Power brake upgrade question

[1970blazin]

I am wondering what my options are for getting better braking power....
I know I can just upgrade to disc front brakes, but what else do I have to do??
Power booster??
Push Rod???
Anything else??
Also I have nice new drums up front is it possible to just do the power booster with the drums up front and NOT switch to the discs???
Sorry if these are stupid questions, I just trying to find out my options.
Thanks-
Diane

[grayw0lf]

You sure can go to power brakes & keep your drums up front. I did it last night. You just need a booster, bracket, & push rod. I may eventually go to discs up front, but it stops just fine w/ drums all around.

John

[JimKshortstep4x4]

A power booster installed on your drum brake system will improve stopping substantially. The biggest drawback with drum brakes is their tendacy to fade with repetitive use, (as in going down a long steep grade with constant use).

Going to discs without power assist will help very little if any on stopping your truck. (Discs don't fade like drums so that would be a plus).

If you go to power discs the master cylinder has to be changed to disc style and the push rod is different for the booster to master cylinder.

Jim

PS: Those are not "stupid" questions.

[CPNE]

Power drums would be a good upgrade, a disk brake conversion is overkill unless one or more of the following apply:
1. Towing heavy loads
2. Frequent driving down steep grades
3. Driving in excessive traffic/stop and go.

For 95% of us, none of these apply, so your cost/benefit ratio is nill. Plus you already have new shoes and I assume they are in good working order. Get yourself the pedal rod/booster bracket assembly off any 67-70 truck, add a new 3/4 ton booster, and bolt on your existing master cylinder/prop valve. If your master cylinder is old, replace that as well. You'll get far more cost vs safety benefits from having a fully serviced power drum/drum system than you will converting to disks.

I will conceed that disks are easier to maintain and are more trouble free (maintenance) in the long run. But don't run out and convert just because someone tells you drum brakes are not safe. The overriding factors are how safe a driver are you and under what conditions do you drive. Remember even with disks it'll still be a 34 year old vehicle and should be driven with that in mind.

[Stepsides 4Ever]

If disc brakes were not superior to drum brakes, manufacturers would still be offering disc brakes as an option. I don't think you will find very many vehicles produced in the last quarter century that did not come standard with disc brakes.

Drum brakes have gone the way of hand-cranked engines, generators, ignition points, and tube-type radios. Granted, you don't actually need any of these things as the originals worked and worked well when properly maintained. The old mechanical brake systems would stop, too, when adjusted properly. Remember the old argument against early hydraulic brakes? if you were driving off a cliff, which would you want to grab ahold of...a cable or a hydraulic hose?

So the argument that if all you want to do is stop, then drum brakes will do the job, is not very compelling, in my opinion.

[grayw0lf]

If I am not mistaken. When converting to discs up front, you do not need a new master cylinder. You need a new proportioning valve.

Correct me if I'm wrong

John

[CPNE]

Originally Posted by grayw0lf

If I am not mistaken. When converting to discs up front, you do not need a new master cylinder. You need a new proportioning valve.

Correct me if I'm wrong

John

You need both. Disks require a larger resevior

[Stepsides 4Ever]

The master cylinder has a residual check valve for both front and rear brake circuits, to hold line pressure at a low value to keep the wheel cylinders from collapsing due to the return spring tension on the brake shoes. Disc brakes have no return mechanism, hence no need for a residual valve, and if you do not remove it you will have a constant drag on the front discs.

Apart from that, disc brakes work on a low volume, high pressure principle, whereas drum brakes work on a high volume, low pressure principle. The master cylinders for disc/drum brake setups are engineered for this difference. That's not to say that a drum/drum master cylinder will not work in a disc/drum setup, just that if you are going to the expense and trouble to convert to a disc/drum setup, why not do the complete job with the right master cylinder for the application? Think about this: knowing the differing operating principles between drum and discs, and knowing you are going to be increasing the line pressure dramatically to the front brakes, would you hesitate at replacing the front brake hoses as well? I suggest that you save your money until you can afford to do the whole job...

[CPNE]

Originally Posted by Stepsides 4Ever

... So the argument that if all you want to do is stop, then drum brakes will do the job, is not very compelling, in my opinion.

Do brakes serve any other function?

