Author Topic: Better Brakes  (Read 5184 times)

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Offline Mozman68

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Re: Better Brakes
« Reply #30 on: October 18, 2009, 05:39:03 PM »
All I know is...Caddy calipers suck on D60's...they just don't fit...and are a bitch to adjust....who needs an emergency brake??  I need real brakes.... :brick:
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Offline oldjeep

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Re: Better Brakes
« Reply #31 on: October 18, 2009, 06:38:16 PM »
All I know is...Caddy calipers suck on D60's...they just don't fit...and are a fruit cups to adjust....who needs an emergency brake??  I need real brakes.... :brick:

Yup, caddy calipers are too small.   I ran Chevy 1/2 ton D44 front calipers on the rear 60 in my CJ, worked great.
Chuck P
The clowns'? Oh, yeah, the clowns. We fight them too — entire armies, spilling out of Volkswagons. We do our best to fight them off, but they keep sending 'em in!
94 YJ - gone
98 ZJ - sons truck
97 TJ - daughters project

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Offline oldjeep

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Re: Better Brakes
« Reply #32 on: October 18, 2009, 06:39:30 PM »
So I did a bit more research and a bit more thinking.  TJ's use the larger master and the booster while still having the same brakes (stock) as most YJ's. (except pre-91's)  From what I've read the pressure goes down as the volume increases.  The larger master gives you the false sense of firmed brakes because they have less pressure for every inch of travel.  The exception is if you increase the booster pressure.  So as long as you increase the booster pressure along with the larger master, it should be OK when using with stock brakes.

Except that braking power increases on disc brakes with increased fluid volume.  You want pressure for drums and volume for discs.
Chuck P
The clowns'? Oh, yeah, the clowns. We fight them too — entire armies, spilling out of Volkswagons. We do our best to fight them off, but they keep sending 'em in!
94 YJ - gone
98 ZJ - sons truck
97 TJ - daughters project

www.oldjeep.com

Offline Jeffy

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Re: Better Brakes
« Reply #33 on: October 18, 2009, 07:12:07 PM »
Except that braking power increases on disc brakes with increased fluid volume.  You want pressure for drums and volume for discs.
That's why I said STOCK brakes.  Use upgraded discs or drums and you'll need more volume.
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Offline sharpxmen

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Re: Better Brakes
« Reply #34 on: October 18, 2009, 08:18:19 PM »
Except that braking power increases on disc brakes with increased fluid volume.  You want pressure for drums and volume for discs.
sorry man but is the other way around, hope you won't take this the wrong way but i'll try to explain.

pressure=lbs/sqin - the smaller the diameter of the cyl (EDIT: master cylinder) the higher the pressure (applied force is in lbs, surface area of the piston in the master cylinder is in square inches). At the caliper is the other way around as the force with which the piston squeezes the pads
applied_force=piston_surface_area*pressure.

so whatever force you apply at the brake pedal is transformed in hydraulic pressure inside the braking system and then at the caliper is transformed in force by the caliper piston(s).

as a matter of fact it varies with the square of the diameter since the piston surface area is PI*Radius^2 (that is 3.14 times square radius)

it might be that on some calipers you need higher volume, that can be because they are larger so in that case you need a larger diam master so you don't reach the end of the travel on your brake pedal (and also you get more clamping force at the caliper due to larger pistons there, so you can have a larger master with no drop in braking performance)

so for the sake of an example (dimensions are exaggerated to simplify the math) if you have a master with a 2'' diameter (1 inch in radius) and you apply a force of 20lbs at the pedal that would result in a pressure of (20 lbs)/(PI*1*1 sq.in.)= 20/3.14 lbs/sqin. If you have a caliper with an 8 inch diameter piston (4 inch radius) the resulting clamping force is (hydraulic_pressure)*PI*4*4= (20/3.14)*3.14*16=320lbs. Now if you have a master with a 4 inch diameter (double than the one before, so a 2'' radius) the pressure will be 20/PI*2*2 = (5/3.14)lbs/sqin and therefore the clamping force at the caliper is (5/3.14)*3.14*16 = 80 lbs, so compare that with 320lbs in the first example a master twice in size will give you 4 times less braking clamping force.

