Rear brake upgrade: 11” to 13”

[DirtyLarry]

Yeah I know, most people are busy jumping through their own pie hole junking rear drum brakes on their 4x4's for rear disk brakes but I don’t totally buy into the rear disk swaps especially with using El Dorado calipers. I hated working on El Dorado calipers when they were on El Dorados let alone to bolt those turds on my toy. No way! The late model GMT800 rear disk swaps are worthwhile but the parts are too pricy.

Anyway, as many of you know, I scrapped my dad’s K20 wrecker last week and plan to swap the wreckers axles into my Suburban but the wrecker had 13” rear brakes. My heavy K10 could benefit more from the larger 13” brakes than the Suburban so I renewed everything on the 13” brake system and swapped them over to the K10 today. WOW! With the combination of the hydroboost I swapped on a couple years ago along with these 13” brakes the big heavy truck stop on a dime now! The dang park brake finally works now too. Actually, it feels like it stops better than my stock Silverado HD with rear disks.

On with the pictures…

Off with the little 11”s




Check out the difference when the 11’s are laid next to the 13’s. I installed the new shoes, hardware and e-brake cable on the 13” backing plates last night so it make the job quick and easy today. That 13” drum is a heavy mofo!








The big 13” drums stick out much further behind the wheel


Rear view of the 11’s before tear down


The only downside is the truck gained more weight but on the other hand, Sunday I replaced the rear winch cable with Viking winch rope so it somewhat balances out with losing some weight and gaining other weight. The junk Smittybilt winch broke yet again so while it was apart I figured it was time to ditch the wire cable...that is where the Viking winch rope came on the scene. I’ve used the Smittybilt winch about 3 times and it has broken 2 of those times. This past time the motor wouldn’t stop running once I hit the switch. This time it needed a new relay pack. Errr

Now I have to get to work on rebuilding these 11" brakes and finish getting the D44 front axle ready for the Suburban.

[blakeduren]

Can you run us through the process of tightening down the spindle nuts etc when putting the drum/hub back on?

[DirtyLarry]

Originally Posted by blakeduren

Can you run us through the process of tightening down the spindle nuts etc when putting the drum/hub back on?

Just tighten the inboard spindle nut until your elbow clicks then install the lock washer and outer spindle nut. Tighten the outer spindle until the veins in your forehead stick out.

Hehe, just like asking my mother in-law for a recipe. She doesn’t measure anything just a dash of this and sprinkle of that. In all reality just tighten the inboard spindle nut enough to set the bearing preload then back it off a tad. The outer nut just needs to be good and snug. I’ve been messing with full floaters since I was in high school so I never really torque anything on these after the first few, just go by feel.

One recommendation is to replace the spindle nut assembly when you have these full-floaters apart as the locking ring/washer dealeo tends to get pretty beat up after being taken a part even once. The Dorman Part number for the spindle nut kit is 05310, Napa’s part number is BK 6301660

Here is a wasted lock ring dealeo. Don’t reuse one that looks like this as I have seen rear hub/wheel assemblies separate from the vehicle when they fail and the spindle nuts back off.


Here is the new Dorman spindle nut kit. Best $45 per side you can spend when bolting a full-floater back together.

[BLAZERMAN]

I did this swap several years ago on a 3/4 ton 14 bolt that I used in my dually...those 13" drums are massive!

On my cab & chassis rear I'm working on now it uses a different type of spindle nut that gets keyed to the spindle and has a wire type retainer..pretty slick way of locking the spindle nut.

[Iron Hauler]

I would like to do this on the 14 bolt I have in my 75 k/20. are all the 13" brakes the same on these, is there anything I should stay awAy from? 3/4 and 1 ton the same? im sure ill have to by a couple of those kits as mine have been apart several times before
Posted via Mobile Device

[DirtyLarry]

Originally Posted by Iron Hauler

I would like to do this on the 14 bolt I have in my 75 k/20. are all the 13" brakes the same on these, is there anything I should stay awAy from? 3/4 and 1 ton the same? im sure ill have to by a couple of those kits as mine have been apart several times before
Posted via Mobile Device

No, actually….not all are the same. The only difference I found is the 1984 and later rigs, albeit 11” or 13”, have a different e-brake connection at the brake drum backing plate. The earlier ones have a two bolt fastening method at the brake drum backing plate while the later have are a push in design. The good news is the Bendix backing plates are very universal in that a backing plate from a 9.5” semi-float POS axle with 13 x 2 brakes is the same as the backing plate for 13 x 3.5 on the big 10.5” full-floaters.

In my next situation where I will be putting a ’78 10.5” axle in an ’89 Suburban I must use the ’89 Suburban’s 9.5” axles backing plates on the 10.5” axle in order to use the later design park brake cables. YES…….Confusing, I know! Since I run manual transmission is almost everything I own a park brake is a must!

