The cheapest way to upgrade the brakes.

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Re: The cheapest way to upgrade the brakes.

Postby Simon_P » Sun 16.11.2014, 09:06

Phil,

An interesting point, but I'm not sure why you have chosen this thread to be "Horrified" rather than the big brake conversions. You may be another 10 or 20 % more horrified there! (actually if you are horrified at 16% you will be double horrified at 30% :roll: )

lotusflasherman wrote:wondering if all pads are worn so pistons are a long way out of the calipers whether the volume of fluid in the circuit is so great that you run out of pedal travel before creating a usable pressure
What is the theory? Unless I have misunderstood, I don't think you mean what you wrote.

You have made some assumptions. What is important, as Dave alludes to, is Pedal displacement/ pedal ratio Vs the displacements in the master cylinder.

You make a good point, but it may have been better not to assume that
lotusflasherman wrote:There seems to be a general ignorance about how these work so I'd better deal with that first
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Re: The cheapest way to upgrade the brakes.

Postby RayD » Sun 16.11.2014, 12:32

:goodposting: Simon.

lotusflasherman wrote:I've just read this thread for the first time and am horrified about what you guys are saying and doing ...


Thanks for the input Phil,

As Simon points out, as you read more you’ll presumably be even more horrified.

lotusflasherman wrote:There seems to be a general ignorance about how these work so I'd better deal with that first


I don’t think the people on here are generally ignorant about dual circuit brakes; certainly all of the people likely to be carrying out their own work will have an understanding of the principle.

lotusflasherman wrote:Next time you are bleeding the brakes with just one bleed valve open press hard on the brake pedal and you'll find where the pedal is when the other circuit is under pressure - check the other wheels don't turn if you want to satisfy yourselves that you have dual independent circuits and the other is still working.


Out of interest Phil, what do you imagine the pedal would be like if you continued pumping until you were actually on one diagonal circuit?

On the off chance you are taking this the wrong way I genuinely don’t know the answer ... if you do, can you tell us how it would differ to johanvanboven’s car with the smaller MC fitted?

Also, what happens to the induced extra pedal travel once it’s on one circuit ... is the problem halved ... does it go from 16% to 8% ... it’s a bit too early in the morning for me to work it out.

The 16% by the way strangely coincides with the effect of having one sixteenth of an inch play in the clevis pin you referred to. (According to measurements posted on here)

lotusflasherman wrote: .... put the original master cylinder back on before a single circuit brake failure sees you wiping out a bunch of school kids waiting for a bus because you haven't understood the implications of swapping master cylinders.


I’ll gladly take this quote out of my post if you’ll do the same. If it turns out fitting a smaller MC presents a danger to anyone I’m sure people will react in a proper manner.

lotusflasherman wrote: And by the way - I can lock my brakes with the standard set up if I'm stupid enough to stand on the pedal that hard but I used to race Mini's with big fat slicks and no servo so perhaps I grew up used to a hard pedal. The fun bit is to get the tyres smoking without locking up and creating flat spots, then you know you've got your braking just right...


Only driving my Élan in a normal fashion I have no idea if the brakes will lock.

I have standard brakes and newish Michelin Pilot Exalto 205/45/16 tyres.

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Re: The cheapest way to upgrade the brakes.

Postby RayD » Mon 17.11.2014, 13:34

While waiting for a response to 16/11/14 12:32 ...

I’m sure Phil knows what he’s talking about but the way it’s come over may be confusing. ( I should talk! :? )

lotusflasherman wrote:YouTube video is fairly good explanation ... It mentions that modern cars should have two systems so one works when other fails and I think that is why Lotus made decisions about pedal travel, pivot points, mechanical advantage, bore size etc etc.


