The Stovebolt Site Forums The Shop Area Driveline Will a disk brake conversion reduce stopping distance?

What precisely will I gain if I change the front Huck brakes in my 41 Suburban to disk brakes using the six lug conversion kit?

A few years ago I commuted to work in bumper to bumper traffic every day for one summer using my bone stock 41 pickup. A common issue was that a modern car would zip in front of me and then slam on the brakes. I would then have to stand on the brake pedal or in one case swerve to avoid hitting the car. I am building my suburban as a`daily driver, so I will probably be installing a dual master cylinder with a brake booster to reduce pedal effort. But I am wondering if a disk brake conversion would effectively reduce my stopping distance.

The only way they will reduce your stopping distance is if you
are having problems with brake fade with your Huck brakes.
I've never had a brake fade problem with my stock '50, 3600
with Huck brakes and I drive my truck in city traffic
regularly. I'm able to lock up the brakes if need be. Of
course with the brakes locked up, my truck takes on the
characteristics of a large hockey puck on ice. And to that,
disc brakes are not anti-lock brakes so that will still
be a problem.

DG

I would bet you will gain some stopping distance just due to the fact the rotors give off heat faster and can take repeated heavy stops in a short amount of time from highway speeds. GM and other manufacturers wouldn't have switch if there was nothing to gain.

I just read a big topic over on the H.A.M.B. site about brakes and valves. What I got from it was drum brakes self set once they reach a point in drum contact. You have very little control over them in heavy braking since they grab the drum a set. Drums are more efficient at stopping a rotating mass then a rotor is, but, you have much more control over a rotor before it locks up due to the higher pressures required to do so. This really only comes into play in panic stops or heavy traffic where quick jabs on the brakes happens.

You will also gain the ability to drive it without adjusting front brakes ever again. How about long term availability to get brake shoes for the Huck brakes?

Joe

You know what they say about opinions Joe, here's mine.
The bottom line, was one of the factors for the switch to disc
brakes. They are 'now' cheaper to manufacture, service and
they do eliminates brake fade. Brake fade being a concern
today with the newer vehicles reaching higher speeds on our
super highway system. If I were driving my stovebolt at
70-80 mph speeds on the Dan Ryan expressway every morning
and night, I would for sure want disc brakes. In normal city
driving, where you rarely get over 40 mph and cruise at 55,
I wouldn't have any problems. One panic stop from 55 mph
doesn't generate enough heat to cause drum brakes to fade
if they are maintained properly. As soon as the rain stops
I'll take Old Blue out on the black top and make one then
jump out and shot the drum with my trusty HF laser Thermo-Meter.
Since you can lock up the wheels with Huck brakes and disc
brakes, then the only variable to stopping distance would
be the weight of the vehicle, choice of tire and road surface.
Bendix brakes are designed so that the shoe is drawn into the
drum (a little) when you apply them, this requires less pedal
pressure over the older Huck brake. Not clear if that is what
is meant by the word "set". They wouldn't take a "set" or they
wouldn't release as you eased up on the pressure.
It's well known, since the introduction of disc brakes that
un-assisted disc brakes take more pressure than a drum simply
because there is less friction surface. You can still lock up
the wheels. The advantage that puts the disc out in front is
that there is more contact surface exposed to the air,
therefore much better heat dissipation than a drum, which
traps the heat in a nearly enclosed area.
The only thing that will prevent either system from locking up
is a very good feel for the braking system or an anti-lock
braking system.

Denny Graham
Sandwich, IL

You are right Denny on all counts. Normal driving is no problem, I sure wouldn't want to hit rush hour every morning and night though. The definition of everyday driver differs so much from person to person, I always figure on the drastic side. I don't even like rush hour in my '03 Toyota !

I added disk to my truck just so the bolt pattern would match the rears, had the rear axle not been changed, I doubt I would have swapped. I run a manual disk drum system and pedal effort is quite high, My old drag race car was manual disk and stopped OK, figured the truck would to. I don't have the same pedal ratio as the car did, but the rest of the system matches. I learned to live with it, nobody else ever drives the truck so I never give it a second though. Power assist would sure help, but then it might get into the touchy brakes, and to me that would be worse then stiff pedal brakes.

