Disc brake conversion problems - Team Camaro Tech
Brakes, Suspension & Steering Conversion questions, Steering & Handling

 
LinkBack Thread Tools Display Modes
post #1 of 13 (permalink) Old Jun 16th, 10, 07:33 PM Thread Starter
 
Join Date: Jun 2010
Location: Ohio
Posts: 3
Disc brake conversion problems

I have a 69 Camaro that was 4 wheel drums that I recently converted the fronts to discs using the 13" big brake kit from performance online. I retained the rear drums (for now). I purchased a master cylinder (1" bore) and proportioning valve from Right Stuff at a swap meet. I told the salesman that I was going to run manual brakes and have disc/drum setup. He told me the MC and prop valve is what I needed. I installed the brakes, new stainless lines, bench bled the MC and bled all four corners until I got a good solid stream of fluid. The problem is the pedal is extremely hard...harder than the all four drums were previously. Braking performance is very poor, worse than the all drum setup. I can't get the fronts to lock up, but I can get the rears to lock up rather easily.

I initially thought that maybe I had too large of a MC, but I called POL and they said that they recommend a 1" MC. Could it be my prop valve? Or will I just need to install a booster? Any other ideas? Thanks!
mark86 is offline  
Sponsored Links
Advertisement
 
post #2 of 13 (permalink) Old Jun 16th, 10, 08:01 PM
Senior Tech
Frank
 
Join Date: Aug 2004
Location: Orlando, Fl
Posts: 2,332
Re: Disc brake conversion problems

The rear drums take very little pressure to work. You need a prop valve in the rear line to hold off the rear brakes so the fronts can work. Get a knob style prop valve, install it in the rear brake, problem solved.
ProdigyCustoms is offline  
post #3 of 13 (permalink) Old Jun 16th, 10, 08:03 PM
RTL
Larry
 
Join Date: May 2010
Location: Portland OR.
Posts: 5
Re: Disc brake conversion problems

Use the factory style prop valve that mounts under the MC. Make sure it is the right part number, they look the same. Separate front lines, one rear line - calipers should never lock up under load.
RTL is offline  
 
post #4 of 13 (permalink) Old Jun 16th, 10, 08:09 PM Thread Starter
 
Join Date: Jun 2010
Location: Ohio
Posts: 3
Re: Disc brake conversion problems

Thanks for the reply.. Well I thought about the adjustable prop valve, but I called both Right Stuff and POL and they both said that the prop valve I bought was a "fixed" style and I did not need to run an adjustable prop valve. Are you suggesting that I go with an original metering block and use the adjustable prop valve? If so, do you know where I could purchase a metering valve?
mark86 is offline  
post #5 of 13 (permalink) Old Jun 16th, 10, 08:11 PM Thread Starter
 
Join Date: Jun 2010
Location: Ohio
Posts: 3
Re: Disc brake conversion problems

Sorry RTL didn't see your post until after I replied. Do you know where I could find a stock style prop valve/metering block?
mark86 is offline  
post #6 of 13 (permalink) Old Jun 16th, 10, 08:40 PM
RTL
Larry
 
Join Date: May 2010
Location: Portland OR.
Posts: 5
Re: Disc brake conversion problems

Metering/hold off valve part number 9223N . It serves as a distribution block and proportioning valve. Year One ?
RTL is offline  
post #7 of 13 (permalink) Old Jun 16th, 10, 09:04 PM
Senior Tech
Frank
 
Join Date: Aug 2004
Location: Orlando, Fl
Posts: 2,332
Re: Disc brake conversion problems

To make it simple you can add a adjustable prop vavle to the rear line
ProdigyCustoms is offline  
post #8 of 13 (permalink) Old Jun 17th, 10, 03:12 PM
Senior Tech
Robert
 
Join Date: Apr 2008
Location: Calif
Posts: 356
Re: Disc brake conversion problems

Did you buy the pol 2" drop with 13" rotors?

