chayden

Explanation by Jeff of Zedworld about ABS - how & why it works etc : ABS and Big Brake Kits -------------------------------------------------------------------------------- The tech answer to the question of how your zed abs system will react to larger calipers / discs is explained a little lower down , it is a bit of a read but well worth it if you want know the definitive answer to the question. The real world solution From the tech answer below it is clear that the abs system can be effected and not in a good way, however and this is crucial to remember when fitting a brake upgrade kit "just because it works on car xxx, it must work on your zed " approach, is way wrong. What you need to ensure is the brake upgrade kits is either designed with the characteristics of the original braking system taken into account to minimise the differences, or the donor car brake system has the same or very similar characteristics and in that way the ABS system WILL work as originally designed. To this end upgrades such as the Nissan Skyline GTR 33/34 Brembo calipers and discs will work with the 300zx set up as the Pressure-Torque And Pressure-Volume Relationships ( explained below ) is compatible, however the Nissan 350z is not, after market kits designed as vehicle multifit are also rarely compatible. One final word of warning, disconnecting or disabling ABS safety systems WILL effect your insurance and could in the event of a fatal accident leave you carrying the can! Jeff TT Definitions ABS – Anti-lock Braking System – An electromechanical control system designed to monitor and influence wheel dynamics, and ultimately vehicle dynamics during braking manoeuvres. In order of priority, these systems are intended to enhance vehicle 1) stability, or the prevention of over steer 2) steer ability, or the prevention of under steer and 3) stopping distance. Typical systems consist of 3-4 wheel speed sensors, an ECU containing the algorithm processing the wheel speed information, a series of solenoid-driven valves, and a pump-motor subsystem which can be actuated to interrupt and release brake fluid pressure from the wheel-end brake components (calipers and such). ABS Control In Super-Slow-Motion In order to best explain how the ABS "depends" on the base braking system, let's have a look at a typical ABS event at the micro level – from the processing algorithm's perspective. Say you are driving down the motorway at 75 MPH ( tut , tut ) when all of a sudden a lorry in front of you spills its load of water across all three lanes of traffic. Now, this alone would not be so bad, except the water is still sealed in large drums anyone of which would certainly make a mess of your zed, time to take evasive action. Being the trained high-speed individual that you are, you immediately lift off the accelerator , dip the clutch (if your zed is a manual), and at the same time hit the brake pedal...but in the heat of the moment you hit it a little too hard!! Previously the ABS ecu was hanging back watching the world go by, seeing a constant stream of 75 MPH signals from its four wheel speed sensors. Let’s call this "observation mode." Upon your application of the brake, however, the ABS snaps to attention, its antenna up, ready for action. You have just hit the brake pedal after all, and who know what’s coming next. After 50 milliseconds (it’s actually much faster than that – 7 to 10 milliseconds is typical – but it easier to work out) the ABS takes another snapshot of the wheel speed information in an attempt to figure out what's going on. This time the wheel speed sensors are all reporting a speed of 74 MPH. Doing a quick calculation, the ABS determines that in order to have slowed 1 MPH in a 50ms period the wheels must be decelerating at a rate of 0.91g’s. Because you are driving a sports car, the engineer who calibrated the system ‘taught’ the ABS that your car is capable of decelerating at this rate, so the ABS continues to hang back and watch the event from the spectator’s booth. No problem so far. The next 50ms, however, are a little more interesting. This time around, the wheels are reporting 72.5 MPH. Now, it may not seem like a big jump, but to slow 1.5 MPH in a 50ms window equates to a deceleration of 1.36g’s. Not alarming, but the ABS ‘knows’ that based on this deceleration level, the wheels are probably beginning to slip a little more than they should – after all, your car is probably not decelerating at quite 1.36g’s..and any error between the two indicates slip. ABS is now in "ready mode." It’s probably too soon to jump in, as the wheels might spin back up on their own in the next 50ms loop, but things are definitely looking bad! As the first drum of water bounce left and right, missing your car by inches, you stay on the brake pedal but push even harder. This time around, the left front wheel speed sensor is registering 68 MPH – a 4.5 MPH drop in the last 50ms, or a deceleration level of 4.1g’s. Doing the math faster than you can (after