Front brake up grade to Wilwood 4 pot

[Dessertrunner]

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[Dessertrunner]

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[bishop]

whats with the extra 5 studs on your brakes? they look really good.

[dragoontwo]

whats with the extra 5 studs on your brakes? they look really good.

Looks like he's using wheel spacers.

[Dessertrunner]

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[SoobCrazy]

So what is the story with this? How did you find these calipers? What are the piston specs? Where did you get the caliper adapters?

Also, it looks like you had to clearance the OEM caliper mounting ears a little bit, any other massaging that goes with this swap?

[fasteract7]

Did you machine the adaptors or out source them ? Pad part number for the thicker type used?

[oab_au]

Did you machine the adaptors or out source them ? Pad part number for the thicker type used?

You have to be joking to think Tony would get some body to make them.:rolleyes:
Probably milled them up after dinner.:)

Harvey.

[Dessertrunner]

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[icingdeath88]

I can post a DXF file of the adapter if you want.

That would be great. Think the 4-pots would fit under 17" wheels? From pics they look like they'd even fit under the stockers. Those look great and I think for the price they should be a great upgrade.

[Dessertrunner]

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[fasteract7]

Probably me not seeing the figure but what is the thickness of the adaptor?

[Dessertrunner]

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[icingdeath88]

Could you make me a pair of the adapters?

[steveherman]

Me too?
Maybe.

[Gamesy]

Group Buy!!!

[fasteract7]

I would be "In" if our Aussie friend feels like it. That .39" bolt you mentioned would fit the Wildwood caliper better..?..is the caliper threaded for what size ?

[SVXRide]

Tony

Looking over the .pdf file and it looks like it might be (?) missing one or two other dimensions needed for someone else to machine up the spacers? If I took a rectangular piece of 10mm 1040, where would I reference the hole locations from?

Cheers,
Bill

[Dessertrunner]

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[oab_au]

Thanks Harvey you are right I designed and machined the adapter plate, the final version that I installed on the car did not need the ears ground that was a earlier version. The pad number is in the post 7816 once I had the bits made and the moods to the calipers the install took less then a hour for both sides and bleeding.

In answer to piston size the SVX has 2 which are 1.6in (40mm)diameter the new calipers have 4 which are 1.75in each, in short you are more then doubling the the force on the disc. Hope that covers the questions asked.

I can post a DXF file of the adapter if you want.
Tony

It does not actually work out like that, the SVX pistons are double acting, pressure is applied to both ends of the cylinder, 2” on the back of the piston, and 2” on the caliper end of the cylinder.

So the SVX has 8sq”, and the Wilwood has 9.6sq”, an increase of 20%.
The big benefit is that the higher pressure is applied equally to both sides of the disk, instead of piston pressure to one side and caliper pressure to the other side, the opposing pistons can freely follow a warped disc.

Harvey.

[Dessertrunner]

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[oab_au]

You had me stumped for a minute Harvey, this is going to be interesting debate.
If I use your point then I am getting pressure on both side of the pistons on both sides so I am get twice as much as you suggest the SVX ones are getting. In other words the SVX has two faces with pressure the Wilwood has 4 faces.

Happy to be proven wrong.
Tony

Not easy to explain Tony.:)
In the Wilwood only the piston area applies pressure to the disc, the back of the cylinder is fixed, so it applies no pressure to the disc.

In the SVX both ends of the hydraulic cylinder, the piston on one side of the disc, and the back of the cylinder, which is connected to the opposite side of the disc, applies pressure to the disc. So both 2” ends of the SVX cylinder apply pressure to the disc. Only one end of the Wilwood cylinder can apply pressure to the disc.

Harvey.

[Dessertrunner]

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[Tireiron]

The major difference being between a fixed caliper and a floating caliper design. In a floating caliper the caliper itself moves which is what applies force to the opposite side of the disc. This is caused by pressure being applied to the caliper itself inside of the piston bore. So in a floating caliper pressure is applied to the rotor on one side by the force on the back of the piston, and on the other side by the force on the caliper.

