TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > Suspension, Steering, Brakes & Wheels
  New Posts New Posts RSS Feed - disc brake conversion
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

disc brake conversion

 Post Reply Post Reply Page  <123>
Author
Message
amx39068 View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Feb/21/2008
Location: Arizona
Status: Offline
Points: 11576
Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/06/2012 at 11:00pm
How would you like me to phrase a response to a post that potentially exposes the OP to a dangerously inadequate brake fluid resevoir when converting to old school disc brakes with a large resevoir engineered into their design?

The OP already clearly stated that he is a little clueless about what master/booster combo to use. Adding variables that only serve to further confuse the issue rather than simplify it serves no purpose, does not answer the original question and creates the potential that the OP will use parts that do not work well thus be exposed to unnecessary risk of brake failure.

Not sure what part of Bill's post you read that supported your position but what I read clearly stated that if all is not working as intended and designed there is the potential that the smaller master disc resevoir could run dry.

Just because a responder may be comfortable taking that risk on their own car, it is not appropriate to impose that added degree of risk on others who may or may not be as knowledgable about brakes and/or as diligent about checking the fluid levels as the person providing the response may be.
Dan Curtis-Owner and CEO AZ AMC Restorations; Facebook: https://www.facebook.com/amcmusclecars/ & Curtis Real Estate Development
Back to Top
toolmanxiii View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Oct/16/2010
Location: Moncton Canada
Status: Offline
Points: 1384
Post Options Post Options   Thanks (0) Thanks(0)   Quote toolmanxiii Quote  Post ReplyReply Direct Link To This Post Posted: Sep/07/2012 at 4:41am
Any small body disc brake booster /master will fit . I installed  one from an 86 eagle into a 74 Gremlin X. just remember the large bowl is always the disc brakes . 
My 71 hornet now has the complete system from a 77 hornet wagon 
And a drum master cannot hole enough fluid to support disc calipers . That is an accident waiting to happen. as pad wear the calipers need more fluid to take up the space . 


Edited by toolmanxiii - Sep/07/2012 at 4:46am
71 360 Hornet sst 83 2wd 360/727 Eagle wagon (crashed)
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 19612
Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Sep/07/2012 at 4:53am
Point taken Dan.

Bill just made the comment that once the fluid is in the piston that's it as far as the reservoir is concerned (more or less). As I previously stated, the reservoir size has nothing to do with the braking capacity or performance.

Modern cars no longer use the larger reservoir. If you don't check the brake fluid for 30-40,000 miles (roughly the life of pads) there will be enough fluid in the large reservoir so that the front discs remain fully functional, that's the only purpose of the large reservoir on an old style disc brake MC. You know this, but for others... As the pads wear the piston doesn't retract as much and a little more fluid remains in the caliper, unlike drum brakes that have return springs that pull the wheel cylinders back to the same position all the time (the adjustment screw is at the bottom, doesn't affect wheel cylinder position).
Frank Swygert
Back to Top
73hornut View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/03/2007
Location: Southern Oregon
Status: Offline
Points: 3129
Post Options Post Options   Thanks (0) Thanks(0)   Quote 73hornut Quote  Post ReplyReply Direct Link To This Post Posted: Sep/07/2012 at 7:30am
I have front disk on the gremlin with the drum master, and have no problems with fluid level. Just check more often, say when you get oil changed.
71 Javelin
74 Gremlin
79 Spirit AMX
Rogue Valley Rumblers
Like Us on FB
https://www.facebook.com/groups/1602825606650796
Back to Top
toolmanxiii View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Oct/16/2010
Location: Moncton Canada
Status: Offline
Points: 1384
Post Options Post Options   Thanks (0) Thanks(0)   Quote toolmanxiii Quote  Post ReplyReply Direct Link To This Post Posted: Sep/07/2012 at 10:34am
I worked at a Garage a few years ago with an older mechanic . He was almost killed when a car fell off the jack and broke his arm. when asked by investigators what happened he said "I don't understand , I've been doing it this way for 20 years" ..... Just because you can does not make it right . If drum masters were made for disc's why make one for disc's .