all, you are busy dodging barrels of spring water), the ABS quickly comes to the conclusion that, unlike the left front wheel at this moment, the car cannot possibly be decelerating at 4.1g’s. Best case is that the car was decelerating at 1.0g (or thereabouts) over the last 50ms, so the ‘real’ vehicle speed is still somewhere around 71.5 MPH, even though the left front wheel speed is reading 68 MPH – a 3.5 MPH error. So, based on a wheel deceleration of 4.1g’s, a slip level of 5% (3.5 MPH¸ 71.5 MPH), and a couple other factors not listed here, the ABS jumps in and enters "isolation mode." (Note that the wheels are nowhere even near "wheel lock" – the 100% slip point.) The first thing the ABS does is shut off the hydraulic line from the master cylinder to the left front caliper, isolating the driver from applying more pressure – after all, it was the driver that got us into this mess in the first place. Next, the ABS starts work in "decrease mode," releasing the excess pressure from the left front caliper in order to allow the left front wheel to re-accelerate back up to the vehicle’s actual speed – 71.5 MPH in this case. Since the ABS knows how quickly the wheel is decelerating (4.1g), how fast the car is actually going (71.5 MPH), and the pressure-torque characteristics of the left front caliper/pad/disc assembly (we’ll come back to this one in just a second), it can precisely calculate how long to open its release valve to vent that extra pressure, leaving just enough pressure in the caliper to maintain 1.0g of deceleration (or thereabouts). Let’s say that calculated time turned out to be 10 milliseconds. Bang! Valve opens, pressure is released, and 10ms later it closes, leaving just the right amount of pressure in the caliper so that the wheel spins back up to exactly 71.5 MPH, but continues to decelerate at 1.0g. Everything is going as planned. Time to close the loop and enter "increase mode." Once the ABS sees that the left front wheel has returned to near the ‘real’ vehicle speed, it slowly reapplies pressure from the master cylinder to make sure that maximum sustainable brake force is being utilised. To this end, the ABS calculates precisely how long to pulse open the isolation valve, slowly building pressure at the left front caliper until once again the left front wheel begins to slip. It performs this calculation based on – you guessed it – how quickly the wheel is re-accelerating, how fast the car is actually going, and the pressure-torque characteristics of the caliper/pad/disc assembly. In our hypothetical little world, the ABS calculated that four pulses of 5ms each were necessary to build the wheel pressure back up to the point that the wheel began to slip again, returning to "isolation mode." The cycle is repeated on all four wheels simultaneously until either the driver gets out of the brake pedal, or until the car has come to a stop. Hopefully, this did not include punting a drum of water or two along the way as the ABS kept all four wheels slips in the 5%-10% range, allowing you to turn and swerve to your heart’s content as the drums bounced out of your path. Happy car, happy driver. The Potential Impacts Of "Big Brakes" Let’s now take the exact same scenario, but add a twist: you are returning home from having that long-sought-after big brake kit installed. You know, the one that required new 18" wheels to clear the 8-piston calipers and 16" brake discs. Driving around the car park you couldn’t believe the improvement in pedal feel and initial bite they displayed. These things must really throw a boat anchor behind the car at high speeds, right? Well, let's see. Resisting the temptation to run in the fast lane at triple-digit speeds, you once again find yourself behind the lorry at 75 MPH. drums fly and you again stamp on the brakes, but with the increased confidence of your new hardware to slow you down in time. Plus, you now know how the ABS works, so you hit the pedal hard confident that you will have both deceleration and steer ability. It couldn’t get any better. Like scenario 1, after the initial 50, 100, and 150 milliseconds the ABS takes snapshots of the wheel speed information and registers 0.91g’s, 1.36g’s, and 4.1g’s on the left front wheel. Again the ABS quickly comes to the conclusion that, unlike the left front wheel at this moment, the car cannot possibly be decelerating at 4.1g’s. Best case is that the car was decelerating at 1.0g (or thereabouts) over the last 50ms, so the ‘real’ vehicle speed is still somewhere around 71.5 MPH, even though the left front wheel speed is reading 68 MPH – a 3.5 MPH error. So far, so good – just like last time. Here’s where things start to get interesting, though. ABS enters "isolation mode" and shuts off the hydraulic line from the master cylinder to the left front caliper, isolating the driver from applying more pressure. Next, the ABS starts work in "decrease mode," and once again calculates that 10ms are required to the excess pressure from the left front