Wedge braking system

[AJP4.2]

I have read many about many different attempts to improve the braking system on a wedege for 'fast road use', which has prompted a discussions between a few wedge owners about the best 'Value for money' modifications that would improve the not so perfect brakes that our Wedges are blessed with as standard.
I am talking about starting with a standard 400 /450SE 4 pot Princess caliper system, and would like to know what views you all have on:

1. Master cylinder (bore size & adjustment of servo actuator bar)
2. Servo - size
3. Larger disks - Advantages when using standard 4 pot calipers
4. Alternative calipers (Other than unsprung weight what do alloy performance calipers give in brake performance & what size pistons had people had experience of)?
5. Brake pads
6. Any other ideas ?

PS I have assumed that the standard rear brakes are OK and only modification is the installation of some cooling ducts.

I am sure I am not the only one who would like to have Cerbera/Sagaris brakes on my Wedge !

Everyones views are welcomed
Thank you

[350Matt]

AJP4.2 said:

I am talking about starting with a standard 400 /450SE 4 pot Princess caliper system, and would like to know what views you all have on:

1. Master cylinder (bore size & adjustment of servo actuator bar)
2. Servo - size
3. Larger disks - Advantages when using standard 4 pot calipers
4. Alternative calipers (Other than unsprung weight what do alloy performance calipers give in brake performance & what size pistons had people had experience of)?
5. Brake pads
6. Any other ideas ?

PS I have assumed that the standard rear brakes are OK and only modification is the installation of some cooling ducts.

OK as we all know wedge brakes are pretty poor, even the 4 pot princess calipers with vented discs aren't great and these are the 'best' wedge brakes.
I always felt that a smaller bore master cylinder or a larger servo woudl help matters to reduce pedal effort, but I never tried this.
Larger discs will help with any brake set-up but the std 280mm disc is not undersized there are plenty of heavier cars using smaller discs out there.
The princess caliper is known to be an inferior caliper especially when compared to modern alternatives, a lot of Capri owners who fitted these are now on mondeo single pot calipers and far superior brakes....
I found green stuff pads to work reasonably well and there are better pads than this but the cost becomes a real factor ( I object to paying £100 for a pair of pads)

To my mind the root of the problem lies with low pedal pressure/ mechanical advantage, so if had another wedge I would look into fitting a slightly smaller bore master cylinder as this is probably the easiest way forward.

[350zwelgje]

Upgraded a long time ago to 300mm 4-pot calipers (hispec by the way and fits in the standard 15 inch wheels), braided hoses together with DOT 5.1 and good fast road brake pads all round (green stuff and mintex) the setup is very good for a car of this age. Fast road never an issue and even track days no problems except for the rears getting too hot (to do list item: still need to install a few ducts to vent air to them).
Ok if larger capacity/more power than standard 350i perhaps it isn't good enough yet....

Rob

[AJP4.2]

Thank you for your input guys. You are thinking exaactly the same as me. Only other thing is much larger calipers.
Is there any more advice others can offer please ?

[rev-erend]

I'm using Princess calipers - dot 5.1 fluid and Tarox fast road pads .. all very good. Not had any problems at all but not been really tested on a track.

Green stuff were also OK..

[shpub]

Don't even think of fitting a small bore master as all it will do is reduce the effective braking. The reason is that the for the same amount of pedal travel, less fluid is pushed into the calipers and the calliper pistons will not move as much. end result is reduced braking effort. So the foot pedal is pushed further to compensate until it hits the floor or the end of the cylinder. Despite how much effort is applied, there isn't enough fluid flowing through to fully move the pistons and apply the braking pressure.

This problem is made worse because of pad knock back where the pads and pistons can be pushed back a fraction. When the brakes are applied, the initial movement of the pedal moves the pistons back. Basically your foot goes to the floor but the brakes will come back when pumped. A smaller bore calliper will make this effect worse as does having big discs. The solution is to fit residual pressure valaves into the brake lines so that a couple of pound pressure is maintained and keeps the pads/piston in place.

You can get the same problem by fitting larger piston calipers. The pedal travel is often increased.

If anything the master should have a larger bore, especially when fitted with larger calipers. I had a "custom" one put together for the 520SE.

One other point is how much is your budget? You can easily spend £1000 on a decent front set up...

Ps. hated the Princess calipers when I had them. Expensive to refurb, very difficult to bleed and really a waste of time IMHO. I've since used Wilwood and Hi spec but I am looking now to going to AP. Wilwood were fine and were transferred to my Griff. I had some problems with the Hispec set up with internal seals failing causing random blockages. One caused the car to go into a tyre barrier at Hethel under heavy braking as the caliper seized on one side. Took some sorting out. My overall experience of Hispec have not been good. The braking setup I have achieves 1.1g.

PPS hated Green stuff as well as they never recovered from overheating and ate discs. Tarox, Ferodo and Mintex all very good.

Edited by shpub on Wednesday 15th April 10:09

[JR]

350Matt said:

Larger discs will help with any brake set-up but the std 280mm disc is not undersized there are plenty of heavier cars using smaller discs out there.
The princess caliper is known to be an inferior caliper especially when compared to modern alternatives, a lot of Capri owners who fitted these are now on mondeo single pot calipers and far superior brakes....

So is the implication that this would be a simple and cost effective solution?

[Pilo-Wedgebits]

Steve,

I'd be interested to know where do you put the residual pressure valve(s) and how many?

[shpub]

I have two: one in each line to the caliper.

[Pilo-Wedgebits]

Is that front calipers only? or both pairs of calipers?

[shpub]

Only to the front. I do have an adjustable balance valve in the feed to the rear.

[Campbell]

You will need residual pressure valves on each each of the lines coming out of the master to the flexies off to the calipers.

Looking on google i found this http://www.wilwood.com/Products/006-MasterCylinder...
I would go for the 2lb ones, it would be nice to have adjustable ones but the install and forget sound good too
Cant say ive had a problem with the SEAC brakes on the front, running DOT5.1 on mintex 1411 pads all round, i did have to replace the rears due to the bleed nipple snapping off...crap, not got the SH remote bleed kit installed, much better now.

May be Steve can let us know what make his valves are?

Cambelt

[shpub]

Wilwood.