GMC Truck Forum banner

1 - 20 of 40 Posts

·
Registered
Joined
·
289 Posts
Discussion Starter #1
Well after many weeks of research I finally pulled the trigger and converted to rear disc brakes. I used the 13"dual caliper setup from a 2001 Tahoe. Took about 3 hours to complete and overall was a huge improvement. I didn't changemaster cylinder, booster, porpotioning valve, or abs module. Just the rear brakes and emergency brake cables. I will post pictures tonight and a full parts list for the conversion. I have less than $500 in mine. Seems every post about this conversion turns into a disc versus drums argument so I wanted to post that it can be done, its relatively cheap, it doesnt freak out the ebcm or abs, and it does improve the braking of the nnbs. Yes I went backwards by using the gmt800 emergency brake setup but that wasn't a priority to me.
 

·
Registered
Joined
·
892 Posts
Very interested in this. Can't wait to see the parts list. Would like to see pics and a how to if you could.
 

·
Registered
Joined
·
93 Posts
same here im stoked to see the parts list
 

·
Registered
Joined
·
564 Posts
I swapped my rear axle a while back for a 14bolt 3:73 equipped one and it had disc brakes since it was a trailering package axle. All I did was swap the parking brake cables and had to bend a the hard brake lines a lil. But it did work fine and i could tell a difference in braking performance. Before I did the swap, i ran the p/n's for my truck vs. a trailering package/6.2 truck and everything in the brake system was identical except the rears.
 

·
Lesson Learned
Joined
·
445 Posts
Now by dual caliper do you mean two calipers or a dual piston caliper. Would like to do this mod. Have no use for a ebrake though
 

·
Registered
Joined
·
78 Posts
Sounds interesting. Would be great if the e brake was just as strong helps save the trans park with the boat attached. Though I wonder how it would affect the warranty.
 

·
Arbeit Macht Frei
Joined
·
358 Posts
The 4 wheel disc(even factory on the NNBS) are way better than the disc/drum combo. My '12 Tahoe stops on a dime compared to my '08 silverado with disc/drum. Much more confident hard braking when needed.
 

·
Registered
Joined
·
564 Posts
I was looking to regear my truck for the 35's, so it was a no brainer to just swap the whole rear end for one with steeper gears AND disc brakes. Truck drives and stops MUCH better now.
 

·
( o) ( o)
Joined
·
2,460 Posts
:popcorn:
 

·
Registered
Joined
·
289 Posts
Discussion Starter #11
OK SOrry for the wait.


The hardest part of the whole build is getting the backing plates for the rearend. Not the sheetmetal backing plate but the aluminum backing plate that mounts to the rearend housing that houses the emergency brake. Most salvage yards will not break apart the rearends to just sell you that part. If they have a busted rearend you can score the parts for cheap. Local autoparts stores do not sell the part either so dealership or salvage yard is your only option. This is why many give up on this because it seems you have to buy a complete rearend just to get the backing plates. SO this starts my list: All part come from a 2001 Tahoe unless stated otherwise. Anything with (JY) after it is something you can get from a junkyard or will come with a complete rearend and you can re-use to save cost.

* Disc brake backing plates 1999-2004 Silverado/Sierra 1999-2004 Tahoe/Yukon (Not sure why there is two types of ebrake hookups but there is. Single piston caliper vehicles will have a D-shaped e-brake hookup, dual piston caliper will have an S shaped e-brake hookup. Whether it is a dual piston or single piston backing plate does not effect what caliper bracket you can mount on it, it effects what parking brake cable you will need. Verify what ebrake hookup you have on your backing plate before buying your cables. Regular cab guys can probably just use Tahoe cables but you will need to verify this on your own.)

* 13" Rotors (Oreilly 580165RGS) QTY 2 ($40) (Upgrade to EBC or other brand just make sure it’s for dual piston or 330mmx96mm)
* Dual piston caliper bracket (Oreilly 14-1127) QTY 2 ($20)(JY)
* Dual piston Caliper Left(Oreilly 18-4764) QTY 1 ($51)(CORE $36) (JY if sealed)
* Dual Piston Caliper Right (Oreilly 18-4765) QTY 1 ($51)(CORE $36) (JY if sealed)
* Left rubber brake line (Oreilly BH620049) QTY 1 ($22)
* Right Rubber brake line(Oreilly BH620050) QTY 1 ($27)
* Left Parking brake cable 143.5 (Crew or Extended cab)(Oreilly BC95992 )QTY 1 ($43 )(from 2001 extended cab 143.5 silverado dual piston)(JY)
* Right Parking Brake cable 143.5 (Crew or Extended Cab)(Oreilly BC95993 )QTY 1 ($49 )(from 2001 extended cab 143.5 silverado dual piston)(JY)
* Banjo bolts (Reused original could not get correct part number)(JY)
* Brake Caliper slider bolts (Oreilly H5068)QTY 2 ($6)(JY)
* Brake caliper slider bolt boots (Oreilly 16114)($6)(JY)
* E brake shoes (Pick your poisin) QTY One per side
* Brake pads (Pick your poisin)
* Disc brake quite/grease
* Sheetmetal backing plates if rusted
* Rear end Dif fluid (DO not reuse your old fluid) (No new gasket needed on NNBS it is reusable)
* Rear end axle seals since you will be in there. If high miles you could do your bearings too.
* 99-04 brake line fittings that screw into rubber caliper hose QTY 2 (I cut the ones off the Tahoe brake lines on the rear axle in the Junk yard)(JY)

