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rallyboy77 · Alfasud Joined: 08 Apr 2003 Posts: 76 Location: Sydney

Hi all,
I am doing some calculations to work out the required master cylinders for a dual master cylinder brake setup with balance bar.

I am wondering if anyone has the diameter of the caliper piston for ATE caliper Alfa 33 front vented disc, and Alfasud rear caliper (also ATE I believe)?

Thanks guys,

Jeremy

Sprintervention · Alfasud Joined: 30 Jul 2004 Posts: 60 Location: York

Jeremy,

try this site, very useful....

http://www.brakesint.co.uk

The size is 48.1 mm I believe, I also think that this size is common to nearly all sud,sprint and 33 front calipers. Don't quote me on that though!

Let me know how you get on with your dual master cylinder set-up, I believe that http://www.ahmotorsports.co.uk do one ready made, using exchange parts I think.

Best wishes
Chris

LDA · Alfa 33 Joined: 28 Nov 2004 Posts: 276 Location: France

i would also like this sort of brake setup on my car so would be very interested in your findings.
were you thinking of a fly off Hydraulic handbrake too?

L.
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rallyboy77 · Alfasud Joined: 08 Apr 2003 Posts: 76 Location: Sydney

I've finished the dual m/c setup.
I have some photos:
http://www.trofeoalfasud.com/index.php?set_albumName=rallyboy77&option=com_gallery&Itemid=&include=view_album.php

Jez

Eddie W · Posted: Fri Apr 08, 2005 10:24 am Post subject:

Hi Jez,A good move but let me offer some advice. Fit a cable off the pedal box with a dash mounted knob and marked for front and rear. It is fatally easy to adjust in the wrong direction in the heat of the moment and wind up with a front bias on the loose and vice versa on the seal. Exciting but not good for times. In my day it was very difficult to find a contra wound cable(wires in both directions so that it doesn't just wind up) but these days they are more readily available. We used Hillman Imp masters with I think .625" bores bearing in mind that there are two of them.
A flyoff handbrake is a definite advantage and very easy to make. All you have to do is move the operation of the pushrod from the button from above the pivot point of the pawl that engages the teeth to below the pivot point. Reasonably simple engineering. Then of course the button is push to lock instead of push to release.
If you do an hydraulic handbrake then be sure to fit a spacer between the mount and the circlip otherwise a stab on the foot pedal can pop the circlip, releasing the piston. Hope this helps>
Regards Eddie
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LDA · Alfa 33 Joined: 28 Nov 2004 Posts: 276 Location: France

Edward · Alfa 33 Joined: 21 Sep 2003 Posts: 307 Location: Bristol

Jeremy,

Can I ask some basic questions in an attempt to catch up on what is a very interesting subject. I notice there is no servo assist - is this made possible by having 2 master cylinders or do you just have to push harder. I was thinking of a brake bias valve in line to the back wheels with the addition of sud rear brakes or similar but i imagine twin cylinders and a balance bar avoids all that. Is it safe to assume on cylinder connects to the rear and vice versa. Basically I want to fit some large four pot calipers to the front of the car and discs to the rear possibly, on the track car and am wondering the best way to go forward to get decent pedal pressure onto a system with lots of stopping power. Had the first track day this weekend with the new car and as I thought standard / tar-ox brakes couldn't cope after 10 laps - off onto the grass - oops. I have some large GTA calipers on the shelf and and looking for some 305 mm bells and rotors to give a large braking ability at the front to stop the car well. With 175 hp on tap and 225 section tyres it goes well but can't even get the tyres to lock up I suggest even during hard braking. Could you help with an basic but full description of how to put the system together that would embelish the photos on the site / link. I will probably remove the 33 bias valve at the back, and go for calipers etc , but if you could describe the general set-up I would be greatful. Is the mention of the fly off handbrake relevant or is this for rallying. To adjust the balance bar can this be done relatively easily to accomodate for wet / dry conditions. How do you fit and set up the balance bar. Which tilton master cylinders did you go for. What was the general cost of components etc.

Thanks,

Edward.
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rallyboy77 · Alfasud Joined: 08 Apr 2003 Posts: 76 Location: Sydney

Our brake system is Alfasud rear calipers and Alfa 33 16v calipers and discs up front running DS3000 brake pads. The system is adequate for the Sud on the loose stuff. When moving to tarmac (the Sud will be retired from "serious" rally soon) we will be upping the front brake components considerably.
Currently, the front master cylinder is .625" and the rear .750" The rear could be a size smaller in our situation.
For information regarding dual master cylinder setup I suggest you goto www.tiltonracing.com and download the docs for the balance bar. There is another doc on setup of dual m/c as well on there I believe, a good read. Installation of the balance bar requires significant modification of the brake pedal, check the tilton docs. The hydraulic handbrake is simply set in the rear line. All the brake lines have been replaced with the braided type. The rear axle bias valve was removed.

Eddie W, don't worry mate we have not hooked up the remote adjuster just yet! Smile

Jez

Edward · Alfa 33 Joined: 21 Sep 2003 Posts: 307 Location: Bristol

Jeremy,

Thanks for the tips - I will have a look at the page shortly, I did realise once I had logged off that part of the reason that there are few sud rear brake mods to a 33 is that it would leave you without a normal handbrake - which is a problem for the MOT.

I was talking to someone today about an alternative that utilises I think the Sud stub axle, a Peugeot caliper and an adaptor bracket ???? I am looking forward to see that - that should give me rear disks to go with larger front disks so I can stop this time.

Could you just explain how the pedal feels without the servo - does it all just become hard work or does the 2 master cylinders somehow compensate??
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Eddie W · Posted: Fri Apr 15, 2005 11:24 am Post subject:

Edward, an alternative to the in line master cylinder for the handbrake is an M/c with resevoir operating on a second set of small calipers for hand brake only.
Pedal effort is relative to the proportion of sizes between m/c and calipers. Some like a booster fitted seperately to front and rear lines and some prefer no booster for more feel. A matter of taste and sizing the ratio of m/c and calipers. Smaller m/cs mean less pedal effort but more travel and vice versa.
Regards Eddie
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Edward · Alfa 33 Joined: 21 Sep 2003 Posts: 307 Location: Bristol

Eddie,

Here's a couple of questions you may know the answer to - if I disconnect the vacuum hose off the engine to the brake servo, is that the same as not having one at all? I.e. is this a way that I can see what the pedal feel would be like without it - or would a non vacuumed servo somehow be different to it being removed all together? Recently I was braking down a hill with the engine off and if that is the same as not having the servo in place then it would make braking significantly more difficult!

Secondly, I accept that pedal effort is related to master cylinder size / configuration but if I had two side by side ( with balance bar ) would there be any decrease in pedal effort or it is simply a one to one ratio of effort regardless of how many master cylinders there were.
_________________
The faster the better.