Just some general info I've collected
Different post and what not... Figure I'd share.


BEFORE you mess with your brakes, read and obey -> Brake Bible (http://pirate4x4.com/tech/billavista/Brakes/)
Cliff notes: Your brakes are a system and it all works together.
Don't just go replacing one piece and expect them to be perfect.
Calipers and Master cylinders need to be matched to one another.


Brake Caliper & MC size info:
Front Brake Caliper Pistons sizes:
Piston Diameter = Vehicle found on ........................... Orginial Master Cylender size Power . Manual
2.934 = 79 Chevy 1/2ton ............................................... Brake Cylinder Bore Size:1 1/8"
2.934 or 3.146 = 79 Chevy 3/4ton ................................... Brake Cylinder Bore Size:1 1/8" or for larger 1 1/4"
3.375 = 79 Chevy 1 ton (Dana 60) ................................. Brake Cylinder Bore Size:1 1/4" or 1 5/16"
2.875 = 79 Ford 1/2ton ................................................. Brake Cylinder Bore Size:1" ........ For Both Power & Manual
2.875 = single piston..........-> 79 Ford 3/4ton .................. Brake Cylinder Bore Size:1" ........ For Power
4.360 = Dual piston 2.18 x 2 . -> 79 Ford 3/4ton ................ Brake Cylinder Bore Size:1 1/16" ........ For Power
4.360 = Dual piston 2.18 x 2 . -> 79 Ford 1ton (Dana 60) ... Brake Cylinder Bore Size:1 1/16"
3.100 = 78 Lincoln Mark V ............................................. Brake Cylinder Bore Size:1 1/8"
2.934 = 79 Jeep Waggy ............................................... Brake Cylinder Bore Size:1 1/8"
2.934 = 91 Jeep Waggy ............................................... Brake Cylinder Bore Size:40 mm & 28.6 mm
2.934 = 77 CJ .................................................. ......... Brake Cylinder Bore Size:1 1/16" .....For Both Power & Manual
2.596 = 82 CJ .................................................. .......... Brake Cylinder Bore Size:15/16" Manual & 1" Power
2.596 = 88 YJ .................................................. .......... Brake Cylinder Bore Size:15/16"
2.596 = 94 YJ .................................................. ......... Brake Cylinder Bore Size:1"
2.596 = 99 YJ .................................................. ......... Brake Cylinder Bore Size:1"
2.595 = 88 XJ .................................................. ......... Brake Cylinder Bore Size:15/16"
3.100 = 86 Dodge 1ton (Dana 60) ................................. Brake Cylinder Bore Size:1 1/8"
7.840 = Four piston 1.87 x 4 . -> 69 Corvette .................. Brake Cylinder Bore Size:1" Manual & 1 1/8" Power
3.260 = Dual piston 1.81 x 2 = 03 Explorer ..................... Brake Master Cylinder Bore Size 1 1/16"
2.595 = 98 TJ .................................................. ......... Brake Cylinder Bore Size: 1" & 1 1/16" (No note about power or manual brakes for size)
2.595 = 05 TJ .................................................. ......... Brake Cylinder Bore Size: 1" & 1 1/16" (No note about power or manual brakes for size)
2.750 = 02 Durango ............................................... Brake Master Cylinder Bore Size 15/16" .......................... Rotor 11.3" x .95" with 6 on 4.5"
4.240 = Dual piston 2.12 x 2 = 03 Durango. ..................... Brake Master Cylinder Bore Size 15/16" ............ Rotor 12.12" x 1.11" with 6 on 4.5"
4.240 = Dual piston 2.12 x 2 = 01 Ram 1500 ................... Brake Master Cylinder Bore Size 1 1/4" ............ Rotor 12.11" x 1.18" with 5 on 5.5"
4.240 = Dual piston 2.12 x 2 = 02 Ram 1500 ................... Brake Master Cylinder Bore Size ?" .................... Rotor 13.23" x 1.1" with 5 on 5.5"
3.540 = Dual piston 1.77 x 2 = 01 Ram 2500 ................. Brake Master Cylinder Bore Size 1 1/4" OR 1 5/16" *
4.240 = Dual piston 2.12 x 2 = 01 Ram 2500 ................. Brake Master Cylinder Bore Size 1 1/4" OR 1 5/16" *
4.020 = Dual piston 2.01 x 2 = 01 Ram 3500 ................... Brake Master Cylinder Bore Size 1 1/4" OR 1 5/16" *
4.240 = Dual piston 2.12 x 2 = 01 Ram 3500 ................... Brake Master Cylinder Bore Size 1 1/4" OR 1 5/16" *



