Decent Brakes on a 70 C10 for today

[bikertim]

I have owned a 1970 c10 short bed for many years, and although I added disc brakes many years ago it still lacks decent braking compared to other newer vehicles. I am starting on the chassis part of the restoration so now is the time to upgrade.

For strong stopping power, what is really the best bang for the buck? Hydrostatic boost or vacuum power brakes?

Can I get really good stopping power and keep the factory 15" wheels or do I need to upgrade to larger brakes/wheel and tires?

Recommendations?

[EVRLET]

I think hydro or vacuum isn’t really the focal point. To me, I look at the caliper. At a minimum I would be at a dual piston, like a Wilwood D52. Most of the cheap “disc brake conversion” kits comes with really crappy calipers, hence the cheap price. Get better calipers and upgrade your brake lines to stainless steel and you’ll notice a big improvement.

[Dynospeed]

I have the basic CCP disk brake kit with majority of factory lines. It stops decently most the time but every now and then I have to pump the brakes. I want to be able to run 15” Wheels at least on the rear. What would be the best brake combo that can still run 15” rear wheels.

[blazer2007]

can 75 corvette disc brakes be used ?

[tinydb84]

Hydroboost will significantly increase the pressure going to the calipers/drums. Increasing the size of the disc in the front would have a sizable effect as well. If you are running 15'' wheels you might be pretty limited though.

[BigTopGT]

My question here is:

My drums immediately lock up the tires in my 67, so how is going to discs up front going to do anything other than continue locking them up?

I'm not sure I'm understanding the value of more brake in a non ABS vehicle, I guess.

[Bigdav160]

Perhaps you should have started a new thread. Three benefits disc have over drums.
1. the are more heat fade resistant.
2. the shed water quickly
3. they are inherently self adjusting

[BigTopGT]

Originally Posted by Bigdav160

Perhaps you should have started a new thread. Three benefits disc have over drums.
1. the are more heat fade resistant.
2. the shed water quickly
3. they are inherently self adjusting

I'm not asking how brakes work, I'm just trying to continue the brake conversation.

If you're not here to talk about things on the forums, why be here at all??

To tell people to "use the search feature"?

Anyway, in a discussion about going with brakes that should provide greater stopping power, I'm simply curious as to whether anyone is seeing an actual stopping distance benefit to non-abs brakes, when smashing the pedal results in the brakes immediately locking up either way.

Not trying to fight here, man.

[PGSigns]

I have the standard disc swap on my 66 and over drums it is a lot better. Now jabbing the brakes will still lock up all 4 wheels, good control with a precise pedal push will bring the truck to a stop much shorter than the drums ever could. I run ceramic pads and good rear brake shoes. I have vacuum power brakes and they work fine.
Jimmy

[67C10Step]

I find disc brakes more predictable and controllable before lock up. That is where all the stopping power resides. Wheels slowing down just before lock up. When the tires lock up you go from rolling friction to sliding friction of the tires. Tires locked up and sliding will typically slide further than tires controlled to a rolling stop without locking. Thus the invent of ABS.

The self adjusting and less fade if worked hard are bonuses as well.

Some folks may not feel the same and I’m cool with that.

[68Stepbed]

Originally Posted by BigTopGT

My question here is:

My drums immediately lock up the tires in my 67, so how is going to discs up front going to do anything other than continue locking them up?

I'm not sure I'm understanding the value of more brake in a non ABS vehicle, I guess.

Originally Posted by BigTopGT

I'm not asking how brakes work, I'm just trying to continue the brake conversation.

If you're not here to talk about things on the forums, why be here at all??

To tell people to "use the search feature"?

Anyway, in a discussion about going with brakes that should provide greater stopping power, I'm simply curious as to whether anyone is seeing an actual stopping distance benefit to non-abs brakes, when smashing the pedal results in the brakes immediately locking up either way.

Not trying to fight here, man.

Keep in mind that disc brakes actually use less force than drum brakes. Disc brakes are "modulated or proportioned" compared to drum brakes. Proof in point is that Front disc/rear drum vehicles have a proportioning valve to limit the disc brakes in proportion to the rear drums.

