brake bore dia

[OpTimuS]

Hey guys as some of you may know I am builing a 6-wheeler, and I have future plans to add an auto box to it so I want fairly good braking capability as I will be left with no engine braking.

What I would like to know is if I run 2 sets of 80-series rear calipers on one master cylinder on 2 sets of 80-series discs, what bore dia of my master cylinder will be needed?
I also plan on running full manual brakes so would a decent braking force be achievable with a 8.7:1 ratio pedal lever?

Secondly on the same master cylinder setup I want to run another braking system for the front of my truck, and with this I plan to run the same pedal lever ratio, but I want to use 4 60-series calipers on the one diff. What master cylinder size would be optimal, is this setup achievable?

Cheers Davo

 

[OpTimuS]

o.k. I have done more reearch and have found that it may be in my best interests to run 1 set of front calipers and 1 set of rear calipers from 1 master cylinder from 1 master cylinder and the other sets from the other master cylinder giving me 6-wheel braking and a redundency should anything go wrong.

I have the options of 5/8", 3/4", 7/8", 1"master cylinder.

I have the option of pedal levers in

• 14 1/4" for a 7.2:1 ratio,
• 15 1/4" for a 8.1:1 ratio,
• 16 1/4" for a 8.7:1 ratio

Cheers Davo.

 

[toymaniac]

I think, even with the largest ratio (8.7:1) you are not going to have enough strength in your legs to stop the truck. A typical vacum brake booster will usually give you about 200lbs. more pressure.

Also, although redundancy is great, if you are trying to push on two MC's you are doubling the force you have to provide to push the fluid. (You have doubled the area).

If you want to have allot of pressure at the calipers, and not have to push very hard with your foot, you need a small diameter MC. Then to get the volumetric change you need, you will want a MC with a long stroke.

So if I were you I would use two 5/8" bore MC's with the longest stroke they make and run two vacum boosters.

Just my $.02

 

[mookie]

ok wtf is this 6x6 stuff all about? are you doing this to your chopped bj60 or have you started a new project or what and why 6x6? and your build threads are lacking in current info...

 

[OpTimuS]

ok wtf is this 6x6 stuff all about? are you doing this to your chopped bj60 or have you started a new project or what and why 6x6? and your build threads are lacking in current info...

hey mookie.
I know that my build-up threads are crap and I have been reallyu slow with this build-up due to work, and being sent on operation to NZ. hopefully around dec I may get a chance to work on my truck. And yes it will be a 6-wheel drive L/C.

 

[OpTimuS]

I think, even with the largest ratio (8.7:1) you are not going to have enough strength in your legs to stop the truck. A typical vacum brake booster will usually give you about 200lbs. more pressure.

Also, although redundancy is great, if you are trying to push on two MC's you are doubling the force you have to provide to push the fluid. (You have doubled the area).

If you want to have allot of pressure at the calipers, and not have to push very hard with your foot, you need a small diameter MC. Then to get the volumetric change you need, you will want a MC with a long stroke.

So if I were you I would use two 5/8" bore MC's with the longest stroke they make and run two vacum boosters.

Just my $.02

With that info in mind I think I will stick to my original plan of 4-wheel discs, and a separate hydraulic hand brake.

Cheers guys.

 

[Tapage]

I recently read this thread .. and come with the ( maybe stupid ) idea run a hydro boost .. buddy that runs it in his F350 said that it's great stuff with the apropiate Hydro pump ..

 

[Tankota]

You can get an electric hydroboost setup. It'd just be an electric PS pump hooked to the hydroboost out of any rig. The dual MCs is not a bad idea, however, I think you're gonna need a leg that looks like Awnolds (when he was in his prime) if you want manual brakes.

 

[mookie]

oh, hey dude, your build up threads aren't crap, you just need to get to work lol! why don't you explain how and why your thinking about making a 6x6 bj60 truggy thing? you might search on pirate 4x4, i've seen some 6x6 tech and info on there in the general forum before....

 

[OpTimuS]

I recently read this thread .. and come with the ( maybe stupid ) idea run a hydro boost .. buddy that runs it in his F350 said that it's great stuff with the apropiate Hydro pump ..

You can get an electric hydroboost setup. It'd just be an electric PS pump hooked to the hydroboost out of any rig. The dual MCs is not a bad idea, however, I think you're gonna need a leg that looks like Awnolds (when he was in his prime) if you want manual brakes.

I have not considered the hydro-boost idea but I have had a look on pirate, and a few other places, (vanco for ex), and I think that a hydro-boost setup could well be the solution, however I have to check up on brake master cylinder dia.
I look at simple math when I do anything on my car, and I think if I want to run the setup I am thinking of I will need a 2” dia master cylinder. I think I will download the brake master cylinder calculator from this site: http://www.pirate4x4.com/tech/billavista/Brakes/#Vancoreview
And go from there.