djr81

Volks are usually really good with caliper clearance. TE37's & CE28's especially.

So do they chafe your bollocks when you head out (ie when they are large) or on the way back after you have scared yourself silly? (ie when they have shrunk to the size of sultanas) I drove a Mazda with a 4 point harness. As I said the lap belts just rode up over my guts - hence if I did have a bingle all that would have happened would be that my spine would have snapped in half. No biggy but I thought a 6 point would prevent that. Looks like another hole in the floor. Goodo. More than one way to lose some weight out of the car.

Let me re-state that. My replacement car (same model etc) will be getting a lightened flywheel attached. Have I driven a cars with different amounts of inertia in the engine. Yes. Do I think the whole world should be on drugs to cope with psychological conditions? Well to be honest sometimes I think it might help. They weren't assertions. They were statements made off the back of a few simple maths calcs. If I have made a blue with the calcs (& I don't think I have) then fair enough, but otherwise what you are saying & what the maths is saying are two very diferent things. As a rule I trust the data more than the seat of the pants experience. Certainly there have been times where I could have swarn a change was for the better only to have the data tell me different. So I guess we are going to have to agree to disagree.

Well you are right in the sense that you need more throttle to achieve more rpm. I don't think that is much of a surprise to anyone. With a lightened flywheel you certainly don't need more throttle to achieve the same rpm, which is the point, really. Yes there is. Just because it goes round (at right angles to the direction of travel) doesn't mean you can ignore its effects in a straight line, ie it still acts as mass. Well if you re-read what wrote you will see I was describing a situation where the car is accelerating in gear - the dumped clutch off the line is slightly different & I described that differently. What you are saying in item three is correct for a start and or a gear change. Well I don't think I did, but anyway. As I explained there are two distinct situations - ie the clutch dump/start from standstill & then the mashing the throttle when already in gear. With a lightened flywheel you need more rpm off the start to get the same launch (due to lower rotational kinetic energy). This can be seen as more throttle, but it is only sort of more. You still need basically the same throttle position for the same rpm - you just need more rpm. The second circumstance ie in gear acceleration you definately need less throttle with a lightened flywheel. This can also be characterised as the amount of throttle needed after the clutch has been dumped. I thought this was what the bloke was asking, but I may have misinterpreted it a bit. I think we basically agree with each other. Just placing different emphasis on different circumstances. Good to see people making sense without resorting to abuse.

I was looking at the fat arse version (I have child bearing hips, all the males in my family have them) of the GP90. They have the benefit of being made here in Oz. Which is always nice. They are a damn fine seat. I assumed the bottom two belts on a six point harness would go through the base of the seat & fix to the same anchorages as the lap belts. Or have I got this wrong, too?

I will try to explain why I disagree with you. Please don't crack the sh!ts if some of it sounds condescending, but I guess other people may read it also. Anyway we have basically two forms of energy of motion. Potential energy. Kinetic energy. Now potential energy is simply energy stored by gaining height. It is equal to mass times height times gravity. ie E=mgh. Believe it or not we can largely ignore it, but we wont. Kinetic energy is the energy stored in motion of a moving body. For a linear case (ie straight line) it is equal to half the mass times the velocity squared. For a rotational case it is equal to half the moment of rotational inertia times the angular velocity squared. As you can see the linear & angular equations are expressed in a very similar way - basically because they are very similar equations & are derived the same way. Now to our case of going up a hill. Assume we are in 4th gear going, say 100km/h. We go 10 metres up the hill (vertically) & accelerate to 110km/h going from 3000rpm to 3100rpm at the same time. The numbers aren't particularly important, but they make it easier to understand. So what happens to our three types of energy? Well if we go up 10 metres we gain 10 metres worth of potential energy. So 1500kg times 10 metres times 9.81 which is the gravitational constant. So that increases by whatever the sum works out to be. What happens to our linear kinetic energy? We have gone from 100 km/h to 110km/h. So we now have 0.5 times 1500 times (110 squared - 100 squared). Technically it should be expressed as metres per second, not km/h but I am not going to work it out, so it doesn't matter. We have a gain in linear kinetic energy because we are now going faster. What happens to out rotational kinetic energy? We have gone from (say) 3000rpm to 3100rpm. So we now have 0.5 times the rotational inertia of the whole drivetrain times (3100 squared - 3000 squared). Again angular velocity should be measured in radians per second but I am not going to do the sum. We have a gain in rotational kinetic energy. This energy is provided by the power of the motor, obviously. This will equal the potential energy gain + the linear kinetic energy gain + the rotational kinetic energy gain + whatever frictional losses we have (eg aero drag etc) So how does a lightened flywheel effect the three sums? Potential energy. Well the gain in potential energy is slightly less because the mass is less. Linear kinetic energy. Well the gain in linear kinetic energy is slightly less because the mass is less. Rotational kinetic energy. The gain here is less because the rotational inertia is slightly less. What does this mean? Simply that the car with the lightened flywheel needs less power to accelerate up a hill than the same car with a heavier flywheel. Less power = less throttle. Why it may feel different. Simply because as you said when you drop rpm on the motor (eg when you launch) there is less rotational kinetic energy to turn into linear kinetic energy. So the motor feels more "gutless" on launch. Which is where I think alot of people get a bit confused. Lastly. My new car is due to be unloaded Monday. When it gets to the workshop I am going to fit a lightened flywheel - and use less throttle getting up the hills around home!

