Brakes won't lock up, help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jmil1974 · 01-03-2003, 11:07 AM

Well, my brakes seem to work fine but I can't get them to lock up on the street. I know my MC is leaking just a bit from the cap. Could this be the problem? I'm using a rebuilt MC from a C20, could this have anything to do with it? New everything under there except one line . . .
It feels great b/c I came from manual drums but I feel it should be better. Anyone?

JimKshortstep4x4 · 01-03-2003, 11:22 AM

Are you using the MC and the proportioning valve off of a C 20
on your truck? Is your truck a C 10?

The C 20 master cylinder is reversed from the C 10 as far as which is the front line and which is the rear and I would expect a difference in the way they operate if you did not use the proportioning valve for the right one.

Do you have power brakes or not?

Jim

jmil1974 · 01-03-2003, 12:15 PM

I am using a prop valve off a C10, but a later model or a van. My truck is a C10, btw. I have power too, booster also from a c20. The bowls are different sizes. I BELIEVE I have the smaller bowl working the front and the larger operating the rear. I KNOW I have the front bowl on the front and the rear bowl going to the rear. Is this how it's supposed to be? I can take some pics this weekend . . .

Zurbo · 01-03-2003, 02:03 PM

Mine are doing the same thing even after a full system rebuild with a new master, new slaves, calipers, rotors, semi metallic pads and shoes, and freshly turned drums. The prop valve and lines were all flushed and working ok. They will lock up on a gravel road but not even come close on dry pavement.

You might want to check uot the suggestions in my other post located here. http://67-72chevytrucks.com/vboard/s...403#post241403

Mudder · 01-03-2003, 03:32 PM

are you guys using the elcheapo pads? I bought the good pads one time for my truck (lifetime warrenty) think they were metalic. They would not work for $hit. I took them back and put the cheap ones back on and presto. Fixed!

jmil1974 · 01-03-2003, 03:36 PM

I'm using whatever comes in gmcpaul's kit. I have no idea if they are semi-metallic or organic.

Tynee · 01-03-2003, 04:13 PM

Maybe I'm insane, but why do you want them to lock up? Better stopping without lock-up, no?

jmil1974 · 01-03-2003, 05:10 PM

Tynee- yes, in theory. You get your best braking by braking right on the verge of locking. Sounds like chirping, like the tires are fighting for traction and almost lose it but never do. I'm sure you have NO idea what that's like, huh? :p To be able to do that repeatedly, you have to have the power to lock all 4 of them up, at the same time, and modulate with your foot just short of that. MUCH more difficult than it sounds. While mine are more idiot proof, I am not getting maximum braking, and I am pretty decent at modulating my brakes to the verge of lockup. Comes from riding motorcycles, and maybe from tearing up my truck as a teenager.

Mudder · 01-03-2003, 07:49 PM

Ok if it feels like you have to push extra hard at a stop sign (harder than you had to push on your old brakes) you have come across the same thin that I did. Within a couple of days driving my truck I took the pads (disk) off and took them back to the parts store. I bought the cheapest pads they had and it was fine. The metalic pads work good on new vehicles but not our trucks sometimes.

Mudder · 01-03-2003, 07:51 PM

When I changed my back drums to disks....it was like night and day better breaking.

Zurbo · 01-05-2003, 12:19 AM

Jmil1974, On my 72, the small bowl side drives the fronts and the large bowl side drives the rears. It appears that all the parts stores here in Wichita only stock the common masters. Mine appears to be a special Delco/morane or Bendix. Hopefully the correct master will fix my braking performance problem. I'm thinking that you might not have the right master for your system as well so it is not developing enough pressure.

01-03-2003, 11:07 AM	#1
jmil1974 Ain't we cute? Join Date: May 2002 Location: Friendswood, TX Posts: 700	Brakes won't lock up, help! Well, my brakes seem to work fine but I can't get them to lock up on the street. I know my MC is leaking just a bit from the cap. Could this be the problem? I'm using a rebuilt MC from a C20, could this have anything to do with it? New everything under there except one line . . . It feels great b/c I came from manual drums but I feel it should be better. Anyone? __________________ 69 C10 2WD LWB Fleet 350/350 power front disc conversion (6 lug disc kit from gmcpauls) and new engine, PS, A/C, fresh fluids, SHE DRIVES! FOR SALE $3900