Lotus applied a dual braking system to comply with the rules, for which they only needed the correct type of MC and the appropriate plumbing ... the “decisions about pedal travel, pivot points, mechanical advantage, bore size etc etc” don’t come into it. If they were doing it again they would choose something entirely different.

lotusflasherman wrote:On the thread I saw somebody claim that he had no brakes when one circuit failed and I don't dispute that but am wondering if all pads are worn so pistons are a long way out of the calipers whether the volume of fluid in the circuit is so great that you run out of pedal travel before creating a usable pressure - just a thought. I'll let somebody else do the maths


There’s no relationship between the wear on the pads and the pedal travel. The wear is automatically taken up otherwise we would all have an indication of brake pad wear from the distance the pedal moves.

lotusflasherman wrote:I don't use my brakes for long - in deep, one hard stab and round we go ... that's what Elans were designed for.


Is it?

If you actually apply this method on a day to day basis Phil I can see why you would be overly concerned about brake failure. Most ordinary people would know in advance of you if a front hose had gone.

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Re: The cheapest way to upgrade the brakes.

Postby Simon_P » Mon 17.11.2014, 19:56

RayD wrote:Also, what happens to the induced extra pedal travel once it’s on one circuit ... is the problem halved ... does it go from 16% to 8% ... it’s a bit too early in the morning for me to work it out.

It's taken me a while Ray but I think you may be right. You would get only half the braking but from half the displacement so 16% would be 8%. Of course the pedal would already be a long way down so the additional 2.85 mm of travel may make all the difference. ....assumeing that only the diameter has changed and the displacements are identical......
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Re: The cheapest way to upgrade the brakes.

Postby epipete » Mon 17.11.2014, 20:57

lotusflasherman wrote:On the thread I saw somebody claim that he had no brakes when one circuit failed and I don't dispute that but am wondering if all pads are worn so pistons are a long way out of the calipers whether the volume of fluid in the circuit is so great that you run out of pedal travel before creating a usable pressure - just a thought. I'll let somebody else do the maths... but it's all theory and what actually happens is more important.


''Twas I, me thinks. I would say that when you press your brakes and suddenly they go slack, the last thing you consider doing is pressing harder (perhaps with the knowledge imparted here I now will, should it ever happen again), I seem to recall pumping them but most of your attention is diverted into looking at hazards and steering around them until you can stop!
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Re: The cheapest way to upgrade the brakes.

Postby RayD » Mon 17.11.2014, 21:52

...

Thanks Simon.

Pete,

Thankfully it's a natural reaction to pump the pedal when the brakes fail as it's the one thing that brings the dual circuit into play.

Unfortunately it's not been clear how well the dual circuit works on an M100 but when Phil gets back to us he'll be able to explain exactly what it's like having driven 30 miles with only half the system working.

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Re: The cheapest way to upgrade the brakes.

Postby lotusflasherman » Mon 17.11.2014, 23:32

Simon & Ray,

sorry guys, been doing my company accounts which are overdue with accountant so not been visiting here, didn't mean to ignore you... but I felt like a break from numbers so came back to see what's happening and see you're waiting on me ... I'll reply to various earlier comments, in no particular order -

What is the theory? Unless I have misunderstood, I don't think you mean what you wrote. & There’s no relationship between the wear on the pads and the pedal travel. The wear is automatically taken up otherwise we would all have an indication of brake pad wear from the distance the pedal moves. - Yes, that's the point, wear is taken up by more fluid filling the caliper piston and the pedal returning to it's 'usual position'. Usually the hydraulic force ratio is only determined by the area of the M/C bore compared to the total caliper piston area. The point to consider is when a circuit has failed and one of the pistons travels freely through the M/C until it reaches the mechanical stop and only then starts pressurizing the healthy circuit. That takes up quite a bit of pedal travel and only the remaining travel is available to pressurize the healthy circuit. My brakes worked with a severed hose but the pedal was almost in the carpet! - somebody else has stated theirs didn't work. Was it because the volume of fluid in their callipers was much greater than in mine because their pads were much more worn? There is a certain volume of fluid trapped by seals in the M/C that is used to increase the pressure of the fluid in the remaining system and usually it achieves a hydraulic lock and further pedal travel increases the pressure according to the mechanical advantage of the pedal geometry. But if the volume of the remaining system is much greater than that amount, hydraulic lock is only achieved right at the end of the stroke and because the pedal has reached the end of it's travel not a lot of pressure can be created, and the driver thinks he's lost everything; but if new pads were in and that volume to compress was less etc .... Have you got the point I'm trying to make?