Rear Brake Caliper Pistons sizes:
Piston Diameter = Vehicle found on .. Piston Part #........ Orginial Master Cylender size Power . Manual
2.126 = 84-90 Lincoln Mark VII ......................................... Brake Cylinder Bore Size:1 1/8"
2.497 = 78 Cadillac Eldorado large . Napa # SDC2422106 ...... Brake Cylinder Bore Size:1 1/8"
2.497 = 78 Cadillac Eldorado large . Napa # SDC2422106 ...... Brake Cylinder Bore Size:1.12500 w/ Hydroboost
2.121 = 79 Cadillac Eldorado small . Napa # SDC2422100 ...... Brake Cylinder Bore Size:1"




I like pictures :p
http://77cj.littlekeylime.com/mrnimages/calipers_many.PNG

Noice! Good info there! Could have used that a time or two....

Been needing some of this. Thanks for takin' the time to gather this up.

sub-d:smokin:

:smokin: Again, a great contribution Mr. N....

Mr. N are you adding these little tech articles to your web page. I have it in my favorites so its easy to find.

and thanks.

hardcore, lol.

Click save, perfect!!!!!

Good on you sir.:smokin:

Excellent work again Mr.N.

Definitely helpful. I just started on a TJ rear disc convo so the info definitely helps. WOuld be great to get more info on MC's, displacement, bore, as well.

Very awesome Mr. N!

Only thing I see wrong is that all the 4 piston calipers have twice as much piston area as what should be calculated... ie: the fixed Toyota calipers w/ (4) 1.680 pistons may have 2.215548 sq in of surface area... but you can't count it 4 times... only twice for a fixed caliper. So instead of 8.78 is should be 4.39 for calculation's sake.

Only reason I know this is I've read the hell out of Billavista's writeup a few times over:D

Thanks guy's for the nice words, glad its helping.


silverback97, Next time I update my web page I'll create a page with links to all the odd data I've collected.


Ignore list (http://pirate4x4.com/forum/profile.php?do=ignorelist) for 66jj, you don't have to listen to me or I, you.


geberhard, I have a few MC Bore sizes above but had trouble connecting different bore sizes with power or manual brakes and/or different calipers. If I find a better source of info I'll update the pic.
Have any idea's on better source?
What I'll do some day, get the math for stock capiler and MC to post the "Vertical Force on Both front Tires (lbs)" numbers :smokin:


Only thing I see wrong is that all the 4 piston calipers have twice as much piston area as what should be calculated... ie: the fixed Toyota calipers w/ (4) 1.680 pistons may have 2.215548 sq in of surface area... but you can't count it 4 times... only twice for a fixed caliper. So instead of 8.78 is should be 4.39 for calculation's sake.

Only reason I know this is I've read the hell out of Billavista's writeup a few times over:D
Flatlander, Not sure I'm following you... or maybe I'm using the Brake cal wrong.

I'm using "Actual Piston Area (each front calliper)" for my numbers; that shows 8.86 (Hind sight I should have noted this better)
The "Total Effective Piston Area (front)" changes if it's floating or fixed from 17.72 to 8.86

Can you expand on this?


.

You bag on all the non hardcore posts on here and post this on here. absolutely funny shit, after ten years you should know where to put stuff....

I just had to know how they relate to each other...

You guy's think the "Hydraulic Ratio" is the best way?

http://littlekeylime.com/MrN/mrnimages/calipers_2_mc.png

From the thread "Hydroboost info (http://pirate4x4.com/forum/showthread.php?t=610945)"

Thank you 66Gladiator401 for the nice post.
Back to the MC bore specs you guys were looking for... I've started a small list and these are for rigs that were mostly hydroboosted... because those are the MCs that are most likely to fit into your hydroboost unlike the majority of the vacuum MCs out there. Note that many later model.... '00+ MC's will also have too large of a stub to fit into ealier hydroboost so measure what'cha got to see what'll fit. Also note that while most vehicle use the 3.40" bolt centers for the MC there is Ford using 3.20" and Dodge using 3.20" and 3.40". I believe that Hummer used both bolt patterns as well and the GM vans with the square aluminum MC... are probably on 3.20" where all their other stuff is on 3.40".

