interesting stuff about brakes.

[Pugglt Auld Jock]

I've been contributing to a discussion about brakes and what to buy in the Panda 2012 section this morning. I suggested people might like to look at Apec Braking's website: https://www.apecbraking.co.uk/ because there is a whole lot of interesting stuff there under their "Resources" heading.

It then occurred to me that you'll only see this recommendation if you're reading the Panda 2012 section and as it's of general and generic interest I just thought I'd post here so more people can see it.

Keep staying safe everyone
Kindest regards
Jock

 

[s130]

Thanks for that. Nice site and sensible information.

Many moons ago when I was doing motorsport I had a long and interesting discussion with both Brembo and Ferodo technical about brake pads and discs.

The background to this was I had inadvisedly fitted TAR.OX performance grooved discs and pads to our Strada Abarth 130TC and our Uno SX. The major problems we were seeing (besides vibration under heavy braking - not good for caliper piston bores) was uneven disc surface wear. This would lead to unpredictable braking and uneven pad wear.

The bottom line from both companies at the time was that grooved, cross drilled, fancy components were a waste of money and provided little or no improvement over a well ventilated and cooled braking system.

Now this of course led to the obvious questions as to when do they sell them. The blunt answer was because they they sell well at premium prices because they look good and sporty despite not really improving performance.

This led to the next phase of "well why do you see top end performance cars with these set-ups and of course top end motor sport vehicles"?

The reply was just as interesting in that there is basically "an edge to be gained" but at the cost of high wear, costly maintenance and frequent components replacements.

They went on to explain that when testing these cross drilled, grooved and other fancy innovations back to back with normal quality vented discs and pads then there is no real difference in performance until you reach exceptional conditions which one should avoid. Ideally the brake pads should never ever get to the operating point where they gas and the float/aquaplane on a layer of gas between the pad and disc surface. The cross drilling and grooving actually reduces braking surface areas but does allow for a quick recovery and expulsion of gas should it occur. But again one should not be operating brakes in these regions if at all possible. However in full blown motor sport it can happen and then cross drilling and grooving can be of assistance. But again they are there for the exception cases.

I was told by both "don't waste your money. Stick with our quality normal braking products and sort your cooling out".

This is what I did and never ever looked back.

For those that ever talked to people competing in the likes of the Italian Intermarque Challenge or the AROC race series and looked at their cars then they all ran bog standard discs and pads and just had really good cooling and "open" wheel designs like the Revolution RFX wheels.

Also a common trick was to actually use very cheap and soft after market pads which would barely last a weekend/race. Being softer they would bite and brake better but wore exceptionally quickly. Again cooling was key.

 

[Pugglt Auld Jock]

Thanks for that s130 I found that very interesting indeed. As you may know from some of my other posts I was professionally involved in motorsport for a number of years when I was just starting out on my working life. Being a Firestone employee it was tyres that were my main concern but suspension design and geometry setup were a very large part of it. The only factor that brakes played in the calculation was how much heat they pumped into the rims!

When younger I ran a number of quite high performance cars - Triumph Vitesse in standard trim but driven "spiritedly", 1275 Cooper "S" with Downton stage 2 engine which I rallied with little success, 1500 Mk1 GT Cortina with engine mods which enabled it to quite comfortably keep up with the Lotus version (what a lovely noise that engine made!) and others. I never modified the brakes in any way but always used quality "big name" components and never experienced any "moments" due to brake limitations. So I find what you've said above to be very very interesting. Thank you for that.

 

[s130]

One brake modification I did do, and still have on the Strada, is that I replaced the rubber brake hoses with stainless steel braided firm wall PTFE hoses. I had them on the Uno as well but their effect was less dramatic.

On the 130TC Fiat fitted bigger pots on the front brakes. The master cylinder almost remained the same but the brake pedal travel increased quite a bit. I did some measurements of pedal travel coupled with the brake pedal linkages (all unchanged from a standard Strada) and to my surprise under heavy pedal pressure the pedal movement and linkages passed their maximum fulcrum/leverage/efficiency point.

For normal road use this was not really a problem but with a steaming hot car, hot day, heat from the brake/callipers and the high brake forces the small expansion of the rubber hoses was enough to make things uncomfortable with a long pedal beyond it's best operating point.

The braided hoses did really improve the situation but still not enough. I had to make a modification to the rear brake drums (equivalent to pulling up the handbrake) to stop the brake shoes from retracting too far away from the drums.