If they were doing it again they would choose something entirely different. - agreed, because they probably wouldn't raid just the GM parts bin but would have a free hand. But very little is designed from scratch these days - better to use proven components in the middle of the bathtub.

As far as driving on one circuit - as long as you get used to how far the pedal goes down first push it's not a problem as long as you realise it ain't going to stop us usual and drive accordingly. Bit similar to towing a trailer with a car - take it easy, leave plenty of room and plan ahead. Pumping the pedal brings it up but the return spring on the piston with no fluid brings it off the mechanical stop so next time they are back near the floor. If you know that you can pump up with the left foot before you need them - technique used by racers to compensate for 'pad knockback'.

I think I read somewhere that dual system should allow for a pipe burst under pressure so pedal will drop but not hit floor and still maintain pressure in other circuit. Think it assumes driver will not understand pumping pedal etc...

Better get back to my numbers... but I'll keep an eye on the forum.

Phil
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Re: The cheapest way to upgrade the brakes.

Postby Fredjohn » Tue 18.11.2014, 01:49

Very interesting thread, but I am afraid a lot goes over my head. However, I have had a "breaking" experience, so here's my brief story.

The short brake pipe from MC to offside flexible caliper pipe split due to rubbing against the chassis. I did not know this at the time: only later investigations established the exact cause of the problem.

I had braked hard on the motorway, and thereafter the brakes felt awful. Stopped at services to look, but couldn't find anything untoward. So carried on and finished the 50 miles or so back to Preston. I had brakes, but not very effective: lots of pedal travel, very unconvincing in operation, but they did slow me down/stop the car. I adjusted my driving, keeping even further back and allowing lots of time for anything, just in case. Pumping the pedal did help, but tried to avoid it and used handbrake occasionally to help out. (yes I know this'll upset the front/rear balance, but it worked)

I cannot remember if the pedal went all the way to the floor or not, but it was pretty close and very worrying, even though the brakes did sort of work. Looking at how a tandem MC works in the pictures above, it is now obvious that one diagonal was inoperative and the other still worked, with the fluid being retained in one half of the reservoir because of the dividing baffle.

Having got to Preston, and discovered the split, I decided the 130 miles back home would be best done with the help of the AA. Got home, new pipe (£3) fitted, and also fitted new flexibles to the front, although they were not really needed. Brakes now back to normal and working very well. I have Wilwoods fitted ilo std, so no issues.

But it mostly seems to prove various points made above, although testing the theory whilst bleeding is decidedly a better option than in use!! Cannot comment on MC efficiency, fluid volumes, pressure vs travel etc etc, just my practical experience of a tandem MC proving it works. I do not intend to repeat the experiment to reconfirm my findings for any doubters out there :lol: :lol:

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Re: The cheapest way to upgrade the brakes.

Postby lotusflasherman » Tue 18.11.2014, 02:28

Only driving my Élan in a normal fashion I have no idea if the brakes will lock.

Would you pass the driving test in it then?

The examiner on the driving test will expect you to:-
Stop the car promptly
Keep the car under control without locking the wheels
Stop the car in the shortest possible distance
Stop the car without endangering other road users


It's a good idea to find out the 'performance envelope', when it's safe to do so, and become aware of how much it changes with varying road surfaces - dry, damp, wet, mud etc. . Then you'll know how to achieve 'Stop the car in the shortest possible distance' without contravening the 'without locking the wheels'.

If you know how quickly you can, or more to the point, cannot stop, you'll be more likely to be 'travelling in the right place, at the right speed, in the right gear'.