caliper in order to allow the left front wheel to re-accelerate back up to the vehicle’s actual speed – 71.5 MPH in this case. Unfortunately, this calculation was based on the standard vehicle’s pressure-torque characteristics of the left front caliper/pad/disc assembly. Let’s talk about this briefly while the drums roll in closer. Pressure-Torque And Pressure-Volume Relationships When a braking system is designed and installed, the components are chosen to provide a certain deceleration level for a certain amount of force applied by the driver to the brake pedal. While the overall relationship is critical, there are many ways to achieve the same end…but fundamentally the parts are chosen to work together as a system. One of the most important relationships for the ABS engineer is the pressure-torque (P-T) relationship of the caliper/pad/disc assembly. In so many words, for a given brake fluid pressure, X, the caliper/pad/disc assembly will build up a certain amount of torque, Y. For the sake of argument, let's assume that adding 100 PSI of brake pressure to the stock caliper in our example vehicle generates 100 ft-lb. of torque. Another important relationship is the pressure-volume (P-V) characteristic of the system. This relationship defines the swelling or expansion of the brake system for a given increase in pressure. Let’s also say that our stock vehicle brake system ‘swells’ 1cc for every 100 PSI. Unfortunately, there are several big-brake systems available today which pay no regard to the original P-T or P-V relationships of the original vehicle…and in fact many make it a point to affect drastic changes in these relationships in order to give the consumer that feeling of ‘increased bite.’ While the upside is certainly a firmer pedal and higher partial-braking deceleration for the same pedal force, the trade-off can be ABS confusion. Back To The Water Drums So, back to our example – the ABS has just calculated that a 10ms pressure reduction pulse was necessary to vent that extra pressure, leaving just enough pressure in the caliper to maintain 1.0g of deceleration (or thereabouts)…but the new system with its decreased P-V characteristics (increased stiffness!) releases twice as much pressure as the stock system in the same 10ms window (the equivalent of a 20ms pulse with the stock system)! Of course, the increased P-T characteristics (bigger discs! bigger pistons!) don’t help either, as now three to four times as much torque has been removed from the wheel as with the stock system, leaving only enough torque to decelerate the wheel at, say, 0.3g. In ABS land this is known as a ‘decel hole’ and feels just like you momentarily took your foot off the brake pedal. Now, given that huge pressure decrease, the ABS quickly enters "increase mode," trying to correct and build the pressure back up near the vehicle’s maximum sustainable brake force. This takes time and time equals lost stopping distance. The ABS calculates precisely how long to pulse open the isolation valve and determines that four pulses of 5ms each are necessary, just like before. Because of the new P-T and P-V characteristics however, after only two pulses the wheel is again being forced into slip, leaving the ABS scratching its head and wondering what’s going on. Not expecting wheel slip so soon, the ABS quickly releases pressure in an attempt to recover, but the damage has already been done. The cycle is repeated on all four wheels simultaneously until either the driver gets out of the brake pedal, or until the car has come to a stop…but this time the ABS is always one step behind. In some cases the ABS is robust to modest changes in the base brake system, but in extreme cases there can be a significant negative impact to the vehicle’s steer ability (increased front wheel slip due to poor control) and a measurable increase in stopping distance (multiple ‘make up’ decrease pulses). So, your chances of stopping in time or swerving to avoid one of the bouncing drums have been decreased. In this game, inches count and you sure need every one. So Big Brakes Are A Bad Idea? Well yes and no in fact, if designed and chosen properly, these upgrades can make the most of these control technologies while providing all of the cooling and thermal robustness advantages these kits have to offer. In many cases fabricated adapter brackets to mount them to a variety of different cars, to market the kit as a ‘one-size-fits-all’ without first determining if the system will be compatible with the remaining foundation braking system. -------------------------------------------------------------------------------- Last edited by JeffTT; 30th November 2008 at 19:04. Reason: spelling Controlled tests conducted and results posted by NickZ32 http://www.300zx.co.uk/forums/showthread.php?t=119968 With that read above, my own discussion thread on the brake upgrades with a very good contribution from Legrath (knowledgable man!) :bow: http://www.300zx.co.uk/forums/showthread.php?t=120045 HTH

