Front brake up grade to Wilwood 4 pot

[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]

Have removed

[oab_au]

Originally Posted by Dessertrunner

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]

Have removed

[oab_au]

Originally Posted by Dessertrunner

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]

Have removed

[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.
Could not have said it better.

Harvey.

[Dessertrunner]

Have removed

[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]

Have removed

[oab_au]

Originally Posted by Dessertrunner

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.
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.