Drum brakes are exactly that, brakes inside of a drum. This causes several issues:
1- They heat up quickly, and don't extract heat well. This is why they "lock up the wheels" as you say. Heat, caused by friction, is what makes brakes work. The quicker they heat up, the faster they work and harder they bite. This is fine for short, minimal use, but extended use causes brake fade. Brake fade is when the friction material has reached or exceeded maximum operating temperature and no longer holds. This is multiplied in a drum since it can't cool down quick enough

2- Too many moving parts. If you've ever taken the drums off to change shoes, you've noticed there's a lot of parts to make drum brakes operate. Disc brakes have pistons, whether it be a single or multiple. Those extra parts have too many failure points. And guess what the number one cause for these failures....heat....as mentioned in the first point.

3- Inconsistent pressure control. Due to the first two points, this causes the hydraulic pressures to be unevenly divided. You may ask, "What does this mean?" Try to panic stop in an all wheel drum vehicle and you'll find out. You'll get the thrill of finding out which particular wheel all that pressure wants to go first causing the vehicle to dart in one direction before the pressure equalize causing all wheels to finally garb and slow you down. That's if you're not in the ditch or into the back of the car that suddenly stopped in front of you because the brakes "locked up" causing you to slide.

Basically the safety in disc brakes is the ability to dissipate heat quickly, maintain a steady clamping force, and less failure points with minimal moving parts.

Now the reason a disc front/rear drum setup is still acceptable is because over 70% of a vehicles braking is done with the front wheels, causing less dependability of the rear drums to stop the vehicle.

[Ziegelsteinfaust]

Like someone mentioned the D52 calipers are a good upgrade, but my first suspect would be the pads.

Cheap pads have a tendency to be grabby, but that is not always the case. They can also feel weak till they heat up.

Performance pads sometimes need heat to properly work. Depending on style of pad your kit came with.

A switch in pad style can reap big rewards for you if they match your driving style.

But I would check the pads/rotors for glazing, and pedal rod first. Since you could still have your break pedal rod in the manual position which makes power breaks feel weak. Since you need to push further in for the same effect.

[SCOTI]

I haven't done the math but I see people suggesting the D52 twin piston caliper. I would verify the pressure/clamping area is actually increased before focusing on a caliper swap. The twin piston arrangement would probably better distribute the pressure applied from end to end of the brake pad if there's not much of an increase in piston compression area.

Better brake pads for sure & an adjustable prop valve to better dial in the rear brakes for the specific vehicle would be my fist steps.

[68Stepbed]

Some of you are highly underestimating the capable performance of the stock disc brakes. 71-72 C10 brake systems used 12" rotors that are a beefy 1.25" thick. Next, the calipers have massive 2 15/16" pistons, which have very aggressive clamping force. If you really want to get serious, look into the 3/4 to 1 ton truck calipers. They use a larger piston(I can't remember the sizes) and make for a good, cheap upgrade alternative.

Compared to most GM cars that have 11" rotors and smaller piston calipers, the GM truck brakes are actually more than adequate.

The two limiting factors on truck brakes are master cylinders, and brake pads. If you don't have the correct master cylinder and proportioning valve, the brakes won't work correctly. Most parts store pads are designed for low noise and low dust, but minimize bite. Just a simple pad change can change braking performance tremendously! I installed a set of Hawk HPS pads on my truck several years ago and it made braking much more efficient, especially since I was autocrossing. The down side is they're noisy and dusty. However, going to a set of Wilwood BP-10 pads will still stop well for daily drivers and occasional cruisers, and have low dust output.

[evanlove]

Bikertim,

Before you go spending a bunch of money on completely unnecessary parts...

... do you have the basic vacuum booster now (and is it functional) or just manual brakes?

... when you did the disc swap did you get the right proportioning valve for disc/drum?

... have you bled the brakes lately?

... are they just old and worn and need basic service?

... are the rear drums doing their part, are the self adjusters adjusting?

The reason I ask all these questions is that your system should work very well with what you have (unless you are carrying very heavy loads maybe).

If it isn't a race truck and you aren't carrying heavy loads down steep hills, just get a normal vacuum booster if you don't have one and service the brakes for whatever they need, they should be plenty good.

[BigTopGT]

Thanks for the detailed feedback and making this such a great discussion, fellas.

Once on the route of running a C5 Corvette disc brake conversion?

It seems like those are available, inexpensive, fairly turn key Beyond a certain point.

[Mike C]

There is a lot of good advice for you in this thread. Almost all of it is increasing the ability of the stock system but you keep wanting to throw money at it...

The Corvette brakes are NOT as good as the truck brakes for the truck application. Get some good pads and shoes, adjust the rears and drive it. Get your drums and rotors turned for a fresh surface. You should have more than enough brake for any sort of 15" tire you would have on it.