There is some overlap in this list because I had two lists and one also includes the size of the calipers used. The general rule of thumb is that the smaller the piston the less pedal pressure but you really need to also factor in how much fluid you need to push to work the size of the pistons in your calipers. This gives you a start.... an idea anyway.

2005 Chevy 3500 (with HB) = 1 15/32”
1995 Astro Van (with HB) = 1-1/4"
1991 F450 (with HB) = 1 5/16”
2005 F450 (with HB) = 1 3/8”
1984 Chevy K10 = 1-1/8" & 1-37/64"; 4WD
’92 S10 = 24 & 36 mm
’90 Chevy 2500 8,600 GVWR = 1 ¼”
1989 Chevy 1500 = 24 &36mm
2000 Chevy 1500 w/hydroboost = 37mm
’99 Camaro = 1”
’98 Blazer = 1”
2002 Chevy 3500 & ’96 P30 Van (disc/disc) = 40mm
1992 Chevy Suburban = 1 1/8” & 1 37/64”
‘99+ Mustangs w/V8 = 1 1/16”
’96-’98 Mustangs w/V8 = 1”
Hummer = 15/16”
’03-‘07 Chevy 1500- 3500 disc/disc = 1 15/32” (dual piston calipers = 2.36”)
’02 Chevy 2500-3500 disc/disc = 37mm or 1.456” or ~1 7/16” (dual piston calipers = 2.0 to 2.25”)
’99-04 F250-F550 =13/16” w/cruise, 1 3/8” wo/cruise (dual piston calipers = from 2.20” or 56mm to 2.362” or 60mm)
’01-05 Dodge 3500 disc/disc = 1 ¼” (dual piston calipers = 2.20” frt and 2.10” rear on DRW, 1.77” for SRW)
’97 F350 disc/drum = 1 ¼” (dual piston calipers = 2.20” or 56mm)
’91 F450 disc/disc = 1 5/16” (dual piston calipers = 2.362” or 60mm)
1980 Cadillac disc/disc = 1”
’88-‘97 (some 2000) GM 1500-3500 disc/drum = (single piston caliper = 3.15”)
’88-‘97 (some 2000) GM 1500-2500 disc/drum = 1 ¼” (single piston caliper = 2.935”)
‘80’s GM Dually truck and Corvette = 1 1/8” (1.125”)
’87 GM Dually step van = 1 5/16”
Astro van disc/drum = 1 1/8 to ¼” (single piston caliper = 2.934”)

I like this collection of info. Thanks saves a ton of leg work!!!

Jason :):homer:

Flatlander, Not sure I'm following you... or maybe I'm using the Brake cal wrong.

I'm using "Actual Piston Area (each front calliper)" for my numbers; that shows 8.86 (Hind sight I should have noted this better)
The "Total Effective Piston Area (front)" changes if it's floating or fixed from 17.72 to 8.86

Can you expand on this?


.

I had time to double check myself just now and I actually had it backwards, sorry about that but anyways...

For fixed calipers everything stays the same... so those numbers are correct. For floating calipers you need to DOUBLE the piston area as the slides allow the piston to act on BOTH sides of the caliper(as I understand it). Here is a quote from the brake bible:

Clamping Force is calculated as:
CF = PM x AT

Where

CF = Clamping Force (lbs)

PM = Maximum hydraulic pressure (psi)

AT = Total effective area of calliper’s pistons (sq. in.) – for fixed callipers this is the actual area of the pistons, for floating callipers this is equal to 2 x the actual area of the pistons



So for instance the Chevy caliper with a single 2.94" piston has an actual piston area of 6.79 sq-in.

For calculation's sake... you need to double that: 13.58 is what you use when calculating the clamping force.


I have the brake calculator on my computer... with the Chevy 2.94" single piston floating calipers I have and the master cylinder I have plugged in I get 889 for the max hydraulic pressure after the brake booster is factored in.

