Elan BBK comparison, kits lack important specs

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Re: Elan BBK comparison, kits lack important specs

Postby lotusflasherman » Thu 16.03.2017, 01:04

dapinky wrote:(2) It'll do those deceleration figures anyway (but it will need to be tested on a Tapley Meter (or whatever the new version of it is called!) to allow for weight distribution - it can't be done on brake rollers).


My friendly MOT guy calls it "The Swingometer" when he gets it out for my Subaru. (Think it's still got Tapley on it.) :lol:
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Re: Elan BBK comparison, kits lack important specs

Postby muley » Thu 16.03.2017, 02:07

dapinky wrote:
muley wrote:Can't wait to see if my Elan is compliant.
Jim


(1) It doesn't matter, ya daft git - the car aint in NZ
(2) It'll do those deceleration figures anyway (but it will need to be tested on a Tapley Meter (or whatever the new version of it is called!) to allow for weight distribution - it can't be done on brake rollers).



(sigh) I know rollers are not brilliant at measuring 'g'..

The point I was +trying+ to make is that half the techhy mumbo jumbo on this thread is pointless. Whether the brakes were modified by a loony in a boiler suit or a NASA scientist it's the real world that counts..
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Re: Elan BBK comparison, kits lack important specs

Postby isuzuowner » Thu 16.03.2017, 03:05

dapinky wrote:
isuzuowner wrote:If you have data to include and a the correct coefficient to multiply the rear force number by to add that, please post it.


There is no simple coefficient of multiplication - far to many variables, including (but not exhaustively) temperature of brake components, material specifications, weight distribution (which is non-constant, depending upon rate of decelleration), specification of brake fluid (degeneration), etc etc...

...so I'm not sure what advantage publishing lots of meaningless data may prove.

Anyway, my brakes work well enough for me - I can lock wheels if I want to (which i don't!), and it passes the annual MOT test. I have used the car on road and track, and never had any great concerns about the efficiency of my (mainly) OE system.
At the same time, I fully accept that the system can be improved, and an 'off=the-shelf' kit from the few specialist suppliers will appeal to many owners who want them to feel a bit better, and be less of a regular maintenance regime.

Basically, if I can lock the wheels on an OE system, then the car won't stop in a shorter distance with ANY other callipers fitted, as the limiting factor becomes the friction between tyre and tarmac.... the difference is in the force required to engage the wheel lock, and the time at which that rotation is stopped after hitting the 'oh s**t' pedal hard.


dapinky wrote:I merely made comments in the chronological order you posted, with no importance to be ellicited from the order.

It wasn't me who mentioned "that's why we have an MOT test", so why ask me about it?

I am fully aware of the published coefficients of friction of various brake materials from different manufacturers, but not quite sure how they are relevant to your points - it is easy to quote things from the interweb, but lists of numbers are pretty useless.

You mention PNM, Hi-Spec and BB kits - and say that you can only find information on one of them......... perhaps because they are all the same (callipers manufactured by Hi-Spec, and sold by PNM under their own name.... the rest of the hardware developed by Bob and utilised in the 'kits'.)

As for your suggestion that proportioning valves are a 'band aid' to cover poor design/selection of components..... well, that means that every manufacturer in the world makes poor choices. You show me ANY car (production) which doesn't use some sort of pressure proportioning system (usually part of the ABS manifold or master cylinder on modern vehicles) and I'd be surprised!

They are fitted to allow a 'standard' shelf part to be used for multiple applications, otherwise every vehicle would have individually made components, even down to different variants of the same car to allow for the extra weight of the original equipment... that would be absurd. It is only to get the bias/split to fall into an acceptable range for expected/intended use.

Anyway, i'm bored now, and shall give up with this pointless diatribe - it is impossible to have a meaningful discussion with someone who either chooses to not listen, or who feels that by regurgitating 'facts' from the interweb, they must be right....after all, we all know that 86.7% of statistics found on the internet are purely inserted to make a point appear valid.


