Rear Disc Conversion

[gpracer1]

If you want better brakes, the only real way is to get BIGGER ROTORS. The further out from the middle that you grab, the more stopping power you will have.

Why are people saying ABS sucks? ABS has no bearing on brake performance until lockup activates it.....or the module does just before lockup.

 

[sparg93]

If you want better brakes, the only real way is to get BIGGER ROTORS. The further out from the middle that you grab, the more stopping power you will have.

Why are people saying ABS sucks? ABS has no bearing on brake performance until lockup activates it.....or the module does just before lockup.

I agree bigger rotors will help immensely (but you need 18's i think for the next step up in size), but so will better pads (incremental) and greater pressure at the caliper (significant).

To debate Hydroboost - once you get to the point of lock up, whether you have hydroboost or vacuum is a mute point, you're already there. Both systems are simply providing extra power to what your leg is exerting on the pedal.

My understanding is that hydroboost essentially gets you to lock up MUCH faster due to the greater pressure going through the caliper. If you're going 20mph, it's barely noticeable...but a panic @ 75mph will make you a believer b/c it's going to take a lot of pressure to get those calipers to exert enough force to slow down that disc.

As an example, if you put 1ton calipers of your 1/2t rig and don't change anything else in your braking system, your truck is going to take a bit longer to stop (and your pedal will touch the floor) b/c the pressure at the caliper is a few hundred PSI lower b/c your MC can only push so much pressure through.

The different between the hydroboost unit and vacuum system are monumental in terms of pressure at the caliper. (there's a good article on-line calculating the difference).

I'm not a brake expert and still in the learning phase...so please feel free to correct my assumptions and improve our understanding of these rigs!!

 

[gpracer1]

As far as stock vs hydraboost, the only difference will be brake pedal effort.

The actual braking capacity is the same, since you have the same rotors and calipers ( I assume) .

I want greater braking capacity, and with larger rotors you get that plus less pedal effort, and there is more metal to dissipate the heat. Nothing worse than coming down hill at 85 mph and hitting the brakes and feeling them heating up and not slowing down so good.

I have 20's on mine, so if I could find a caliper, bracket, and rotor that was bigger, I would do it in a heartbeat. (for cheap)

 

[sparg93]

The actual braking capacity is the same, since you have the same rotors and calipers ( I assume) .

I want greater braking capacity, and with larger rotors you get that plus less pedal effort, and there is more metal to dissipate the heat. Nothing worse than coming down hill at 85 mph and hitting the brakes and feeling them heating up and not slowing down so good.

I have 20's on mine, so if I could find a caliper, bracket, and rotor that was bigger, I would do it in a heartbeat. (for cheap)

It depends on how you define capacity and what you use your rig for. If you upgrade from vacuum to hydro (and don't change anything else), you will see a HUGE improvement in braking, but no improvement in heat dissipation ability. If you add in larger calipers and discs, those items will further increase the improvement.

However, just buying larger calipers w/o increasing the fluid being transferred to it will have negative consequences. The piston is larger in 3/4t and if you keep the same MC and vacuum, you won't change the amount of pressure behind the fluid...therefore lower binding pressure. It's the pressure on the pads exerted by the caliper that slows the disc down...lower pressure, lower ability to slow down (that's at least how I see it).

With your 20's, I would get bigger discs, 3/4t calipers (like you mentioned) and upgrade to hydroboost. If $$ was tight and you had to select the highest ROI, I personally think hydro upgrade would be a big improvement over larger discs...BUT the cost for a new/remanuf hydro + labor is considerably more then larger discs.

If you do a lot of downhill towing and you feel your pads burning up, on priority I would upgrade the pads and buy larger discs...saving hydro for another day.

If you go forward with this, measure the stopping distances for us (before/after)!!

 

[gpracer1]

First thing I did was change the warped stock rotors to Raybestos Wave rotors and some Hawk pads, stock rear JB6 drums.

The one thing that a rear disc conversion will fix is the soft/low pedal and never having to adjust.

Ultimately I would like a rear disc setup, and larger front rotors.

 

[sparg93]

The one thing that a rear disc conversion will fix is the soft/low pedal and never having to adjust.

Interesting - how would rear discs fix the soft/low pedal? (i haven't heard that before, so i'm definitely interested to hear more)

 

[gpracer1]

On a vehicle with front disc and rear drums, the pedal height is determined by the shoe adjustment. If you were to adjust them so the rears were locked, the pedal would be really high and firm, but they never are. Also the first thing to move when you touch the pedal is the rear brakes/shoes , and the travel is far if they are not kept adjusted all the time.