Brakes
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The reason a RP valve shouldn't needed is because disc brake calipers have no retraction mechanism like a drum brake. A drum brake has springs that pull the shoes away from the drum, calipers don't. It would take 'vacuum' applied to the brake fluid to cause the caliper piston to retract- and that's what happens when the MC is BELOW the calipers and the fluid tries to run "downhill" to the MC. | The reason a RP valve shouldn't needed is because disc brake calipers have no retraction mechanism like a drum brake. A drum brake has springs that pull the shoes away from the drum, calipers don't. It would take 'vacuum' applied to the brake fluid to cause the caliper piston to retract- and that's what happens when the MC is BELOW the calipers and the fluid tries to run "downhill" to the MC. | ||
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If you have a soft pedal w/a 4-wheel disc non assisted brake system it could be due to air in the lines- bleeder screws on the bottom (calipers swapped side to side) will cause air to be trapped and a soft or spongy pedal. A too-high pedal ratio, a defective MC, or too small MC bore will also cause it. | If you have a soft pedal w/a 4-wheel disc non assisted brake system it could be due to air in the lines- bleeder screws on the bottom (calipers swapped side to side) will cause air to be trapped and a soft or spongy pedal. A too-high pedal ratio, a defective MC, or too small MC bore will also cause it. | ||
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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. | 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. | ||
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| + | ==Pedal ratio/bore size vs. pressure output== | ||
| + | <table border="1" cellpadding="2" cellspacing="0" width="595"><tr bgcolor="#CCCCFF"><td class="tdName" width="25%">'''Pedal Ratio'''</td><td class="tdName" width="25%">'''Bore Size'''</td><td class="tdName" width="25%">'''Pounds Input'''</td><td class="tdName" width="25%">'''PSI Out'''</td></tr><tr class="trLight"><td>6:1</td><td>1-1/8</td><td>75</td><td>453</td></tr><tr bgcolor="#eeeeee" class="trDark"><td>6:1</td><td>1 </td><td>75</td><td>573</td></tr><tr class="trLight"><td>6:1</td><td>7/8</td><td>75</td><td>748</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>377</td></tr><tr class="trDark"><td>5:1</td><td>1 </td><td>75</td><td>477</td></tr><tr bgcolor="#eeeeee" class="trLight"><td>5:1</td><td>7/8</td><td>75</td><td>623</td></tr><tr><td bgcolor="#oooooo" colspan="4"></td></tr><tr ><td>4:1</td><td>1-1/8</td><td>75</td><td>302</td></tr><tr bgcolor="#eeeeee" class="trDark"><td>4:1</td><td>1</td><td>75</td><td>382</td></tr><tr class="trLight"><td>4:1</td><td>7/8</td><td>75</td><td>499</td></tr></table><p> | ||
===Brake boosters=== | ===Brake boosters=== | ||
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