Your post about proportioning valves was after my last comment, I will start there. I mentioned "If you have a coefficient to correct for the proportioning valve, please post it", which was a bit of a trap, because I had already researched that topic rather thoroughly and found none.
In the course of the discussion of other discussions, there is reference to the Wilwood proportioning valve, and some comment that it has a larger range of adjustment than what Lotus used on the Elan. I have direct experience using the Wilwood proportioning valve, in attempting to resolve a brake biasing problem in a car put together by someone who did not do the math. The front brakes were a little better than the originals, and the rears were quite a bit better than the originals. And the car would spin pretty prolifically every time the brake pedal was used.
Wilwood states that their valve can provide a "57% reduction in line pressure". That is not a 57% reduction in braking force. Only the hydraulic pressure. And that is not a reduction from zero, it is a curve. Brake force increases normally at lower pressure, and when the line pressure meets the resistance of the spring inside the valve, it continues to increase at a slightly reduced rate. The adjustment knob moves the transition point up or down. So full pressure with partial application of the pedal, slightly reduced pressure under full application of the pedal. But the rotor diameter and brake pad friction compound remain the same, and this is why that proportioning valve have just a very small range of impact on the overall braking.
I mentioned that car with the excessive rear braking force. I started with higher friction front pads, changing from .38 to .54 cf. That didn't solve the problem. Next I installed that same Wilwood proportioning valve, and after small adjustment steps, had the valve turned to the fully off position, with the maximum limit to the rear brake circuit. That almost reduced the rear braking force enough. Better, but not enough reduction in the rear braking force.
At that point, I sat down and did the math. And the solution was to change to larger piston calipers, and drop the pad cf down to .44. That was a 12% increase in front braking force. The brake proportioning valve was turned to the fully open position, and is no longer needed.
The range of adjustment of the brake proportioning valve was less than 12% of the rear braking force. And a 12% change in braking force was enough to change a car from spinning to dead stable.
And that's how inputting all those specs and figuring out what the actual braking force is, and being able to compare the braking forces produced by different combinations of parts, is useful.

The calculation is for braking force at the rotor.
Weight distribution and weight transition are not part of the braking force. These are considerations when deciding what braking force is needed or desirable, but they do not affect the braking force that the parts are able to generate between the rotor and the pad.
The temperature of the pad does affect the braking force. For the sake of comparison, I have used the coefficient at ambient temperature, because this is going to be how the brakes act upon panic stop in traffic. For determining braking force under constant heavy braking, you have to find the operating temperature of the rotor under those conditions, and a graph showing cf across the temperature range. That is a little beyond attempting to put together a simple comparison of three or four combinations of parts (brake kits). But it does point out that a pad with a flat curve that is consistent across its temperature range is desirable. Most of the pads mentioned with these kits fall into that category. And any of the pads that would be streetable would fall into that category.

"Quoting numbers is useless". Well, if those numbers are not understood, perhaps. If you want to correct those numbers, please point to what you believe is in error and state your case.
No one has provided any reason the specs I have found, the method of calculating the braking force, or the results is in any way inaccurate or erroneous.
The response is a flat refusal to even look at or consider the data. Similar to a refusal to believe that the world is round.

I mentioned that PNM appears to be using Hi-Spec calipers.
I also pointed out that Hi-Spec do not state what size pistons are in the calipers they provide with their kit for the Elan. And neither does PNM.
This site has no FAQ. I can find no statement posted by someone who purchased any of these that they measured what was delivered to them.
Additionally, I pointed out that both Hi-Spec and PNM may very well be providing calipers with different piston sizes to difference customers, if they tailor their kit to what they believe the customer wants/needs.
That may be good for the individual customer, but makes comparison of the product performance from one customer to the next a problem. A customer wants the performance recommended by another customer, and receives something different.

Proportioning valves in pre-ABS production cars are rare. Adjustable proportioning valves in a production car is not just rare, it is a liability problem. Anything the customer can adjust that might result in making the vehicle dangerous to operate, is something that the customer can screw up, cause damage or injury, and then the customer can sue the vehicle manufacturer for delivering a product that is unsafe or can be made unsafe with the adjustment provided. This is why almost no one manufactures and sells a car with adjustable spring perches, camber plates, and the full compliment of suspension adjustment like threaded diagonal arms and multiple suspension mounting points.
Please do not confuse residual pressure valves with proportioning valves. A residual pressure valve keeps a small amount of pressure in the rear hydraulic circuit, to compensate for the additional length of the pipes attached to the rear brake calipers. This prevents the rear brakes from disengaging too much so that they are ready to push the pads against the rotors at the same time as the front brakes.
Just about every car has a residual pressure valve. It is located in the master cylinder. It is not adjustable, and may be easily confused with a proportioning valve. But it does not do the same thing.
Most auto makers sit down and calculate out the braking force similarly to the method we are discussing, using the rotor diameter, caliper piston size, and brake pad coefficients. And they select those parts to work together as they are and without something like an adjustable proportioning valve.
You mention changes within variants of a vehicle, but you fail to recognize that the standard practice is to specify different parts for the different vehicles, such as the common practice among auto makers of specifying a different brake pad compound, in the same pattern, between a base model and a upper level model. This is easy to see with Brembo's popular brakes, and cars using the same brake pad pattern, such a the four piston front found on Evo, Sti, Mustang, Camaro, Corvette, several Cadillacs, and even a few Vipers. They do make this caliper in different piston sizes. But each of those vehicles has a different pad compound provided to the vehicle manufacturer to tailor that caliper to their use. And some of those models have changes in the pad compound over the range of model years, when the vehicle manufacturer decides something needs to be changed. They all have the same shape and thickness, and are available from just about every performance pad maker. But what performance compound is desirable for one specific vehicle to match the original or make an improvement, can be very different from another vehicle using that same pattern. And most good pad makers will know which compound not to use with which vehicle, because it does not even meet the minimum friction level of the original pad for that vehicle.
As far as proportioning valves on production vehicles, I know that none of the Isuzu vehicles made between 1972 and 1995 have proportioning valves. I haven't seen any on Honda, Nissan, Toyota, Mitsubishi, Chevrolet, Ford, or Dodge.
On this side of the world anyway, that particular item on the Elan is an anomaly.