I did an Improver Driving Course in my first Elan, Privilege Insurance were giving 15% off premiums at the time if you did it and they part funded it. Interesting afternoon with a Police High Speed Driving Instructor from Essex Police HQ sitting next to me expecting me to 'show that you can drive briskly and not afraid to cruise at the legal limit, plus 10%, when circumstances permit' and 'to demonstrate how hard the brakes can be applied without locking in an emergency stop.' He said he expected them to squeal but not 'zzzzzzz' and would look behind for skidmarks as evidence of locking. Then he asked me to try locking them to find out when it happened and how the car behaved. Behaved very well actually but it was on a straight empty road in Norfolk.


If you actually apply this method on a day to day basis Phil I can see why you would be overly concerned about brake failure.

I'm not overly concerned about brake failure but am happy to use the performance of the car on a day to day basis - otherwise I see no point in owning an Elan.
I grew up in the backseat of my dad's MG Y type Saloon, followed by his Magnette ZB and remember the MG motto "Safety Fast" - always thought Lotus should have "Safety Faster" as theirs...

I must say I'm wondering why people are upgrading their brakes when they possibly don't use the full potential of the standard set up. I have EBC dimpled and slotted discs with Greenstuff pads on No2 Elan, that's on a SORN, and latest acquisition, No3, is still standard. I do find the Greenstuff pads are 'not there' when cold but standard pads not a problem. Some time I'll do some back to back comparison on 'hot performance' ...

Had a lot of fun and success in a 1000cc Mini Racing Saloon - 11cwt, about 100 bhp at the front wheels and very sticky 6" slicks taught me how to drive in the early 70's.. Elan is very similar, FWD, power to weight slightly less, so think I know what I'm doing... at a rough guess I've done 135,000 'Elan miles'.. very quickly, very safely...

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Re: The cheapest way to upgrade the brakes.

Postby lotusflasherman » Tue 18.11.2014, 03:04

John,

that's an 'interesting' experience - so a metal pipe rubbed through due to vibration? Must check all mine are properly clipped in!

I had a lorry trailer numberplate come off in front of me and go under nearside wheel arch as I approached a roundabout on the A46 in Newark area heading to Lincoln... bit of clattering in wheel arch and suddenly brake pedal was near carpet as I braked for the roundabout... entry was clear so I took it a bit faster than planned rather than brake hard on one circuit. (Wasn't sure how the rear brake bias valve would alter the balance so didn't stamp on them hard). Flexible hose had got chopped through. I carried on into Lincoln, about 30 miles, to a Halfords where I bought some fluid to top up, wipes to clean off the fluid before it destroyed my paintwork but they hadn't got the right hose so I bought a hydraulic hose clamp and some tape and clamped off the severed hose and taped it securely out of the way and refilled the system. That gave me 2 rear brakes and the OSF, and the pedal back to the normal position so I then drove 50 miles to Pat Thomas, Lotus Guru at Keveldon Motors at Pode Hole near Bourne for him to replace all my flexible hoses with Goodrich Armoured hoses. All in all, a useful learning opportunity... but quite expensive!

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Re: The cheapest way to upgrade the brakes.

Postby Simon_P » Tue 18.11.2014, 09:36

lotusflasherman wrote: but if new pads were in and that volume to compress was less etc ....Have you got the point I'm trying to make?

Yes, I think so!
I think that you are suggesting that we should consider the compressibility of brake fluid due to the additional volume in the calliper. A theory which I again urge you to reconsider.

As for the pedal displacement due to the failed circuit - That will be the same whatever the M/C diameter . Since we are considering the remaining pedal travel after failure, I have used the calculations in the earlier post the difference would be 8% more travel which equates to 2.85mm free travel on the stock set-up.

Assuming of course that the internal displacements of the two master cylinders are the same - I don't know that, I just cross referenced the part number given.

lotusflasherman wrote:Pumping the pedal brings it up but the return spring on the piston with no fluid brings it off the mechanical stop so next time they are back near the floor.

