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
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!!
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?
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
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.
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.
Any machine engineering shop could skim the discs. You won\'t need an RX-7 specialist for that.
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.
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.
my mate ferrari 360 modena has two brake calipers on the back for some reason ??
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.
Please Please do not skim old Disc\'s on a high performance sports car as you risk the disc explodeing and killing yourself !
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.
Quote from: mullinsI\'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.
Quote from: TonyCDucting 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!
Quotemy mate ferrari 360 modena has two brake calipers on the back for some reason ??
d-king
The second caliper is for the handbrake
Ive seen simple ducting on world rally cars that simply ducts air streight on to the disc , surely that will make a difference. Ive got two 3" holes in the front of my bumper that I was planning on running ducting from much like cold air ducting for the air filter. Im gonna try and find some pics of what I mean.
As far as technique goes I could probably benifit form some tutoring
(http://www.eng.hawaii.edu/~panos/brakeduct_4.jpg)
this is what i mean, think this is on an mx5
I\'m sure it will help (not sure what effect cooling one side more than the other will have? ... probably too detailed to be worrying about for anything other than an OEM application or top level racing i.e WRC or F1
Notice as well that the mx5 has had the dust covers removed.
Quote from: mullinsI\'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.
QUOTE]
Sorry but I have know of a guy in a beemer that went into a lamp post after a disc exploded and whilst he walked away he sued the pants off the company that skimmed them for his written off car!
If you look at the FD disc you will see that there is a light weight disc with very little meat on them compared to many and so sorry but skimming a worn warped FD disc is crazy in my opinion and I would be very surprised if you would ever skim out a bad warp in any disc within any manufacturers tolerances
I am all for saving money but the also club cant have the situation happening where potentially someone reads something here then goes and has an accident and then blames the club, hence my warning "disclaimer"
I agree if it\'s warped i wouldn\'t skim it, but that\'s not what you disclaimer said - it advised against ANY skimming.
Quote from: mullinsI agree if it\'s warped i wouldn\'t skim it, but that\'s not what you disclaimer said - it advised against ANY skimming.
Yep stand by that as my warning post above is the easiest way of detering people from potentialy ending up with a dangerious part and protecting MRC !
Very sorry you don\'t like this statment but it is best for the Club
Dont skim you\'re discs what ever you do.
Out of interest why not ?? All we are talking is a few thou a side ??
Shaun
Sorry just read the above information...................................
Just seems very odd, ok serious runout would wreck the disc and skimming would ruin the structural integrity of the disc, but then it would be out of tolerance and un-usable anyway. I think there is only about 1mm of wear in a brake disc anyway for these cars.
Sorry if I\'ve mis-informed anyone. I\'m a time served CNC turner and wouldn\'t think anything of it if the runout was minimal, thats all they do when they manufacture the disc.
That would be my own choice and obviously not the clubs and the decision would be only on my own equipment.
Shaun
Guess I wont get the discs skimmed then :) . Wasent gonna anyway think it was just someones suggeston.
Right next question then is where would I get a couple of caliper rebuild kits and is it a specialist job to rebuild them or would it be something I could do myself?
Rebuilding the calipers carries all the same risks as skimming discs.
Im sorry for putting my nose in the discussion, but I have to ask you:
What setup where you running when you had the warping, and how worn where they. I know alot of people, as some has said here. You could get a very nice brake setup with new discs, new pads, new fluid and maybe add braided lines. To start everything up with adding a set of calipers to a setup that is already good sounds "dumb" imho.
A friend of mine went along for a ride in my car with standard brakesetup, not on the track though. And he was amazed at the stoppingpower.
Best regards, Daniel
Often a warped disk isn\'t warped at all. What has happened is that some of the pad material has been welded to the disk face. This often happens if you get the brakes very hot and then leave the brakes on when stationry - IE: sitting on the pedal whilst queueing back into the pits, or putting the handbrake on. Even coming to dead stop if the brakes are very hot and leaving your foot on the pedal.
It pays to leave the handbrake off, and every couple of minutes push the car half a wheel turn or so to allow the brakes to cool evenly after a race.
or just back off for the last couple of laps and let the car cool down on the move. Sitting with the brakes on also provides a really good path for conducting heat from the hot brakes into the caliper and hence heating the fluid.
Yogi, lets just check something.
You say you think you had brake fade?
Can you tell us exactly what happened, what were the symptoms, and what did the pedal do.
Setup that ive got is Grooved Discs, Not sure of the pads, stock clipers and braided brake lines.
The brakes usually work really well but on track you could feel the change in the brake pedal having to push it a bit further after the first few high speed breaking zones and not biting quite so well. Aprox 140 down to 40-50 through the chicane. Everyone seamed to be braking early . My technique was to break a bit earlyer and not brake quite so hard as the other cars.
Im not gonna be going to modded nationals now so im going to take the calipers off and check them and possibly re build them.
What you are describing is just over heated pads and fluid. No point over- hauling the callipers unless you\'v got sticking pistons or leaking seals or something.
BY the way, the braking technique you described actually puts more heat into the discs and pads then heavy, short braking.