Got to love GM for their consistency in parts interchangeability though! Just figuring out the correct concoction of parts to make it all work is fun part.

[OldCreek]

Once again, Larry, you've educated me! I've been planning on doing a disc brake conversion on the 14 bolt I bought for my 1 ton build. But, I never realized it had 13" drums. Now, I may not switch them out....

I was planning on using a driveline e-brake/Cutting Brake set up for the np205...to keep or not. It still could be useful to have and I already paid for it!

[72longbed]

I remember when I converted my 14 bolt full floater with 13" drums to disk brakes, and weighed the pile of parts I took off when done. My truck lost 75 lbs that day.

I converted the HO72 Eaton to disks too. Old Creek, I'd be interested in learning more about that "Cutting Brake" / Parking Brake for the NP205? What can you tell us about it? Any pics of the setup?

Thanks.

[OldCreek]

Check High Angle Drive Line in Cal: http://www.highangledriveline.com/e_brake.html

I've never used one. It appears that it would have greater holding power than regular drum e-brakes but I'm guessing at that...

[aotte1]

Larry,

Very good information you posted.

Interested in upgrade to 13" drums too, for Dana 60, is it correct that your discussion above is for Eaton rear axle? How much applies to '71 Dana 60s with 12x2.5 brake shoes?

A few questions, on possibility of upgrading a '71 Dana 60 12x2.5 brake to 13 inch drums. Thinking of two/three possibilities while keeping stock axles:
1). We're their Dana 60 applications that used 13" drums which can be switched to '71; and

2). Can Dana 70 13" brakes be switch, all from backing plate out. Maybe 80s Suburbans?

3). Other option, e.g. 70s Fords 3/4 ton that used 12x3 brake shoes, chevy dually brakes



Thanks,
Les

[DirtyLarry]

Originally Posted by aotte1

Larry,

Very good information you posted.

Interested in upgrade to 13" drums too, for Dana 60, is it correct that your discussion above is for Eaton rear axle? How much applies to '71 Dana 60s with 12x2.5 brake shoes?

A few questions, on possibility of upgrading a '71 Dana 60 12x2.5 brake to 13 inch drums. Thinking of two/three possibilities while keeping stock axles:
1). We're their Dana 60 applications that used 13" drums which can be switched to '71; and

2). Can Dana 70 13" brakes be switch, all from backing plate out. Maybe 80s Suburbans?

3). Other option, e.g. 70s Fords 3/4 ton that used 12x3 brake shoes, chevy dually brakes



Thanks,
Les

My rear axle is a Corp 10.5 14 bolt. Much different than Dana rear axle. Not sure what all can be swapped in the Dana rear axle world as I've never messed with them other than just maintenence work.

[mike16]

Originally Posted by aotte1

Larry,

Very good information you posted.

Interested in upgrade to 13" drums too, for Dana 60, is it correct that your discussion above is for Eaton rear axle? How much applies to '71 Dana 60s with 12x2.5 brake shoes?

A few questions, on possibility of upgrading a '71 Dana 60 12x2.5 brake to 13 inch drums. Thinking of two/three possibilities while keeping stock axles:
1). We're their Dana 60 applications that used 13" drums which can be switched to '71; and

2). Can Dana 70 13" brakes be switch, all from backing plate out. Maybe 80s Suburbans?

3). Other option, e.g. 70s Fords 3/4 ton that used 12x3 brake shoes, chevy dually brakes



Thanks,
Les

I'm interested in the same idea, upgrading dana 60 drums with bigger drums. I'll be watching this post. looking forward to good info.

maybe dana 60 drum brake upgrade should be a whole new thread????

[ranger danger]

Originally Posted by OldCreek

Check High Angle Drive Line in Cal: http://www.highangledriveline.com/e_brake.html

I've never used one. It appears that it would have greater holding power than regular drum e-brakes but I'm guessing at that...

Any idea who makes an e-brake kit for the drive line on a Dana 60 2x4?

[JIMs70GMC]

I am doing the same thing Larry, swapping a CUCV rear under my K5. Going to keep the 13" drums.

[aotte1]

Larry, thanks for more information on which axles you upgraded to 13".

Mike, agree going to start new thread for Dana 60 brake upgrade.

Les

[special-K]

Are you saying you have a drum brake on the driveshaft of your C/20? I have seen those on the C/30s with 11K# axle option. If you show a picture we might know exactly what you have

[ranger danger]

Originally Posted by special-K

Are you saying you have a drum brake on the driveshaft of your C/20? I have seen those on the C/30s with 11K# axle option. If you show a picture we might know exactly what you have

No. I'm saying I have a Dana 60 rear and would like info on a disc e-brake mounted to the piniun.