Except that the open system will always have displacement X, the pressurised system will pump-up,
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Re: The cheapest way to upgrade the brakes.

Postby dapinky » Tue 18.11.2014, 11:42

Simon_P wrote:I think that you are suggesting that we should consider the compressibility of brake fluid due to the additional volume in the calliper. A theory which I again urge you to reconsider.

I hope no-one is suggesting that brake fluid is 'compressible' - NO fluid is compressible, so if your does compress, it has got gas somewhere in the system :(


Simon_P wrote:As for the pedal displacement due to the failed circuit - That will be the same whatever the M/C diameter . Since we are considering the remaining pedal travel after failure, I have used the calculations in the earlier post the difference would be 8% more travel which equates to 2.85mm free travel on the stock set-up.

As I said about a dozen posts ago (so we agree)..... although it isn't quite 50%, as the first part of the piston travel is used to close off the compensator valve, so has no (or very little) bearing on braking effort - again, like Simon, I haven't dismantled the cylinders so don't know how much travel is needed to close the valve and actuate the brakes - but from normal driving, you don't need to move the pedal far to get some retardation, so it is a very small consideration.

As such, even if we suggested that it is down from 16% to, say, 10% (or should that be up to 6% depending on your interpretations :roll: ), then we are talking about 0.5mm of travel.... if it is that marginal that 0.5mm makes a difference, then perhaps you need to remove some underfelt from the footwell!!


On a seperate(ish) but alluded to topic....

.... Anyone who knowingly continues to drive their car (elan or otherwise) on a public road with a braking system which doesn't operate correctly is not only foolhardy, but a downright liability (in my opinion), and they should consider whether it would be better for the rest of us for them to take the bus.

Continueing a journey with only 3 of the brakes working (and the rear two at only 35% pressure) would be an interesting one for a lawyer to argue in court....

Any 'failsafe' mechanism is only intended to stop you as quickly and safely as possible after the initial event, not to allow you to continue your journey on a wing and a prayer.
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Re: The cheapest way to upgrade the brakes.

Postby RayD » Tue 18.11.2014, 16:02

...

Thank you for the reply Phil and sorry for the impatience.

lotusflasherman wrote:Was it because the volume of fluid in their callipers was much greater than in mine because their pads were much more worn?

No

lotusflasherman wrote: ...but if new pads were in and that volume to compress was less etc .... Have you got the point I'm trying to make?


With no fluid compression there is no change attributed to the pad thickness.

lotusflasherman wrote: As far as driving on one circuit - as long as you get used to how far the pedal goes down first push it's not a problem


With your experience of operating one circuit brakes about 200 times over 30 miles you will know more about the feel of it than anyone.
I was trying to get to know how you imagined it would differ on johanvanboven’s car with the smaller MC to bring about your reaction to reading about it.

lotusflasherman wrote: Think it assumes driver will not understand pumping pedal etc...


I don’t think people need to understand pumping the pedal, I think it comes naturally.

Ray wrote:Only driving my Élan in a normal fashion I have no idea if the brakes will lock.


lotusflasherman wrote: Would you pass the driving test in it then?


I think I probably would Phil, I had a Driving School when I was 19.

lotusflasherman wrote: It's a good idea to find out the 'performance envelope', when it's safe to do so, and become aware of how much it changes with varying road surfaces - dry, damp, wet, mud etc. Then you'll know how to achieve 'Stop the car in the shortest possible distance' without contravening the 'without locking the wheels'. If you know how quickly you can, or more to the point, cannot stop, you'll be more likely to be 'travelling in the right place, at the right speed, in the right gear'.


I’ll keep that in mind.

Oooops.jpg


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Re: The cheapest way to upgrade the brakes.