Just my 2 cent's 

Edited by toolmanxiii - Sep/07/2012 at 10:41am
71 360 Hornet sst 83 2wd 360/727 Eagle wagon (crashed)
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 19612
Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Sep/07/2012 at 4:01pm
If you don't understand the differences and why they are there, and why they MAY not matter, then you don't need to make changes. In some cases, such as for the 3.1" piston "Big Bendix" calipers, the MC needs to be different. Some disc system have a longer stroke as well as a larger piston, and some have a stepped piston with a larger section for the front brakes and a smaller one for the rear (I know that's how Wagner made some of their early drum dual MCs, not sure if anyone makes a disc/drum setup like that or not).

I can tell you from taking the MCs apart that the small piston calipers use the same internal dimensions as the drum brake MC. The only difference is the size of the reservoir, and I've already explained why the reservoirs were originally designed that way -- as well as why they aren't any more.

At least the older 60s cars also used a different pedal for power vs. manual brakes. The reason is that the power brake cars used a bell crank to transfer motion up 3-4" for clearance. That's why the bracket holds the booster out from the fire wall, so there is room for the bell crank and the booster can be moved up to clear the intake on sixes, left cylinder bank on V-8s. The bell crank needs a bit more pedal stroke, not much, an inch at most. If you use a booster setup with a manual brake pedal the pedal will go to about 1/2" from the floor. You have to change or modify the pedal to sit about an inch higher to have the needed stroke without feeling like you're running out of brake pedal.


Edited by farna - Sep/07/2012 at 4:05pm
Frank Swygert
Back to Top
toolmanxiii View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Oct/16/2010
Location: Moncton Canada
Status: Offline
Points: 1384
Post Options Post Options   Thanks (0) Thanks(0)   Quote toolmanxiii Quote  Post ReplyReply Direct Link To This Post Posted: Sep/07/2012 at 6:28pm
I understand the difference in masters . I have rebuilt enough of them . but read what you just said . we  do not know what he is running for calipers or master . so its better to go with the proper parts . yes some internals are the same . but what happens if you take the car in and tell the mechanic to top up the brake fluid while getting the oil changed and he forgets ? I check mine often as I do all fluids . but most people don't . sorry if you think I'm saying you are wrong that was not the intent . I think you should build a car for the next guy that might own it . 
71 360 Hornet sst 83 2wd 360/727 Eagle wagon (crashed)
Back to Top
ramblinrev View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: Dec/28/2008
Location: Wisconsin
Status: Online
Points: 11473
Post Options Post Options   Thanks (0) Thanks(0)   Quote ramblinrev Quote  Post ReplyReply Direct Link To This Post Posted: Sep/07/2012 at 6:41pm
Gentlemen, I think we have a difference of opinion here. Farna has made his points clearly, and they haven't satisfied all of you. I never encourage cutting corners on brake work and I don't sense that Farna does either. Maybe give it a rest...Wink

Edited by ramblinrev - Sep/07/2012 at 6:41pm
74 Hornet Hatchback X twins (since 1977)
62 American Convertible (still worth the $50 I spent in 1973!) AMCRC #513, AMO #384
70 AMX 360 4-speed (since 1981)
Back to Top
toolmanxiii View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Oct/16/2010
Location: Moncton Canada
Status: Offline
Points: 1384
Post Options Post Options   Thanks (0) Thanks(0)   Quote toolmanxiii Quote  Post ReplyReply Direct Link To This Post Posted: Sep/08/2012 at 3:52am
71 360 Hornet sst 83 2wd 360/727 Eagle wagon (crashed)
Back to Top
amx39068 View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Feb/21/2008
Location: Arizona
Status: Offline
Points: 11576
Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/08/2012 at 9:29am
Originally posted by toolmanxiii toolmanxiii wrote:

http://rust-free-parts.com/BP.html



That's Greg Beyer's website. He is no longer in Phoenix and rumor has it that he moved up to NoCal in Lodi to work with someone who was formerly an AMC vendor. It is my understanding that Greg was able to move most of his small parts but not sure if he ended up scrapping all the cars or not.
Dan Curtis-Owner and CEO AZ AMC Restorations; Facebook: https://www.facebook.com/amcmusclecars/ & Curtis Real Estate Development
Back to Top
 Post Reply Post Reply Page  <123>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.141 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or