The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1960 - 1966 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 10-14-2024, 09:30 AM   #1
Knothead
Registered User
 
Knothead's Avatar
 
Join Date: Mar 2007
Location: south carolina
Posts: 251
Soft Brake Pedal

Current project is using a 1979 K10 frame and suspension. Utilizing brake system from same, everything is new except hard lines. Drums , Rotors, proportioning valve , brake booster , Master Cylinder also were replaced. I can get a firm pedal but after cranking engine pedal fades to the floor? The brakes will hold the truck when in gear. Also will stop truck . Can’t get a good pedal with it running? Ordered another MC just to eliminate that as maybe the problem. I’m scratching my head on this one , looking for some suggestions and input. If it matters it is an 6.0 LS engine,thanks
Knothead is offline   Reply With Quote
Old 10-14-2024, 10:30 PM   #2
cwcarpenter98
Senior Member


 
cwcarpenter98's Avatar
 
Join Date: Jan 2018
Location: Hickory Flat, GA
Posts: 4,483
Re: Soft Brake Pedal

Did you drill a new hole for the power brake pedal ratio?
__________________
Christian Carpenter

1963 C10 - Frankentruck 283, Muncie 3 speed with overdrive
Overdrive wiring here
1963-ish truck bed trailer - Half-Wit

1981 C10 - Penny 305, th350 --> Soon to be 350, Saginaw 4 speed

1995 Dodge Dakota Sport

"I'll put it simple: if you're going hard enough left, you'll find yourself turning right." - Doc Hudson
cwcarpenter98 is offline   Reply With Quote
Old 10-15-2024, 03:40 PM   #3
forestb
Registered User
 
forestb's Avatar
 
Join Date: Jan 2009
Location: Burbank, CA
Posts: 3,619
Re: Soft Brake Pedal

Are you getting enough vacuum? I had a lot of problems with brakes due to having too large of a cam which decreases vacuum.

Last edited by forestb; 10-15-2024 at 03:47 PM.
forestb is offline   Reply With Quote
Old 10-15-2024, 03:43 PM   #4
forestb
Registered User
 
forestb's Avatar
 
Join Date: Jan 2009
Location: Burbank, CA
Posts: 3,619
Re: Soft Brake Pedal

Quote:
Originally Posted by cwcarpenter98 View Post
Did you drill a new hole for the power brake pedal ratio?
I thought that drilling the new hole was so that after converting to power breaks the brakes are too sensitive and by moving the hole you are making it less sensitive.
forestb is offline   Reply With Quote
Old 10-15-2024, 10:26 PM   #5
cwcarpenter98
Senior Member


 
cwcarpenter98's Avatar
 
Join Date: Jan 2018
Location: Hickory Flat, GA
Posts: 4,483
Re: Soft Brake Pedal

Quote:
Originally Posted by forestb View Post
I thought that drilling the new hole was so that after converting to power breaks the brakes are too sensitive and by moving the hole you are making it less sensitive.
Someone who has done that conversion will have to chime in on that question. I kept my truck non-power, even with the front disc swap. My initial question was partly to help the conversation begin since that's a common question anyways
__________________
Christian Carpenter

1963 C10 - Frankentruck 283, Muncie 3 speed with overdrive
Overdrive wiring here
1963-ish truck bed trailer - Half-Wit

1981 C10 - Penny 305, th350 --> Soon to be 350, Saginaw 4 speed

1995 Dodge Dakota Sport

"I'll put it simple: if you're going hard enough left, you'll find yourself turning right." - Doc Hudson
cwcarpenter98 is offline   Reply With Quote
Old 10-15-2024, 10:32 PM   #6
AcampoDave
Registered User
 
AcampoDave's Avatar
 
Join Date: Feb 2013
Location: central California
Posts: 2,759
Re: Soft Brake Pedal

^^^ I did that too. They work just fine unboosted. Sure, you have to push harder but no more so than the factory brakes required.
AcampoDave is offline   Reply With Quote
Old 10-16-2024, 08:46 AM   #7
Knothead
Registered User
 
Knothead's Avatar
 
Join Date: Mar 2007
Location: south carolina
Posts: 251
Re: Soft Brake Pedal

Thanks for the input, I’m chasing my tail on this one ! I did the math equation on pedal ratio and it came out to what it’s supposed to be for power assist brakes. I’m going to recheck it again and make sure I did it correctly
Knothead is offline   Reply With Quote
Old 10-16-2024, 05:30 PM   #8
Knothead
Registered User
 
Knothead's Avatar
 
Join Date: Mar 2007
Location: south carolina
Posts: 251
Re: Soft Brake Pedal

THANKS EVERYONE!!! Y’all steered me right to the problem . I had the ratios for the brake pedal backwards .I was thinking 6:1 for power assist and 4:1 for manual ???? Drilled a hole in the correct location and now I have a BRAKES and a firm pedal !!
Knothead is offline   Reply With Quote
Old 10-21-2024, 02:27 PM   #9
MikeN
Senior Member
 
MikeN's Avatar
 
Join Date: Oct 2007
Location: Marietta, GA
Posts: 803
Re: Soft Brake Pedal

Glad you got it fixed - drilling the lower hole is a must.
MikeN is offline   Reply With Quote
Old 10-21-2024, 04:06 PM   #10
geezer#99
Registered User
 
geezer#99's Avatar
 
Join Date: Aug 2009
Location: Bowser
Posts: 13,713
Re: Soft Brake Pedal

Quote:
Originally Posted by MikeN View Post
Glad you got it fixed - drilling the lower hole is a must.
Not always!
If you have a bellcrank between your firewall and booster you use the existing hole.

https://www.speedwaymotors.com/Power...iABEgJdvvD_BwE
geezer#99 is online now   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 04:44 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com