish_Alley on August 28, 2011, 09:37:04 am
brakes fall in the Suspension forms. but anyway check your fluid see what color it is, bleed them like beast said. test your back brakes i do this by power braking and seeing how easy they spin. or you can jack the rear put in neutral have someone step on the brakes and try to spin the tires this will tell you if they work at all
Title: Re: Brakes
Post by: zieg85 on August 28, 2011, 09:56:01 am
I cant post anywhere else.
My brakes feel very weak. Do I need a new master cylinder or it there an easy upgrade. In the future I would like to some bigger brakes on the front and get rid of the drums in the rear. any ideas. thanks

Weak in what area??  Is it pedal feel?  There are many things that could be going on at once.  Please explain exactly what is going on and someone will chime in.  I have seen it all brake wise on these trucks and am here to help as well as other members here.  The stock brake set ups on our trucks stop very well as they are sized for the GVW rating of the truck if everything is in proper working order.
Title: Re: Brakes
Post by: mats1985gmc on August 28, 2011, 12:02:31 pm
For some reason it wouldn't let me post anywhere else
the pedal feels full. I have New pads, new rotors. the brakes are bleed and the master cylinder is full. I was driving at approx 60 kph and had to brake heavy. it felt very weak and wouldnt lock up.
Title: Re: Brakes
Post by: zieg85 on August 28, 2011, 12:11:58 pm
For some reason it wouldn't let me post anywhere else
the pedal feels full. I have New pads, new rotors. the brakes are bleed and the master cylinder is full. I was driving at approx 60 kph and had to brake heavy. it felt very weak and wouldnt lock up.

If you have power brakes and it felt like you were having to stand on a brick to stop, it could by the power vacuum brake booster.  If that is fine you may need to replace the rubber brake lines feeding your calipers.  It made a "WHOLE" world of difference with my 1985 C10 about a month ago.  It also fixed a pull to the right issue when braking that I thought might have been an upper control arm bushing going out...
Title: Re: Brakes
Post by: Irish_Alley on August 28, 2011, 03:56:28 pm
i have the same problem in my 79 i replaced the booster to have the same problem. it seems to be the master cylinder just haven’t had time to change it
Title: Re: Brakes
Post by: muddpuppy01 on August 28, 2011, 10:31:10 pm
a master cylinder going bad general leaks down when on the brake pedal ie at a stop light fully stopped and the pedal slowly goes to the floor.

a bad brake booster generally you would here a air leak when the brake pedal is depressed

I would go ahead and replace the front rubber lines just for general maintenance sake. Then I would check to make sure the back brakes are in good condition and adjusted properly and might as well change that rubber hose as well.

you are a little short coming with the way the pedal feels soft, hard, or hard to press
Title: Re: Brakes
Post by: Irish_Alley on August 29, 2011, 08:46:51 am
pedal slowly going to the floor i thought was air in the lines along with it feeling spongy. well i know its not my rubber lines cause it did it with them and with the ss ones
Title: Re: Brakes
Post by: muddpuppy01 on August 29, 2011, 09:59:08 am
every time I had to deal with brakes that had the pedal go down slowly to the floor was due to the seals in the master cylinder leaking internally. Spongy pedal would air in the lines.

When bleeding brakes don't be bashful about going through brake fluid. Most of the time people don't change it out anyway. so that would be a good time to get all the old fluid out and new fluid in. 
Title: Re: Brakes
Post by: thirsty on August 29, 2011, 10:56:55 am
every time I had to deal with brakes that had the pedal go down slowly to the floor was due to the seals in the master cylinder leaking internally. Spongy pedal would air in the lines.  

This could be a bad rear wheel cylinder also.