Both arguements have merit. I was addressing it from a cost/benefit standpoint for most trucks, under most circumstances, for most drivers. The psychological benefits may make it worthwhile to you, but the safety benefits are still minimal (again under most circumstances). However, if you feel safer, you have a tendency to driver more aggressively, thereby minimizing any or all safety gain. I see this played out every winter, it's the guy with the 4x4 that whizzes past you on the snowy road that is often in the ditch 1 mile up the road.

[Stepsides 4Ever]

I think we can both agree that safety is a relative term, and also that disc brakes are more safe than drum brakes. What would also be even more safe would be not to drive at all, and the argument becomes ludicrous at this point.

I agree with you that properly maintained drum brakes provide a level of safety such that most resonable people would not hesitate to ride or drive in a vehicle that had them. Where I think we disagree is in the "cost/benefit is nil" aspect...I think disc brakes are worth every penny. As a matter of fact, most of us use them every day, so much so that we take them for granted. And when you get behind the wheel of your favorite truck on the weekend, you have a tendency to forget that Ol' Blue, she don't stop on a dime like the new ones do. But then I use my brakes a lot, because here in Southern California we have a lot of traffic and not everyone knows how to drive.

If you have someone nearby that has disc brakes on their truck, do the test: in a panic stop situation, which stops first: drums or discs? Then try the test again. Who wins?

[FRENCHBLUE72]

Diane I am sure that wes or frank could hook ya up with what ever set up you go good luck and keep us posted on what you decide to do..

[CPNE]

Originally Posted by Stepsides 4Ever

... But then I use my brakes a lot, because here in Southern California we have a lot of traffic and not everyone knows how to drive....

I think that is why we percieve things differently and you fall into my 5% (20%?) category (excessive traffic/stop and go). I'm fortunate to live where life is "slower" and the nut behind the wheel is properly torqued down I can't remember the last time I had a panic stop, much less 2 or more in a row.

The gain for me would not be worth the cost/effort, for your environment it is. Again, supporting my initial points for Dianne to consider.

No question about the "fade" factor, disks win every time. I do have a 67 1 ton with drums and that truck stops every bit as well as my later model disk trucks. Probably due to the oversized shoes and drums installed on 1 tons however.

[69K10 Tank]

So my question to add to all of this, will a disc/drum master cylinder/booster set up work with a drum/drum brake system?

[Stepsides 4Ever]

will a disc/drum master cylinder/booster set up work with a drum/drum brake system?

No, mostly because it is lacking the residual valve in the front brake circuit, but it is also engineered for a different application so there may be other compatibility issues as well. As pointed out earlier, the reservoirs are larger for a disc brake master cylinder, because disc brakes generate a bunch more heat than drum brakes. A booster is a booster, though, so you can use your manual brake master cylinder with the disc/drum booster, provided the pushrod(s) are correct...

[JimKshortstep4x4]

Disc and drum master cylinders are different and should be used with their respective systems. Boosters will work in either system.

Not knowing 1970blazin's situation, a power drum setup might be appropriate. We run a 70 4x4 with power drums and it stops extremely well. We don't have steep grades to contend with so fading is not an issue. I agree with CPNE, drum brakes do work well and they can be considered as an option depending on the type of driving that is done.

Jim

[Stepsides 4Ever]

At the risk of belaboring this, I agree wholeheartedly that power drum brakes are a vast improvement over non-power brakes, and most certainly you can and probably should perform that upgrade. I've done that very thing on our '56 Nomad, as well as a '67 Chevy II Nova SS bought brand new that we no longer own, and I'm very comfortable with them, so please don't misinterpret. The cost/benefit of a full-on disc brake conversion, on the other hand, is a highly subjective decision, so only you can make that call.

[1970blazin]

Thanks for all the input guys! I love this board- even if we sometimes "disagree"--- it is nice to hear all sides of this topic.
I am definately going to do the power brake booster, and I am still juggling the idea of the discs up front. We could probably get ahold of a front axle off a 71 or 72 and just swap them with mine.
If I swap the front then I would also need:
1. master cylinder/brake booster
2. push rod
3. proportioning value??

I will not be in bad traffic, or hauling loads, or worrying about steep downgrades, BUT
I will have the 2 most important things in my life in the back seat- my 2 boys! :-) Stopping is very important, and I don't want to have to "stand" on the brakes to stop- especially with these short legs! Ha!
Diane

[LONGHAIR]

The most important thing in all of this is the proportioning valve. The risidual valve has to be there for the drums (front or rear) and it cannot be there for discs. The only real need for the larger volume of a disc brake master cylinder is for the volume need as the pads wear down. The rear brakes are adjusted by the screw adjusters at the bottom and the fluid requirement doesn't change as the shoes wear. If you keep an eye on the fluid level, you will be ok.
The amount of fluid need during the actual stop is not that much different.
An adjustable prop. valve is a good idea though.
The biggest benefit of discs on the front is in the "automatic fluid adjustment" that keeps the brakes working more evenly. You don't get a pull from one side being out of adjustment.

