Wilwood 256 pot worth the money, plus help needed!

Hi,
 any help would be great, 
I'll start off we my set up currently 
I've got vw11 Calipers at the front and drums at the back, 
(This is wear I can't find any help)
I've taken my servo off and the brake linkage bar,  just got a 17mm Master cylinder off a mk2 polo so it's a straight push! 

I want to upgrade the brakes got 15"s so thinking 256 discs would fit, 

Any one used those wilwood 4 pots? Worth the money and does any one know if they would work on just the 17mm master cylinder I'm using? 
Or any over brake set ups that would work and be cheaper? 
Thanks lex 

I had wilwood 256 but needed a 25 mm master cylinder to move enough fluid for them to work well.  Bit much for the power I had at the time. Hardly any wheels fit without spacers due to the size of the calipers. I would go for a gm vaxhaull 280 or 256 swap unless you have a racecar

Hi,

So you need to do some maths here, I recently got some help with this for my setup (thanks Martin), which has never been as good as I hoped.

Three main factors are at play:
(1) Bore size of your master cylinder.
(2) Area of your brake capper pistons.
(3) Brake pedal ratio and hence how much leg pressure you can apply.

I use to run Girling 54mm sliding callipers (so they count as dual piston for area calculations) with 256mm disks and a 16V master cylinder (3:1) and 22mm servo.
Piston area for these callipers is 54x54x0.785x2=4580mm²
15" wheels work fine for this setup.
The brakes were brilliant !

In redesigning my brakes I chose to go for a HRG pedal box with 0.625" twin master cylinders with a twin remote servo (1.9:1), Wildwood 4 Pots and 280mm disks. You need 16" wheels to clear the calipers.
I chose to do away with the servo and linkage because it was tapping on my alternator (16VG60).
To start with I did not have the dual remote servo and the brakes were awful.
I then added the servo and the initial braking was ok but it faded away rapidly.
Taking a look at the piston sizes of my Wilwoods revealed that they were 1.38", with a bit of calculation that revealed a piston area of:
1.38" pistons = 3860mm²
So I had managed to reduce the piston area from 4580mm² !! and hence the braking force available :-(
I just ordered a Wildwood 4 pot kit suitable for a Mk1 that is really designed for the larger servo. Don't get me wrong if you stood on the brakes they would lock up and bounce the car out of the rollers at MOT time, but the feel of them was horrible.

The servo just reduces leg pressure, but does not increase the overall brake efficiency.

To make this clearer, Martin gave me these rough calculations:

"A VERY simplified way of looking at it is this:
If you apply 10kg of foot pressure to a pedal with a ratio of 5:1 and a 0.625" master cylinder the caliper would apply:
Foot pressure x pedal ratio x MC/Caliper ratio
Current Wilwood (10 x 5) x (3860/198) = 975kg
Girling 54           (10 x 5) x (4580/198) = 1156kg
1.62" Wilwood    (10 x 5) x (5320/198) = 1343kg
1.75" Wilwood    (10 x 5) x (6208/198) = 1567kg

This equation isnt real world as its assumes 100% bias to the front MC and only a single caliper (i.e motorbikes) but it does give a good indication."

So I had managed to reduce the braking force by about 180kg on each wheel, made even worse by the wider disk as the force required further out is more as well.


Increasing the piston size in the callipers will increase the force at the brakes but will also increase pedal travel.
Increasing the master cylinder size with also increase the force of the brakes but at the expense of a "solid" feeling pedal !!
It is a balance !!

I have now bought some 1.75" Wildwood 4 pots that are awaiting fitment over Christmas if it is not too cold. These may apply too much force, time will tell but you cannot get the 1.62" ones any more.

Hope this helps.

Thanks lhasadre ams but sadly that sort of went over my head! 

I've got a 17mm mc because from what I heard the smaller the bore the softer the  pedal will be, and because it's just working off the mc it's pretty hard as it! 

I like the sound of the vauxhall set up just because be cheaper! 
Would the Vauxhall brakes be better then say mk2 golf 16v what I seen people do? 
 
 was thinking rear disc conversion as well but got mixed views on if it's worth it or not, plus because I'm just running it with a  straight to push to the master cylinder would it work ok? 

why was the brake linkage and servo removed. has it passed an mot?

the 17mm mc is easier to press because it moves less fluid than a bigger one. whatever brakes you put on they are going to feel worse than if you had a servo and larger mc fitted.  

personally i wouldnt remove the servo unless its a showcar that is never driven fast on the road or a track car.

apart from price i dont think there is much difference in vw or gm calipers

rear discs dont stop you any quicker than drums and are designed for a servo equipped car with a larger mc



  

Rear disks are great for two reasons:
(1) They look good :-)
(2) They pedal feel never alters as the pads wear down, unlike those pesky auto drum adjusters that just don't work very well.

However you will not gain anything from brake performance, in fact you do not want the rear to brake any harder that it already does.

You should be able to get the same brake efficiency and feel without a servo - however it will take some experimenting to get the master cylinder and caliper piston sizes just right to give a good pedal feel and enough braking force on the disks. I am still experimenting !!

Needed to get a new servo and linkage because they was damaged 
So seen the 17mm mc straight push done before and like how clean it looked with out them, 
But yeah on the down side braking isn't as good or just doesn't feel as good!

Mk2 golf set up sounds good mite just go for that and see how that works, 



Oh and yeah passed the mot fine 2 years in a row with the same set up, so guessing it can't be that bad! 

Sorry to revive a old topic, been searching for information on rear disk conversion, I have the stud axles, carriers and just ordered the hand brake cables and calipers (mk3 golf) 

Ive just painted my servo and it's looking nice. 

I see and rear a lot upgrade to the mk2 servo and master cylinder…  I know this is tried and tested but will my brakes still be good enough with the original servo and master cylinder. 

I have vauxhall calipers that I acquired years ago. But I may be happy with just the mk1 gti front brake set up with rear disks. 

Has anyone got any experience with the set up above ? 

Thanks