Rear disk brake conversion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bugs4121 · 05-01-2003, 06:10 PM

Hey everyone............I know this has been brought up on different occasions but I have been saving up to do the rear brakes on my 72 K20 that has the eaton 3rd member dropout in it and now I am going back and forth on whether to stay with my drum setup or go with the disk conversion .....my drums are shot so I will have to replace those anyhow what I am asking is to have is all the pros and cons to both the drums and the disk and the best place to get the disk setup if I decide to go that route.

cleatussnow · 05-01-2003, 08:09 PM

In my opinion the best thing about disk brakes... other then they stop a heck of a lot better than drums is if you have ever had water in your brakes before and then tried to stop.. it does not work. Disk brakes wipe clean with each turn, they are the only way to go.

Sorry I cannot help on where to get a kit but I have been told that you want to make sure that your front brakes are better than your rears. So you do not want to have single piston fronts with cross-drilled and vented six piston brakes in the rear....

just my opinion.

Cleatus

nu2-72 · 05-01-2003, 09:40 PM

Look below this thread. It is on this page. Echobit for brackets, a-tron for hoses and salvage yards or parts stores for the rest. http://67-72chevytrucks.com/vboard/s...threadid=50269

Beast388 · 05-02-2003, 03:34 PM

The only disk-brake kit that I know of for the Eaton is thru Blackbird's Custom Trucks .

The thread that nu2-72 refered you to is all about the Corporate 14 bolt 73-up axle.

nu2-72 · 05-02-2003, 07:41 PM

I believe that the bolt pattern is the same for both and they both take 12.5" rotors. I have both here. Let me check again.

bugs4121 · 05-04-2003, 10:56 AM

thanks guys...I am gathering all the info before I make that choice but so far I am leaning towards the disk conversion my only draw back so far is that I dont know that much about rear disks and if I will need to add a brake proportioner to the rear brakes......... so the rear wont lock up........... but any more info you can add to my project so far will be greatly appreciated..... thanks for the info please keep it coming

nu2-72 · 05-04-2003, 01:16 PM

I have been out under my truck and in the garage. The truck is in the wet driveway. Anyway, here is what I know.
I currently run the original 10 bolt dog-dish Eaton with 4:10.

nu2-72 · 05-04-2003, 01:18 PM

The measurement across bolts is about 3 5/16".
Sorry, it is dark under there.

nu2-72 · 05-04-2003, 01:19 PM

This is verticle on the 10 bolt.

nu2-72 · 05-04-2003, 01:21 PM

This is my 79 14 bolt with 3:73 posi. The shock mounts have been moved as well as the axle pads.
Again measures 3 5/16".

nu2-72 · 05-04-2003, 01:29 PM

I checked with the local parts stores and they tell me that 3/4 rotors are the same 71 up and the 1/2 ton and 3/4 calipers are the same.
Since the bolt pattern appears to be the same for both axles I would say they are the same for mounting brackets. The only difference that I have discussed with people that make the flat brackets is the spacers.
Since I have made my own spacers, I do not need theirs. Many of the spacers provided are pipe cut to length. I have machined solid rings to provide 360 degree support.
Also, since you are going to 4 wheel disc and using front rotors and calipers you can modify the backing plates from a 4 wheel drive.
Thats how they hold them on the front. Difference is the front mount is 6 bolts and the rear is 4. Also the ID of the rear is slightly larger than the front and has to be opened up.

05-01-2003, 06:10 PM	#1
bugs4121 Registered User Join Date: Nov 2002 Location: Bowie,Maryland Posts: 56	Rear disk brake conversion Hey everyone............I know this has been brought up on different occasions but I have been saving up to do the rear brakes on my 72 K20 that has the eaton 3rd member dropout in it and now I am going back and forth on whether to stay with my drum setup or go with the disk conversion .....my drums are shot so I will have to replace those anyhow what I am asking is to have is all the pros and cons to both the drums and the disk and the best place to get the disk setup if I decide to go that route. __________________ -1972 K20 longbed -350 4 Barrel -4 speed

05-01-2003, 08:09 PM	#2
cleatussnow Registered User Join Date: Jun 2002 Location: Pleasanton, CA Posts: 162	In my opinion the best thing about disk brakes... other then they stop a heck of a lot better than drums is if you have ever had water in your brakes before and then tried to stop.. it does not work. Disk brakes wipe clean with each turn, they are the only way to go. Sorry I cannot help on where to get a kit but I have been told that you want to make sure that your front brakes are better than your rears. So you do not want to have single piston fronts with cross-drilled and vented six piston brakes in the rear.... just my opinion. Cleatus __________________ "What we are dealin' with here is a complete lack of respect for the law...." Beuford T. Justice

05-01-2003, 09:40 PM	#3
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	Look below this thread. It is on this page. Echobit for brackets, a-tron for hoses and salvage yards or parts stores for the rest. http://67-72chevytrucks.com/vboard/s...threadid=50269 __________________ 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; 05-01-2003 at 09:43 PM.

05-02-2003, 03:34 PM	#4
Beast388 Suburbans RULE! Join Date: Jan 2000 Location: Clinton, IA 52732 Posts: 689	The only disk-brake kit that I know of for the Eaton is thru Blackbird's Custom Trucks . The thread that nu2-72 refered you to is all about the Corporate 14 bolt 73-up axle. __________________ --Ben 71 GMC Suburban 4X4 The "Beast" 388 CID Stroker, TH350, NP205, 8-lug D44, 14BFF w/ Detroit, 4.10:1 gears, 4-Wheel Disks 4" Lift, 35" MT/R's.

05-02-2003, 07:41 PM	#5
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	I believe that the bolt pattern is the same for both and they both take 12.5" rotors. I have both here. Let me check again. __________________ 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

05-04-2003, 10:56 AM	#6
bugs4121 Registered User Join Date: Nov 2002 Location: Bowie,Maryland Posts: 56	thanks guys...I am gathering all the info before I make that choice but so far I am leaning towards the disk conversion my only draw back so far is that I dont know that much about rear disks and if I will need to add a brake proportioner to the rear brakes......... so the rear wont lock up........... but any more info you can add to my project so far will be greatly appreciated..... thanks for the info please keep it coming __________________ -1972 K20 longbed -350 4 Barrel -4 speed

05-04-2003, 01:16 PM	#7
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	the rain has stopped I have been out under my truck and in the garage. The truck is in the wet driveway. Anyway, here is what I know. I currently run the original 10 bolt dog-dish Eaton with 4:10. 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

05-04-2003, 01:18 PM	#8
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	The measurement across bolts is about 3 5/16". Sorry, it is dark under there. 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

05-04-2003, 01:19 PM	#9
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	This is verticle on the 10 bolt. 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

05-04-2003, 01:21 PM	#10
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	This is my 79 14 bolt with 3:73 posi. The shock mounts have been moved as well as the axle pads. Again measures 3 5/16". 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

05-04-2003, 01:29 PM	#11
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	I checked with the local parts stores and they tell me that 3/4 rotors are the same 71 up and the 1/2 ton and 3/4 calipers are the same. Since the bolt pattern appears to be the same for both axles I would say they are the same for mounting brackets. The only difference that I have discussed with people that make the flat brackets is the spacers. Since I have made my own spacers, I do not need theirs. Many of the spacers provided are pipe cut to length. I have machined solid rings to provide 360 degree support. Also, since you are going to 4 wheel disc and using front rotors and calipers you can modify the backing plates from a 4 wheel drive. Thats how they hold them on the front. Difference is the front mount is 6 bolts and the rear is 4. Also the ID of the rear is slightly larger than the front and has to be opened 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

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