The alternative solution would have been to fit a larger bore master cylinder (same throw so as to keep the brake pedal linkages) but doing this would of course require the fitting of a larger diameter servo unit to compensate for the reduction in braking pressure cause by the large diameter master cylinder.

I've always been one for simple and practical fixes.

For the Strada's improved brake cooling besides using more open RFX wheels I initially toyed with the idea of removing the front fog lights and using tube ducting to get air onto the brakes/disc.

I soon gave up on that as the solution was staring me in the face. On the Strada/Regata then the front suspension uses a single piece track control arm that is held in position but a substantial stay rod/arm that goes to the vehicles front cross member. It is angled at about 45 degrees. I made two aluminium deflector plates that mounted to the stay rod/anti-roll bar (which runs the same path). So now all that air going under the front of the car was deflected into wheel/brakes. Simple and effective.

HOWEVER for safety reasons I replaced my nice aluminium deflectors with the bottoms of two gardeners seed/potting trays. These had those mould ribs / diamond shapes in the bottom to reinforce them, also pre-drilled for the simple "T" fish plate mount and would deflect and/or break off if they encountered anything else other than air.

She still has them fitted which causes some amusement and discussion when people see them.

 

[s130]

I would also like to moderate / temper my above brakes/braking posts.

It is a fact that for every situation (be that cosmetic, functional engineering / etc) then there will be a variety of views, opinions, proven facts and unproven facts. This position/situation is the fundamental basis of engineering and scientific input into what can be complex and possibly controversial arenas where the examination, fact finding and testing etc. become so important in supporting or not supporting any given "position".

Thank goodness we have these examination and potential intervention avenues available to all of us. To put this into a little more fundamental perspective then if you have been born then sadly you will die. If you have not been born then you can't die or cease to exist. These are what are more commonly know as "boundary conditions". They exist (as far as I know) across all engineering and scientific theatres.

What is more interesting is that within these boundary conditions everything and anything can change. It is this uncertainty that drives us all to better ideas and solutions BUT NEVER EVER PERFECT.

So my Strada braking conservations with the like of Brembo and my vehicle implementations are just a final and far from perfect solution/implementation to the problem of staying within boundary conditions.

I can pretty much guarantee that others have tackled braking and all sorts of other challenges and come up with viable solutions and this is brilliant and so may it last.

And here in lies a little clue about real engineering. No design is ever perfect. Real engineers learn, adapt and improve their next designs. The cycle continues.

Real engineers/scientists do not discard other people's designs and views. To do so is (I have no appropriate words).

There is also the so called "over engineering" of a design. Example would be if the maximum ever conceivable force on a component would X then a design for 3X or 4X would be one's target. 100X would be beyond scope etc. and thus over engineered.

Sometimes over engineering is required and perfectly acceptable but each case has to be on merit. e.g. putting F1 braking onto a Fiat Panda (assuming F1 brakes would even work a ambient temperature) is an example of an over engineered and inappropriately delivered engineering solution.

So what am I driving at? Well it is just human nature to see a thick piece of wood and think "this is strong and what I need". Meanwhile the radically thinner but two ply laminated bit of wood is discarded on the basis of size. Oh what a mistake to make. We all tend to do it and will do so in the future. Sadly none of us tend to step back and question what we see and feel. Quite sad really but a fact.

Me - guilty as charged!
+

 

[DaveMcT]

I have all round HEL braided hoses on the 100HP Panda. They don't improve the utimate braking power but the immediate braking is fantastic. It probably saved me when a back brake locked causing the car to over-steer as I was able to release the pedal and let the car recover the slide.

The problem was the hand brake shaft seal jamming the brake on the other side. I have a Bigg Red seal kit. Now waiting for a pair of 90 degree bent nose circlip pliers to get the hand brake mech apart. I found them on eBay from a seller in Bradford. Lucky because 99% were in China. Silly me for not checking the seller's actual address because they are coming from all the way from China.

Braided hoses are a big benefit on the Panda 100HP because one 600mm hose replaces two rubber hoses and a length of steel pipe. If you don't want the sharp feeling pedal just leave the fronts with OEM type hoses.

My bikes have all had sintered brake pads on iron or stainless discs. They last a lot longer than organic pads and stop a heck of a lot better. The discs do wear faster but when you add up the cost of organic pads every 6000 miles the sintered lasting 3x as long are still cheaper despite the discs wearing faster.


BTW, you can get sintered pads for Fiat cars but the costs are silly money.