Adding Rear disc Brakes, which way to go?

[Kenz72K5]

Ok, been a member for a couple of years, havent been very active as far as posting, but do read many. I started my build almost 3 years ago, this 72 Chevy K5 had been used as a Hunting Rig. but had a LS1 and a 6L80 that runs like a Scolded Dawg! I recently Retired from working on Jets after almost 38 yrs. from the DFW area, and Moved My K5, My 2017 ZR2 and Wife to The Big Island of Hawaii. so parts are hard to come by, It will be a Full Time Convertible. My Brakes are questionable at best, so im wanting to add Disc's to the rear. Im wondering if I would be better off finding a rear end from a later model GM truck with factory disc's, or getting a kit. im thinking of adding a Hydroboost system to it also. Any recommendations on which rearend would be
best, as a lot of Old trucks are still on the Islands! TIA !

[LS short box]

I would contact Tobin at Kore3.com. He's a brake specialist more geared towards the pro-touring crowd but he might be able to help.

[Kenz72K5]

Thanks! will do, was thinking maybe others may have done a similar swap and would know which rear ends would be a simple swap.....

[Richard]

Personally, I am a fan of using off the shelf parts for wear items like brakes. Reason I used the 2006 2500HD rear axle with disk and 2009 Ram 3500 brakes on my custom D60 front axle in my build. Rear axle width is real close to the front axle width (stock) on my 72 K10. Rear axle matches front now instead of being shorter like stock. Your 72 K5 would have the same axles as my K10. There is a six lug axle in the same year that would fit your needs. Details can be seen in my build thread.

[franken]

Ask why you want rear disk brakes. They add little braking effect but look cule.

[Richard]

Originally Posted by franken

Ask why you want rear disk brakes. They add little braking effect but look cule.

More modern, OEM's would not have switched without a reason. It costs them money. In my case, needed an 8 lug axle. No reason not to use something more current. Probably never have to do rear brakes again because my truck will not haul anything. Disk brakes do not fade as much as drums in wet conditions.

[franken]

More modern means cheaper, not better. It costs you little to maintain rear drum brakes for the same ~25% effectiveness.. Spend the money on something that makes a difference.

[jjzepplin]

I would find out what is wrong with your current brakes before you upgrade. Your hoses could be bad or something more simple.

[A1971Blazer]

Originally Posted by franken

More modern means cheaper, not better. It costs you little to maintain rear drum brakes for the same ~25% effectiveness.. Spend the money on something that makes a difference.

Originally Posted by jjzepplin

I would find out what is wrong with your current brakes before you upgrade. Your hoses could be bad or something more simple.

I agree, I just rebuilt the entire braking system on my '70 K/5 with disc fronts, now it will lock all 4 wheels with no problem.
The front brakes do most of the stopping, and if it can lock the wheels with rear drums, I see no reason to put disc on the rear, other than cosmetic appeal or you just want to lock the rear wheels more easily.

[cdub2010]

If your engine doesnt produce enough vacuum, a swap to hydroboost is a good idea. I really dont notice a huge difference in brake performance in my vehicles based on booster type. If you want to swap to disc or hydroboost, you cant really beat factory parts for reliability and serviceability. A rear disc axle swap to a newer one with a parking brake is a good idea, its the one thing im lacking and I dont like about my 14 bolt rear disc swap on my k20. I will add I have had no better performance than the original drums after the swap.

[truckster]

Originally Posted by franken

Ask why you want rear disk brakes. They add little braking effect but look cule.

Originally Posted by franken

More modern means cheaper, not better. It costs you little to maintain rear drum brakes for the same ~25% effectiveness.. Spend the money on something that makes a difference.

I'm an old guy who has no problem with drum brakes, but I can see younger guys wanting something they're more familiar with.

[hemi43]

Originally Posted by franken

Ask why you want rear disk brakes. They add little braking effect but look cule.

What he said!

Old axles are not designed for rear disc brakes and you shouldn't put them on regardless if some company makes them.
The only old axles that are suitable for rear disc are the Ford 9" and the Dodge 8 3/4" with pressed on bearings amongst a few others.
If your diff uses C clips, keep the drums. There's too much side play therefore you risk having spongy brakes that you will never get rid of. There's nothing wrong with rear drum brakes.
Do what you want, but I've been in this game for many years.

[H8tulooze1]

I bought this one, was easy but the only bad thing was the E-brake cables about 3" too short. I bought a universal e-brake cable kit, no issues.

https://www.ebay.com/itm/230620582265

[Tom Vogel]

If you add Hydroboost, you will not need rear disks.

[jaros44sr]

Originally Posted by tom vogel

if you add hydroboost, you will not need rear disks.

x2

[Richard]

Originally Posted by franken

More modern means cheaper, not better. It costs you little to maintain rear drum brakes for the same ~25% effectiveness.. Spend the money on something that makes a difference.

There are advancements in technology. I am old school, but am willing to accept that new things may offer benefits. I needed to swap, what are the benefits to put an older axle in? Installing 14" front disks and 13" rear disks + hydroboost in my truck if anyone cares.

[franken]

Again rear brakes provide ~25% of braking. Changing them to disk costs money and provides no benefit unless brake fade is an issue.
You can spend your money on whatever you want, but one wonders why when the improvement is cosmetic.

[Richard]

Originally Posted by franken

Again rear brakes provide ~25% of braking. Changing them to disk costs money and provides no benefit unless brake fade is an issue.
You can spend your money on whatever you want, but one wonders why when the improvement is cosmetic.

Again, I needed an 8 lug axle for my project. Sourcing an old 14 bolt axle in my area, rebuilding and re gearing would have cost me the same or more than what I spent on the AAM 11.5 + the regear. There is no downside.