Need help with Braking problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71Subman · 10-28-2005, 03:17 PM

Hey guys, I am at a loss to figure out why my brakes don't work like (I think) they should. I have new rotors/pads and Drums/shoes all the way around. new master and wheel cylinders. I have bled the lines to the point I can do it in my sleep. My booster seems to be working OK and I have replaced the rubber lines with braided steel (when I did the lift). The brakes feel fine, pedal-wise, and work fine under 'normal' braking, but I can not by any stretch of the imagination or slamming of my leg(s) get my suburban to stop fast (in a panic stop situation), let alone lock the tires up (unless I'm driving on ice. Am I expecting too much? I have to leave LOTS of room in front of me in traffic, to make sure I have time to stop. It feels like an overzealous ABS, but I couldn't find that on the options list for my 71 Sub.

I have even resorted to taking it to 'experts' and have been told that my brakes just need to 'break in'. Well, there's about 3,000 mile on them now and no change. Any ideas??

70chevc10 · 10-28-2005, 04:04 PM

you mentioned a lift. did you do all of the brakes and lift at the same time? IF you did, and you put bigger wheels/tires on at the same time, that might be why?

also, i think you'll get more responses if this is in the engine/drivetrain forum

71Subman · 10-28-2005, 04:08 PM

Actually, I did the brakes before the lift. Then did the Braided Steel lines with the lift and tires. No difference before or after the lift and tires.

70chevc10 · 10-28-2005, 04:10 PM

did you bleed the brakes passenger rear, driver rear, passenger front, then driver front, in that order?

71Subman · 10-28-2005, 04:13 PM

Yup. Ran my son ragged getting in and out of the truck to pump brakes and check the fluid level, too. :-)

71Subman · 10-28-2005, 04:17 PM

It really feels like the booster is not all there, but I have been told that they either work or don't, no in between. I have tested it and it does provide some boost to the brakes. The pedal/stopping feeling, in panic mode though, is like when your engine dies and you have no booster...just can't push hard enough to make it work like it should.

70chevc10 · 10-28-2005, 04:23 PM

is it possible that your not getting enough vacume (like maybe a big cam or a leak somewhere)?

71Subman · 10-28-2005, 04:25 PM

Possible, but the engine is stock and runs fine. Any idea how much vacuum should be at the booster?

70chevc10 · 10-28-2005, 04:33 PM

nope, but i know someone here will know. might check a manual if you have one.

70rs/ss · 10-28-2005, 05:32 PM

I have had many a Blazer with the same problem (symtoms) I have been told it is the booster. Some places sell that smaller compact booster that is supposed to solve the problem. And the booster can be leaking and sort of work, so I'd look into a new booster mastercylinder combo (cheaper together than apart) and make sure to bench bleed as the stroke on the peddle is not long enough to get all of the air out. It takes two tubes from the brake line fittings and they loop into the resevoir. Push the piston in with a screwdriver or long rod (untill it stops moving and then let it out) after a couple of strokes you should notice no air bubbles, and then it is ready to go on the vehicle for bleeding the way you described above. my .02 cents, and it has worked for me. I can put myself through the windshield with 35"'s.

**N2TRUX** · 10-28-2005, 05:58 PM

I moved this to the Burb forum to see if it might get more attention.....

I'm inclined to agree with 70rs/ss. It could be a weak booster. Before you change the booster, try bench bleeding the master cylinder. Air can get trapped and conventional bleeding will not always remove it. If that doesn't work, try gravity or pressure bleeding the system. It still may have air trapped.....

**special-K** · 10-30-2005, 08:17 AM

Where`s the picture of the brakes????

10-28-2005, 03:17 PM	#1
71Subman Registered User Join Date: Oct 2003 Location: Everett, Wa Posts: 138	Need help with Braking problem Hey guys, I am at a loss to figure out why my brakes don't work like (I think) they should. I have new rotors/pads and Drums/shoes all the way around. new master and wheel cylinders. I have bled the lines to the point I can do it in my sleep. My booster seems to be working OK and I have replaced the rubber lines with braided steel (when I did the lift). The brakes feel fine, pedal-wise, and work fine under 'normal' braking, but I can not by any stretch of the imagination or slamming of my leg(s) get my suburban to stop fast (in a panic stop situation), let alone lock the tires up (unless I'm driving on ice. Am I expecting too much? I have to leave LOTS of room in front of me in traffic, to make sure I have time to stop. It feels like an overzealous ABS, but I couldn't find that on the options list for my 71 Sub. I have even resorted to taking it to 'experts' and have been told that my brakes just need to 'break in'. Well, there's about 3,000 mile on them now and no change. Any ideas?? __________________ Noise Makin', Gas Gusslin', Big Ass Metal Monster! 1983 3/4 4x4 P/U (the Sub is gone) 1967 Firebird (Drag racer) 1967 Firebird (resto in progress) 1999 Camry (Wifey's econo-rail ) 1997 VW Jetta (Daughter's cruiser) 1989 Le Mans (just extra for the boys to drive)