01-03-2003, 12:15 PM	#3
jmil1974 Ain't we cute? Join Date: May 2002 Location: Friendswood, TX Posts: 700	I am using a prop valve off a C10, but a later model or a van. My truck is a C10, btw. I have power too, booster also from a c20. The bowls are different sizes. I BELIEVE I have the smaller bowl working the front and the larger operating the rear. I KNOW I have the front bowl on the front and the rear bowl going to the rear. Is this how it's supposed to be? I can take some pics this weekend . . . __________________ 69 C10 2WD LWB Fleet 350/350 power front disc conversion (6 lug disc kit from gmcpauls) and new engine, PS, A/C, fresh fluids, SHE DRIVES! FOR SALE $3900

01-03-2003, 02:03 PM	#4
Zurbo Registered User Join Date: May 2001 Location: Bel Aire, Kansas, USA Posts: 186	Mine are doing the same thing even after a full system rebuild with a new master, new slaves, calipers, rotors, semi metallic pads and shoes, and freshly turned drums. The prop valve and lines were all flushed and working ok. They will lock up on a gravel road but not even come close on dry pavement. You might want to check uot the suggestions in my other post located here. http://67-72chevytrucks.com/vboard/s...403#post241403 __________________ Zurbo's Chevy - 1972 Black/White Cheyenne Super. 402 Big Block /THD 400, factory air and tilt. My other Chevy - 1998 Camaro SS Last edited by Zurbo; 01-03-2003 at 02:12 PM.

01-03-2003, 03:36 PM	#6
jmil1974 Ain't we cute? Join Date: May 2002 Location: Friendswood, TX Posts: 700	I'm using whatever comes in gmcpaul's kit. I have no idea if they are semi-metallic or organic. __________________ 69 C10 2WD LWB Fleet 350/350 power front disc conversion (6 lug disc kit from gmcpauls) and new engine, PS, A/C, fresh fluids, SHE DRIVES! FOR SALE $3900

01-03-2003, 04:13 PM	#7
Tynee I miss this truck. Join Date: Dec 2001 Location: Lexington, KY U.S.A. Posts: 2,863	Maybe I'm insane, but why do you want them to lock up? Better stopping without lock-up, no? __________________ '07 GMC Acadia SLT. Sweet ride. '08 Crew Cab Z-71 short bed. Really like this truck A LOT.

01-03-2003, 11:22 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Are you using the MC and the proportioning valve off of a C 20 on your truck? Is your truck a C 10? The C 20 master cylinder is reversed from the C 10 as far as which is the front line and which is the rear and I would expect a difference in the way they operate if you did not use the proportioning valve for the right one. Do you have power brakes or not? Jim

01-03-2003, 03:32 PM	#5
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	are you guys using the elcheapo pads? I bought the good pads one time for my truck (lifetime warrenty) think they were metalic. They would not work for $hit. I took them back and put the cheap ones back on and presto. Fixed!

01-03-2003, 05:10 PM	#8
jmil1974 Ain't we cute? Join Date: May 2002 Location: Friendswood, TX Posts: 700	Tynee- yes, in theory. You get your best braking by braking right on the verge of locking. Sounds like chirping, like the tires are fighting for traction and almost lose it but never do. I'm sure you have NO idea what that's like, huh? :p To be able to do that repeatedly, you have to have the power to lock all 4 of them up, at the same time, and modulate with your foot just short of that. MUCH more difficult than it sounds. While mine are more idiot proof, I am not getting maximum braking, and I am pretty decent at modulating my brakes to the verge of lockup. Comes from riding motorcycles, and maybe from tearing up my truck as a teenager. __________________ 69 C10 2WD LWB Fleet 350/350 power front disc conversion (6 lug disc kit from gmcpauls) and new engine, PS, A/C, fresh fluids, SHE DRIVES! FOR SALE $3900

01-03-2003, 07:49 PM	#9
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Ok if it feels like you have to push extra hard at a stop sign (harder than you had to push on your old brakes) you have come across the same thin that I did. Within a couple of days driving my truck I took the pads (disk) off and took them back to the parts store. I bought the cheapest pads they had and it was fine. The metalic pads work good on new vehicles but not our trucks sometimes.

01-03-2003, 07:51 PM	#10
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	When I changed my back drums to disks....it was like night and day better breaking.

01-05-2003, 12:19 AM	#11
Zurbo Registered User Join Date: May 2001 Location: Bel Aire, Kansas, USA Posts: 186	Jmil1974, On my 72, the small bowl side drives the fronts and the large bowl side drives the rears. It appears that all the parts stores here in Wichita only stock the common masters. Mine appears to be a special Delco/morane or Bendix. Hopefully the correct master will fix my braking performance problem. I'm thinking that you might not have the right master for your system as well so it is not developing enough pressure. __________________ Zurbo's Chevy - 1972 Black/White Cheyenne Super. 402 Big Block /THD 400, factory air and tilt. My other Chevy - 1998 Camaro SS

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