67 Rear Drum Brake - Pontiac GTO Forum
User Tag List

 
LinkBack Thread Tools Display Modes
post #1 of 2 (permalink) Old 12-20-2015, 12:26 AM Thread Starter
 
Join Date: Dec 2015
Posts: 11
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
67 Rear Drum Brake

Ok....

Im doing a complete frame off on my 67 GTO but im stumped on the rear brake drum. Here is the situation when I took the rear drum cap off there was a wheel cylinder that was a 15/16 bore. When I go to look up replacement parts for the 67 the only one that pops up is a wheel cylinder with a 7/8 bore. I went ahead and ordered the one with a 7/8 bore and put it on the backing plate now the problem is when I put the pistons on the wheel cylinder it pushes the brake pads all the way out and there is no way that I can push the cylinder in any more. Im starting to wonder if maybe once in the car life time if the rear end was switched out with a 66 or maybe im just not getting it right. When I look at the other side with the 15/16 bore everything is sitting in place correctly. If I was to order the 15/16 bore and place it back on there would it effect anything? Will my brake lines still fit? Just to give you a run down on what I have going on. I did a disc brake conversion on the front and the portioning valve is a Disc/Drum set up now. Also, the I have also added a brake booster for power assist. Thanks in advance.
67PONGOAT is offline  
Sponsored Links
Advertisement
 
post #2 of 2 (permalink) Old 12-20-2015, 02:20 PM
 
Join Date: Jan 2015
Location: Injun Territory, 'Merica!
Posts: 1,611
Mentioned: 0 Post(s)
Tagged: 1 Thread(s)
Quoted: 121 Post(s)
'64-72 Pontiac A body station wagons typically had 1/16" larger diam wheel cylinders. Olds and Buick A body's used wider drums and wider sealed axle bearing axles, often different rear backing plates, and the oddball wheel bearings used on the early Buick and Olds a body SW's are a PITA to source replacements for.

45+ years of brake jobs...Over the years, wheel cylinders were often replaced. Occasionally, entire loaded backing plates have also been swapped out, not just rears, so not that surprising. Substituting 1/16" larger bore wheel cylinders has been a fairly popular mod for decades, typically it's combined with a slightly larger bore master cylinder. I have a couple pair of A body SW wheel cylinders, will be doing a comprehensive comparison braking test with, combined with special matrix shoes, stiffer return springs, and cryoed drums. the special matrixshoes and springs are from Muscle Car Brakes.
Pinion head is offline  
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO Exhaust, Suspension, Alignment, Fuel Tank and Brakes.

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Pontiac GTO Forum 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 for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Need help with rear drum parking brake adjustment BierManVA 1964-1974 Tempest, Lemans & GTO Exhaust, Suspension, Alignment, Fuel Tank and Brakes. 4 02-10-2015 02:01 PM
Rear drum brake woes SPCMarty 1964-1974 Tempest, Lemans & GTO Exhaust, Suspension, Alignment, Fuel Tank and Brakes. 11 04-28-2013 08:02 AM
69 GTO Rear Drum to Disc Brake Conversion Kit jtwoods4 1964-1974 Tempest, Lemans & GTO Exhaust, Suspension, Alignment, Fuel Tank and Brakes. 9 02-11-2012 04:55 PM
Rear Drum Parking Brake Not Working jtwoods4 1964-1974 Tempest, Lemans & GTO Exhaust, Suspension, Alignment, Fuel Tank and Brakes. 4 01-12-2012 08:21 AM
Drum Brake Help Falco21 1964-1974 Tempest, Lemans & GTO Exhaust, Suspension, Alignment, Fuel Tank and Brakes. 10 07-20-2011 05:01 PM

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