In a fixed caliper design the caliper itself cannot move. So there needs to be pistons on both sides to apply force to both sides of the rotor. One side of the rotor gets force by pressure applied to the back of the pistons on that side, and the other side gets force from pressure applied to the back of the pistons on that side. The force on the caliper does not apply any pressure to the rotor.

To use the example with hydraulic rams you would need to set it up differently.

To equal a fixed caliper brake system you would need two rams opposite eachother mounted to fixed, unmoveable points, pressing on an item in the middle, call it X. In this there would only be forces on the pistons pressing on X.

To equal the floating caliper system, you would have one ram which is mounted to a moveable plate. The piston of the ram would press on one side of X, and the moveable plate would press on the other side of X. In this setup you have force pressing on the piston in one direction, and on the base of the ram in the other direction because the ram can move on its mounting plate.

[oab_au]

Yehhhhhh.:D
Could not have said it better.:)

Harvey.

[Dessertrunner]

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[Tireiron]

The rotor is a fixed piece. You need force on both sides of it to make the car stop. In a fixed caliper system you have pistons on both sides that give the pressure needed. In a floating caliper design the pistons are only on one side of the rotor. Something has to give force onto the other side of the rotor for the system to work. The pressure on the pistons is also pressing the caliper away from them causing that force to be transmitted to the opposite side of the rotor. There is a force on the back of the piston pressing into the rotor, and there is another equal force on the caliper pushing it away from the piston pressing on the other side of the rotor. If a floating caliper was fixed, it would only apply force to one side of the rotor which would not give the clamping action needed to stop the vehicle because the rotor is fixed. There has to be a second force active to get the clamping pressure needed on the fixed rotor to make it stop.

[Tapani]

Calculate the forces from a given pressure, make a drawing and see how the forces act.

Harvey is correct.

/T

[Dessertrunner]

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[oab_au]

Okay Harvey it seems I have to eat hubble pie, you are correct, you would think us young guys would know better then to challange you older guys.

Its seems that the arguement in support of fixed capilers is more complex then pressure. In my case it was because the floating ones kept floating away from the disc when I was on dirt so I had topump the brakes before I go any. I noticed that all the good 4WD had gone to fixed capilers.

Keep well.
Tony

Tony don’t let it worry you, its one of those things you take of granted, and don’t really look into.:cool:
As I said before,
“ The big benefit is that the higher pressure is applied equally to both sides of the disk, instead of piston pressure to one side and calliper pressure to the other side, the opposing pistons can freely follow a warped disc.”

The sliding calliper is really medieval, it only has price as its benefit. It only works well when new, then the slide pins freeze up and the frame distorts. Any movement of the disc on the hub will push the piston back, not move the slides. With the opposed piston set, it only has to move fluid from one side to the other, so it can follow the disc regardless of any hub, frame flexing or movement of the disc. A far superior set-up.

Tony did you weigh the two sets to see if there is a reduction in unsprung weight?

Harvey.

['E']

Okay Harvey it seems I have to eat hubble pie, you are correct, you would think us young guys would know better then to challange you older guys.

Harvey is immortal but tireiron is only 31, glad you worked it out though :lol:

[Dessertrunner]

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[bazza]

Something else worth getting is the STI brake master cylinder and pedal setup. The pedal length and the cylinder diameter all change the feel and bite of the brakes. If you can get the SVX to bite like a GDB+ STI (2002 onwards) you are in for one heck of a fun ride! On hard braking they will lift the rears off the ground and throw you through the windscreen!!

['E']

Hi Harvey,
I didn't weigh them but now you mention it I will,

Darren what are the piston sizes on your 6 pot Brembo,s

Ill measure pot and pad size soon.

The 6 pot brembos have three different sizes, small medium and large with the small meeting the rotation first, this is to eliminate shudder and promote even pad wear for smooth fast braking.

Just for a comparison of weight the brembos are 5.4kg and solid 355x32 rotor is 12.4kg

['E']

Ok pot sizes are 2x25mm, 2x30mm and 2x35mm and pads are 165x55mm with a total surface area of 18,150mm2

[Dessertrunner]

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['E']

Okay I am stuffed I don't know what is happening,
piston surface area of Brembo's is 2,157sqmm,
piston area of Wilwood is 3,038 sqmm,
Existing calipers piston area is 2,512 sqmm,

It seems the experts say that you calculate piston pressure by taking the pistons on one side and calculate the area.