Ive got I feeling the pistons maybe sticking a bit as well. I could have left my breaking later but everyone else was driving so slowly id have gone into the back of them.
So is allways better to brake as hard as possible for the shortest period of time?
Yes, although it\'s more comlicated than that. You aslo need to tape the presure. So you very quickly go from no braking to as much pedla presure as the car will take without locking up (and that will nee dot be modulated through feel as you slow down/surface changes/weight transfers), then as you approach the point where you are goign to turn (prsuming we are only braking in a straight line and not trail-braking), you begin to relax the pedal presure until you are off the brake just at the turn in point. What you should not get when you release the brake pedal is the front of the car lifting up as the weigth trasnfers off the nose - that is why a car will understeer on turn in after hard braking.
You can practice on the roads - same principal, so if coming up to a red light, barke firmly (no need to rush at it - just getting a feel for braking sensitivity) and then ease of the presure so you stop exactly where you want to with no bobing up of the nose.
if you find you are braking harder and harder as you approach your turn in point on the track, then you need to brake harder in the first place. But don\'t just stamp on the pedal - you still need feel and smoothness.
braking is probably the hardest part of track driving to be good at - it\'s much more complex than appears - you can use the same sensitivity to then brake in corners, etc. or in wet conditions, use the final squeeze of pedal presure whilst in a turn to help the nose bite on the slippy surface.
Quote from: shaunwilSorry just read the above information...................................
Just seems very odd, ok serious runout would wreck the disc and skimming would ruin the structural integrity of the disc, but then it would be out of tolerance and un-usable anyway. I think there is only about 1mm of wear in a brake disc anyway for these cars.
Sorry if I\'ve mis-informed anyone. I\'m a time served CNC turner and wouldn\'t think anything of it if the runout was minimal, thats all they do when they manufacture the disc.
That would be my own choice and obviously not the clubs and the decision would be only on my own equipment.
Shaun
Agreed Shaun. As long as your within the manufacturers low limit on disc thickness. Skimming is no issue. If you find a company, like extreme, with a hub skimmer, the discs can be skimmed whilst bolted to the car. This trues the discs to the hub and gives the smallest run out possible.
A word of advice if your \'home\' skimming. Make a mandrel to mount the disc to (skim the mounting face prior to mounting the disc) and machine both sides without dismounting the disc. They are very sensitive to run-out.
Regards,
Jonathan
I\'ve enjoyed this thread more for the great advice from TonyC on braking techniques.
As for skimming a disc you would at least need a set of soft jaws in the lathe and still need to clock the part up in the jaws with a micron dti on a reference face and diameter to make sure the disc is square in the jaws. Im not completly sure that they could be done off a mandrel, the inside bore of the discs is very short and you would need a hardened mandrel and press. Then the part would need to be turned between centres !
Shaun
Shaun
The mandrel takes the form of the hub. The disc is bolted to mandrel in the same way as it is on the car. I have used this technique twice before with good results. The key is to face the mandrel off, then bolt the disc to it. Thus reducing runout to a miniumum.
The real trick is machining the back face. To make a tool large enough to reach round and stiff enough to cut true is difficult. I had problems with hard spots pushing the tool off leaving high spots (where the metal of the disc had been hardened during use). I had to take a large cut to remove the surface hardness.
Clive is correct on disc thickness. There is very little stock on Mazda discs. To keep the mass down. Always surprises me when I see people putting huge heavy disc combo\'s on track cars.
You can get heavily cranked V style tools that don\'t need much room. Plus we used to used a smaller C style tip that didn\'t need alot of room, plus they made them in wiper inserts.
As said there is only about 1 or 2mm of metal on the disc, theres absolutely no point in touching it if its near the bottom limit.
Shaun
Quote from: mullinsRebuilding the calipers carries all the same risks as skimming discs.
I\'d love to know how you reached this conclusion?
So where would be the best place to get a rebuild kit from?
Quote from: yogibearSo where would be the best place to get a rebuild kit from?
We sell front seal kits for the front calipers for from memory £35 plus vat for a set.
Quote from: BrettI\'d love to know how you reached this conclusion?
You\'re not going out and buying a new part so you have all the same risks (human error, poor workmanshipm, etc)
What i\'m saying is that any sort of rebuild/modification of parts carries risks and skimming is no different to rebuilding a set of calipers.
True, but you accept a certain amount of risk every time you fit a new or reconditioned part - theres always a chance that a duff part will slip through the net. Personally if I can repair something then I will - I\'m smart enough not to attempt to use something that doesnt meet or exceed the requirements.
Not having a go - you\'re first statement was just a little to sweeping for my tastes :)
Im exactly the same, if I can repair a part rather than replace it then I will. Also there is the knowledge that if you have done the job your self then it has been done properly.
Quote from: MazdarotarypartsQuote from: mullinsI\'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.
QUOTE]
I am all for saving money but the also club cant have the situation happening where potentially someone reads something here then goes and has an accident and then blames the club, hence my warning "disclaimer"
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I can\'t believe that MRC can be in anyway be liable for an opinion posted on the forum.
Should someone suggest that an individual stick their turbo where the sun don\'t shine, I can\'t see how the club could be liable for any internal injuries that ensued!!
Martin H
Martin H