10-28-2005, 04:04 PM	#2
70chevc10 Registered User Join Date: Jun 2004 Location: Puyallup, WA Posts: 535	Re: Need help with Braking problem you mentioned a lift. did you do all of the brakes and lift at the same time? IF you did, and you put bigger wheels/tires on at the same time, that might be why? also, i think you'll get more responses if this is in the engine/drivetrain forum

10-28-2005, 04:08 PM	#3
71Subman Registered User Join Date: Oct 2003 Location: Everett, Wa Posts: 138	Re: Need help with Braking problem Actually, I did the brakes before the lift. Then did the Braided Steel lines with the lift and tires. No difference before or after the lift and tires. __________________ Noise Makin', Gas Gusslin', Big Ass Metal Monster! 1983 3/4 4x4 P/U (the Sub is gone) 1967 Firebird (Drag racer) 1967 Firebird (resto in progress) 1999 Camry (Wifey's econo-rail ) 1997 VW Jetta (Daughter's cruiser) 1989 Le Mans (just extra for the boys to drive) Last edited by 71Subman; 10-28-2005 at 04:08 PM.

10-28-2005, 04:10 PM	#4
70chevc10 Registered User Join Date: Jun 2004 Location: Puyallup, WA Posts: 535	Re: Need help with Braking problem did you bleed the brakes passenger rear, driver rear, passenger front, then driver front, in that order?

10-28-2005, 04:13 PM	#5
71Subman Registered User Join Date: Oct 2003 Location: Everett, Wa Posts: 138	Re: Need help with Braking problem Yup. Ran my son ragged getting in and out of the truck to pump brakes and check the fluid level, too. :-) __________________ Noise Makin', Gas Gusslin', Big Ass Metal Monster! 1983 3/4 4x4 P/U (the Sub is gone) 1967 Firebird (Drag racer) 1967 Firebird (resto in progress) 1999 Camry (Wifey's econo-rail ) 1997 VW Jetta (Daughter's cruiser) 1989 Le Mans (just extra for the boys to drive)

10-28-2005, 04:17 PM	#6
71Subman Registered User Join Date: Oct 2003 Location: Everett, Wa Posts: 138	Re: Need help with Braking problem It really feels like the booster is not all there, but I have been told that they either work or don't, no in between. I have tested it and it does provide some boost to the brakes. The pedal/stopping feeling, in panic mode though, is like when your engine dies and you have no booster...just can't push hard enough to make it work like it should. __________________ Noise Makin', Gas Gusslin', Big Ass Metal Monster! 1983 3/4 4x4 P/U (the Sub is gone) 1967 Firebird (Drag racer) 1967 Firebird (resto in progress) 1999 Camry (Wifey's econo-rail ) 1997 VW Jetta (Daughter's cruiser) 1989 Le Mans (just extra for the boys to drive)

10-28-2005, 04:23 PM	#7
70chevc10 Registered User Join Date: Jun 2004 Location: Puyallup, WA Posts: 535	Re: Need help with Braking problem is it possible that your not getting enough vacume (like maybe a big cam or a leak somewhere)?

10-28-2005, 04:25 PM	#8
71Subman Registered User Join Date: Oct 2003 Location: Everett, Wa Posts: 138	Re: Need help with Braking problem Possible, but the engine is stock and runs fine. Any idea how much vacuum should be at the booster? __________________ Noise Makin', Gas Gusslin', Big Ass Metal Monster! 1983 3/4 4x4 P/U (the Sub is gone) 1967 Firebird (Drag racer) 1967 Firebird (resto in progress) 1999 Camry (Wifey's econo-rail ) 1997 VW Jetta (Daughter's cruiser) 1989 Le Mans (just extra for the boys to drive)

10-28-2005, 04:33 PM	#9
70chevc10 Registered User Join Date: Jun 2004 Location: Puyallup, WA Posts: 535	Re: Need help with Braking problem nope, but i know someone here will know. might check a manual if you have one.

10-28-2005, 05:32 PM	#10
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,271	Re: Need help with Braking problem I have had many a Blazer with the same problem (symtoms) I have been told it is the booster. Some places sell that smaller compact booster that is supposed to solve the problem. And the booster can be leaking and sort of work, so I'd look into a new booster mastercylinder combo (cheaper together than apart) and make sure to bench bleed as the stroke on the peddle is not long enough to get all of the air out. It takes two tubes from the brake line fittings and they loop into the resevoir. Push the piston in with a screwdriver or long rod (untill it stops moving and then let it out) after a couple of strokes you should notice no air bubbles, and then it is ready to go on the vehicle for bleeding the way you described above. my .02 cents, and it has worked for me. I can put myself through the windshield with 35"'s.

10-28-2005, 05:58 PM	#11
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,023	Re: Need help with Braking problem I moved this to the Burb forum to see if it might get more attention..... I'm inclined to agree with 70rs/ss. It could be a weak booster. Before you change the booster, try bench bleeding the master cylinder. Air can get trapped and conventional bleeding will not always remove it. If that doesn't work, try gravity or pressure bleeding the system. It still may have air trapped..... __________________ Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra" Last edited by N2TRUX; 10-28-2005 at 06:00 PM.

10-30-2005, 08:17 AM	#12
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,863	Re: Need help with Braking problem Where`s the picture of the brakes???? __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ Last edited by special-K; 10-30-2005 at 08:18 AM.



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