EDIT: I didn't account for the booster added force to the master but that is the same in both instances so for this example is not relevant.
« Last Edit: October 18, 2009, 08:22:50 PM by sharpxmen »
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
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Offline oldjeep

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Re: Better Brakes
« Reply #35 on: October 19, 2009, 05:29:26 AM »
I'm talking about the amount of fluid moved via the reservoirs, not the bore of the MC.

sorry man but is the other way around, hope you won't take this the wrong way but i'll try to explain.

pressure=lbs/sqin - the smaller the diameter of the cyl (EDIT: master cylinder) the higher the pressure (applied force is in lbs, surface area of the piston in the master cylinder is in square inches). At the caliper is the other way around as the force with which the piston squeezes the pads
applied_force=piston_surface_area*pressure.

so whatever force you apply at the brake pedal is transformed in hydraulic pressure inside the braking system and then at the caliper is transformed in force by the caliper piston(s).

as a matter of fact it varies with the square of the diameter since the piston surface area is PI*Radius^2 (that is 3.14 times square radius)

it might be that on some calipers you need higher volume, that can be because they are larger so in that case you need a larger diam master so you don't reach the end of the travel on your brake pedal (and also you get more clamping force at the caliper due to larger pistons there, so you can have a larger master with no drop in braking performance)

so for the sake of an example (dimensions are exaggerated to simplify the math) if you have a master with a 2'' diameter (1 inch in radius) and you apply a force of 20lbs at the pedal that would result in a pressure of (20 lbs)/(PI*1*1 sq.in.)= 20/3.14 lbs/sqin. If you have a caliper with an 8 inch diameter piston (4 inch radius) the resulting clamping force is (hydraulic_pressure)*PI*4*4= (20/3.14)*3.14*16=320lbs. Now if you have a master with a 4 inch diameter (double than the one before, so a 2'' radius) the pressure will be 20/PI*2*2 = (5/3.14)lbs/sqin and therefore the clamping force at the caliper is (5/3.14)*3.14*16 = 80 lbs, so compare that with 320lbs in the first example a master twice in size will give you 4 times less braking clamping force.

EDIT: I didn't account for the booster added force to the master but that is the same in both instances so for this example is not relevant.
Chuck P
The clowns'? Oh, yeah, the clowns. We fight them too — entire armies, spilling out of Volkswagons. We do our best to fight them off, but they keep sending 'em in!
94 YJ - gone
98 ZJ - sons truck
97 TJ - daughters project

www.oldjeep.com

Offline sharpxmen

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Re: Better Brakes
« Reply #36 on: October 19, 2009, 07:58:23 AM »
I'm talking about the amount of fluid moved via the reservoirs, not the bore of the MC.

i guess i misunderstood since the larger the bore the more volume you get - you also get more volume with more travel but didn't think of that at the time.
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
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Offline Mozman68

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Re: Better Brakes
« Reply #37 on: October 19, 2009, 06:31:13 PM »
Yup, caddy calipers are too small.   I ran Chevy 1/2 ton D44 front calipers on the rear 60 in my CJ, worked great.

Yep...looking at bolt on mid 80's GM truck calipers instead so I can keep my big rotors.
2009 Audi S5....what....its 4wd...sort of....

czjeeper

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Re: Better Brakes
« Reply #38 on: October 24, 2009, 10:13:31 AM »
I swapped in the '95 booster and master.
It actually made a really big difference.
Since it is all stock, it was pretty easy w/out any fabbing.
The only thing I needed was adapters to go from my brake lines to the new master.

My '92 MC has a front fitting that is 5/16, the rear is 1/4 and uses inverted flare fittings.
The '95 uses a M12 on the front, and a M10 on the rear with bubble flare fittings.
So, not only do you have to change the fitting size, you have to change the fitting type.
It would be easiest if a one piece adapter existed, but I can't seem to find one.
SO, on the '95 master, I am using 3 fittings on one and 2 on the other. It works, but is pretty ugly.

Here is a quick'n'dirty install:

This project goes better if you bench bleed the MC before installation.
The booster studs are different on the '95 than on my '92. Make sure you get the correct nuts before starting! Oddly enough, the '92 spacer/booster nuts worked on the '95 booster/MC studs. I only needed new booster/spacer nuts.
Remember to chock your wheels!
Okay, with the adapters, MC, and booster in hand I started the project.
Start inside the cab, looking up at the pedal/pushrod union.
The pedal on my '92 had an odd retaining clip for the push rod.
Pop this loose and wiggle the rod off the pedal.
Unbolt the MC from the booster and gently move it aside without damaging the brake lines.
On my '92, I did not have to unbolt the spacer from inside the cab. I just unbolted the booster from the spacer.
I needed to remove the airbox, and unplug the vacuum line from the booster.
The old booster pulled out pretty easily.
The new '95 booster came with a boot installed on the push rod, so I discarded the old '92 protective cover.
Before sliding the booster flush to the spacer, go into the cab and line up the push rod with the pedal to prevent any binding.
The new booster slid onto the spacer with a little persuading. The studs are larger, but go in without any hassle. I was prepared to drill out the spacer holes, but did not need to.
After checking alignment with the pedal, push the booster the rest of the way in. Go into the cab and slide the push rod onto the pedal, reinstall the retaining clip.
Tighten the nuts on the booster to spacer.
I then installed the adapters on my bench bled '95 MC.
Unbolt the brake lines from the old MC.
Carefully bend the lines over from the passenger side to the new drivers side location for the new MC.
Loosely thread the lines into the adapter on the new MC.
Install a new MC to booster seal. My booster came with a new seal.
Carefully install the new MC onto the booster, taking care that the pushrod slides into the MC.
The studs are a different size than the '92 so install and tighten the new nuts.
You should now be able to do any final tweaking of the brake lines.
Tighten the brake lines and top off the MC with DOT 3 fluid.
Reinstall the vacuum line to the new booster, and the airbox.
Go back into the cab and contort yourself to get a good view of the pedal, pushrod, and sensor switch.
On the '92 pull/push the threaded switch toward the pedal until there is contact with the pedal and switch "button".
My brake lights stayed on after this swap and I needed to adjust the switch.
After testing the brakes at a VERY slow speed and verifying that there were no leaks I took it for a spin.
Everything seems fine.
I am going to let the brakes gravity bleed over night.
If there is any air in the line (squishy pedal) I will bleed them.
I will comment on the effectiveness of this swap after driving it for a few days.