[MACKL]

One more issue, your drum brakes may have the 6 hole lug set up. When converting you will have to add the cost of new wheels as well as the brake parts. On the plus side, you have a much better selection of wheels in the 5 lug set up.

[Jeepster376]

Nice discussion on the disks vs drums.

I think if your looking to improve the brakes on your driver the booster is an easy upgrade, disk conversion could be considered for a later upgrade. But if your putting a whole new truck together now, I'd do the front disks now for a better driver and simpler maintenance forever.

[Stepsides 4Ever]

The only problem with an adjustable proportioning valve is that you have to adjust it, which involves slamming on the brakes and seeing which locks up first, front or rear. As long as you don't mind doing this on a back road somewhere, the adjustable ones that I've seen are less expensive than the OEM/replacement parts...and, they are new units, not 30-something years old. Keep in mind, however, that we have an inherent problem: the rear of our trucks, unladen, is very light...but put a load of feed back there, or a pallet of bricks, and weight distribution changes pretty dramatically. Some newer vehicles have a mechanical device that compensates for this, but we don't, so all you can hope for is to get it close, and drive accordingly.

I'm pretty sure, once you've installed the power booster, that you will feel a lot more secure in your ability to stop. That may be all you need, like CPNE said. In a panic stop situation, though, you really need to stand on the brakes early on, when your rate of speed is at the highest. Unfortunately, that is the point where you will feel the brakes "fade", requiring substantially more effort to bring your speed down. We have a 11,000-lb. GVWR 27-foot motorhome that I have had to panic stop, more than once (we've had it for 15 years), and anybody that tells you that power disc brakes will not "fade" is not being truthful. I have actually had to use both feet on the pedal, because I couldn't apply enough controllable pressure with one foot. Have you ever wondered why power brake pedals are wider than non-power brake pedals? Now you know. I think they should all be wider, wide enough so that when my wife thinks I should be stopping, she can apply the brakes from her side of the vehicle instead of just stomping on the floor...

So, basically, here's the deal: do you opt for the 3/4- or 1-ton booster/master cylinder, or a newer dual-diaphragm unit, and tread very lightly on the pedal during your normal day-to-day driving, or do you go with the 1/2-ton booster and hope you'll never need more than that? Keep in mind that, whater your choice is, you'll have made a substantial improvement over what you have now, so you can't possibly make the wrong choice here.

[LONGHAIR]

The only problem with an adjustable proportioning valve is that you have to adjust it,

Dude are you Serious? The wide pedal is from the transition years from "stick to automatic". Have you ever seen a stick with the wide pedal?..........NO! The wide pedal comes from the old tendancy to use both feet!

The whole motorhome thing is BS. If you can't control the power you put to one foot(and use 2) that is your problem...(BS respose). Most of the people around here are fanatics that drive their trucks for fun...........NOT as everyday work trucks.

It's all about driving accordingly ............assuming you can.............

The only problem with an adjustable proportioning valve is that you have to adjust it,

And the problem here is??????????????

The only real difference between 1/2 and 3/4 ton brakes is the bolt pattern and when you jump up to 1 ton they are hydrauliclly powered instead of vacuum powered.

1970blazin................Go with the power drums and keep an eye on adjustment..................good money NOT chasing bad

[Stepsides 4Ever]

It is what it is.

[72gord]

The only real difference between 1/2 and 3/4 ton brakes is the bolt pattern and when you jump up to 1 ton they are hydrauliclly powered instead of vacuum powered

I would have to disagree there..yes the bolt pattern is different, but the rotors are usually larger diameter and sometimes thicker(depending on year and model) and the drums will be wider and also larger diameter. At least that is my experience with most brake systems on these trucks and Blazers. Just my 2 cents worth!

[FRENCHBLUE72]

Diane you can use a newer axle with disk brake's and should be able to keep those nice wheel's you got not sure if the back spacing is different that maybe something to look at... My blazer has disk brake's and when my boy is in the truck it does give me a certian comfort knowing that if I have to panic stop I can...