Postby cliff » Tue 18.11.2014, 16:25

lotusflasherman wrote:
I must say I'm wondering why people are upgrading their brakes when they possibly don't use the full potential of the standard set up. I have EBC dimpled and slotted discs with Greenstuff pads on No2 Elan, that's on a SORN, and latest acquisition, No3, is still standard. I do find the Greenstuff pads are 'not there' when cold but standard pads not a problem. Some time I'll do some back to back comparison on 'hot performance' ...

l


My first drive in an Elan was when I picked mine up and drove it from Stroud to Frankfurt, I was pretty horrified to find how poor the OE brakes were even with green stuff pads fitted. They certainly didn't give me too much confidence on the autobahn. Even after making sure the system was in good condition, I was never happy with them so I replaced the fronts with Wilwoods and the rears with the PNM conversion.

My Elan now brakes like a modern car and I know that I can stop. While I might not use the full potential, I do drive my car a lot faster than most UK based owners. Much of the road to Frankfurt is unrestricted and I usually cruise at about 110 mph, a comfortable speed with some left for playing. I am happy in the knowledge that I can safely stop when some clown (usually in an NL plated car - sorry HJ) pulls out doing 60 mph.

I have kept the standard MC, although it has been replaced, I do have different Wilwood calipers to most conversions though.

Slightly off topic, I wonder about the how useful Improver Driving Courses really are, given that the instructors have usually never lived outside the UK and driven in places like Germany, Italy or the Middle East where driving is a whole different ball game. They are also forced to quote the mantra that anything over 70 mph is dangerous rather than explaining that 70 mph was an experimental arbitrary figure dreamed up in 1965 and later made permanent and that the UK has the lowest speed limits in Europe.
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Re: The cheapest way to upgrade the brakes.

Postby dapinky » Tue 18.11.2014, 17:45

cliff wrote:Slightly off topic, I wonder about the how useful Improver Driving Courses really are, given that the instructors have usually never lived outside the UK and driven in places like Germany, Italy or the Middle East where driving is a whole different ball game. They are also forced to quote the mantra that anything over 70 mph is dangerous rather than explaining that 70 mph was an experimental arbitrary figure dreamed up in 1965 and later made permanent and that the UK has the lowest speed limits in Europe.


Lots of thoughts on this one.....

Firstly, I would say that ANY Enhanced/Advanced driving course is worthwhile - but the student needs to be willing to accept that their current level of driving can improve! Some (many?) think that there is nowt that they can be taught, and for them it is a waste of time, effort and petrol....

But the majority of road users (perhaps I could even be so bold as to suggest that this applies more to Women than men, and to persons of a certain age more so than youngsters) will see an improvement in their driving style which has all sorts of benefits for themselves and other road users.

The biggest thing to accept is that Advanced driving is NOT about going faster - it's about driving at an appropriate speed for the prevailing (and anticipated) conditions, with road/vehicle sympathy and an understanding of the Laws of Physics.

These principles can be adopted wherever you then drive. Although I have never lived in Germany, Italy or the Middle East, I have driven in all of them, and have to agree that their ideas of road possitioning are a tad different than in the UK - but the principles are the same. For a really exciting challenge, you may wish to try driving in rush hour in Saigon (which seems to last 23 hours every day), or Hong Kong - where I'm fairly sure that the Chief Examiner of Driving Standards took personal instruction from Stevie Wonder.

I agree about the speed limits, but that is a whole new arguement - if everyone drove 'properly' in accordance with the principles of Advanced driving, then there would be no need for ANY published speed limits, and no-one would have any accidents attributable to driver error.

Having driven at a speed (indicated) of just shy of 190mph on a UK road, I have to say that our roads are not designed for that sort of thing, and one slight curve of the road which I'd never even noticed at 'normal speeds' (read:- up to 140mph) was like a 90 degree right which left me wishing that I'd slowed down a tad coming down the Long Ashton bypass (for those that know the A370 road into Bristol).

I much prefer to do my fast driving on a track, and have been known to be likened to 'Miss Daisy' whilst piloting my own car on open roads :(
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Re: The cheapest way to upgrade the brakes.

