I"ll not disagree, but I think we're talking about easier or gentler.
brake Power
- Thread starter GooSe77
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increasing the clamping pressure with a 80 series twin diaphram booster or in my case with a second booster definitely improves the stopping ability on otherwise standard brakes ie: same rotors, callipers and pad surface area etc but it also comes with its liabilities that the extra clamping and stopping force creates additional heat and friction on the standard brakes resulting in easier and quicker overheating and boiling fluid etc and hence brake fade and/or loss of brakes. My second booster theoretically gives me a max of 1470 psi on the front callipers and makes my truck stop effortlessly like a late model brand new car so I have to pay particular attention to how I'm braking if I'm trying to drive like a racecar down long hills or towing a car trailer I can cook the brakes up and overheat them pretty easily if I'm not driving sensibly, it doesn't happen often and in fact I've only ever done it once on a long steep windy down hill with a car trailer with my other cruiser on it (without trailer brakes) and I should have known better I was driving way too fast for the load and trying to stay with the flow and speed of the other traffic, if you drive foolishly you can lose brakes pretty easily but if you drive sensibly you'll have good strong brakes all day long 
I understand. I'm not familiar enough with how the '70 brakes perform, but the components are similar and of the same vintage as my '62. it takes a bit of foot pressure but I can lock all 4 corners, the goal being not to, of course.
On dry pavement or gravel and dust roads, it's about adequate.
On wet pavement, loose gravel wet, or wet, grade, turned or cambered, it's less than adequate. throw in extra weight or raise the center of balance, it's inadequate and can be unnerving.
So I try to adjust my driving behavior, knowing what the shortcoming's are.
In every braking scenario I can think of, where I'm pushing anywhere near the limits of what my rig can do, it is never additional braking force that I need, cause I can lock 'em. it's instead more "slowing" without locking that I need..
So I've never thought I needed more pressure.
At one point years ago, I went with a modified (basterdized) proportioning valve, and I played with the fore/aft, and could go left/right on the rear. if it improved some road situations, it degraded others. And in all cases, what I need is more slowing, not more squeeze on the pad, that'll cause them to lock.
I know you can get improvement by putting disc's on the rear.
And bigger brake cylinders are an obvious advantage.
But short of those, good pads, good rotors, clean fluid and minimal lengths of good flex line seem to be the best I've been able to do.
These experiences are with a '62, not a 70. YMMV
On dry pavement or gravel and dust roads, it's about adequate.
On wet pavement, loose gravel wet, or wet, grade, turned or cambered, it's less than adequate. throw in extra weight or raise the center of balance, it's inadequate and can be unnerving.
So I try to adjust my driving behavior, knowing what the shortcoming's are.
In every braking scenario I can think of, where I'm pushing anywhere near the limits of what my rig can do, it is never additional braking force that I need, cause I can lock 'em. it's instead more "slowing" without locking that I need..
So I've never thought I needed more pressure.
At one point years ago, I went with a modified (basterdized) proportioning valve, and I played with the fore/aft, and could go left/right on the rear. if it improved some road situations, it degraded others. And in all cases, what I need is more slowing, not more squeeze on the pad, that'll cause them to lock.
I know you can get improvement by putting disc's on the rear.
And bigger brake cylinders are an obvious advantage.
But short of those, good pads, good rotors, clean fluid and minimal lengths of good flex line seem to be the best I've been able to do.
These experiences are with a '62, not a 70. YMMV
60, 62 and early 70's have the same brake system save for a few minor differences. Stock brakes may be adequate for stock applications, but myself and most people here are in need of better brakes for non standard applications, myself I run very heavy 35'' wheels and tyres and my vehicle is heavy.
Discs on the rear provides no improvement in single application braking ability, drums have way more surface area for the pad to work on. Discs big advantage is cooling and cleaning for repeated hard stops.
With the mods mentioned and drum rear I can lock up all 4 tyres on the tar road with a heavy load on board, no chance with the factory stock setup.
I especially like the lighter pedal feel for extended hard driving, ie spending a few hours going fast with repeated braking, makes it a less tiring experience.
Discs on the rear provides no improvement in single application braking ability, drums have way more surface area for the pad to work on. Discs big advantage is cooling and cleaning for repeated hard stops.
With the mods mentioned and drum rear I can lock up all 4 tyres on the tar road with a heavy load on board, no chance with the factory stock setup.
I especially like the lighter pedal feel for extended hard driving, ie spending a few hours going fast with repeated braking, makes it a less tiring experience.
well said.