I guess it all comes down to what you are willing to live with.

Thanks for the replies.

Sounds like the best course to take is to refurbish the drums, and see if I am not happy with the results, before I convert to disk brakes.

I was able to lock up the rear tires on my pickup, and it happened quite easily. I never tried to get the front tires to lock up - didn't seem like a good idea. I never noticed any fade. I was running Coker bias ply tires which seem to have poor traction.

The Suburban has better weight distribution and will have radial tires, so I am anticipating better stopping even with stock brakes.

Shot some video of the '50 with it's Huck brakes in panic
stops from 60 mph this morning. One going and two right after
each other coming back. Eight minutes total but 4.6 GB so it
would take a couple of days to upload it to YouTube, so....I
guess all I can do is report the results.
Started out at 75°F, after first stop, drum rim read about
166°F. Return trip, hard braking twice from 60 mph and the
reading was around 275°F. Still stopping straight ahead and
still could lock up the brakes with enough pressure, but no
brake fade. I just pushed it till the rears started to scuff
a bit. Not looking to flat spot the tires or spin out on the
two lane blacktop.
If I were turning laps on the mile, or running Watkins Glen,
I'd certainly opt for the disc's but, normal average
driving.....these are good enough for me.

DG

I have drum/drum with dual m/c and booster on my panel. Man, it'll stand you on your head. No brake problems here and I do "get on them" quite a bit as I'm usually heavy on the gas. Repeated hard braking on a steep grade may get me some fad but I'm smarter than that now....I think.
Around here we have "Saluda grade" and if you can make it there your good to go. Been down it several times in the panel no sweat as long as I don't "ride" the pedal.

Sput, not trying to tell you something that you don't already know, but when you set up your refurbished drums and new Huck shoes, don't be surprised if the brakes act squirrely until the new shoes wear until they match the contour of the turned drums.
I have had to make 2 or 3 brake adjustments over a short amount of miles to get mine to finally act right. Now they are as dependable as any brakes I have ever had. I like to think of my drums acting as a lathe, form-fitting my shoes as I drive until they match radii (a little plural word which seems like a big word, eh?).
Carl

Carl is right on with that suggestion. I didn't have any
problem with my '50 3/4-ton. I turned the drums myself
thanks to a then time friend who got me access to a brake
drum lathe. I took just the lightest clean up cut and that
may be the reason.
I did the brakes on a friends '50, which he'd had the drums
turned by an auto machine shop and I think they took them to
the max. The first time out I really had to stand on the
brakes to get it do stop even though we had a solid pedal
right up to the top. Back at the garage, looking at the
scrub pattern on the shoes, showed that they were only
contacting on a small portion of the shoe:
http://www.pbase.com/dennygraham/image/115452306

The truck only had a few miles (maybe less than 20) before it
was torn down to the frame for the body restoration. That was
a few years back and it's nearing completion this fall.
Because of my major move to the new place, I've not had time
to work with him on the truck but I've forewarned that the
brakes are not going to be at their best till he gets some
miles on them and the shoes get lapped in.
The practice of arcing the shoes to fit the turned drums went
the way of the dinosaur with the flood of cheap off shore
drums, so rather than turn them, they were just replaced if
available in many instances. Plus the EPA came down on the
shops about the grinding dust.

dg

...cheap source of off shore drums....

Denny, I hear you loud and clean. A good friend of mine who runs a frontend/tire shop turns ALL new rotors before he installs them on a car. It may be just the slightest amount ground off but over the years he has found doing this to be well worth the time. I myself have seen them turn some new drums on various occasions over the past 8 or 10 years and its amazing what I've seen......but now surprises to you and me!

Good information - thanks.

Alvin, is that a 1" bore master cylinder with a 7" dual diaphragm booster in your panel?

Sput, I can't remember but I got it from PirateJack out of Asheville, N.C. 2010 I paid $169 for it.
The number is PBUFMCT4754 to check it out. I think their web site is Piratejack.net

....I may have the papers in a file if you don't see it.

