Custom pedalbox Dax de Dion

[skorpion]

I was wondering who designed/build a custom pedalbox for his dedion ?

My plan is to do so because the current masterservo has too little vacuum while the engine idles (big cam). On the other hand, the hinges of the Dax pedalbox are not safe to my feeling. They can jam when the grease is gone.

An option is too use a 12Volt vacuumpump from a Diesel car but that is just a tissue against bleeding ;O)
Now planning to go for a dual mastercylinder setup. Wilwood or Tilton floor mounted pedalboxes look good but expensive. Making an own setup seems cheaper and more flexible regarding installation for the Dax (designed to fit).

In order to make the calculations, I need the diameters of the Jaguar XJ40 calipers. Does anyone know them by heard (front and rear) ?

Regards,
Skorpion

[madjohnny]

I think I still have my old ones in the garage, I can measure them for you tomorrow if no one else gets back to you in the meantime.

[TINKA]

Have you got the one way valve fitted as this should overcome most of your problems surely.

[dave]

Originally Posted by skorpion

I was wondering who designed/build a custom pedalbox for his dedion ?

My plan is to do so because the current masterservo has too little vacuum while the engine idles (big cam). On the other hand, the hinges of the Dax pedalbox are not safe to my feeling. They can jam when the grease is gone.


Regards,
Skorpion

Hi Andy.
Unless you are running quad down draughts you should not have a problem with servo vac. so long as you have a none return valve fitted in the vac. hose.
The servo stores more than enough vac. for a number of brake presses even with the engine turned off.
You may have something else adrift if you are having trouble with your pedals sticking as it is not something I have had a lot of feedback about. However I have had just 2 customers whos brakes would bind from time to time and I think this might be resolved by fitting a spring to ensure the brake pedal is pulled all the way back when you release your foot from it.
Your car being LHD should be better than the RHD cars for pedal operation as the pedal levers are at a better angle in relation to their pivot points.

[skorpion]

The one way valve is fitted and tested. With my previous engine I didn't had the vacuum shortage problem. The new engine has propably less vacuum due to bigger cam. Perhaps I have to recheck for leaks at the connecion with the servo vacuum.

I had it last week for the first time that my brakes were binding...It felt like they where stuck. I pulled over, lifted the car and didn't saw anything...restarted the car and revved the engine and it braked okay again.
What is causing this binding ? Is it typical caused with the jaguar components or is it due to the Dax pedalbox or/and the Ford Escort Mastercylinder setup ?

What is the meaning of "running quad down draughts" ?

Does anyone know the diameters of the calipers ?


Regards,
Skorpion

[wilf]

"Quad down draughts" - a set of four twin-venturi Weber carbs, that stand vertically upright and so the air goes "down "them. Like those often fitted to the 289 race cars.

You might get by with an additional vacuum reservoir tank - a lot easier than redesigning the pedal box. And you may not like the feel of unservo'd brakes - they can and do work, but the difference between them and your "daily drive" may mean that you never feel "happy" with the brakes on the Cobra.

[dingocooke]

Hawk sell a twin non servo pedal box, although its bascially a Tilton with a bigger price tag...
Wilf is correct in that although the non servo set up works, it feels wooden in comparison to modern (over) servo'd car set ups.

I'd take Dave's advice (he has built 115 Daxes!!) and fit a brake pedal return spring, and make 100% sure you have no leaks from manifold to servo, my Cleveland with 270 degree cam has loads of vacuum.
Also, check that you PCV connections are good, and that the valve is operating properly (shake it, if it rattles, its good, if not its full of contamination and will be stuck open, losing you lots of vacuum)

[dave]

Here's a couple of piccies to go with Wilf's post:-

[skorpion]

Thanks guys, I now know what a Quad down draughts means ;O)
They look nice !

I have an 750 cfm dual pumper carb. The cam has duration of 248in 258ex @0.050.

Next run I will check again for leaks. A vacuum reservoir is indeed a good option.
Will reconsider all the new inputs.
Thanks for the warnings about non-servo setups,
Skorpion

[dingocooke]

mmmmm dem quads are sooo nice, I want....(I also want sandra Bullock dipped in baby oil and dropped round here, oh I can dream dammit...)