Guys - I have a worn OEM steering wheel on my Zed. While it looks tatty and I have a replacement wheel with boss adaptor, I am loath to replace it anything other than the original wheel. Based on the pricing of an OEM wheel (which is horrendous - you'd buy a donor car cheaper) this won't happen. I feel that somethings just look better in stock, and the steering wheel to me is one obvious example (personal taste of course-so no offence intended). Now does anybody know, if there is any company/individual who can refurnish the outer ring/grip part of the steering wheel? Does such a service exist or has anybody got it done. If you have, any chance of some pics. Thanks in advance.

Belated birthday wishes Paul. Hope you enjoyed it.

If the BOE cut interest rates by up to .5% in the next week or so as is expected, I personally see the value of the GBP£ weaken in the short term. This is compounded by the latest unemployment statistics and the housing situation. The US economy is in a dire situation right now, and the question is can it get any worse? Probably not, as the risk of deflation has not developed any momentum. Over time the UK currency will strenghten again and quicker than if it was part of the Euro. Control of your currency is key to this. However getting back to the 2 : 1 ratio - I don't think you will see that this year. My personal opinion only.

And without doubt yours is one of the nicest examples :bow:

Nice Speedo's Tony. I'm always on the lookout for the 300 plus kph speedo (whether that be Abflug, Z, Nismo, Mines etc) for mine at reasonable money. Mine is originally a jap tt car that had the conversion to mph done for the UK roads before I got. So I want to convert it back to kph.

First of all are you sure that it is 425mm Long and 200mm Wide (15" long x 8" wide) and not the other way around? If it correct then you will experience an element of turbo lag compared to other SMIC's but while this may be the case, it will be an improvement on the stock intercoolers. For a very good guide and read on the SMIC's comparison click on this link. It gives a much better explanation of the compression, charge face, turbo lag and why it happens etc.. http://www.zdriver.com/forums/showthread.php?t=19694 HTH

Size is important alright but Biggest doesn't mean its best. Long intercoolers cause pressure drops which inturn creates an element of turbo lag. It will be interesting to learn of the dimensions of the ones you have sourced.

No need for apologies. Hope your mum gets better soon.

S4 would be my choice

No worries Dave. Hope you'll be up and around in no time. Happy New Year.

I had a problem with my wipers but only on the intermittent and also off. Intermittment didn't work properly. If I switched them off, they could stop anywhere in the wiping cycle. Your's is probably displaying another symtom of the same issue with the switch. I just changed the wiper motor and everything worked perfectly. Cheap part to pick up second hand and easy to install. Its located under the right hand side (as you would look at the engine bay by standing in front of the car) scuttle panel. HTH

Happy Birthday

Very good job there mate. well done

I misread the wheel size of the 18's. Because mine are 30/18's I had assumed yours were too when in fact they were 40/18's. The 30/18's would have kept the "complete" wheel size the same. Amazing how the eyes read what the mind perceives.