Postby Simon_P » Tue 18.11.2014, 18:34

Dave,
I have no idea why you are quoting me? I have responded to Phil! I'm not sure what your point is! have you read what I have written in context?

Half the system is working so it has half the effect so it is about 8% - not sure where you get 0.5mm from? what is that about underfelt?

I chose my words carefully! All fluids are compressible, even brake fluid.

Ray,
You are in luck old Mini's and beards are back in!

Cliff,
What a coincidence my first trip was to Frankfurt!

Phil,
Is that Druids?
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Re: The cheapest way to upgrade the brakes.

Postby dapinky » Tue 18.11.2014, 19:16

Simon,

I was quoting your post to offer support to your arguement, but also to address a couple of 'minor' (percieved by me!) errors....

Half of the system may well be working, but due to the piston travel NOT operating over ALL of it's travel (due to having to close the valves to the reservoir), the 16% does not halve to 8%, as the first bit of both pistons' travel has little effect on the braking pressure, and this bit of movement is present whether there is a leak or not.... (but for the sake of your arguement against Phil, it may well be irrellevant.

The 0.5mm comes from the piston travel excess between operating at 8% and slightly different, to allow for the portion of travel where pressure doesn't increase.

The underfelt refers to the amount of room that the pedal can travel before coming to a stop (as per an earlier post of mine), and was perhaps, a trifle flippant of me to include!

I still maintain my principle of fluid compressibility, and dissagree that ALL fluids are compressible.... Some more so than others, and not *ALL*.

It is accepted wisdom that Glycol based brake fluid is about 1.9x less compressible than Silicone fluids, but in normal use, it is also accepted that brake fluid doesn't really compress to an appreciable amount (otherwise they wouldn't use it!).

In fact, you need to apply some huge amounts of Pascals of pressure to cause a very small compression (and then it is down to the temperature increase more so than the actual pressure - (Physical Laws), but, yes, I accept that glycol will diminish in volume by 12.3 ppm during a temperature increase of 100 Celcius, IF 14 x 10 (to power) -11 KPa is applied within a sealed container.

However, we will never see that sort of pressure in a brake system, but continual applications of the system WILL increase the temperature, leading to boiling of the fluid, and as soon as it goes over about 112C the water absorbed in the glycol will come out of solution and boil, adding gas (steam) to the mix, which is VERY compressible - and that is where the real problem lies :wink:
Dave

Just the one now, but this one's mine! - and it will be finished eventually..... - but also temporary custodian of a project until it is finished enough for Angie to drive it

go on - click this link - you know you want to!
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Re: The cheapest way to upgrade the brakes.

Postby RayD » Tue 18.11.2014, 20:06

Simon_P wrote:
Ray, You are in luck old Mini's and beards are back in!



Simon, I'm the one behind the camera ... without a beard :D

Ray
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Re: The cheapest way to upgrade the brakes.

Postby Simon_P » Tue 18.11.2014, 20:36

Dave,

OK I see - I thought that you were suggesting that I was considering Brake fluid to be compressible. Which for practical purposes it is not - Hence my comments to Phil that I didn't think he meant what he wrote.

I apologise for my flippant comment about under felt - I knew what you meant, just don't agree with your maths. I expect we all felt the sensation of compressed underfelt!

If we assume that M/Cs are identical except for bore.
Then all displacements are constant - Pedal slack, valve actuation etc
If the effect of the reduced bore is a 16% increase in pedal displacement on a working system.
Then the additional displacement for half the system will be 8%

Fluids are only considered compressible or incompressible for modelling purposes. If they were actually incompressible they would not change density with temperature, and would not transmit sound.
Lets Just agree that Brake fluid is incompressible which was the thrust of my comment to Phil. :wink:
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Re: The cheapest way to upgrade the brakes.

Postby Simon_P » Tue 18.11.2014, 20:38

RayD wrote:Simon, I'm the one behind the camera ... without a beard :D
Well then now is your chance!
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