67-72 brake linkage in 60-66? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

vortech71chevy · 03-02-2016, 02:29 PM

Hey guys, just replaced all my components in my brake system and converted to power brakes and front disk, ran new lines, replaced all drum components etc. I used 71-72 components in the swap. The feel of the pedal and the stopping ability is definately not where I want it to be... I have bled it and bled it and bled it... I have drilled the brake pedal 1" down for the linkage and it still doesn't stop anywhere as good as my 71 shortbed did (to be fair the brakes on that truck worked better than most stock systems). Which had me thinking about the possible differences... I then remembered that my 71 used a compound linkage system that reduced brake pedal travel and effort and maximized travel to the master cylinder. This gave the feel in that car of a pedal feel that rivaled a modern car. Can the compound linkage be adapted to the 60-66 models? I no longer have the 71 for reference and I'd like to hear if anybody has used it/tried it before I start throwing money back at it...

Secondly, my brake issue is not getting better with any amount of bleeding but still made me think there is air in the lines. As I depress the pedal, there is significant take-up on the pedal with no braking response at all. There is then a sudden surge of brake pressure and the car stops too abruptly. Any thoughts?

Thanks in advance for all the help. I've finally got my lab to swb conversion finished, t56 in place and brake/suspension stuff done, I'm gettin antsy to get her buttoned up and go cruising!

vortech71chevy · 03-06-2016, 12:02 AM

Anybody???

LT1 Burb · 03-06-2016, 12:08 AM

I used 71 brake stuff in my 66 suburban and it stopped on a dime, your master may be the problem. Did you bench bleed it well. Did you use the 71/72 master with the proportions get valve?

vortech71chevy · 03-06-2016, 05:57 PM

Yep, bench bled and all that, I have good vacuum and all my connections are good. I used a cpp proportioning valve with the factory components. I was thinking of replacing the master since they're so cheap, and spend the whole stinking day bleeding it just to make absolutely sure there's no issues... I still am interested to hear if anybody has used the compound linkage successfully in a 60-66 tho.

**MikeN** · 03-08-2016, 02:19 PM

Quote:

Originally Posted by vortech71chevy

H As I depress the pedal, there is significant take-up on the pedal with no braking response at all. There is then a sudden surge of brake pressure and the car stops too abruptly.

After swapping to a dual reservoir master cylinder and a vacuum booster, my brakes are the same as you describe. I cannot figure it out, and like you, I'm getting frustrated.

**The Rocknrod** · 03-08-2016, 02:48 PM

Did you set the booster push rod to the master cylinder correctly?:
http://www.mpbrakes.com/techtalk/how...r-cylinder-gap
Pedal ratio should also be checked for the situation you have:
http://www.classicperform.com/TechBo...hoot.htm#pedal

03-02-2016, 02:29 PM	#1
vortech71chevy Registered User Join Date: Jan 2008 Location: South Hill Puyallup, WA Posts: 78	67-72 brake linkage in 60-66? Hey guys, just replaced all my components in my brake system and converted to power brakes and front disk, ran new lines, replaced all drum components etc. I used 71-72 components in the swap. The feel of the pedal and the stopping ability is definately not where I want it to be... I have bled it and bled it and bled it... I have drilled the brake pedal 1" down for the linkage and it still doesn't stop anywhere as good as my 71 shortbed did (to be fair the brakes on that truck worked better than most stock systems). Which had me thinking about the possible differences... I then remembered that my 71 used a compound linkage system that reduced brake pedal travel and effort and maximized travel to the master cylinder. This gave the feel in that car of a pedal feel that rivaled a modern car. Can the compound linkage be adapted to the 60-66 models? I no longer have the 71 for reference and I'd like to hear if anybody has used it/tried it before I start throwing money back at it... Secondly, my brake issue is not getting better with any amount of bleeding but still made me think there is air in the lines. As I depress the pedal, there is significant take-up on the pedal with no braking response at all. There is then a sudden surge of brake pressure and the car stops too abruptly. Any thoughts? Thanks in advance for all the help. I've finally got my lab to swb conversion finished, t56 in place and brake/suspension stuff done, I'm gettin antsy to get her buttoned up and go cruising! __________________ "We must reject the idea that every time a law is broken, society is guilty rather than the lawbreaker. It is time to restore the American precept that each individual is accountable for his actions." Ronald Reagan

03-06-2016, 12:02 AM	#2
vortech71chevy Registered User Join Date: Jan 2008 Location: South Hill Puyallup, WA Posts: 78	Re: 67-72 brake linkage in 60-66? Anybody??? __________________ "We must reject the idea that every time a law is broken, society is guilty rather than the lawbreaker. It is time to restore the American precept that each individual is accountable for his actions." Ronald Reagan

03-06-2016, 12:08 AM	#3
LT1 Burb Registered User Join Date: Sep 2010 Location: Winchester Oregon, formerly Vancouver BC Posts: 2,949	Re: 67-72 brake linkage in 60-66? I used 71 brake stuff in my 66 suburban and it stopped on a dime, your master may be the problem. Did you bench bleed it well. Did you use the 71/72 master with the proportions get valve?

03-06-2016, 05:57 PM	#4
vortech71chevy Registered User Join Date: Jan 2008 Location: South Hill Puyallup, WA Posts: 78	Re: 67-72 brake linkage in 60-66? Yep, bench bled and all that, I have good vacuum and all my connections are good. I used a cpp proportioning valve with the factory components. I was thinking of replacing the master since they're so cheap, and spend the whole stinking day bleeding it just to make absolutely sure there's no issues... I still am interested to hear if anybody has used the compound linkage successfully in a 60-66 tho. __________________ "We must reject the idea that every time a law is broken, society is guilty rather than the lawbreaker. It is time to restore the American precept that each individual is accountable for his actions." Ronald Reagan

03-08-2016, 02:48 PM	#6
The Rocknrod Moderator Join Date: Aug 2011 Location: China Spring, TX Posts: 7,280	Re: 67-72 brake linkage in 60-66? Did you set the booster push rod to the master cylinder correctly?: http://www.mpbrakes.com/techtalk/how...r-cylinder-gap Pedal ratio should also be checked for the situation you have: http://www.classicperform.com/TechBo...hoot.htm#pedal __________________ Master Chief, US Navy, Retired 1964 C10 Step-side Short Bed - In Progress 2009 2500HD Duramax LTZ 1948 GMC Panel 1956 Big Window Stepside 1953 5 Window Chevy Stepside 1932 Coupe New Seat Foam for Bench Seats?



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