I've got her to run, but need her to stop. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Blaze69 · 05-01-2003, 06:08 PM

Hi all,
Been awhile since I last posted, anyway here's my problem.
As I posted a while ago I was in the process of changing over to front disc on my '69. It took me a bit but I finally got it finished (somewhat). Here's what I've done so far:

1: swapped out the front end (that's a given), replaced the discs, pads, hoses, calipers and bearings.
2: bought new drums for the rear.
3. made new hoses (lines) to match the new setup.
4. Bled the **** out of the system, I now have clear fluid running to all the wheels.

What I didn't change was the booster or master cylinder.

My problem now is that when I got to stop I don't have any brakes on the first attempt. But, if I lightly pump the pedal the vehicle will damn near lock up.

I hope that someone out there can give me some advice on this matter. I would sure hate to have to take it into the shop and pay someone else for something I should fix.

Thanks.

**Palf70Step** · 05-01-2003, 06:12 PM

Sounds like master cylinder is going bad....plus since you now have discs..you should change to a disc brake master cylinder and proportioning valve...otherwise your brakes are going to be super erratic and may cr@p out alltogether at the most inconvient time.

SEVEND2 · 05-01-2003, 06:35 PM

I agree with Palf70step, cylinder and valve may need replacing.

**68 Stepside** · 05-01-2003, 08:38 PM

Nice Avatar

*Randy70C-10* · 05-01-2003, 08:52 PM

If you did all that work on the brake system, you should always change the master cylinder!! (cheap investment)

Blaze69 · 05-02-2003, 08:36 AM

When I changed over to the new system, I used the master cylinder and proportioning valve from the donor vehicle. You may be right and I'll have to try swapping in a new one.

One other thing.....the MC that I have now has two bleeder screws at the base (one for front and one for rear). When I went to the store to get a new one it didn't have the screws. Should this be a concern or not?

If all that has been said is true, then I still don't understand why the brakes would be so touchy. Is it because I have gotten used to the plush style of the new vehicles and lost my touch with the old school? Since I didn't replace the valve with a new one could that be the cause?? If not what other routes could I pursue???

Thanks again.....

05-01-2003, 06:08 PM	#1
Blaze69 Registered User Join Date: Apr 2001 Location: Arizona Posts: 147	I've got her to run, but need her to stop. Hi all, Been awhile since I last posted, anyway here's my problem. As I posted a while ago I was in the process of changing over to front disc on my '69. It took me a bit but I finally got it finished (somewhat). Here's what I've done so far: 1: swapped out the front end (that's a given), replaced the discs, pads, hoses, calipers and bearings. 2: bought new drums for the rear. 3. made new hoses (lines) to match the new setup. 4. Bled the ** out of the system, I now have clear fluid running to all the wheels. What I didn't change was the booster or master cylinder. My problem now is that when I got to stop I don't have any brakes on the first attempt. But, if I lightly pump the pedal the vehicle will damn near lock up. I hope that someone out there can give me some advice on this matter. I would sure hate to have to take it into the shop and pay someone else for something I should fix. Thanks. __________________ 1969 Blazer: 350/350, 4X4, HEI, Edlebrock carb/intake, dual flowmasters, np205, 3:07's and the rest is mostly stock. The front end disc swap is finally complete** 2002 Z71 Tahoe. CAI, Flowmaster 40, Silverstars in high, low and fogs and a bunch of mods (upgrades) inside and out.

05-01-2003, 06:12 PM	#2
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 47,216	Sounds like master cylinder is going bad....plus since you now have discs..you should change to a disc brake master cylinder and proportioning valve...otherwise your brakes are going to be super erratic and may cr@p out alltogether at the most inconvient time. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

05-01-2003, 08:38 PM	#4
68 Stepside huh? Join Date: May 2000 Location: Washington, Illinois Posts: 5,690	Nice Avatar __________________ Someday when I'm lonely, Wishing you weren't so far away, Then I will remember Things we said today. RIP El Jay

05-02-2003, 08:36 AM	#6
Blaze69 Registered User Join Date: Apr 2001 Location: Arizona Posts: 147	When I changed over to the new system, I used the master cylinder and proportioning valve from the donor vehicle. You may be right and I'll have to try swapping in a new one. One other thing.....the MC that I have now has two bleeder screws at the base (one for front and one for rear). When I went to the store to get a new one it didn't have the screws. Should this be a concern or not? If all that has been said is true, then I still don't understand why the brakes would be so touchy. Is it because I have gotten used to the plush style of the new vehicles and lost my touch with the old school? Since I didn't replace the valve with a new one could that be the cause?? If not what other routes could I pursue??? Thanks again..... __________________ 1969 Blazer: 350/350, 4X4, HEI, Edlebrock carb/intake, dual flowmasters, np205, 3:07's and the rest is mostly stock. The front end disc swap is finally complete 2002 Z71 Tahoe. CAI, Flowmaster 40, Silverstars in high, low and fogs and a bunch of mods (upgrades) inside and out.

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05-01-2003, 06:35 PM	#3
SEVEND2 Registered User Join Date: Aug 2001 Location: Menifee, Calif, USA Posts: 2,145	I agree with Palf70step, cylinder and valve may need replacing.

05-01-2003, 08:52 PM	#5
Randy70C-10 Account Suspended Join Date: Mar 2001 Location: Virginia Beach, Va. U.S.A. Posts: 15,320	If you did all that work on the brake system, you should always change the master cylinder!! (cheap investment)



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