The fact is the Brembo will stop a car far quicker the the standard calipers so what is going on.
Tony

Stopping power can't be attributed to just pressure applied, rotor diameter and pad surface area are also play a roll. Fluid efficiency would also play a part, the relationship between fluid capacity of the pistons and the master cylinder would also make a difference. Wilwood calipers is larger then stock calipers while brembo calipers are smaller than stock calipers which would mean efficiency of the master cylinder would increase in relation to the brembo calipers along with increased rotor diameter and friction surface area. Our stock brakes would stop better if you could increase the distance from the hub and the surface area of the pad

[Dessertrunner]

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[Tireiron]

Whats the pad area of each of the 3 calipers, OEM, brembo and wilwood? Larger pads have more friction area. That has to be taken into account along with pressure on the pads. With equal pressure the larger pad will stop better. With equal pad surface, the greater pressure will stop better. With all 3 of them having different pressure and different pad size there are a lot of variables to figure before knowing which stops better.

[Dessertrunner]

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['E']

Why don't you rig up a pressure gauge between the pads of the calipers? Then you could apply the hydraulic pressure of the Svx master cylinder and lines, after all that is the only data that really matters.

I think the wilwoods fluid capacity may be too large

[Dessertrunner]

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['E']

Just finished the trial I now have to eat double humble pie with Harvey, the theory I had was wrong. Time to move on.
I think Bazza's point about the master cylinder would have a lot of benfit far more then I thought at first.
Keep well.
Tony

I wonder what if any differences exist, I have a feeling the Svx master is bigger

[Dessertrunner]

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['E']

Anyone know the bore of a STI,
Smaller bore then the SVX will mean more pressure on the brakes and therefor more stopping power with the same caliper.

Although too much pressure will make the wilwoods flex giving poor pedal feel

[Tapani]

Anyone know the bore of a STI,
Smaller bore then the SVX will mean more pressure on the brakes and therefor more stopping power with the same caliper.

http://forums.nasioc.com/forums/showthread.php?t=1456630

/T

['E']

http://forums.nasioc.com/forums/showthread.php?t=1456630

/T

Svx master cylinder is 1/16 same as Sti

[dragoontwo]

Svx master cylinder is 1 1/16 same as Sti

Fixed it for you.

['E']

Lol thanks

[Dessertrunner]

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['E']

This is what I built for one of my carshttps://dl.dropboxusercontent.com/u/91210059/Mid%20Engine/PICT0662.JPG

That looks awesome but why?

[Dessertrunner]

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['E']

This is what I built for one of my carshttps://dl.dropboxusercontent.com/u/91210059/Mid%20Engine/PICT0662.JPG

I am using Matts rally car on the track now and from what Bazza showed me its important the be able to adjust the brake balance between the front and back by a simple method. Bazza would be better to explain his experiance. I am mucking around with realy heavy duty calipers from Wiwood.
Tony

Ok you're splitting the lines front and back, makes sense to me now

[bazza]

Svx master cylinder is 1/16 same as Sti

Excellent. That's good to know.

I'm not one for figuring out brake math ie, caliper size vs piston size vs cylinder size as I've seen so many people come up with answers which are opposite to what I see on the track or street.

But I know bigger brakes not only stop the car better but give far better control - I found the smaller piston and smaller rotors are prone to lock up far easier - the pedal is very "on" or "off". The bigger the rotor and cylinder - the more control you have and you can get closer to the edge without locking up. Obviously the more metal you have the more heat it will handle and the longer it will go before overheating / fading / boiling fluid. I have ally spacers, ally wheels, ally brembo calipers and at the end of a session - the rims are hot to touch - everything is sucking heat away nicely from the pads and they never fade or boil.

Tony, if that brake bias setup is for the track car - maybe consider deleting the brake booster. You'll get better feel and save weight.

[Gamesy]

Why did desertrunner remove his info?

[Tireiron]

He got his feelings hurt by someone on the internet and is handling it like a mature adult.