4speedfunk

After 240k miles with my factory rear drums, I couldn't take it anymore. They have sucked since day one, and I have been looking for an excuse to dump the entire axle for a later model version. The other day, I finally had just the reason...the old semi-float blew an axle seal and soaked the shoes. Rather than fix it, I opted to replace the whole thing. The truck is a 1999 Suburban K2500 (old body style). It had some sort of heavy duty rear axle with gigantic drums, 4.10s, and a Gov-Lok. It was not the traditional Corp 14-bolt most of know of but, it did have a round cover with 14 bolts. Frankly I don't know what it was and don't care. It is removed right now and leaking all over my shop floor!

So I pulled a REAL 14-bolt (diamond-shaped cover) from a 2005 K2500HD Silverado (6.0 gas). It was also 4.10 geared, also had a Gov-Lok, but...it had factory discs and was a full floater. Just the upgrade I was looking for! There were some slight differences in how it bolted up...e-brake cables, perches, and u-joint size. But, none of these issues were any big deal. I have the axle installed and bled the brakes today. Now my questions are focusing on the master cylinder. This Burb came with hydro-boost and I thought I would try to keep the original master cylinder but, I seem to have a huge amount of brake pedal travel and the brake light stays on. It stops but, not very well. So, I want to try a master cylinder from a 2001 Burb (new body style) which probably used a similar disc brake system. Does anybody out there know anything about drum to disc swaps on this truck? Help is appreciated, and I have a 1200 mile trip coming up in a week.

tech2

https://www.onallcylinders.com/2013/...cylinder-faqs/

4speedfunk

Thank-you. That confirms my suspicions. I'm going to try the 2001-up Suburban MC.

Terminal Frost

Not to hi-jack this thread but you did what I need to do.
By chance do you have a list of needed items that were replaced because of the swap.
I am a tenured tech so this swap is something I can fully do.
I have a '98 C2500 with the one wheel peel...massive drums and gears for pulling a house down the road LOL
Were the wheels a direct swap?
And further more, good lookin' rig!!!

4speedfunk

DRUM TO DISC REAR AXLE SWAP UPDATE:
Things you need to know when swapping 2005 K2500 HD disc brake rear axle into a 1999 OBS K2500 drum brake Burb...

The later model HD 14-bolt has some differences from the axle that came in my Burb. First, the U-joint is larger and I chose to get a new driveshaft made but, you could probably use an adapter joint. Second, the HD axle seems to have slightly taller spring perches, so this will require new u-bolts and also add about an inch of lift to your rear suspension. Additionally, the perch spacing is narrower by about an inch...so I used a ratchet strap to pull them into position and tighten the u-bolts. The e-brake system is totally different, and I used the rear cables from the 2005 and mated them to the single front cable from the 1999. This required me to use some $.89 cable clamps from Rural King...works great.

Immediately after the axle swap, I had an issue with the right rear caliper sticking, so I had to replace it. I had ordered a 2001-up K2500 Suburban master cylinder but, it did not show up in time to get it installed. I had a 700 mile road trip planned from Indy to DC, and I had no choice except to go for it. The stock pre-2000 K2500 drum brake hydroboost master cylinder DOES work with the post-2000 K2500 rear discs. However I think it could work better with the correct master cylinder. There seems to be a lot of pedal travel but, it does stop well. E-brake works well, and overall I'm very happy with the swap. I will be upgrading the master cylinder in the next month or two...


New HD disc brake axle is a very close bolt-in. Forgive the nasty shocks...those are temporary.


This came from a very rusty 2005 HD, so it needed new brake lines and a new cover (Dorman). Taller perches required new u-bolts.




Finally...the rear discs this truck has always needed!


Redneck e-brake splice...works awsome, and costs less than a cup of coffee.


Here is the original pre-2000 hydroboost master cylinder. This is for rear drum and front disc brakes. I will be replacing it with a post-2000 version that is designed for use with front and rear disc.

P.S. I'm running stock Alcoa alum. wheels (16"x7") and they fit fine. I will be upgrading to Hummer H2 wheels (17"x8.5") after the SAS.