Twin Stock Calipers???

[yogibear]

Ive just been having a bit of a thought after my forst forrey on track at donnington and experianced quite a bit of brake fade and think I warped my front discs.

 I have a pair of front calipers that I have had lying around for a while and am wondering if it would be at all feasable to fit them mounted on the front of the discs. Ive seen two sets of four pots mounted on some cosworths before.

I am planning on getting larger discs as well to compliment the extra calipers.

Any thoughts on this idea as a low cost option for getting more stopping power

[nikp]

I believe the theory is sound. For a while, the Stewert formula one team were running 2 sets of front calipers. Mind you, if you did do it, you might find you have far too much front brake bias and end up locking fronts all the time. Another set required on the back then!!

[nikp]

Interesting idea! Mind you, i don\'t know how you\'d mountit: you\'d need a bracket - but how to bolt it to the front upright? Is there room?

[MikeLMR]

sort out the setup you have already before you change, adding another calliper is only going to make cooling things even harder !

and as with most things you need to strike a balance with brakes so budget to do something with the rear brakes as well as the fronts otherwise all you will end up with is a car that has a massive front bias to the brakes which is very poor for stopping power ... they key to stopping quickly (the rears do a surprising amount when setup correctly) is to get front and rear pulling up in harmony.  one HUGE word of warning though about messing around and tuning the brake bias. Standard brakes are set with safe bias, the front brakes will (nearly) always lock before the rears if you mess with the brake bias you can end up with situations when the grip changes (wet, ice etc.) where your new setup and bias setting will cause the rears to lock first ... you just need to realise that you are driving what is moving toward a "race" setup on the street and you need to drive accordingly .

Don\'t forget fitting two pairs of calipers on the front also doubles the amount of fluid needed to be moved by the master cylinder

[yogibear]

Hi Guys thanks for the constructive comments.

Ive been looking at another site that has a how to on fitting a master cylinder from a mazda 929 which increases the length and width of the brake cylinder.

The car is becoming fast road / track focused mainly, it doesent leave the garage if its wet or there is snow forcast anywhere in the UK .

Im going to be fitting my new tein coilovers later this week so im going to have a look at the brakes and see if I can come up with some kind of bracket that would allow for the extra callipers to be mounted. Im also going to be attaching some extra ducting onto the front brakes to aid with the cooling.

Dont worry I wont be rushing into this blind. Ill take some pics and bounce some ideas around.

[shaunwil]

The other thing you could do is get WGT to skim the front discs to remove the warp. If there is enough material available. Not sure if this helps it from not warping in the future though.

As for the twin calipers, I think pineapple racing does a kit for the 1st gen, but not the fd.

[nikp]

Any machine engineering shop could skim the discs. You won\'t need an RX-7 specialist for that.

[yogibear]

A friend of mine has a laithe in his garage that I could skim the discs with.

Suspension has arrived so im gonna have a look shortly.

[TonyC]

If it was you r first visit to a track don\'t discount how much technique pays in causing brake fade. I\'ve instructed a lot of people on tracks and braking is no where near as easy to do right as you migth think. Braking too long, dragging brakes, braking to much - all these can quickly wipte out even the best brakign system. So at the next track visit do book an instructor and specifically ask about braking techniquie. As a rule of thumb it shoul dbe very hard for a very short period of time. An emergency stop almost. I\'ve spent whole days in caterhams teaching this to people in the past.
Beyond that, before trying dual calipers and stuff, consider the pad material and brake fluid. And the disk thickness - if the disks were alreayd quite worn and gettting thin they will overheat faster.
Ducting to the brakes is quite hard to do so it is effective, air flow radiates out from the centre of the disk - it is not dragged through the vents on the disk - so you need to duct air to the centre and allow it to be drawn out as it spins to cool the disk.
A larger, thicker disk will withstand more heat.

For step 1, make sure the disk is in good condition, ty a harder pad compound, check the fluid (change it if it a year ot two old - it will already be carrying too much air for track driving if it is), and think about technique.

When you\'ve dont that, then I\'d start to look at big brake kits.

[d-king]

my mate ferrari 360 modena has two brake calipers on the back for some reason ??

[nikp]

Brake fluid is only really effective for 2 years (as TonyC says). Past that it has absorbed water, which will heat and boil, creating air pockets which translate into brake fade.

I recently gone from standard pads (which still had a reasonable amount of pad left) to mintex extreme pads, and the different is very, very noticeable.

[clive]

Please Please do not skim old Disc\'s on a high performance sports car as you risk the disc explodeing and killing yourself !

[mullins]

I\'ve never heard of a disc exploding and killing anyone (1st gen ones are prone to cracking under very hard racing conditions). As long as they\'re within manufacturers tollerance skimming them this isn\'t a problem.

My main concern with 2 calipers would be more un-sprung weight. You should talk to circuit racers who make do with near standard brakes for some ideas.

[TonyC]

I\'ve never heard of a disc exploding and killing anyone (1st gen ones are pro You should talk to circuit racers who make do with near standard brakes for some ideas.

I\'ve raced for years with cars where the rules foced you to use standard brakes, I wasn\'t even allowed vented discs on one car. They all would take a 20 minute race with no fade race in, race out. And that was with some fierce, race pace braking.

For improvments on the standard, go for pads, fluid, disk thickness (and quality), calliper condition and technique.

[RemarkLima]

Ducting to the brakes is quite hard to do so it is effective, air flow radiates out from the centre of the disk - it is not dragged through the vents on the disk - so you need to duct air to the centre and allow it to be drawn out as it spins to cool the disk.

Agree with Tony on the technique, also decent pads and some Castrol SRF fluid with braided hoses and you should be good!

Unless you start to run slicks as well

But RE ducting, the only way I\'ve seen it work is to get a bell made for the centre of the disc, then have bolt on discs. Then have channels in the bell that match up with the rotor and duct to the inside of the bell so it forces the air through the disc. But take a lot of effort and canny engineering!

One of the Lotus boys had this setup and could then you cheaper lower temp pads!