TOOLS
* Double flare brake line tool
* Axle bearing removal and installation tools (If you decide to do this part)
* Mighty vac/similar vac or pressure bleeder

It seems like a lot but if you plan it right you can convert it in 3 hours and be back on the road. Just get all your parts together before tear down.

Im not getting into detail on common mechanical parts in the how to. If you don’t know how to do something in the how to please google it or search because it’s a common mechanical procedure.

* Lift the truck and remove rear wheels, rear brakes drums, shoes and ebrake cables. (Do not remove brake line yet) Remove Rear end dif cover and drain fluid. Remove Dif pin, c-clips and axles. (Youtube has video).
* Using brake line wrench loosen brake lines from back of backing plate. Grab your bleeder screw caps (Little rubber caps found on bleeder screw of caliper or back of your drum brake backing plate) and push them over the removed brake line to seal brake line from leaking.
* Remove the 4 bolts holding Drum brake backing plate to axle.
* Remove replace axle seals/bearings if you are going to. Be careful to not damage wheel speed sensor reluctor wheel located behind axle bearing inside axle tube.
* Install Disc brake backing plates to axle. I used the original drum bolts and torqued to 80 ft lb's. The passenger side will have the ebrake lever hookup in the 6 oclock position or on the bottom and the drivers side will be in the 3 oclock position or to the rear of the truck. The plates will not install like they did on the NBS trucks because the axle nut plate is not oriented in the same way. You will end up being 45 degrees off from what the NBS is.
* RE-install axles, c-clips, and dif cover, refill with fluid.
* Install emergency brake cables and shoes. Route cables like original cables were. The passenger side cable Is a bit on short side but it’s the only option so you may have to get creative in the routing.
* Install ebrake shoes. (Watch youtube video howto. Make sure pin inside ebrake cylinder is installed correctly.
*Install rotors
*Install caliper bracket, caliper, pads, etc. They will be pointing towards the top of the truck Cab if installed like mine.
*Install rubber brake line to caliper using banjo bolt and 2 crush washers.
*Locate where you want to cut original brake hard line so it make a smooth connection to new disc brake rubber line. Cut line with brake tube cutter and install tahoe brake line fitting onto hard line. Using double flaring tool flare line and connect hard line to rubber line.
* Bleed brakes. This is the tricky part because how the caliper is clocked the bleeder screw is not the highest point and air will stay trapped in caliper if you don’t do this step. I removed the upper caliper bolt and rotated the caliper straight up. Removed brake fluid cap on master cylinder. Installed mighty vac manual hand held tool. Pulled 20 inches of vacuum then cracked bleeder screw. Shake and tap caliper while fluid is being pulled through caliper it will loosen all the air bubbles. Once you have clear fluid close bleeder screw and reinstall caliper bolt. Putting Teflon tape around bleeder screw threads will help holding a vacuum if you go vacuum route. Pressure or gravity bleeders will not have to use Teflon tape.
* Use normal brake bleeding process on front wheels. I bled the front just to pull fresh fluid into the front calipers. Keep fluid level topped off in master cylinder.
* Check for leaks
*Install wheels
*Verify brakes and ebrakes work
*Test drive
* Find dirt/gravel road and engage ABS by standing on brakes over 8 mph. I did this at about 35 mph about 4 times. This purges all air that could have made its way into abs module.
* Re-bleed brakes if pedal feels spongy after abs engagement. Air would be pushed out to calipers making spongy feel if air was in abs module.


Enjoy the new brakes! I verified the theory of EBCM controlling the rear brake bias by lowering my rear suspension setting cali style (simulating heavy tow load) and rear brakes would almost instantly lock up and trigger abs on hard brake. When I lifted the rear(hotrod rake) I could stand on the brakes on a hard brake and rears did not lock up. Pretty crazy how smart these vehicles have become.

I'm sure I have missed some things but this will get someone a long ways into the process. For the people that say just swap the whole rear-end these are the factors. The NBS Disc brake rearends may not have the 4 channel ABS ports/connections needed on a NNBS. May have to move spring perches bracket on rear end housing. Have to change and setup gears if the gears were different. The NNBS disc rear end is a much more viable solution for plug and play but still verify gears. The NNBS tahoe rear will need bracket cut and moved. The NNBS rear calipers are all single pistons versus NBS dual piston caliper.
 