Well they are the other two problems. Because my thing isn't as race orientated as yours & becasue I have to travel a bit to get to the circuits I wanted to retain the normal belts. I have seen this done with fixed back seats but you have to be a bit careful in the selection. Not sure how to get around the side mount/seat buckle problem, however. Submarining is why I don't want to use a 4 point harness. I find they ride up on my guts too easily (maybe my guts wobble too much over the bumps or something) hence I wanted to use a proper 6 point harness. Hell if you are going to be strapped in you may as well be STRAPPPED IN.

Mmm, the bolts in the Moonface kit for the front end didn't look anything special. Maybe I need to look again. The manual does have a cryptic note on page CH-228. See attachment. Oh and Andrew if you are after some rear spacers I have a pair at home (2nd hand) for sale.

Well fair point. I was working on the idea that I would fit a harness & seat to my new car. Unfortunately it looks like I will have to do some more work as I want to keep the lap/sash arrangement as well as a harness. The buckle being attached to the seat frame complicates things if you want to replace the frame with a fixed side mount system.

You may want to detail what the stamp duty rates etc are as they vary markedly from state to state.

I can't offer an opinion as to which tyres are best on the track, but I can give you a bit of an idea of what to look for: 1. Stiff sidewalls. You will get more body roll on a street tyre than on an R compound tyre. Stiff sidewalls help prevent this. 2. Fewer circumferential grooves in the tyre. Basically the tread blocks will chunk on the tyres if you are having a good go on the track. They tear away from the outside of any tread blocks. Therefor the fewer "outsides" you have the bettter off you will be. 3. Don't worry so much about compounds. But nonetheless the hardness of the treadface is an indicator. You tend to damage them more by chunking them than by wearing them. Not to put too fine a point on it road tyres are a bit of a disaster on the track. You will have much more fun if the budget can stretch to a proper R compound. or even some of the less sticky half house measures like the Falkens which feel ok but don't deliver the lap times. Lastly if you are going to the track get yourself a good pressure gauge (Not a ghey one from Supercheap or wherever) & a pyrometer. By measuring the tread temperature at three points across the face of the tyre you can determine the correct pressure by ensuring the difference between the outside & the middle measurement is the same as the difference between the inside & the middle. You won't get all three the same on a road car simply because it wont have enough -ve camber.

I am going from memory here, so I may be compeltely wrong. (As opposed to not going by memory & being completely wrong anyway, which happens to me a lot these days) Anyway if you look at the bottom left hand corner of page BF70 of the R32 Gt_R manual. It replaces the anchor bolt on the seat buckle which goes into the seat rail according to the drawing. You probably have a point about the location, but they never seem to have a problem with the lap sash done that way...

Hmm, I will take a proper photo of my car & post it (after easter). But as I said the eye bolts just go in place of the usual retaining bolts. On both the outside & the inside.

Good will check that out. I was wondering more so how people anchor the shoulder belts, not the lap belts.

I used bolts that replace the normal ones in the floor. The normal bolts secure the buckle & the bottom of the lap-sash belt tot he floor. You replace them with eye bolts & hook the harness into the eyes.

