Locking up brakes

ckruzer

ckruzer

Infidel
Joined
Jul 2, 2015
Location
asheville nc
Curious if anyone had any input. Cant lockup brakes

36x14 tires. 3/4 ton chebby rotors and calipers f/r. Running a MBM 7" double diaphram booster with a stock CJ/YJ master. Im also running 3,000 PSI rated flexible (not braided) from front to rear.

Would you think the line or the master is the issue?

Im rolling the dice on the master, you?
 
The specifics of your setup don't mean anything to me, but using all flexible line is really not doing you any favors and is probably adding a lot of unnecessary fluid volume change during braking. Why aren't you using hard line for the chassis runs?

3000psi line doesn't mean that it won't expand a lot, it just means it won't burst.
 
Jody Treadway said:
Why do you want them to lock up? You can't control a skidding vehicle
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Because if I can then it means I don't have a breaking power issue. Way too little power it feels like. Not even enough power to hold me still on a steep incline.
 
Fabrik8 said:
The specifics of your setup don't mean anything to me, but using all flexible line is really not doing you any favors and is probably adding a lot of unnecessary fluid volume change during braking. Why aren't you using hard line for the chassis runs?

3000psi line doesn't mean that it won't expand a lot, it just means it won't burst.
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That's a good point.

Why? Simply because I thought it was a good idea? Evidently not. Lol. I had them and wanted to see how well they performed.
 
ckruzer said:
Curious if anyone had any input. Cant lockup brakes

36x14 tires. 3/4 ton chebby rotors and calipers f/r. Running a MBM 7" double diaphram booster with a stock CJ/YJ master. Im also running 3,000 PSI rated flexible (not braided) from front to rear.

Would you think the line or the master is the issue?

Im rolling the dice on the master, you?
Click to expand...

At minimum, you need a 1/2 ton chevy master, be even better if you went bigger. The CJ master just doesn't move enough fluid volume for the calipers.
 
There's a Lot of varying PSI & differentials, that's Over my head! Master Cylinder bore/stroke vs. caliper piston size! Boost or lack of, per the Booster, & is the push rod & vacuum correct? o_O
 
maulcruiser said:
At minimum, you need a 1/2 ton chevy master, be even better if you went bigger. The CJ master just doesn't move enough fluid volume for the calipers.
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Awesome. Thanks! The dodge 2500 should be a direct swap
 
rodney eppes said:
There's a Lot of varying PSI & differentials, that's Over my head! Master Cylinder bore/stroke vs. caliper piston size! Boost or lack of, per the Booster, & is the push rod & vacuum correct? o_O
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Over mine too!!!

As far as I knew vacuum was vacuum and I presumed a 5.3 hose would be superior to the 4.2 hose lol.
 
Dodge 1500-3500 mc. I bought an 01 I think. They'll clear the hood fine and only require the lengthening of the threaded pushrod. I haven't even installed mine yet, it's just sitting here looking at me like: "Big dumb single purpose truck part reporting for duty... can I ride? Yes, no, maybe?"
I can point you in the direction of a good quality flaring tool to build your own brake lines. It comes in handy to know how, even though at first you'll find yourself hurling inanimate objects at and through a wall, but once you get it, you're good.
 
This is my favorite tutorial on this subject. I followed his math/logic and my brakes work great even considering I moved to 4-piston calipers all around and added a literal ton to the weight of my truck when I SASed it.

Brake Upgrade
 
Ordered E350 master. its a 1-1/8 bore. With my double d booster, should be all set. If it looks up good, would like to keep the flexible lines unless anyone has any input why not to?

#notanexpert
 
FYI...

Assuming everything is working in the caliper/pad/rotor department... If you have little or insufficient clamping force on your calipers, you need a smaller bore master cylinder. A larger bore master cylinder will flow more fluid, but will make less clamping force at the calipers.

Lines have less effect than you would think. People are running nylon, tubing (like the tubing that comes with your oil pressure gauge!) for brake lines and having no issues. Including racers!
 
What's the stroke length comparison between the E350 and the YJ mc?
Just got intresting......
 
ol'Jeeps said:
FYI...

Assuming everything is working in the caliper/pad/rotor department... If you have little or insufficient clamping force on your calipers, you need a smaller bore master cylinder. A larger bore master cylinder will flow more fluid, but will make less clamping force at the calipers.

Lines have less effect than you would think. People are running nylon, tubing (like the tubing that comes with your oil pressure gauge!) for brake lines and having no issues. Including racers!
Click to expand...

Following the guides in the link provided Brake Upgrade and some friendly input went with the 1-1/8 (3/4 ton size) as opposed to the 1-5/16 wonton, or the 1-1/16 quarterTon.