·
Registered
Joined
·
289 Posts
Discussion Starter #12
Brakes look tiny inside a 26" wheel lol

IMG_20130122_220429.jpg

IMG_20130129_161216.jpg

IMG_20130129_161227.jpg

IMG_20130129_161352.jpg

IMG_20130129_161235.jpg

IMG_20130125_221215.jpg

S-Hook ebrake cable
 

·
Registered
Joined
·
289 Posts
Discussion Starter #13
Now by dual caliper do you mean two calipers or a dual piston caliper. Would like to do this mod. Have no use for a ebrake though
Yes Dual piston sorry about that.

I swapped my rear axle a while back for a 14bolt 3:73 equipped one and it had disc brakes since it was a trailering package axle. All I did was swap the parking brake cables and had to bend a the hard brake lines a lil. But it did work fine and i could tell a difference in braking performance. Before I did the swap, i ran the p/n's for my truck vs. a trailering package/6.2 truck and everything in the brake system was identical except the rears.
Bar far the easiest way to do the swap. I have narrowed my rearend and installed an eaton truetrac, richmond 4:56 gears and moser hardened axles so I had to keep mine :)

Sounds interesting. Would be great if the e brake was just as strong helps save the trans park with the boat attached. Though I wonder how it would affect the warranty.
The ebrake will be just as strong as a GMT-900 but over time the GMT-800 ebrake gets weak and you have to do maintenance on it. It will void any warranty related to brakes and rear end as you have to take it apart. Swappig in a complete new NNBS disc brake rear would be the best option if your worried about warranty. I voided every warranty on my truck in the first week I owned it.

I was looking to regear my truck for the 35's, so it was a no brainer to just swap the whole rear end for one with steeper gears AND disc brakes. Truck drives and stops MUCH better now.
True story, Feel much safer in the truck now.
 

·
Registered
Joined
·
93 Posts
so gonna hit up oreilly's next week and start stocking up parts. except parking brake. dont care about it right now i just want real brakes. later on ill do parking brake maybe. i never use it. handy you figured this out i need to replace my shoes and drums.
 

·
Registered
Joined
·
177 Posts
Great Thread, this really should become a sticky! I added up all the parts and i am at 282 at oriely's right now.

I called my local Gm dealership and talked to the parts department today, to find out the GM part #. Everywhere i went this morning had the part shown, but no part nubmer was listed.

Below are as follows.
There are 2 different types as stated before. I do not know which part number belongs to which style, but here they are. you can find both brackets on amazon for around 35$ each.

Gm part numbers

89026798

and

89026786

One difference is the number of clips the bracket has at the bottom from what I was told.
 

·
Registered
Joined
·
289 Posts
Discussion Starter #17
I'm using part number 89026786 on my truck. Looked both of them up you posted and verified it to my pictures. Everything still working like a champ on my install.

Great Thread, this really should become a sticky! I added up all the parts and i am at 282 at oriely's right now.

I called my local Gm dealership and talked to the parts department today, to find out the GM part #. Everywhere i went this morning had the part shown, but no part nubmer was listed.

Below are as follows.
There are 2 different types as stated before. I do not know which part number belongs to which style, but here they are. you can find both brackets on amazon for around 35$ each.

Gm part numbers

89026798

and

89026786

One difference is the number of clips the bracket has at the bottom from what I was told.
 

·
Registered
Joined
·
177 Posts
I am in the process of buying new wheels as well. K see you use the extensive kit, I have it as well. how close are you rear wheels to the bags? any issues with the 26"? I know I need to narrow my rear, how much did you have to narrow it? an what is your offset now with the 26" wheels?

Thanks in advance man! I will have to post a pic of my truck for you to see!



I'm using part number 89026786 on my truck. Looked both of them up you posted and verified it to my pictures. Everything still working like a champ on my install.
 

·
Registered
Joined
·
289 Posts
Discussion Starter #19
Im running firestone 2500lb bags on the rear and have an inch between the bag and tire. Only issue with 26's is you need to regear or risk blowing the transmission. How much you need to narrow is based on your offset. 26x10 +28 mm wheel needs 2 inches total narrow. Zero offset wheel needs 4 inches total narrow. A +50 mm offset wheel doesnt need to be narrowed. This is all for laying frame, not body. When narrowing the rear you can buy new axle shafts from Moser or have the stock axles shortened and resplined. To respline the stocks you have to narrow at least 4 inches.

Back to the original topic it seems we have completed the parts list and install for a disc brake conversion now, how does this get a sticky lol?

I am in the process of buying new wheels as well. K see you use the extensive kit, I have it as well. how close are you rear wheels to the bags? any issues with the 26"? I know I need to narrow my rear, how much did you have to narrow it? an what is your offset now with the 26" wheels?

Thanks in advance man! I will have to post a pic of my truck for you to see!
 
1 - 20 of 40 Posts
Top