A pig in the poke.
Relation to other idioms and expressions. The English colloquialisms such as turn out to be a pig in a poke or buy a pig in a poke mean that something is sold or bought without the buyer knowing its true nature or value, especially when buying without inspecting the item beforehand.


Without quantifying the braking force of a brake system (stock or big brake kit), there is no way to compare and make an educated decision.
It is like buying a pig in the poke.
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Re: Elan BBK comparison, kits lack important specs

Postby isuzuowner » Thu 16.03.2017, 03:22

clemo wrote:...playing nicely .

...rubbing some up the wrong way .


You may wish to direct some scrutiny to your membership for the generous portion of ridicule and insult they have directed toward me, specifically regarding political and nationality based topics, which are completely inappropriate to the topic of automobiles or polite conversation.

That is not how I treat a guest in my home, and it is certainly not not how I expect to be treated when I offer help to others.

Your membership is apparently completely unaware that this country has a rather deep divide at the moment on politics, and directing remarks about either side of the spectrum to anyone is considered inappropriate.

I will add that I know many, many, many unkind comments regarding most topics of the United Kingdom. I have not used any of those. The level of my restraint in the face of the continued attacks by your members is considerable.


There are plenty of websites devoted to arguing about politics. This is not one of them.

There are plenty of websites devoted to bigotry and hate. This is not one of them.

Prove my assessment of this website is correct. Put an end to the insults and ridicule that your members are directing toward me.
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Re: Elan BBK comparison, kits lack important specs

Postby HJ2 » Thu 16.03.2017, 08:48

It is not the content of your posts that make me rise my eyebrows, it's the way you bring them accross the floor. Mainly the attitude between the lines does not help. What is it that you try to accomplish here?
A forum is not different from the real world. If the format of the message is not accepted by the audience, the content will be lost without a way to repair the relationship.

You could always start a forum of your own and bring whatever message you have across there to an audience that will fit you.

Here you just harvest what you seed

You seem knowlegable to add to the forum. With a few small attitude adjustments you could become a valuable member.
I whish you wisdom for now. Really!

(Typed on my phone, excuse me for the typo's)
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Re: Elan BBK comparison, kits lack important specs

Postby dapinky » Thu 16.03.2017, 11:53

Just too many points to bother with - even if I could be arsed to read them all fully.

We are not going to agree on many points, mainly, I suspect, because of my previously-mentioned dissimilarity of language - you call it one thing, i call it another, and maybe they're the same, but maybe not. USA and UK (EU) have totally different ideas on 'vehicle build' and what the average owner should be allowed to adjust and play with.

You say that a Prop Valve is a 'band aid' but then state that you use different .cf pads to adjust bias - wow!...... at least a prop valve will retain a far more calculable operation over a range of conditions, whilst different pads will work differently even as they are being used....

(and yes, I DO understand the maths behind it all, I DO use different pads for different applications, I DONT test vehicles on a public road, I DO have access to some good research, and just because you can't find the data on the interweb, it doesnn't mean that it doesn't exist - just that YOU can't find it..... (and, NO - I won't point you to it - - if you were entitled to access to it, you'd have it :wink: ).

I fully understand how the Willwood prop valves work, and one of my links gives all the theory on it...

...however, the one thing i DO agree with you on is the 'personal insults' bit - which is why I had brought it up previously. There is no place for such things here or elsewhere.

Anyway, I've had enough of banging my head against a brick wall, and have run out of patience......