The other available 1" option is the same size as my current situation and to go smaller --- dont know how? GoKart hardware? Lol

Thanks for your input man on the lines!!!! My idea was hey - if im above the max psi threshold and the lines dont balloon (they dont), then why bother with hard lines? why settle with rust issues when looking for dry rot is a 4 second ordeal and can be more easily replaced? Lol

Im keeping a super close eye on the lines. Need to do some rerouting too on the axles, etc.
 
XJsavage said:
What's the stroke length comparison between the E350 and the YJ mc?
Just got intresting......
Click to expand...

1" vs 1-1/8" (hypertech, i think the CJ/YJ may be 15/16 or something iirc)

Went with the 1-1/8 because hoped that its 3/4 ton purpose would mate well with 3/4 ton calipers. lol.

Im running a 7" dual diaphragm booster over the stock single diaphragm 8 inch
 
If you want to read up on it: BillaVista.com-Brake Bible Tech Article by BillaVista. There is a calculator there that can help you figure out what you need.

ol'Jeeps said:
FYI...

Assuming everything is working in the caliper/pad/rotor department... If you have little or insufficient clamping force on your calipers, you need a smaller bore master cylinder. A larger bore master cylinder will flow more fluid, but will make less clamping force at the calipers.

Lines have less effect than you would think. People are running nylon, tubing (like the tubing that comes with your oil pressure gauge!) for brake lines and having no issues. Including racers!
Click to expand...

x2. Bigger master doesnt always mean better brakes. You have to account for volume and pressure.

If your pedal feels right but you cant stop, you likely need more volume. If the pedal is hard, you need more force or less volume. Given that you have a booster, you can run a larger volume master. With manual brakes it takes a little more thought to get the right combination.
 
Couple more thoughts on flex linew.
It's more sensitive to heat, abrasion and snagging. All can by minimized just keep that in mind doing when routing.

Also dry rot isn't your only (main) concern. It will break down internally and obstruct/prevent force transfer before it dry rots.

Metal line also dissipates heat better than rubber hose.

Works fine in race applications as stated where it's changed regularly.
 
ckruzer said:
If it looks up good, would like to keep the flexible lines unless anyone has any input why not to?
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Spongy/vague pedal feel? Hose expansion gobbling up fluid volume? You're starting with the worst type of hose material for expansion under pressure, and then you're making your entire pressure line system out of it.....

You may or may not care about how dead the pedal feels, but I certainly wouldn't tolerate that in any of my vehicles. You already lose feel with too much brake assist, then you're throwing tens of feet of rubber line in the mix...

FYI, nylon brake lines don't have a very long service life (not an issue in racing) and aren't DOT legal. They're also sensitive to nicks and abrasion. Many of the racing classes have outlawed them because of the high failure rate, but I've heard that is mostly due to damage sensitivity from poor installation.
Too many risks to run on the street (there are better options with virtually no compromise), but may be a okay option on a buggy IF you know that the operating pressure won't be an issue. Budget for frequent replacement as preventative maintenance.
 
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Ron said:
Also dry rot isn't your only (main) concern. It will break down internally and obstruct/prevent force transfer before it dry rots.
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If I'm thinking correctly, or comparing correctly rather, can't a braided encased plastic line also be deformed by stretching and/or internally ruptured like a brake rubber hose can? I had an issue that went on for weeks that ended costing me multiple wheeling trips and two calipers before a buddy pointed out to me that flexible brake lines can't take being stretched because of the difference in elasticity between layers. Looking at it, you couldn't tell though. And he was right. It would transfer fluid under pressure but the second the fluid went flacid, it took forever for the system to equalize the pressure from the caliper.
Of course I still use soft lines in short segments but I prefer hard metal lines for brakes and even fuel, just so I can visually check for damage and repair on the trail if need be (yes, I carry a flaring tool and 3/16"-3/8" fittings and couplers in my tool bag. I'm THAT guy). And its cheaper. ;)
 
ok ok ok lol :beer:

ill work on converting to hard line asap. need to pick up a flaring tool, and some line/nut hardware
 
Bottom-line pricing on Mastercool 70092 at ToolTopia.com
This is the one I have. It's a good one for doing it manually and has done an estimated 120 perfect leak-free flares from 3/16 on up. It'll take some time to get good at it though. At first, if you can get 7 good flares out of 10, you're about up to standard. If you're a perfectionist, maybe 4 or 5. Leave a few extra incges of playroom on each end just for having to redo some of them. Videos on the procedure are helpful and if it's a real-time video of one flare that's 10 minutes long, dude wasn't exactly taking his sweet time with it. Expect 10 minutes per flare between prep time and test fit. Thrown objects can harm walls, automobiles and mailboxes.
RkWQeGR.jpg
 
thats the exact same one at autovance. ill just rent it fo free. haha

what line size do you recommend? 5/16 is standard right?
 
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