OK, well first things first - it is nice to be nice. So maybe it is not so polite to tell people to ^*#@ off all the time. Secondly, it is usually an indication of someone having a lack of proof that they trot out their qualifications. So if you want to get into pissing competition about how qualified an engineer should be before making a statement then I would submit my degree from UWA & 10+ years as a practising mechanical engineer. Now, with regard to stored energy. There are two situations we need to consider: 1. When the clutch in disengaged, ie there is no drive. In this circumstance a lighter flywheel will reduce the inertia of the motor & allow it to gain or lose revs more easilly. You notice it when you blip the throttle & also to a lesser degree when you dump the clutch. It usually makes the car more driveable except off the line. 2. When the car is being driven by the motor the motor & the flywheel are connected to a few things. Like the clutch, the gearbox, tailshaft, the diff, the halfshafts, the wheels etc etc. It is also propelling the body of the car along. So as I said the engine "sees" approx 1500kg of mass that is needs to propel. In all that a lightened flywheel makes next to no difference. Lastly, you said "A lighter flywheel can't store as much energy, hence, you need to supply more energy from the engine to go up hills." Now I had thought the idea was to ACCELERATE up the hills, not just coast up them. That being the case a lightened flywheel will allow the car to accelerate that little bit faster both because of its lower mass & its lower rotational inertia. The faster you go the more energy is stored in the flywheel, so unless you are trying to get up the hill and slowing down whilst doing so you cannot recover ANY of the energy stored by the flywheel. As an aside: Seeing as you are an engineering student you would remenber that the energy of a rigid body in rotation is described by the equation: T=05xIxwxw. (read as Tee eqauls half I omega squared) So lets assume our new flywheel is 80% of the rotational inertia of the heavier,older one. It means you need an extra 826 rpm (ie an increase of 7000 to 7826rpm) to store an equivalent amount of energy in the flywheel. Unfortunately you will also be storing much more energy in the crank, pistons, conrods, cams, pumps, drives etc etc. So the difference in stored energy is more likely to be down near a couple of hundred rpm.

Please don't take this the wrong way, but that statement is just plain wrong. The motor will be dragging 1500kg of car up the hill. So a kilo or two in flywheel weight imakes no difference at all.

I have a 3.5 inch system on my car. Can't hear the thing over the tyre noise. As for sizing it is important to remember that pressure drops of gas flow through pipes are strongly a function of the gas temperature. What does this mean? Well the MOST important bits to get right are the front bits. The least important bit is the exhaust tip...

In todays paper... A Victorian man has become the first driver to permanently lose his car under the state's anti-hoon laws. son of rajab, 43, pleaded guilty to four counts of driving while disqualified between January 23 and February 14 this year. Under laws introduced in July last year, drivers caught drag racing, doing burnouts or committing other "hoon" acts such as reckless speeding and driving while disqualified, can have their cars impounded for 48 hours for a first offence. They face a three-month impound order for a second offence and the permanent confiscation of their car for a third offence. Victorian Police Minister Bob Cameron today welcomed the magistrate's order. "These tough new laws hold hoons accountable for their actions and hit them where it hurts most - by taking away their vehicle," he said in a statement. The best bit: In a hearing at the Castlemaine Magistrates Court yesterday, Terrence son of rajab, from the central Victorian town of Drummond, was ordered to forfeit his blue 1980 Toyota Corona fastback You're kidding me, aren't you.

The other fun thing some aligners do is confuse per side with total. So I asked for 2mm rear & got 2mm per side. So I just write down 1mm toe in per side rear etc. Do the same for the front too as most shops don't understand toe out or why anyone would want it. To be honest I found that 2mm per side rear toe just made the thing bump steer at the back. But maybe that's just me.

All gone quiet on the Davidson front, however. He was sort of the next big thing last year too.

Not knowing what the hell I am talking about never stopped me from expressing an opinion. Try this, pretty straight forward. http://www.stoptech.com/tech_info/faq_rotorsystems.shtml

Actually, for much of his life James Hunt was a reefer smoking pisshead. He cleaned up his act in the end - just before he died from a heart attack. I think there is a lesson in that for all of us. Favourite James Hunt quotation. "We can't quite see the pits from our commentary position." Explanation: The commentary postition was in the BBC studio in London. The race was in Mexico.

The only reason I changed my airbox to pod filters was to allow the use of larger Air Flow Meters. The Z32 units don't even look like fitting. For the kind of hp you are talking about the airbox is fine. Just use a good filter eg a K & N.

The thing that used to sh!t me about Murray was the number of mistakes he used to make/still makes. WOW! Oh, sorry, got carried away. Bring back James Hunt I say. "Ricardo Patrese is complete rubbish etc etc"