Disc Brakes Worth It?

[DTrain]

Wondering if a disc brake conversion is worth it? I’ve got a ‘99 OBS CCLB k3500 SRW. It’s big and heavy and has a trailer hooked up 50% of the time.

I’ll be getting into a four corner brake job this winter, which means a full tear down of the drums too which very last due. Aside from sweat equity, I can’t see too much price difference in a full drum rebuild and disc conversion. So I’m wondering what the advantage is of one or the other.

Other then a couple backwoods camping trips a year, this truck is on the road only. I do pull mountains where I’m at, which is the hardest thing I ask of the brakes.

 

[letitsnow]

I switched to discs on my '99 K2500 when facing a similar rebuild as you. Mine is the semi float rear.

My truck now seems more daily driver friendly in town - almost seems like the on/off of the brakes happens quicker. There is basically no maintenance with the discs back there. I don't notice any more power just from the discs.

Most aftermarket/mods just aren't bolt on and go - you (most times) seem to have to finish designing stuff for them. If you rebuild the oem brakes, that isn't an issue.

For the use that you have described, and if you don't mind adjusting your drum brakes - I would rebuild them.

 

[DTrain]

Yeah, that’s kind of what I was wondering. The truck has seemed to stop pretty good as is over the years. Those drums back there are humongous, so if there’s no difference really noticeable, I don’t mind to adjust from time to time.

 

[toomanyhobbies]

I went full hydroboost conversion with a GMT800 booster and the little shop rear disk kit and powerstop rotors and calipers in front. It was a lot of work to get all of the parts together and get it right but if I had to guess I would say it reduced the stopping distance by 1/2, but that's only compared to the standard half ton brakes not the giant 2500/3500 rear drums.

 

[stutaeng]

I've thought about this as well. I have the same similar truck with 5.7/Auto. There are bolt-on kits that are pretty economical nowadays, most likely from the ever-so-popular 14 bolt FF.

Here's one kit:https://lugnut4x4.com/product/14-bolt-full-float-rear-disc-conversion-kit/

https://offroaddesign.com/catalog/14FFdisckit.htm#When_converting_to_disc_brakes

However, there's seems to be some issue with Ebrake? So I think that will drive up the cost.

The disc setup will be lighter; as you pointed out the rear drums are ginormous!

 

[Frankenchevy]

Disc conversions to 14ff typically utilize front calipers from a 1/2 ton truck which offer no e-brake or rear calipers off of something like a 78 caddy el dorado. They have provisions for cable pull parking brakes, but take some work to get them right. I went with the latter on my 14ff equipped truck. I bought the calipers new and they didn't come with the armature that connects the caliper's piston to parking brake cable. I had to figure it out on my own.

My truck is a CUCV and came with an np208 transfer case unlike most k30s. there are companies out there that make driveline brakes for np205s. however, if your state has inspections, which mine does not, hydraulic parking brakes may be an issue. If not, there may be a solution to the transfer case in your truck. A line lock is also an option, but again may bleed off pressure over time.

The other thing I swapped was the brake proportioning valve, due to the factory one being designed for disc/drum. You'll also likely need to rework the rear brake lines.

The benefits are possible performance advantages in muddy/wet conditions, shaving 100lbs of mass off the rear axle (much of which is rotational mass) and ease of future maintenance.

Hope this helps some.

 

[stutaeng]

Disc conversions to 14ff typically utilize front calipers from a 1/2 ton truck which offer no e-brake or rear calipers off of something like a 78 caddy el dorado. They have provisions for cable pull parking brakes, but take some work to get them right. I went with the latter on my 14ff equipped truck. I bought the calipers new and they didn't come with the armature that connects the caliper's piston to parking brake cable. I had to figure it out on my own.

My truck is a CUCV and came with an np208 transfer case unlike most k30s. there are companies out there that make driveline brakes for np205s. however, if your state has inspections, which mine does not, hydraulic parking brakes may be an issue. If not, there may be a solution to the transfer case in your truck. A line lock is also an option, but again may bleed off pressure over time.

The other thing I swapped was the brake proportioning valve, due to the factory one being designed for disc/drum. You'll also likely need to rework the rear brake lines.

The benefits are possible performance advantages in muddy/wet conditions, shaving 100lbs of mass off the rear axle (much of which is rotational mass) and ease of future maintenance.

Hope this helps some.

So did the stopping characteristics change at all? Decreased stopping distance? Does your truck have hydroboost setup?

 

[Frankenchevy]

So did the stopping characteristics change at all? Decreased stopping distance? Does your truck have hydroboost setup?

Yes, it is hydroboost. My rear brakes weren’t great when I got the truck and it still had the load sensing valve over the rear axle. This was a valve on Squares that had an arm that went from the frame to rear axle to “sense” the load in the bed. With 1-1/4ton suspension, my trucks rear suspension would rarely squat down, so the rear brakes probably weren’t receiving much pressure due to that.

There was a GM service bulletin to bypass the valve—so when I rebuilt the brakes, I did. Now, they get full available pressure from the proportioning valve. That alone was probably enough to notice a difference, so it’s not really an honest comparison.

The load sensing valve used to be where I circled. I don’t believe GMT400 trucks have anything similar.

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[Gibson]

The load sensing valve used to be where I circled. I don’t believe GMT400 trucks have anything similar.

I don't know about all of them, but my '94 CC, 9,200 GVW SRW had one,, the '97 Sub, 8,600 GVW does not have one.

 

[95C1500]

I have torn apart, cleaned, adjusted, etc my drum brakes multiple times over the last 7 years of ownership. I hate them. They constantly make noise, constantly need adjusting, constantly have parts failing (shoe hold down pins fell out once.. yes, I did install them correctly). They are just a headache.

I am swapping to discs eventually. The money is the only reason I haven't yet. If nothing else, disc brakes are, in my opinion, easier to work on. Even if I have the same issues, I'd rather replace disc brakes than drum brakes.