[BigTopGT]

Originally Posted by Mike C

There is a lot of good advice for you in this thread. Almost all of it is increasing the ability of the stock system but you keep wanting to throw money at it...

The Corvette brakes are NOT as good as the truck brakes for the truck application. Get some good pads and shoes, adjust the rears and drive it. Get your drums and rotors turned for a fresh surface. You should have more than enough brake for any sort of 15" tire you would have on it.

Without knowing much about the truck disc brakes, what don't you like about the C5 brakes? (C5 brake data attached)

Honesty, the only reason I brought it up is because I actually have a setup (calipers, rotors, pads, etc...) sitting around my office.

Free is a tough price to beat.

[SCOTI]

There's nothing wrong w/C5 discs. The larger rotors def dissipate heat better vs. the stock truck rotor OD limitation.

To say C5 pistons don't have as much clamping force would require a caliper to caliper comparison IMHO.

[68Stepbed]

Originally Posted by BigTopGT

Without knowing much about the truck disc brakes, what don't you like about the C5 brakes? (C5 brake data attached)

Honesty, the only reason I brought it up is because I actually have a setup (calipers, rotors, pads, etc...) sitting around my office.

Free is a tough price to beat.

C5 brakes aren't a bad option. But...yes, there's a but...by the time you buy or fabricate the parts to mount them to your spindles, you could almost just buy the upgraded parts we're referring to for less money. Remember, trucks use larger bearings on the spindles and rotors than most other GM cars and Corvettes.

[71cheyennesuperlongb]

I think what Mike C meant was the truck caliper has more clamping force than the C-5. Also remember the C-5 was about 1000 lbs lighter than our old trucks.

[BigTopGT]

Originally Posted by 71cheyennesuperlongb

I think what Mike C meant was the truck caliper has more clamping force than the C-5. Also remember the C-5 was about 1000 lbs lighter than our old trucks.

That makes sense.

Maybe I'll Robb the brakes of my C6 ZO6 for the truck.

[71cheyennesuperlongb]

I am not a brake expert by any means, I was going on what I've read here by people who do know.Rob at NOLIMIT had some good info on brakes for our old trucks in his Make it Handle thread if I remember right.

[theastronaut]

If your current brakes will lock up your current tires then you need stickier tires, not stronger brakes.

No one has mentioned tires, tire compound, grip level of the tires... You could have the most powerful brakes in the world and if you're running all season or older tech "performance" tires (Radial T/A, Cooper Cobra or similar) then you're not going to stop as quickly as better tires would allow.


Example: My '88 Ford Festiva (yes, the throwaway econobox) has front rotors that are literally smaller than my hand with single piston calipers, $6 semi-metalic pads, 30 year old original solid rotors that are grooved badly (more surface area for the pad!) and very small/narrow drums in the rear. But I have 100 treadwear Toyo R888 DOT track tires on it and coilovers that control the body motion. Anyone would look at the brakes and laugh and say that they're too small and need to be upgraded... but the "anemic" stock brakes will send you through the windshield if you're not buckled in because the tires actually grip and make the car stop instead of locking up and sliding. It's violent if you nail the brakes at 70 mph, pulling wayyy over 1g. Even with such sticky tires, it'll lock up the tires at 80, so the tiny stock brakes are all it needs.

If your stock-style 12" brakes aren't strong enough to lock up the tires then you have issues that need to be addressed, not parts that need to be upgraded. My old '66 C10 had stock D52 style calipers and 12" rotors and even with manual brakes it would easily lock up all season 215/75-15 tires up front. They were plenty powerful enough as-is, and stickier tires would've helped the truck stop even better before needing stronger brakes.

[Mike C]

Heat rejection is about mass, and the 12” truck rotors that are 1 1/4” wide have excellent heat rejection. They also have the 5x5 bolt pattern for truck wheels to bolt up to. They were designed for a truck and balanced for the truck. The stock brakes were good enough the only change GM made to them from 71-91 was to. Make the rotor have LESS mass on some later trucks. GM considered them to be sufficient for Suburbans that weighed 1000# more than a truck.

Spend some $$$ on good brake pads and if your rotors are close to minimum spec get some new ones. Otherwise get them turned for your new pads. Work at making sure system is bled, and as mentioned above, a compliant but firm suspension and sticky tires really take it to the next level. If you want it to feel more powerful and you have manual discs, the power booster will help with that.

And when you need to service it, factory 71-72 parts can be used for the brakes without having to figure out what all parts have been combined for a different solution.