So, there is a breakdown of the install.
I am sorry I didn't have any pics. I had to do this at 10 at night to keep my apartment manager from griping at me.
This little project took me about 45 minutes.
Tools I recommend are a good set of flare wrenches and racheting end wrenches (the space between the booster spacer and firewall pretty tight).
« Last Edit: October 24, 2009, 10:21:55 AM by czjeeper »

Offline neale_rs

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Re: Better Brakes
« Reply #39 on: October 24, 2009, 02:31:19 PM »
Was this '95 booster offered with ABS brakes, tow package or something like that? My YJ is a late '95 with TJ style oil pan, TJ style windshield hood rubber bumpes, etc. and does not have this large booster   :confused:
'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch

Offline dwtaylorpdx

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Re: Better Brakes
« Reply #40 on: October 24, 2009, 02:54:32 PM »
The way to get around the adapter issue is to take the brake lines
from the master to the prop valve to a hydraulic shop and have
them change the MC ends. They can put the correct flare on tube
and the correct fittings.

So will the earlier 92-94 MC fit the 95 booster?
I don't remember if any body asked...

Dave
94 YJ - 2.5 Hesco Cam B&B Ported - AX5 Trans w/Centerforce Dual Friction Clutch - 4" Rough Country Lift W/Skyjacker Shocks - D44 Rear/ARB - D30/ARB - ARB Compressor - Warn M8000 in Custom Bumper - Reunell Rear Bumper - Metalcloak 6" Body Armor Kit - Tuffy Console - 265x85-16 Tires - 2M Radio

Offline Jeffy

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Re: Better Brakes
« Reply #41 on: October 24, 2009, 06:26:54 PM »
The problem with the 1995 booster is that it seems to be only used by the late 1995 Jeep.  I couldn't find anything else that used it.  Also, it's not all 1995 so you have to know what you're looking for.  I would use the new master as it's just slightly larger and the one that TJ's use with the same stock brakes.  The older master should fit though.
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Offline dwtaylorpdx

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Re: Better Brakes
« Reply #42 on: October 24, 2009, 07:00:26 PM »
That's what I would have guessed.

I'm going to be doing the brakes on my
YJ pretty soon and I'm thinking of a upgrade.

Wish they had used Bolted calipers instead of the sliders,
woulda made things way easier...

Has anybody messed around with the 1/2 ton rotors and
calipers off a full size dodge pickup? AS I recall some were
the same bolt pattern 5x4.5.

Dave
94 YJ - 2.5 Hesco Cam B&B Ported - AX5 Trans w/Centerforce Dual Friction Clutch - 4" Rough Country Lift W/Skyjacker Shocks - D44 Rear/ARB - D30/ARB - ARB Compressor - Warn M8000 in Custom Bumper - Reunell Rear Bumper - Metalcloak 6" Body Armor Kit - Tuffy Console - 265x85-16 Tires - 2M Radio

Offline Jeffy

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Re: Better Brakes
« Reply #43 on: October 24, 2009, 07:09:41 PM »
That's what I would have guessed.

I'm going to be doing the brakes on my
YJ pretty soon and I'm thinking of a upgrade.

Wish they had used Bolted calipers instead of the sliders,
woulda made things way easier...

Has anybody messed around with the 1/2 ton rotors and
calipers off a full size dodge pickup? AS I recall some were
the same bolt pattern 5x4.5.

Dave

Have you checked out Vanco's brakes?
Youtube Channel: https://www.youtube.com/channel/UCZNlr60GXH5OlKIFrT7P6mg
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"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

Offline sharpxmen

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Re: Better Brakes
« Reply #44 on: October 24, 2009, 08:30:29 PM »
Was this '95 booster offered with ABS brakes, tow package or something like that? My YJ is a late '95 with TJ style oil pan, TJ style windshield hood rubber bumpes, etc. and does not have this large booster   :confused:

my '95 has a single diaphragm as well, but i did find one at the junkyard and pulled the booster and MC off of it, need to find some time to install it - and it seems that i am in for some fun with the fittings.
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end