EDIT: here it is. Yes its 7" scroll to the bottom....
http://www.piratejack.net/index.php?route=product/search&search=PBUFMCT4754

It came with brackets that bolt to chassis along with pedal. Nice set up.

Can you run the power booster and dual master with a stock 3 speed on the colum and a clutch?

Bicounty, I have not did it with a 3 speed. However, I have a 700R4 stuffed undermine and it does clear good. The set up hugs the chassis pretty good and I have at least one rod coming down to the tranny without any problems.

...be patient for a day or two I'm sure someone who has done it will chime in....or start your own, a new thread, with this question.

I did find that the ease of only having to adjust the rear brakes made my life much easier,also no pulling due to misadjusted brakes

Incorrect brake adjustment does not caused a pull. It only makes the brake pedal lower. It's physically impossible for a brake to do any stopping until ALL the shoes are in contact with the drums, so adjustment-related pull stories are fairy tales. Restricted front flex lines and/or sticky wheel cylinder pistons can result in a brake pull, but adjustment? No way, no how!
Jerry

Agree with that Jerry, hydraulic pressure should be the same at
all points in the system when the pedal is applied. Something
is restricting the pressure, air in the line, some component
binding up, contamination on a shoe or uneven contact surface
area would be the only things that would cause it to pull to
one side.

We talked about stopping distance for a Huck brake in a
panic stop a while back. Well....I was a very bad boy on
Monday. Was coming back from a trip down south doing 55 mph
on a two lane black top road out in the country. Had my cell
phone up to my ear talking to a buddy and, as we are so
often warned about, it took my attention away from my
driving. All of a sudden something pulled my attention back
to the road and about 60 or 70 feet in front of me was a
traffic control guy with his Stop/Slow sign turned to Stop.
I hit the binders and with the tires screeching on the
pavement, brought Old Blue to a stop right along side the
guy, who had taken a couple of steps off to the side of the
road. It was hot and I had the windows down and he leaned in
thru the passenger side and said "Nice truck, ya want to
sell it?" Maybe it's about time was my red faced reply,
sorry bout that, I was day dreaming. He turned the sign
to Slow and said, "Go ahead...and no more daydreaming."
Thank god I've kept those Huck brakes in good repair all
these years and they did their job. Disc's wouldn't have
done any better.
I was lucky and this was a really good awakening. If I'm
gonna talk on the phone, I'm pullin' off to the side of
the road from now on.
dg

70ft stopping distance at 55 mph is pretty spectacular. My modern econobox is rated at about 103 feet stopping distance at 55 mph and I thought it was pretty good. Are you running radial tires?

Yes, brand new 215/85R 16 Michelin's installed a couple of weeks ago. I didn't stop and
take a tape measure out, nor go back and measure the exact distance. I estimated it by
stepping off a distance from the house to the barn that looked close to the point that I woke
up and hit the brakes.
I’m terribly sorry but I was off by a couple of car lengths. So just to be exact and satisfy the
net pickers on the forum, there always has to be at least one you know, I did a test and
took some data this time.
The closest I can come to duplicating the stop was by repeating it on the blacktop in front of
my house, which I just did a few minutes ago.
The exact distance from when I took my foot off the gas at 55mph, in line with my mailbox
and applying the brake, just short of locking up the rear tires was a measured 117 feet 4 ½
inches! Hope that satisfies the engineering urge for perfection.
I wasn’t quite as hard on the tires this time as I was the other day when a construction
worker was directly in front of me. Then I did actually have to lock up the rear tires for a few
seconds.
http://www.pbase.com/dennygraham/image/161326548
Denny Graham
Sandwich, IL

The advantages of disk brakes are, 1, few moving parts. 2, less "fade" with repeated stops(more air, better cooling). 3, Less money to make, fewer parts(more profit for the Company). 4, Easy to wipe water off of brake surface. 5, Simple to turn and clean up for repair.
Stopping distance is a function of contact patch(tire profile) and friction(rubber compound) If you want to improve stopping distance, use a soft tire and make it wider. As long as the brakes can stop the tires you have enough.