Good post above you make good valid points Hulsty, when I put my first set of 35" tyres on my old FJ75 it tipped it over the balance point and I ran out of brakes I couldn't stop the thing properly, the particular tyres weren't that heavy but the rolling circumference was too much for the stock brakes, I did a complete brake overhaul, skimmed rotors, ground drums, new pads and rear shoes, re-kitted callipers and new rear slaves etc etc and the brakes still needed 4 big jokers to jump on the brake pedal at the same time to pull it up hence I upgraded to rear disc's and an additional booster and on a scale of 1 to 10 my brakes went from 1 to 10.
rear discs don't really make a truck stop any better but they are more reliable and far less maintenance in an off road environment, our conditions here is a lot of mud and as soon as you put your drums into mud they wont work again until you pull them apart and clean the mud out and re-adjust them, if you don't clean the mud out it dries and turns into grinding paste and cant escape the housings and disintegrates the linings on the shoes, I had one brand new set of shoes last under 300km before they wore down to steel
rear discs don't really make a truck stop any better but they are more reliable and far less maintenance in an off road environment, our conditions here is a lot of mud and as soon as you put your drums into mud they wont work again until you pull them apart and clean the mud out and re-adjust them, if you don't clean the mud out it dries and turns into grinding paste and cant escape the housings and disintegrates the linings on the shoes, I had one brand new set of shoes last under 300km before they wore down to steel
Thanks for the input guys.
My brake pedal bracket broke one morning under a sudden stop at 25 mph. It ripped out of the upper mounting and almost caused me to hit the truck in front of me. My rig has 33 inch tyres and wasn't loaded. It has had the worst brakes ever since I've owned it and I keep it in great mechanical condition all systems are up to spec. That episode really freaks me out.
I am encouraged to hear of the 80 ser mod or an additional booster to help apply more pressure but have not tried it. As far as I can tell it is the only solution as my slotted dba rotors and carbon ceramic pads made little difference.
I am just not into hitting anything with this truck. More thoughts?
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My brake pedal bracket broke one morning under a sudden stop at 25 mph. It ripped out of the upper mounting and almost caused me to hit the truck in front of me. My rig has 33 inch tyres and wasn't loaded. It has had the worst brakes ever since I've owned it and I keep it in great mechanical condition all systems are up to spec. That episode really freaks me out.
I am encouraged to hear of the 80 ser mod or an additional booster to help apply more pressure but have not tried it. As far as I can tell it is the only solution as my slotted dba rotors and carbon ceramic pads made little difference.
I am just not into hitting anything with this truck. More thoughts?
Sent from my iPad using IH8MUD
If you cant see that increased pedal pressure increases stopping power and reduces stopping distances you must be kidding.
Think of it like this,, gently touch the brake pedal with about 2lbs of pressure from 30mph and see how long it takes to stop then get up to 30mph asd stomp on the pedal (increased pressure) damn if that dont stop quicker even with the same brake surface area and other parameters.
Some 70's (mine is one) you used to stand on that pedal and pray it would stop,, it just seemed that there was not enough assist.
I rebuilt master cylinder and had whole system gone over,, they still need a lot of pedal pressure to get it stopping and it is nearly impossible to lock up the wheels unless it is raining.
Think of it like this,, gently touch the brake pedal with about 2lbs of pressure from 30mph and see how long it takes to stop then get up to 30mph asd stomp on the pedal (increased pressure) damn if that dont stop quicker even with the same brake surface area and other parameters.
Some 70's (mine is one) you used to stand on that pedal and pray it would stop,, it just seemed that there was not enough assist.
I rebuilt master cylinder and had whole system gone over,, they still need a lot of pedal pressure to get it stopping and it is nearly impossible to lock up the wheels unless it is raining.
KbushNZ where are you getting it fitted. I am wanting to do the same.
I have a RHD drive non-turbo (yet!) and would love to do this mod. Can you give me a little more detail? You were able to swap the booster but not the master? I'm not familiar at all with the 80 series parts... Thanks!
I did the same that Hulsty recommended on my LHD BJ70. You can see the brake modifications from post 356 to post 362:
https://forum.ih8mud.com/threads/1985-bj70-story-and-modifications.608045/page-18
Hope this illustrates what Hulsty mentioned above.
https://forum.ih8mud.com/threads/1985-bj70-story-and-modifications.608045/page-18
Hope this illustrates what Hulsty mentioned above.