...... have a week off to consider if this forum is the best place for you to bring your knowledge, or if you would be better off elsewhere.
Dave

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Re: Elan BBK comparison, kits lack important specs

Postby Steve A » Thu 16.03.2017, 12:23

:roll: If he doesn't respect the cars we drive or the people that drive them, then there's not really a place for him on our forum. :smt039
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Re: Elan BBK comparison, kits lack important specs

Postby lotusflasherman » Thu 16.03.2017, 12:53

Steve A wrote::roll: If he doesn't respect the cars we drive or the people that drive them, then there's not really a place for him on our forum. :smt039


:agree:

The statement "A bias valve on a production car is typically a sign of someone in the engineering department not picking the right parts, discovering the error too late, and scrambling to fix that problem too close to the production date." is written by somebody who either doesn't understand the basics of engineering, or is an internet troll... Your choice, matey. :lol:

Bit fed up with 'Isuzu good, Lotus bad' mentality, particularly when expressed with such ignorance about weight transfer and brake balance, but it's been in every post he's made...

So :wtf: are these ...BRAKE-PROPORTIONING-VALVE-Isuzu
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Re: Elan BBK comparison, kits lack important specs

Postby steve matthews » Thu 16.03.2017, 15:29

I drive my M-100 on track several times a year. I find the Wilwood set up with the bias valves working properly totally exceptable. We run 3 different front pads
that are matched to the rears that are matched to the track conditions.
How it works is not my concern. The Engineer (know to this forum) sets up the car for 1. Safety 2. Performance.

The braking I experience in my Fed. M-100 with the Wilwood set up far exceeds my 350-Z Nismo set up that is better than the 91 Corvette set up.

Steve - My 2 cents :-D
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Re: Elan BBK comparison, kits lack important specs

Postby par » Thu 16.03.2017, 15:57

dapinky wrote:Anyway, I've had enough of banging my head against a brick wall, and have run out of patience......

...... have a week off to consider if this forum is the best place for you to bring your knowledge, or if you would be better off elsewhere.


Aw no :( ...

...this was building up to a great April Fools treat and re-naming the site to Isuzu Owner Central in recognition of the helpful input from our friendly Isuzu owner!!
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Re: Elan BBK comparison, kits lack important specs

Postby Rambo » Thu 16.03.2017, 20:47

Have a nice holiday Isuzuowner. Hope you come back refreshed :cheers:
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Re: Elan BBK comparison, kits lack important specs

Postby clemo » Thu 16.03.2017, 20:55

Rambo wrote:Have a nice holiday Isuzuowner. Hope you come back refreshed :cheers:



He is over there on the naughty step .
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Re: Elan BBK comparison, kits lack important specs

Postby HJ2 » Thu 16.03.2017, 20:57

Dapinky Fine, the Forum nanny :lol:
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Re: Elan BBK comparison, kits lack important specs

Postby lotusflasherman » Thu 16.03.2017, 21:02

I've noticed on this forum that some people remove the name Isuzu from the cam cover when tarting up the engine. Never understood why ... until just recently :lol:
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Re: Elan BBK comparison, kits lack important specs

Postby clemo » Thu 16.03.2017, 21:16

lotusflasherman wrote:I've noticed on this forum that some people remove the name Isuzu from the cam cover when tarting up the engine. Never understood why ... until just recently :lol:



i did just spit out some of my tea whilst laughing ....
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Re: Elan BBK comparison, kits lack important specs

Postby GeoffSmith » Thu 16.03.2017, 23:53

HJ2 wrote:Dapinky Fine, the Forum nanny :lol:

Shush you. You and your none-popularist voting nation. :twisted:
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Re: Elan BBK comparison, kits lack important specs

Postby dapinky » Fri 17.03.2017, 01:27

What! - - I'm being fined for doing the right thing????

Or is another attempt at humo(u)r by someone who should know better???

....or maybe an insult lost in translation to (Queens) English???

....I almost gave a f**k then - must calm down.......
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Re: Elan BBK comparison, kits lack important specs

Postby Simon_P » Fri 17.03.2017, 05:05

Dave, you have the patience of a saint.
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Re: Elan BBK comparison, kits lack important specs

Postby Simon_P » Fri 17.03.2017, 05:06

GeoffSmith wrote:
HJ2 wrote:Dapinky Fine, the Forum nanny :lol:

Shush you. You and your none-popularist voting nation. :twisted:
have you got a smiley thing for that?
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Re: Elan BBK comparison, kits lack important specs

Postby HJ2 » Fri 17.03.2017, 09:46

Relax Dave, It's a compliment actually!
Image

For the rest: good luck with your Brexit first.
I think that the country of this non-popularist voter will be busy selecting a new cabinet for the next 1.5 year :oops:
'Turkisch delight' anyone during these Belgian situations? I'll buy, so no double Dutch :lol:
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