caliper backing plates explored - The 1947 - Present Chevrolet & GMC Truck Message Board Network

nu2-72 · 11-25-2009, 03:03 PM

I am going to post a bunch of pictures here. This is in no way the definitive answer on plates and I am learning all the time. This is just what I have found and would love more input if anyone has more.
I owe D. Passmore and duallyjam an appology for a mis-identification on a plate. Hope this helps clear some stuff up.

nu2-72 · 11-25-2009, 03:10 PM

I am working on my truck and the front axle is missing one of the dust shields on the Dana 44. Trying to find a replacement has been almost impossible because of the age and rust.
So I decided to go with later model solid steel backing plates.
I purchased three plates from a local yard stating that I needed 3/4 ton and I ended up with 1/2 ton. He said they are all the same. Wrong.
While the calipers and pads are the same, rotors are different and so the mounts are different as well.
1/2 ton rotors measure 11.86" OD and 3/4 ton are 12.5" OD. This changes the plates just a little bit but it is enough that if you try to use the 1/2 ton pltes on a 3/4 ton, the rotors will cover up the caliper threaded holes and will not work.
Obviously the difference is .860" and divided over the diameter is .320" radius. That is enough to mess with mounting the caliper.

nu2-72 · 11-25-2009, 03:15 PM

I ended up buying a complete truck for the plates that I needed. But I have decided to use the solid plates on the rear axle instead.
I am showing a dust shield that has a half moon shape and these came from a 1/2 ton truck.
My 3/4 ton has dust shields with two tabs and a notch between. They are also a little heavier gauge than the 1/2 ton.

nu2-72 · 11-25-2009, 03:23 PM

The confusion on my part started when David was looking for 1/2 ton plates and duallyjam posted a pic that looked like 3/4 ton to me. But he pulled them from a Blazer so they had to be 1/2 ton.
I am still trying to learn all the different configurations and sizes. Shouldn't be too many.
I took the heavy plates and drilled the four bolt pattern for the rear axle flange into the plates. I then mounted the plate to the axle. Next was to press the wheel studs out and remove the drum. Then a rotor was added and the assembly was placed on the axle. I used this assembly to measure the distance needed to install the caliper and that determined my spacer width. Next I built the spacers and added 1/4" to the width. This allowed me to turn a 1/4" step. I then bored the backing plates with the new diameter for the spacer allowing the step to set into the 1/4" plate flush to the inside. I bolted the spacer to the axle slid the plate on, set a caliper on and rotated the plate until the bleeder was straight up and marked the set. I will TIG weld the inside and MIG the backside. Plates and spacers will be all one piece.

nu2-72 · 11-25-2009, 03:25 PM

few more

nu2-72 · 11-25-2009, 03:27 PM

last pics are under my old truck.

11-25-2009, 03:03 PM	#1
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	caliper backing plates explored I am going to post a bunch of pictures here. This is in no way the definitive answer on plates and I am learning all the time. This is just what I have found and would love more input if anyone has more. I owe D. Passmore and duallyjam an appology for a mis-identification on a plate. Hope this helps clear some stuff up. Attached Images __________________ 72 3/4 4x4 350 4spd 72 3/4 4x4 350 auto 2004 Duramax Silverado 4x4 2006 Duramax Crew cab 4x4 2010 Harley Ultra Limited 2011 Harley Street Glide

11-25-2009, 03:10 PM	#2
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	Re: caliper backing plates explored I am working on my truck and the front axle is missing one of the dust shields on the Dana 44. Trying to find a replacement has been almost impossible because of the age and rust. So I decided to go with later model solid steel backing plates. I purchased three plates from a local yard stating that I needed 3/4 ton and I ended up with 1/2 ton. He said they are all the same. Wrong. While the calipers and pads are the same, rotors are different and so the mounts are different as well. 1/2 ton rotors measure 11.86" OD and 3/4 ton are 12.5" OD. This changes the plates just a little bit but it is enough that if you try to use the 1/2 ton pltes on a 3/4 ton, the rotors will cover up the caliper threaded holes and will not work. Obviously the difference is .860" and divided over the diameter is .320" radius. That is enough to mess with mounting the caliper. Attached Images __________________ 72 3/4 4x4 350 4spd 72 3/4 4x4 350 auto 2004 Duramax Silverado 4x4 2006 Duramax Crew cab 4x4 2010 Harley Ultra Limited 2011 Harley Street Glide Last edited by nu2-72; 11-25-2009 at 03:32 PM.

11-25-2009, 03:15 PM	#3
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	Re: caliper backing plates explored I ended up buying a complete truck for the plates that I needed. But I have decided to use the solid plates on the rear axle instead. I am showing a dust shield that has a half moon shape and these came from a 1/2 ton truck. My 3/4 ton has dust shields with two tabs and a notch between. They are also a little heavier gauge than the 1/2 ton. Attached Images __________________ 72 3/4 4x4 350 4spd 72 3/4 4x4 350 auto 2004 Duramax Silverado 4x4 2006 Duramax Crew cab 4x4 2010 Harley Ultra Limited 2011 Harley Street Glide

11-25-2009, 03:23 PM	#4
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	Re: caliper backing plates explored The confusion on my part started when David was looking for 1/2 ton plates and duallyjam posted a pic that looked like 3/4 ton to me. But he pulled them from a Blazer so they had to be 1/2 ton. I am still trying to learn all the different configurations and sizes. Shouldn't be too many. I took the heavy plates and drilled the four bolt pattern for the rear axle flange into the plates. I then mounted the plate to the axle. Next was to press the wheel studs out and remove the drum. Then a rotor was added and the assembly was placed on the axle. I used this assembly to measure the distance needed to install the caliper and that determined my spacer width. Next I built the spacers and added 1/4" to the width. This allowed me to turn a 1/4" step. I then bored the backing plates with the new diameter for the spacer allowing the step to set into the 1/4" plate flush to the inside. I bolted the spacer to the axle slid the plate on, set a caliper on and rotated the plate until the bleeder was straight up and marked the set. I will TIG weld the inside and MIG the backside. Plates and spacers will be all one piece. Attached Images __________________ 72 3/4 4x4 350 4spd 72 3/4 4x4 350 auto 2004 Duramax Silverado 4x4 2006 Duramax Crew cab 4x4 2010 Harley Ultra Limited 2011 Harley Street Glide Last edited by nu2-72; 11-25-2009 at 03:41 PM. Reason: added info

11-25-2009, 03:25 PM	#5
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	Re: caliper backing plates explored few more Attached Images __________________ 72 3/4 4x4 350 4spd 72 3/4 4x4 350 auto 2004 Duramax Silverado 4x4 2006 Duramax Crew cab 4x4 2010 Harley Ultra Limited 2011 Harley Street Glide

11-25-2009, 03:27 PM	#6
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	Re: caliper backing plates explored last pics are under my old truck. Attached Images __________________ 72 3/4 4x4 350 4spd 72 3/4 4x4 350 auto 2004 Duramax Silverado 4x4 2006 Duramax Crew cab 4x4 2010 Harley Ultra Limited 2011 Harley Street Glide

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