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powerplay
03-08-2005, 06:19 PM
Hi,
I'm looking to upgrade my front 76 camaro discs. I have 17" wheels and comparing Baer and Wilwood. The Baer system is the Track with 13" rotors, PBR 2 piston calipers, and later B body spindles. The Wilwood has 12" rotors and 4 piston calipers. Independent of cost, which is the preferred system for stopping power?
Thank you. Your comments would be appreciated.

HOT OHC
03-08-2005, 10:11 PM
ah, scroll down about 8 posts or so.

powerplay
03-09-2005, 05:36 AM
My basic question is, is a Baer 13" rotor with a 2 piston caliper better than a Wilwood 12" rotor with a 4 piston caliper, or vica-versa? These kits are the largest that will fit my 17" wheels. Whats more important the rotor diemeter, or number of caliper pistons.
Thanks

dennis68
03-09-2005, 06:27 AM
Rotor diameter plays a bigger role in stopping performance, ultimately tires are actually the determining factor in stopping distances.

Tom Nickols
03-13-2005, 06:36 PM
I would be simplfying a lot and ignoring pad co-efficient of friction.
stopping torque=(presure X area) X radius

work out what the surface area of all the pistons are in the caliper and multiply by brake line pressure.

you would imagine that the 4 piston would have a higher surface area.

Multiply the force by the radius to the center of the pad. This is where the large disc catches up.

The larger number wins. Intuatively 0.5" will not make up for twice the number of pistons. But I would be interested if someone went to the effort of working all the kits out into a chart and dividing the effective torque by $.

force(lbs)=pressure(lbs/in2) X area(in2)
stopping torque(lbs.in)=force(lbs) X radial distance(in)

Wilwood dynalite big brake 12.19" disc
4x 1.75" pistons, approximate effective Radius 5.1"

Baer Track PBR caliper with 13 rotor
2x 1.75" pistons, approximate effective Radius 5.5"

Works out that Willwood should be 85% more effective for the same pedal effort. Should point out that both brake kits will be capable of locking the wheels at speed, it just comes down to pedal feel.
Strangely the Wilwood 6 piston has 15% less piston area than their 4 piston. This smaller area with the larger brake diameter makes them equal in braking effect, making me think the only reason for going big is for brake fade/cooling reasons (and bragging rights). The down side being extra un-damped wheel mass.

Bear in mind the Baer caliper floats, inherently this has a risk of binding and only working on one pad as the milage goes up and the dirt increases. Baer`s advantage is that a large disc can dissipate heat more effectively.

I bought the Willwood on cost and design principal, turns out that theoretically they should work better too.

TEDDYS CAMARO
03-14-2005, 02:00 PM
What About The C-5 Brake Conversion? How Does That Compare To The Other Brake Systems?..............teddy

Tom Nickols
03-24-2005, 01:04 PM
As far as I am aware the PBR kit uses the C-5 caliper.

USAZR1
03-24-2005, 03:10 PM
The Track kit uses a C4 caliper. The GT kit uses the C5 unit. If you decide on the GT set-up,be aware that some 17" wheels will not clear the C5 caliper.

427v8
03-25-2005, 03:18 PM
I would be simplfying a lot and ignoring pad co-efficient of friction.
stopping torque=(presure X area) X radius

work out what the surface area of all the pistons are in the caliper and multiply by brake line pressure.

you would imagine that the 4 piston would have a higher surface area.

Multiply the force by the radius to the center of the pad. This is where the large disc catches up.

The larger number wins. Intuatively 0.5" will not make up for twice the number of pistons. But I would be interested if someone went to the effort of working all the kits out into a chart and dividing the effective torque by $.

force(lbs)=pressure(lbs/in2) X area(in2)
stopping torque(lbs.in)=force(lbs) X radial distance(in)

Wilwood dynalite big brake 12.19" disc
4x 1.75" pistons, approximate effective Radius 5.1"

Baer Track PBR caliper with 13 rotor
2x 1.75" pistons, approximate effective Radius 5.5"

Works out that Willwood should be 85% more effective for the same pedal effort. Should point out that both brake kits will be capable of locking the wheels at speed, it just comes down to pedal feel.
Strangely the Wilwood 6 piston has 15% less piston area than their 4 piston. This smaller area with the larger brake diameter makes them equal in braking effect, making me think the only reason for going big is for brake fade/cooling reasons (and bragging rights). The down side being extra un-damped wheel mass.

Bear in mind the Baer caliper floats, inherently this has a risk of binding and only working on one pad as the milage goes up and the dirt increases. Baer`s advantage is that a large disc can dissipate heat more effectively.

I bought the Willwood on cost and design principal, turns out that theoretically they should work better too.

I disagree with your math.
On a fixed caliper you only count the pistons on one side.
The 13" Baer system ( sadly ) will have more stopping torque due to the larger rotor dia. But as mentioned it's pretty minimal. I can post the formulas if anyone wants to wade through it.

One thing to look at is actually the rotor width. If memory serves the Wilwood system has 1" thick rotors. 1.25" rotors would be MUCH better.