As far as your hard pedal, are you certain you have a 1" bore and not a 1 1/8" bore, the corvette masters with 1 1/8" bore come in both shallow and deep hole configurations.
1stGenLvr is offline  
post #9 of 13 (permalink) Old Jun 17th, 10, 10:38 PM
Senior Tech
JAY
 
Join Date: Jul 2009
Location: TUCSON AZ
Posts: 726
Re: Disc brake conversion problems

I'm running adjustable p-valve on my rear brakes of my 68 Chevelle. I had to break in the brakes, at first I was sorry I did the swap but as time goes by it gets better brakes. j


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

66 SS Chevyll
67 Elcamino
68 Malibu 2dr
69 Camaro Convertible
JAYARTER is offline  
post #10 of 13 (permalink) Old Jun 17th, 10, 11:49 PM
Moderator
David Pozzi
 
davidpozzi's Avatar
 
Join Date: Nov 1999
Location: Central California, USA
Posts: 10,096
Re: Disc brake conversion problems

If your 13" front brake kit uses a smaller piston area than stock factory discs, then the prop valve you bought isn't going to work. The kits with late model Corvette or Camaro aluminum calipers all require a much smaller master cylinder.

I tried manual brakes on our 2nd gen Camaro with Baer 13" rotors, the kit came with a 15/16" bore MC, it didn't work, I went down to a 13/16" bore and it would stop if I stood on the pedal, but it wasn't easy enough to drive hard on a race track or autox for repeated laps. I think a 3/4" bore might have worked but I couldn't find one.

I put on the 15/16" bore MC and installed a stock sized power booster with a knob adjust proportioning valve in the rear line, it works perfect. A 1" bore will probably work on a booster system too. I have that on our 68 Camaro with Baer brakes.

David

Check my web page for First Gen Camaro suspension info:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

67 RS 327 original owner. 1965 Lola T-70
davidpozzi is offline  
post #11 of 13 (permalink) Old Jun 18th, 10, 10:31 AM
Gold Lifetime Member
Matt
 
Join Date: Feb 2006
Location: Fairhope Alabama
Posts: 436
Re: Disc brake conversion problems

X3 on the adjustable proportioning valve. You can fine tune it to your cars weight bias and it will still work if you ever go to a 4 wheel disc setup. Factory Proportioning valves are only designed for the stock brake, wheel and suspension set up. They might work with changes to the system but you will be leaving some braking performance 'on the table' without the fine tuning you get with an adjustable unit.
-Matt

Dad bought his '69 'Camuchi' used '70, i started driving it in '77 at 14,gassing it up for him, he fixed it up for me in '79, now i am fixing it up/w my 3 boys & 2 girls, and Dad is looking down making sure i do it right
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Thanks Dad.
Camuchi is offline  
post #12 of 13 (permalink) Old Jun 18th, 10, 12:16 PM
Senior Tech
Robert
 
Join Date: Apr 2008
Location: Calif
Posts: 356
Re: Disc brake conversion problems

Quote:
Originally Posted by davidpozzi View Post
If your 13" front brake kit uses a smaller piston area than stock factory discs, then the prop valve you bought isn't going to work. The kits with late model Corvette or Camaro aluminum calipers all require a much smaller master cylinder.

I tried manual brakes on our 2nd gen Camaro with Baer 13" rotors, the kit came with a 15/16" bore MC, it didn't work, I went down to a 13/16" bore and it would stop if I stood on the pedal, but it wasn't easy enough to drive hard on a race track or autox for repeated laps. I think a 3/4" bore might have worked but I couldn't find one.

I put on the 15/16" bore MC and installed a stock sized power booster with a knob adjust proportioning valve in the rear line, it works perfect. A 1" bore will probably work on a booster system too. I have that on our 68 Camaro with Baer brakes.

David
I have 13" Corvette C5 on a 1955 Chevy with LT1 Camaro rear discs. It has a 1 1/8" bore master with 8" booster and non adjustible GM prop valve, brakes workbetter than great.
1stGenLvr is offline  
post #13 of 13 (permalink) Old Jun 18th, 10, 06:35 PM
Gold Lifetime Member
Don
 
Join Date: Jan 2005
Location: 2 Dog Town in West Texas
Posts: 11,154
Re: Disc brake conversion problems

On my last order from RightStuff, the 4 port master cly was sent to me (ended up leaking) and they sent me a two port and I kept the 4 port. In the box was a bullet looking cone spacer? Fits on the master cly plunger rod? I just wonder it this spacer is in the m/c plunger and you did not notice it and its causing a problem?

I have factory front disc and went to rear disc conversion also. I used the distributon block they sent me , removed my orfice and sold it along with the factory drum brakes.

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
zdld17 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome