hydroboost.... what master cylinder??

[riotwarrior]

....for those whom wonder about hydroboost brakes on the stock 3/4 and 1 tons...I installed it with the 1 5/16 MC on my Bronco and near spat my teeth through the windshield when I first hit the brakes hard....kinda over kill for a 1/2 ton brake system but oooo soo good!

 

[The Warden]

....for those whom wonder about hydroboost brakes on the stock 3/4 and 1 tons...I installed it with the 1 5/16 MC on my Bronco and near spat my teeth through the windshield when I first hit the brakes hard....kinda over kill for a 1/2 ton brake system but oooo soo good!

There's no such thing as too much braking power

 

[icanfixall]

There's no such thing as too much braking power

Thanks Tim.. Saying you have too much brake power is like saying you have too much *** in your life.. HMMMM.. Not so. This is one place where more is better. One does not need to use all of the brakes. It simply means you have more than you normally need. Thats a great feeling too.

 

[The Warden]

Saying you have too much brake power is like saying you have too much *** in your life.. HMMMM.. Not so. This is one place where more is better. One does not need to use all of the brakes. It simply means you have more than you normally need. Thats a great feeling too.

Agreed COMPLETELY!! It amazes me how much people talk about wanting to haul heavy, increase engine horsepower/torque, etc, but don't think about upgrading the most important system on their vehicles. What's the point in being able to pull a 20K trailer up a hill if you can't stop it safely? (Yes, I know that, in that case, trailer brakes are critical, but you still need as much vehicle braking as possible...what if the trailer brakes fail?)

 

[FarmerFrank]

Out of curiosity, what would you guys pay for a complete system out of junk yard? Pedals, ps pump, the works.


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[FarmerFrank]

Now that's more my style. Hard to find f450's in junk yards around here, one place wants 250 for the booster but they are always steep. The cheap yard will get one In someday


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[jaluhn83]

All ya have to do is the math on which MC is best. The size of the brake cylinders has no bearing on the volume, only on the filling time. If you take a 1-1/8" and put 50 lbs foot pressure on it, you get ~1580 lbs system pressure, take the 1-5/16" and put 50 lbs foot pressure on it and you get ~3200 lbs system pressure. That system pressure is mutiplied by the size of the brake cylinder piston area. If either MC size does the job for the stopping load, thats all that matters.

This kinda concures with what icanfixall found.

With respect, disagree - your math is backwards.

With the 1 1/8 cylinder you have ~1 sq in or piston surface area. 1 5/16 is 1.35 sq in. Assuming the same force is applied, the larger cylinder will produce less pressure - pressure = force times area.

So all things being equal, the larger cylinder with make less pressure with the same force applied....

However, the volume of fluid moved is greater for a given stroke with the large cylinder.

So the larger cylinder, all other things being equal will take a shorter movement of the petal, but more force to produce the same net braking effect.

Now, the caveat to this is that we're considering the booster and the petal to be the same in both cases. However, what we usually do is swap the vacuum booster with 1 1/8 cylinder for the hydro with 1 5/16. The hydro setup given more effective multiplication of the petal force (ie, small force pushing on the petal equals more force on the master cyl piston) due to the more powerful booster and the change in the pin location on the petal.

However, a side effect of moving the pin up on the petal is that the effective stroke of the brake master is reduced. That is, the fixed amount you can press the petal down before hitting the floor equates to a shorter distance the piston moves.

This in turn means that with a smaller cylinder you may have less then the optimal of reserve braking, since you have to move the petal further to move the same amount of fluid.

The short and simple version is that the system is designed as a whole - petal, booster & cylinder. Use all 3 together for the best results because it's all matched design wise.

 

[riotwarrior]

With respect, disagree - your math is backwards.

With the 1 1/8 cylinder you have ~1 sq in or piston surface area. 1 5/16 is 1.35 sq in. Assuming the same force is applied, the larger cylinder will produce less pressure - pressure = force times area.

So all things being equal, the larger cylinder with make less pressure with the same force applied....

However, the volume of fluid moved is greater for a given stroke with the large cylinder.

So the larger cylinder, all other things being equal will take a shorter movement of the petal, but more force to produce the same net braking effect.

Now, the caveat to this is that we're considering the booster and the petal to be the same in both cases. However, what we usually do is swap the vacuum booster with 1 1/8 cylinder for the hydro with 1 5/16. The hydro setup given more effective multiplication of the petal force (ie, small force pushing on the petal equals more force on the master cyl piston) due to the more powerful booster and the change in the pin location on the petal.

However, a side effect of moving the pin up on the petal is that the effective stroke of the brake master is reduced. That is, the fixed amount you can press the petal down before hitting the floor equates to a shorter distance the piston moves.

This in turn means that with a smaller cylinder you may have less then the optimal of reserve braking, since you have to move the petal further to move the same amount of fluid.

The short and simple version is that the system is designed as a whole - petal, booster & cylinder. Use all 3 together for the best results because it's all matched design wise.

Well said and just to add to this, the different pin location on the brake pedal adds more leverage to the actual piston on the booster if comparing the two. The Hydro pedal has a pin closer to the pivot as mentioned and this equates to a lower pedal effort and greater pressure induced on the boosters input.

This is why it is imperative to use the correct pieces designed as an integrated system to maintain balance of it.

Changing parts could in theory lead to problems, perhaps with insurance but I'm no expert so I'll leave that one for ya'll to ponder!