Editing Brakes (section)
Jump to:
navigation
,
search
===Master cylinders=== A dual reservoir master cylinder (MC) is used in any modern vehicle and should be used on older vehicles that had single reservoir master cylinders. Usually a drum brake master cylinder will not work for disc brakes because the bore size is too small, and the drum brake MC may have a built in residual valve. ====Power master cylinder diameter and pedal ratio==== Most times, a master cylinder for a power brake system should have a pedal ratio of about 4:1 when using a master cylinder bore diameter of 1-1/8". ====Manual master cylinder diameter and pedal ratio==== Most times, a master cylinder for a manual brake system should have a pedal ratio of about 6:1 when using a master cylinder bore diameter of 1". As a rule of thumb, a pushrod attachment point on the brake pedal about 1" above where the power brake attachment point was (closer to the pivot point) will be about right for a manual brake system. If using a bore larger than 1" on a manual system, the brake pedal effort can become very high. [[File:Pedal ratio1.jpg|thumb|700px|left|Pedal ratio guidelines from mpbrakes.com]] <br style="clear:both"/> The problem sometimes encountered when using a disc/drum manual MC on a 4-wheel disc system is inadequate volume to the rear disc brakes. Calipers take more volume than drums. If there's not enough volume, the pedal will bottom before the brakes are fully applied and the pedal will not be firm. To use a disc/drum MC on a 4-wheel disc system, the MC needs to be capable of about 1200 psi and has to have adequate volume to operate the rear disc calipers. The MC bore needs to be about 7/8" to 1", and the pedal ratio needs to be around 5:1. Be sure to remove the residual pressure valve to the rear drums. An adjustable proportioning valve can be used to adjust the front-to-rear brake bias. =====Pedal ratio/bore size vs. pressure output===== <table border="1" cellpadding="2" cellspacing="0" width="595"><tr bgcolor="#CCCCFF"><td class="tdName" width="20%">'''Pedal Ratio'''</td><td class="tdName" width="20%">'''Bore Size'''</td><td class="tdName" width="25%">'''Pounds Input'''</td><td class="tdName" width="25%">'''Approx. PSI Out'''</td></tr><tr class="trLight"><td>6:1</td><td>1-1/8</td><td>75</td><td>450</td></tr><tr bgcolor="#eeeeee" class="trDark"><td>6:1</td><td>1 </td><td>75</td><td>575</td></tr><tr class="trLight"><td>6:1</td><td>7/8</td><td>75</td><td>750</td></tr><tr><td bgcolor="#oooooo" colspan="4"></td></tr><tr bgcolor="#eeeeee" class="trLight"><td>5:1</td><td>1-1/8</td><td>75</td><td>375</td></tr><tr class="trDark"><td>5:1</td><td>1 </td><td>75</td><td>475</td></tr><tr bgcolor="#eeeeee" class="trLight"><td>5:1</td><td>7/8</td><td>75</td><td>625</td></tr><tr><td bgcolor="#oooooo" colspan="4"></td></tr><tr ><td>4:1</td><td>1-1/8</td><td>75</td><td>300</td></tr><tr bgcolor="#eeeeee" class="trDark"><td>4:1</td><td>1</td><td>75</td><td>380</td></tr><tr class="trLight"><td>4:1</td><td>7/8</td><td>75</td><td>500</td></tr></table><p>
|
Editing help
(opens in new window)
Personal tools
Log in / create account
Namespaces
Page
Discussion
Variants
Views
Read
Edit
View history
Actions
Search
Navigation
Main Page
Recent changes
Random page
Help
All articles
Start a new article
Hotrodders forum
Categories
Best articles
Body and exterior
Brakes
Cooling
Electrical
Engine
Fasteners
Frame
Garage and shop
General hotrodding
Identification and decoding
Interior
Rearend
Safety
Steering
Suspension
Tires
Tools
Transmission
Troubleshooting
Wheels
Toolbox
What links here
Related changes
Special pages
Terms of Use
Copyright
Privacy Policy
Your Privacy Choices
Manage Consent