I ****ing hate rats and mice :mad: Back of the brush to the top of the head and he wouldn't have been worrying about the outside temperature. I invested in nature instead of traps. Got a cat called Salem. He will kill anything that moves and when he decides, he ain't afraid of anything. One morning I looked out the window and saw him chasing Rocky (our Rottweiler) across the back lawn. No word of a lie!

Wow - it's amazing that the wheel choice made such a difference. I presume its down more to the tyre width than wheel diameter?

I guess it would have been just me and you. I see from posts that Trish was having problems with her car. Anyhow we can meet up in the next week or so..

Thanks to all for the replies so far. From a weight perspective I suppose I'm lucky in that mine being a SWB slicktop with no cruise control etc, it weights about 100kgs lighter than most LWB Zed's. Jimmys post linked by Nick, gives me a good guide as to what I can remove or would like to remove. Regarding the weight distribution, if anything with the additional soundproofing, amp, carpc and sub, the weight in the rear will increase slightly versus the front. Is this a good thing? Can I ask also the following - what are the benefits to retaining the AIV, EGR etc? On the Hicas front, I refreshed mine with new parts and I'm more than happy with retaining it.

Thanks Nick. I didn't explain what was going on in my head enough. From a speed perspective, I was hoping for guidance with figuring out if I increased my BHP through engine upgrades, would this have the same effect as reducing the overall weight by xx kgs? This equation probably doesn't even exist. The handling issue is something that I hadn't even thought about and what you say makes absolute sense. When I get the respray and have the engine out, I'll remove some of the unnecessary items to try to compensate for the increased soundproofing. Thanks, Colm

Can anybody explained the benefits of weight loss versus BHP increases or vice versa? The context being, that I want to make my slicktop faster and more powerful but definitely without sacrificing the creature comforts. In fact I plan to add some weight with the ICE system and soundproofing that I am lining up. Is there a rough guide of say - 50kg (for all of you still on the old imperial system :tongue: ) of weight loss would be equal to an approximate x amount of BHP increase. I do realise an equation like that wouldn't be that simple as there would be other factors etc.. but just as a guide. Cheers

How many (if any) are heading to Longford tomorrow and what time?

Don't worry - come Summer the Pound will have regained some of its strenght. The only reason it has weaken so much is due to the recession and the fact that the BOE have slashed your interest rates. The ECB has a much higher base interest rate but this is expected to be cut in Q1. If it is cut significantly (a sign the eurozones recession is deepening) then you will see the value of the Pound increase. Your weaken currency and low interest rates is very "valuable" to you now. Your mortgage repayments and bank borrowings have become cheaper. Your exports have become cheaper and imports competing with your own suppliers are becoming more expensive. Use the savings on your mortgage repayments to fund your trips to Europe in the Zed :) Of course it will also strenghten when your economy comes out of recession and the BOE raises interest rate, thereby making it an ideal, stable currency into which foreign investors can hold their cash. The Vat reduction and weakening value of the pound has really benefitted the shop owners, businesses etc in the North of Ireland. The carparks are full of southern reg cars. Asda in Enniskillen took in £60k in the first hour of trading one morning, majority of which was from Southern shoppers. Believe me, the currency is and will increase trade. Give you an example, I'm interested in buying a second hand steel frame building of roughly 6000sqft. Six months ago one would have cost me in Euro (from the UK - £17000 plus delivery) €24,500 which made it too expensive. Today in euro it will cost me €18,500 which means I will buy it from the UK rather than purchasing it here or in Europe. As a result when trade increases, your unemployment will fall and foreign receipts will flow through your economy, benefitting everybody even if only through the maintenance of public services.

The short article I read, said that initially all models will be petrol but it said that Infiniti are considering launching diesels engines for the European market. That to me, means they really plan to get serious in Europe over the coming years.

Infiniti the luxury car brand developed between an alliance between Nissan and Renault is to be launched in Ireland with one main dealer around the Dublin area. They plan for developing brand awareness over the coming years in Europe. I expect that if they are launching in Ireland they will also be doing so in the UK in 2009 (if its not already there). This is the famous marque that is in the US for the past 20 years.