[j2rkt88]

Awsome post... I'm getting ready to do a differential swap on my 1984 GMC Camper special that has a 9.5" semi floater and the 13" drums which has been making noise for years, but now the pinion seal failed and the noise has gotten much worse.
I acquired a 1977 C-20 with the heavy commercial suspension (G51?) with a 10.5" 14 bolt and the same 13" brakes. I'm keeping that huge front sway bar !!!.
I noticed, the E brake set up is completely different between the two trucks and was flummaxed as to what to do, but .... if... the backing plates between the two differentials will interchange, then I'm back in business. I just wish the drums and brake parts would interchange also.
Anyway.. great post.

[treborjm]

Sorry for the newb question.

I can't seem to find a definitive answer...

Will a square body (80's) 2WD 3/4 Ton 14 bolt FF axle fit a '84 K10 shortbed?

I can't figure out what the differences are after a VERY short search tonight. Was thinking that I had seen a link on the pirate site to an axle buyers guide.

I can get my hands on a couple of different 80's 2WD 14 Bolt FF axles, but want to make sure. I'd rather not have to weld perches/shock mounts.

EDIT: I found this site, (http://www.pirate4x4.com/tech/billav...ble/index.html) which makes it sound like the axle would work... but, I'm hoping someone will chime in and clarify.

Thanks

Rob

[DirtyLarry]

Originally Posted by treborjm

Sorry for the newb question.

I can't seem to find a definitive answer...

Will a square body (80's) 2WD 3/4 Ton 14 bolt FF axle fit a '84 K10 shortbed?

I can't figure out what the differences are after a VERY short search tonight. Was thinking that I had seen a link on the pirate site to an axle buyers guide.

I can get my hands on a couple of different 80's 2WD 14 Bolt FF axles, but want to make sure. I'd rather not have to weld perches/shock mounts.

EDIT: I found this site, (http://www.pirate4x4.com/tech/billav...ble/index.html) which makes it sound like the axle would work... but, I'm hoping someone will chime in and clarify.

Thanks

Rob

The short answer is yes, a 2wd or even 4wd ¾ ton rear axle will bolt right into a ½ as the perches are in the same location. 1 tons have different spring perch locations where the perches need to be cut off and moved when installing a 1 ton rear axle into a ¾ ton or ½ ton.

As an example, the 10.5” FF that has been in the back of my 1978 K10 for the past 20 years came from a 1976 C20. That said, keep in mind 10.5” 14 bolts get harder to find in ¾ (20 series trucks) after 1980 as most ¾ tons were equipped with the 9.5” 14 bolt semi floater beginning in 1981 as part of the weight reduction thing GM had going on. 10.5” full floaters were still used albeit typically only in ¾ tons with big blocks or diesels. A 2wd Suburban all the way to 1991 with a 454 or diesel will have a 10.5 full floater 99% of the time. The spring perches line up with a ½ ton too so Suburban make great vehicles to pirate axles from.

Edit: one last thing... don't forget the obvious pieces that need to be dealt with when doing a full floater swap. The U-bolts, spring plates (u-bolt plates need to come from the axle donor truck), u-joint and park brake cables need to be dealt with as well.

[sweetk30]

and 2wd shock tabs were flip flopped on the axle .

[DirtyLarry]

Originally Posted by sweetk30

and 2wd shock tabs were flip flopped on the axle .

Some, but not all. I've seen a few different shock tabs in 3/4 ton 10.5" full floaters. My buddy just recently got one out of a 77 C20 with really tiny shock tabs where as others I have seen had longer tabs for longer shocks.

[treborjm]

Good Stuff!!! Flopped as in the direction, front to back is different?

Now... I just need to find some 13 inch mounting brackets. No plans for disk brakes for me.

Thank you!

Rob

[1950Bowtie]

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[Toomanysubs]

Can anyone help???
I have a 1987 Chevy suburban 2500. It is a 350 gib with th400 trans. 4X4 it started life with a 9.5” semi floating rear. The carrier had a lot of slop and I had a 10.5” full floating rear out of another truck. Ever since I installed it the stopping power has been horrible. All of the rear brakes are new except drums which were cut and well within tolerance. I didn’t change the booster or master or proportioning valve. Also my truck still has the rear weight/level sensor and the brake lines do go through it. But they always did. My other two suburbans are a 1982 3/4 two 2wd. And I can lock it’s brakes up if I push the pedal too quickly. It is a 9.5”. Am I just expecting too much from the 10.5” brakes? Thank you in advance for any help or suggestions I really appreciate it. This is my plow truck and I’m trying to get it figured out before the snow flies. Again thank you!