If you change the caliper to a fixed dual piston caliper(change B34 to "2" instead of "1" and B38 to "1" instead of "2") and you get the sam exact pressure and all that good stuff.

So when it comes to clamping force, if you are comparing a fixed vs floating caliper, you need to take the 2x floating caliper piston area into account, so in reality the Chevy 3/4 ton 2.94" caliper will give you more effective piston area(13.57... not 6.74 as your chart says) than the Toyota quad 1.68" fixed caliper which you were correct with 8.87 effective piston area.

:homer:

I have D44/d60 axles from a J truck, 8 lug. I was told the disc's on it, and the one's that are on the rear, are Chevy disc's. Last dude ran a Corvette MC and it worked fine. I can't match up any numbers from above for what I think I have......

Can I assume the brakes that came on the stock Jeep trucks are these:

2.934 or 3.146 = 79 Chevy 3/4ton ................................... Brake Cylinder Bore Size:1 1/8" or for larger 1 1/4"

And how do I tell the difference on which setup I have, the 2.934 or the 3.146?


And Mr. N, awsome information. Thanks a bunch for putting stuff like this out.

I had time to double check myself just now and I actually had it backwards, sorry about that but anyways...

For fixed calipers everything stays the same... so those numbers are correct. For floating calipers you need to DOUBLE the piston area as the slides allow the piston to act on BOTH sides of the caliper(as I understand it). Here is a quote from the brake bible:



So for instance the Chevy caliper with a single 2.94" piston has an actual piston area of 6.79 sq-in.

For calculation's sake... you need to double that: 13.58 is what you use when calculating the clamping force.


I have the brake calculator on my computer... with the Chevy 2.94" single piston floating calipers I have and the master cylinder I have plugged in I get 889 for the max hydraulic pressure after the brake booster is factored in.

If you change the caliper to a fixed dual piston caliper(change B34 to "2" instead of "1" and B38 to "1" instead of "2") and you get the sam exact pressure and all that good stuff.

So when it comes to clamping force, if you are comparing a fixed vs floating caliper, you need to take the 2x floating caliper piston area into account, so in reality the Chevy 3/4 ton 2.94" caliper will give you more effective piston area(13.57... not 6.74 as your chart says) than the Toyota quad 1.68" fixed caliper which you were correct with 8.87 effective piston area.

:homer:


Thanks for taking the time flatlander757 to explain it better than I could and correcting and double checking the info :D

And how do I tell the difference on which setup I have, the 2.934 or the 3.146?

Best way is to just pull it and check...

(Plus you need to check the pads, see how much was left... or something like that :grinpimp:)


Not like this, but from piston edge to edge
http://77cj.littlekeylime.com/img/Dana60/Build/cb/Dana_60_brakes_caliperbracket_halfton5point5inch00 1.jpg

Good thread. I found it while trying to find the diameters for the stock scout calipers I had and the chevy calipers that replaced them. Turns out factory scout II calipers are 3.1" diameter.

source:
http://www.binderplanet.com/forums/showthread.php?t=17817

Scout II disc/drum master is 1.125" diameter

I shit you not I was looking for this information today. Thanks Brad.

Ben, thanks for the nice words and the link.

I shit you not I was looking for this information today. Thanks Brad.
Glad it helped Rod.

yes, going through this now... so good timing and thanks
ben

Glad it helped Ben

Bump for a good tech thread on brake caliper & MC sizing.

I had time to double check myself just now and I actually had it backwards, sorry about that but anyways...

For fixed calipers everything stays the same... so those numbers are correct. For floating calipers you need to DOUBLE the piston area as the slides allow the piston to act on BOTH sides of the caliper(as I understand it). Here is a quote from the brake bible:

Clamping Force is calculated as:
CF = PM x AT

Where

CF = Clamping Force (lbs)

PM = Maximum hydraulic pressure (psi)

AT = Total effective area of calliper’s pistons (sq. in.) – for fixed callipers this is the actual area of the pistons, for floating callipers this is equal to 2 x the actual area of the pistons

So for instance the Chevy caliper with a single 2.94" piston has an actual piston area of 6.79 sq-in.

For calculation's sake... you need to double that: 13.58 is what you use when calculating the clamping force.


