something for old mechanics to think on,

ericlb · Sep 21, 2017

looks like my right foot injury is permanent, annoying, but ill add it to the list of other body damage , what i need is to increase the power assist on the brakes on one of my trucks, i have only old trucks, thats how i like it, but my 2 chevys, a 80 and a 83, both 1 ton duallys both flatbeds and heavy have hydroboost systems, stomp on the brakes and they stop, fast, now my 71 ford 1 ton is the heaviest it weighs close to 11000 lbs just by itself, its vacuum assist power brakes on a drum system, stopping is more a general idea, than a activity, my injury doesnt allow me to put a whole lot of pressure, [read both feet] on the brake peddle to stop this thing fast, i have a steady 15 lbs of vacuum available to the booster, and both it and the master cylinder are new, any ideas how to increase the assist?

jeffcat · Sep 21, 2017

Can it be retro flitted to disks if it now has drums? Had a friend who fitted the fronts on his VW Karman Giha. A lot more stop.

ericlb · Sep 21, 2017

not sure on disc setup, the big body change came in 73, along with some chassis changes too and discs on f350's, but i cant find out if those will retrofit to the 71 spindle, or what bearings ect will fit to make it work, 1/2 ton stuff is everywhere, but the 350's are almost never mentioned

Super H Mike · Sep 21, 2017

Aftermarket offers lots of hydro-boost set ups made for street rods and such which might work but will be a little pricy. How about a hand brake type lever that is meant for handicapped operator ? With those you can still use the foot brake normal but if you had to stop hard you could also grab the lever and pull. Or fit a hydro boost from a newer truck, junkyard parts.

merlynr · Sep 21, 2017

(quoted from post at 08:08:38 09/21/17) not sure on disc setup, the big body change came in 73, along with some chassis changes too and discs on f350's, but i cant find out if those will retrofit to the 71 spindle, or what bearings ect will fit to make it work, 1/2 ton stuff is everywhere, but the 350's are almost never mentioned

What is that F350 hauling around? My F350 with dump bed weighs 6480 empty and when I haul 3 tons of gravel it doesn't stop as good as empty.

JDEM · Sep 21, 2017

1971 was available with disc brakes in front as an option. If it was my truck, I change it over to discs IF I could find a junked F350 with front discs to get the parts from. Drum or disc front in 1971 both use a 8.8" vacuum booster. I doubt using a hydraulic booster would make any difference. Not even sure why it is used on some rigs. My 1/2 ton Chevy Blazer has hydroboost and so does my Chevy minivan.

Janicholson · Sep 21, 2017

The use of a disk brake booster and Master cylinder can increase the effective pressure (disks require dramatically more PSI to clamp the disk. I make no guarantee the pedal motion will be as before because the drums take more displacement to work. Keeping the adjustment on the original drums pretty close should work. (as in all safety related changes, Make sure you have an absolutely stone solution before roading the truck). Jim

used red MN · Sep 21, 2017

Cat, that is a "blueberry to watermelon" comparison there, lol (thinks apples) I would also recommend the disc brake swap as well. You'll have to look in some way back in the sticks junkyard that didn't crush all there older vehicles when scrap metal was way up several years back.

430WLPG · Sep 21, 2017

I have just what you need a wrecked 71F350 with front disc brakes I'm in Sw Oklahoma

ss55 · Sep 21, 2017

Unless you are looking for a major project, I would use the other trucks or start looking a replacement that you can drive comfortably with that injury. Maybe trade the lot for one newer one.

rusty6 · Sep 21, 2017

Before I went to the work and expense of converting a truck to front disk brakes I'd want to actually drive one and see how well it stops and how much pedal pressure it requires. I'm thinking of the 71 Chev/GMC pickups that I drove. Seems to me the front disk equipped trucks took more foot pressure on the pedal and didn't stop any better than drums.

Hobo,NC · Sep 21, 2017

Google "LARGER BORE MASTER CYLINDER FOR A FORD TRUCK"

I remember going to a larger bore master on some 80's for better performance and there was a up grade for older boosters to get'er to whooo down better.

merlynr · Sep 21, 2017

(reply to post at 08:48:40 09/21/17)

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The gvw on my 71 is 10,000 lbs.

rfridy76 · Sep 21, 2017

I had 1970 f350 that had disc brakes on front.Had to replace rotors an calipers ,that was in 1988 .Darn near broke the bank back then.

mj · Sep 21, 2017

Drive one of the Chevys!

Hobo,NC · Sep 21, 2017

Damm rite chebbys don't have good brakes never have and never will...

teddy52food · Sep 21, 2017

Check into getting a hand control for the brakes?????

Janicholson · Sep 21, 2017

Sorry I do not mean to flame, but a larger diameter will make the pedal pressure increase, not decrease. The area of the piston
needs to be smaller to increase the pressure. Jim

El Hombre · Sep 21, 2017

(quoted from post at 20:39:17 09/21/17)
Google "LARGER BORE MASTER CYLINDER FOR A FORD TRUCK"

I remember going to a larger bore master on some 80's for better performance and there was a up grade for older boosters to get'er to whooo down better.

It's the other way around; the smaller bore gives you more brake affect with the same pedal pressure. The downside is you run out of pedal if you need more fluid movement than the smaller bore can deliver. It's like using a hand pump with a big cylinder versus one half it's size. Like a 125psi tire on a racing bicycle, you can't push hard enough to move a big piston, they're 1/2" diameter in bike pumps.

I've had a BMW 900 for over 30 years. It has twin disks up front and a 17mm master bore. The factory changed to a 15mm a couple of years after my bike was made. That was done after enough complaints of needing a superman grip to slow the dam thing. Today they would have a 12 or 13mm in there, as peeps like a 2 finger brake that can lock the front wheel.LOL

I've got the 4 piston discs on my '70 Camper Special F-250. Everything stock and it'll work up and down in the Sierras with a 10 foot camper in the bed and a trailer with 4 Huskys in it being towed.

You really need a good booster with discs because you don't have the self-energizing deal like when drum shoes are trying to jam themselves against the drums...it's all just how hard the booster will boost.

David G · Sep 21, 2017

This is probably not approved, but swap the long shoe to the front and the short to the back, it will decrease pedal pressure, as the front shoe will grab a little.

Hobo,NC · Sep 22, 2017

That may have been why we swamped out the masters on them they would run out of pedal are have a low pedal. A bigger bore sure helped them tho...

First thing I would do is confirm Booster health then Vacuum source, booster check valve and by all means put a new vacuum line to the booster.

ericlb · Sep 22, 2017

the 71 is a hydraulic ladder truck [35 foot with a fold out man bucket], also its the farm mechanics truck, as far as i can tell when new it was part of a fleet order for mtn bell, and was purchased as a chassis cab, then sent to Oakland ca. for body installation and suspension mods, more leaves in the spring pack basically

ericlb · Sep 22, 2017

all 3 trucks are custom commercial bodied trucks, not pickups, which one i drive depends on what we need to do

Hobo,NC · Sep 24, 2017

Been busy... In the link if he reads them he will find useful info on how to match up a good combination for his truck that is if he's all in...

None of this will resolve a mechanical issue nor a parts mismatch if he goes the rout of attempting to upgrade his brakes from original. Do the research before you put the parts on the vehicle...

The main player in the equation is engine vacuum is 15 enoufh is 15 available all the time...

No offence taken...

something for old mechanics to think on,

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