Wildblue19
I'm Awesome
Long time lurker, 1st post here.
I have been working on a budget "big brake" upgrade for my 93 Burb, consisting of the new 2019+ Silverado 13.6" rotor. This idea came from my research which showed that the new trucks use a huge rotor but share the 6x5.5" bolt pattern and 78mm center bore diameter as the OBS K1500 rotors. They provide much more thermal mass to resist brake fade and increased braking torque.
I bought these rotors from summit and they fit perfectly over the factory 6 lug hub.
Of course, larger wheels will be necessary - I plan to fit 18s to the truck but some 17s may fit.
I originally wanted to use the 2019 Silverado 4 piston calipers, but the width between the bolts on the caliper meant that I wouldn't have enough meat on the factory spindle to make a conversion bracket.
After several trips to the auto parts store, I found that a 2005 ram 1500 caliper fits well and is a twin piston caliper with only a 7% greater piston area over the 2.94" single piston factory caliper. Therefore, a master cylinder swap may not be necessary. These calipers also have a much larger pad surface area when compared to both the OBS and 2019 caliper pads.
In order to fit the larger rotor, I had to cut off the "ears" on the factory knuckle that the caliper uses to slide on. Not an issue as the 2005 ram calipers use a built in bracket and don't require sliders on the knuckle.
After cutting the ears and old caliper mounting bolts out, the 2005 caliper fits well between the remaining material left on the knuckle. Reference picture for illustration.
I modeled the system in fusion 360 and found that the cast iron knuckle is more than strong enough to withstand the braking load of the new caliper and rotor combination (forces derived from a simple energy equation). I found that 1/2" or thicker 4140 or stronger steel is required for the conversion bracket for an acceptable factor of safety (4+).
I decided to use 3/4" 17-4 PH stainless for its corrosion resistance and ease of machine ability for the bracket - will be milling this weekend and provide updates. Material sourced from McMaster.
I also milled the factory knuckles where the adapter plate will mount, however I found the surfaces to be within less than 10 thou of each other so this may not be necessary.
Attaching pics of my progress as it comes along.
I originally pulled two knuckles off of a 1991 K1500 pickup, however I found out after the fact these trucks dont have the 4WAL ABS sensor mount points that my 93 has. So, if you would like to embark on this project yourself I have two of these knuckles for sale in great condition.
Feel free to post thoughts on anything I may have overlooked and other input. Thanks.
WB
I have been working on a budget "big brake" upgrade for my 93 Burb, consisting of the new 2019+ Silverado 13.6" rotor. This idea came from my research which showed that the new trucks use a huge rotor but share the 6x5.5" bolt pattern and 78mm center bore diameter as the OBS K1500 rotors. They provide much more thermal mass to resist brake fade and increased braking torque.
I bought these rotors from summit and they fit perfectly over the factory 6 lug hub.
Of course, larger wheels will be necessary - I plan to fit 18s to the truck but some 17s may fit.
I originally wanted to use the 2019 Silverado 4 piston calipers, but the width between the bolts on the caliper meant that I wouldn't have enough meat on the factory spindle to make a conversion bracket.
After several trips to the auto parts store, I found that a 2005 ram 1500 caliper fits well and is a twin piston caliper with only a 7% greater piston area over the 2.94" single piston factory caliper. Therefore, a master cylinder swap may not be necessary. These calipers also have a much larger pad surface area when compared to both the OBS and 2019 caliper pads.
In order to fit the larger rotor, I had to cut off the "ears" on the factory knuckle that the caliper uses to slide on. Not an issue as the 2005 ram calipers use a built in bracket and don't require sliders on the knuckle.
After cutting the ears and old caliper mounting bolts out, the 2005 caliper fits well between the remaining material left on the knuckle. Reference picture for illustration.
I modeled the system in fusion 360 and found that the cast iron knuckle is more than strong enough to withstand the braking load of the new caliper and rotor combination (forces derived from a simple energy equation). I found that 1/2" or thicker 4140 or stronger steel is required for the conversion bracket for an acceptable factor of safety (4+).
I decided to use 3/4" 17-4 PH stainless for its corrosion resistance and ease of machine ability for the bracket - will be milling this weekend and provide updates. Material sourced from McMaster.
I also milled the factory knuckles where the adapter plate will mount, however I found the surfaces to be within less than 10 thou of each other so this may not be necessary.
Attaching pics of my progress as it comes along.
I originally pulled two knuckles off of a 1991 K1500 pickup, however I found out after the fact these trucks dont have the 4WAL ABS sensor mount points that my 93 has. So, if you would like to embark on this project yourself I have two of these knuckles for sale in great condition.
Feel free to post thoughts on anything I may have overlooked and other input. Thanks.
WB
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