I have the brake calculator on my computer... with the Chevy 2.94" single piston floating calipers I have and the master cylinder I have plugged in I get 889 for the max hydraulic pressure after the brake booster is factored in.

If you change the caliper to a fixed dual piston caliper(change B34 to "2" instead of "1" and B38 to "1" instead of "2") and you get the sam exact pressure and all that good stuff.

So when it comes to clamping force, if you are comparing a fixed vs floating caliper, you need to take the 2x floating caliper piston area into account, so in reality the Chevy 3/4 ton 2.94" caliper will give you more effective piston area(13.57... not 6.74 as your chart says) than the Toyota quad 1.68" fixed caliper which you were correct with 8.87 effective piston area.

:homer:

I think this is an error in the Brake Bible. The only difference between floating and fixed calipers is that one floats and the other doesn't.

http://i78.photobucket.com/albums/j116/jimkeith/misc_crap/caliper.jpg

If the pistons are all the same size and the line pressure is the same, the forces denoted by the red arrows are all the same.

To help prove this point, imagine a caliper with two pistons on one side and one piston on the other. The single piston will exert a force dictated by its area and the line pressure. If the pistons on the opposite side were to push harder, it would displace fluid behind the single piston and the piston would retract into the bore. They are all hooked to the same fluid so the pressure can't rise, the caliper would just shift to the side of the two pistons.

You bring up a great point, I've been wanting to find out yes or no for sure. In searching I found this:

Why pressure from only one side?

This can be a little confusing and some very smart people have gotten caught. But it really isn’t that hard to understand if we shift our thinking a bit. First, ignore whether or not the caliper is fixed or floating; it doesn’t matter, and in a minute you’ll see why.

Imagine that you are holding a book between your two open hands. Now squeeze on the book. If your left hand is pushing with 25 pounds of force, then your right hand has to push back with that much force or the book will move across your chest. Each of your hands is a brake pad, and the book is the rotor. The force between the pad and the rotor is only 25 pounds, not 50. And it is the force between pad and rotor that determines the frictional force generated on the brake rotor.

In this respect there is no difference between floating and fixed calipers. The other side just acts to keep the rotor centered in the caliper, one moves the whole caliper, the other moves the other pistons.

But wait! There are still two pads, one on each side. If we replace one pad with a ball bearing surface the force on the rotor from the brake caliper would be reduce about half. So we have to count both pads, but using the force generated by one side of the pistons.

Thanks Tim for the bump.


"The other advantage is the single piston design is easier to bleed. The disadvantages are it heavier, retains heat, requires approximately 100 pounds of pressure more to "slide" the caliper and requires more volume of brake fluid due to the diameter of the piston."
Brake Article© by Dean Oshiro 1994 (http://www.hotrodheaven.com/tech/brakes/)

That article Dean Oshiro is another great brake primer, but the quote you mention only talks about it in a negative, not a positive for more braking force.

I would think that if it were a great positive Dean would have mentioned it in his article.

I also did a bunch of searching last night trying to find any other sources that stated that a floating caliper doubles the clamping forces and had no luck.

Not saying that it isn't right, just trying to confirm for sure one way or the other.





BTW- Thanks for the thread Mr.N, it helped me figure out a problem we were having here in the shop.

Thanks Tim for the bump.


"The other advantage is the single piston design is easier to bleed. The disadvantages are it heavier, retains heat, requires approximately 100 pounds of pressure more to "slide" the caliper and requires more volume of brake fluid due to the diameter of the piston."
Brake Article© by Dean Oshiro 1994 (http://www.hotrodheaven.com/tech/brakes/)


Finally someone gets it right. Accurate surface area calculations for floating calipers require you double the area of the piston to measure the clamping force.

The above is partially correct if it is referring so SOME floating calipers where the caliper body takes the load of the brake pad and can cause some binding force when moving in the bracket (think 80s Chevy calipers).

Modern floating calipers do not hold the brake pad in place. They are bolted to a bracket that holds the pad, and the floating caliper simply does the job of clamping the pads together. If you look on the first page at some of the newer caliper designs it will make a bit more sense.

Here's a picture of what I am talking about:

F-350 caliper bracket:

http://images.oreillyauto.com/parts/img/large/a1c/v2/141009-lef.jpg