'76 K25 Brake Rotor Replacement... How?

[Rust-O-Matic]

I wanna replace the front brakes on my '76 GMC K25, pretty much in their entirety (pads, rotors, calipers, hoses, etc.). I believe the axle is a Dana 44, 8 lug, and does not have locking hubs, as this truck has the full time NP203 transfer case.

This is probably a stupid question, but how does the rotor come off? Does the rotor and hub come off as an assembly like a 14 bolt? Is it held on there with a nut that takes a special socket? I'm rounding up supplies and was wondering if I need to acquire a large spindle nut socket, or any other special stuff before I get started.

My '74 service manual does not appear to show a breakdown for the 'full time' style hub assemblies, only the locking type, so I'm not sure if that info is relevant to mine.

I searched several threads on this site as well, but can't seem to find exactly the same setup as mine. I must be overlooking something, I assumed these were super common. Any input would be appreciated.

[MJN]

The hub and rotor come off as an assembly. The drive flange is held on with 6 studs and under the center dust cap is a snap ring. With the flange removed you will need a special socket to take the spindle nuts off, then the whole hub and rotor will come off the spindle. You'll have to press the wheel studs out if you want to replace the rotor and then probably replace the studs while you're at it. The spindle nut socket is the only special tool you'll need unless you're doing ball joints at the same time.
I had the same drive flanges on my '74 K20 until I switched it to a NP205 and put Spicer hubs on.
There is also a pdf file of the Dana 44 service manual located at this thread http://67-72chevytrucks.com/vboard/s...d.php?t=545416
The second page shows the drive flange, studs, snap ring, dust cover, etc. used on the 8-lug Dana 44 with external style hubs (1st design 1973-1977).
Scroll down until you get to the axles/steering section.

[Rust-O-Matic]

Perfect! Thank you for the thorough reply. The breakdown in that PDF is exactly what I wanted to see.

[MJN]

Sure thing- glad to help. Post some pictures too while you're at it, always good to see what we're all working on.

[Rust-O-Matic]

Here's a quick recap of how this went and a few pics.

I've included a pic of all the parts I replaced with their numbers visible on the boxes. Not pictured were also a pair of calipers from Carquest, and a pair of Dorman speed bleeders, which I think were #12701. The calipers came with new slider bolts, so I didn't end up using the ones in the pic. The black box with the X through it is an unrelated box of brake hose clips from a different project. Not sure how that got mixed in.

1. Lift up the truck and remove hideous '90s wheels.

2. Marvel at how crusty the existing parts are.

3. Remove caliper slider bolts (3/8" allen) and caliper.

4. Remove (6) drive flange bolts.

[Rust-O-Matic]

5. Pry dust cover off, and remove circlip around end of axle shaft.

6. Slide drive flange off of axle shaft.

7. Get a 4 prong spindle nut socket, 2 3/8" diameter

8. Remove outer spindle nut. It's freakin tight.

9. Slide lock washer off, and remove the inner 4 prong spindle nut.

[Rust-O-Matic]

10. Slide the rotor and hub assembly off.

11. & 12. Press old wheel studs out.

13. Pull inner hub seal and remove bearing.

14. Clean and repack bearings, clean hubs, reinstall bearings and new seals.

[MJN]

Looks good- you got lucky and the drive flange bolts all came out on yours. Mine still had the original studs and I had several break off. If you're that far in, especially since everything in there is turning since it's a full-time 4x4, its not a bad idea to pull the caliper bracket and spindle and replace the spindle seals and bearing, as well as check/replace your axle shaft u-joints.

[Rust-O-Matic]

15. Press new wheel studs in.

16. Install hub and rotor onto spindle, reassembly is reverse of disassembly.

Spindle nut torque values seem to vary depending on what I read. I torqued the inner ones to 50 lbs while turning the rotor, then backed it off 1/4 of a turn. The outer nuts I torqued to 125 lbs. Also, I was not able to reuse the original metal flange gaskets, and instead used a little black silicone.

17. Install new rubber hoses, calipers, pads, slider pins, and speed bleeders. Bleed brakes, slap those ugly wheels back on, and call it a day.

I should be good for another 50k or 40 years, whichever comes first.

[Rust-O-Matic]

Originally Posted by MJN

Looks good- you got lucky and the drive flange bolts all came out on yours. Mine still had the original studs and I had several break off. If you're that far in, especially since everything in there is turning since it's a full-time 4x4, its not a bad idea to pull the caliper bracket and spindle and replace the spindle seals and bearing, as well as check/replace your axle shaft u-joints.

Yeah, it's kinda one of those "where do you stop?" type of things. This truck is used almost entirely around my property and sees maybe 100 miles a year on the highway. I'm confident there's all sorts of other things that need to be inspected and replaced, but it's just not really worth the effort or expense as long as it's still serviceable.

Unrelated side note, before I owned it this truck was used to backfill graves. The flatbed has a pto driven dump cylinder under it.

[sweetk30]

also after pressing in wheel studs do a road test and re check lug nut torque . then also again after 50 miles . this is a good thing to do since you are re seating the studs from being removed .

[67pro-street]

Thanks for the great write up and photos! I've got a question as I just bought a 75 K20 and need to do a front brake job as well. for the rotor and hub assembly, did you use a hydraulic press to separate the two and then also have to press them back in, or can you use a hammer and drift to separate the two pieces and be able to transfer the hub back to the new rotors? Thanks!

[Rust-O-Matic]

Originally Posted by 67pro-street

Thanks for the great write up and photos! I've got a question as I just bought a 75 K20 and need to do a front brake job as well. for the rotor and hub assembly, did you use a hydraulic press to separate the two and then also have to press them back in, or can you use a hammer and drift to separate the two pieces and be able to transfer the hub back to the new rotors? Thanks!

No sir, no press required. I just used a hammer and large flat blade screwdriver to separate the two pieces.

[67pro-street]

Awesome, thank you for the help! Have a great night!