Well said Steve!!!!!

dg

My '50 3100 makes all of the noise of a vehicle coming to a full stop, just takes a while more to actually do so. I have to concentrate on leaving more space in front of me and think ahead for sideways escape routes.
I am just glad that the fit and feel of the old truck is drastically different than my other vehicles so that I don't forget which one I am driving!
EVERYONE should do what DG did and do an emergency stop in a safe place so that they know just what they are dealing with.
You really don't want to do that the first time in traffic!
Carl

That's not strictly true, since the sliding friction of the tire is less than the rolling friction. Metal bars shoved through spoked wheels would also stop the tires and wheels, but would likely result in a longer stopping distance compared to more conventional brakes.

One of the reasons I posed the question in the first place was because I too had been told a theory similar to that mentioned by Joe H. in the second post: Disk brakes apply the braking in a more linear manner than drum brakes, which in practice allows them to more closely approach the point of lockup before reaching it.

But this effect is not likely significant, if it even exists (at least for Huck brakes, which are not self-actuating). Clearly Denny's truck displays exemplary stopping performance, equivalent to a modern 3/4 ton truck. This tells me that the replacement of the Huck brakes would not be worth the money or the damaging effect to the truck's appearance.

Thanks for all the responses.

I purchased the kit from Performance on line for the front of my 53 3100, and was told the power booster and clutch pedals would work in the stock position IF using a floor shift. There could be interference with the shift linkage coming from the column shift.

My truck has a T5 so it is not a problem for me.

jim

I just started to install a Classic Performance Products disc brake kit in my stock 1950 1/2 ton. So far so good but the stock 16" wheels hit the caliper whith the 12" discs . I have to look for a set of wheels that will clear the caliper. The instructions mentions this and give three companies that can supply some wheels. I will get on the phone tomorrow and do some calling around. Any one out there that have done this have a source for stock looking wheels.

I did some grinding on my calipers and to the inside of my wheels to make them fit.

Scratch Stockton Wheel off the list

I wouldn't use them to change the air in my tires

And.....what's the beef Gus?
dg

I think the beef would be the problem presented by one of our members showing a cracked wheel that Stockton had welded together. Remember that one Denny?

I remember the cracked welds

Also, in my case, I ordered custom backspaced Wheels to clear the P.O.L. Kit. when they finally arrived after a few months delay, there were not backspaced, they were stock and didnt clear.

Stockton refused to take them back and correct the problem.

The only way I cold use them was to use a spacer and still had to file the caliper down .

Not what I paid big bucks for.

I checked the clearance and I don't think I could posibly grind enough off the caliper without damaging the caliper. I will definetly have to get new wheels. In defence of CCP they did mention this in their instalation instructions. I'm asuming they must have run into this problem before I wish they could have given some specs on the back spacing and offset so I would at lease know what I'm looking for. If your thinking about installing discs on your truck and pricing out the cost you better add the cost of a new set of wheels to the project.

Oh yeah, Charlie's reworked wheels?
Was that Stockton? That was the only complaint that I've ever
heard about Stockton Wheel. Of course I've only been aware
of them for a bit more than a decade.
And that's a real bummer that they wouldn't honor your order.
Things like that need to be brought out in the open so the
rest of us don't get stung.

dg

I used to buy wheel blanks from Stockton back in the early 1970's when I was running a 1/4 mile dirt track car about 40 miles south of them in Merced CA. We made our own centers from 1/4" steel plate and welded in right angle braces between the lug bolt holes. They were heavy, but they would take a LOT of abuse from wheel-rubbing with the other cars in the turns. We also welded in a piece of 1/4" steel bar stock around the bead area.

I doubt if any wheel vendor would sell a blank wheel without a center these days- - - -too much liability!
Jerry

I’m experiencing a lot of that inconsiderate driving,too. I have a ‘41 and a ‘56 both with manual transmissions I’m continually plagued by young folk who pull right up to my bumper when I’m stopped on an uphill incline... I only have TWO legs people!!