Also the Dynalites are a very small caliper. Not a lot of pad. The superlight 4 is a superior caliper...more $$ tho

Tom Nickols
04-01-2005, 01:12 PM
Don't be daft

How can you only count the pistons on one side? brake fluid isn't clever enough to determine it's on the wrong side of the caliper to be effective.

Very basic math / physics force=presure X area

dynlite has twice as much area than PBR caliper

By the way thick disc's don't make you stop quicker they cool better as they can have more surface area. MARGINALY better if you are track racing. MUCH better would come from a Aluminum Metal Matrix disc as on the original LOTUS Elise.

LTorres
04-01-2005, 02:29 PM
[QUOTE=Tom Nickols]Don't be daft

How can you only count the pistons on one side? brake fluid isn't clever enough to determine it's on the wrong side of the caliper to be effective.

Very basic math / physics force=presure X area

dynlite has twice as much area than PBR caliper


In my humble opinion your both right...Since there are 4 pistons in the calipers mentioned above there truly is more area. However, just the same as a Baer caliper with non-opposing pistons, when it comes to clamping force only one side can be calculated.

Tom if your theory were correct then how do you suppose pressure is applied to the outboard pad on a non-opposing piston set up like the Baer calipers? Your math is right but it seems as though some confusion on clamping force. Real simply put if you had 1,100psi at the caliper and a total of 4.75 area you would generate clamping forces up to 5225lbs of force, while this number is accurate it has to be divided in 2. Since one side is applying force to the other they in turn cancel each other out. IF they were both applying pressure from the same side with perhaps a brick wall on the other side that was stationary then you could say "Yeah now I'm generating the FORCE of all 4 piston's area" which would be 10,550lbs of force. If you know of a system that generates this kind of clamping force post it up here.

427v8
04-02-2005, 04:53 AM
[QUOTE=Tom Nickols]Don't be daft

How can you only count the pistons on one side? brake fluid isn't clever enough to determine it's on the wrong side of the caliper to be effective.

Very basic math / physics force=presure X area

dynlite has twice as much area than PBR caliper


In my humble opinion your both right...Since there are 4 pistons in the calipers mentioned above there truly is more area. However, just the same as a Baer caliper with non-opposing pistons, when it comes to clamping force only one side can be calculated.

Tom if your theory were correct then how do you suppose pressure is applied to the outboard pad on a non-opposing piston set up like the Baer calipers? Your math is right but it seems as though some confusion on clamping force. Real simply put if you had 1,100psi at the caliper and a total of 4.75 area you would generate clamping forces up to 5225lbs of force, while this number is accurate it has to be divided in 2. Since one side is applying force to the other they in turn cancel each other out. IF they were both applying pressure from the same side with perhaps a brick wall on the other side that was stationary then you could say "Yeah now I'm generating the FORCE of all 4 piston's area" which would be 10,550lbs of force. If you know of a system that generates this kind of clamping force post it up here.

No one believes me? OK Read this (http://www.hotrodheaven.com/tech/brakes/brakes1_index.htm) (last paragraph )

Q ship
04-02-2005, 10:04 AM
Don't be daft
He's not daft, he's correct.
Maybe a little real tech (http://www.stoptech.com/whitepapers/formulas%20for%20vehicle%20braking%20dynamics.pdf) would be appropriate here.

427v8
04-03-2005, 06:38 AM
He's not daft, he's correct.
Maybe a little real tech (http://www.stoptech.com/whitepapers/formulas%20for%20vehicle%20braking%20dynamics.pdf) would be appropriate here.

But, what if I like being Daft???:seizure:

Tom Nickols
04-03-2005, 09:25 PM
Ok, may be I'm the daft one....

But the real way we should compare calipers is like this.

427v8, we should not remove half the 4 piston caliper, we should double the sliding caliper. I wasn't till I recovered from the hang over of having a baby (not directly!) that I drew a free body diagram.

Start with a sliding caliper- the pressure in the piston chamber applies to the piston face. It also applies to the caliper chamber in the opposite direction, to the exact same magnitude. The piston pushes against one side on the disc and the caliper pushes against the other. The fact the equal each other and the caliper slides means the disc doesn't get pushed side ways.

With an opposed piston caliper the force on the caliper halves cancel each other out.

So therefore both calipers (4 piston opposed and 2 piston sliding) will generate the same clamping force if the pistons are the same size.

Correction to bad math... baer track is 8% more effective (theoretically) than wilwood 12.19 big brake.

Although according to Tony Huntimer fixed opposed calipers give "better braking feel and faster responses" (Pro-Touring book)

Also as floating calipers non-piston side isn't infinitely stiff my guess is that it isnít likely you'll get symmetrical pressure distribution on both side of the disc.

Daft Tom

427v8
04-04-2005, 06:13 PM
Daft Tom,
8% is 8%... But you have to subtract the sliding force of the single piston caliper which I've seen as being 100psi(?) or was it pounds...

Ii have single piston calipers on my Daily Driver and it always eats pads on the piston side first. Kinda proves your symmetrical issue don't it. ( of course GOOD floater are probably much better!)

I personally upgraded from 4 piston cast iron Vette calipers to Willwood SL4s when I noticed that my stock pads were starting to look like footballs. thin at the front and back, thick in the middle. Wannna talk about a soft pedal??

I hope the Wilwoods are stiffer, track time will tell.

Daft Keith