mikel

Cheers Pn Mad - mine is 200mm diameter inside the mesh - I'll try to extract it without completely destroying it to check the flat diameter. Agree going back to standard air box is an option but will cost more and require fettling. It is a worry how poorly the HKS performs on tests however The 3A seems to work well, but I haven't seen one that has a 100mm throat as a direct swap Mike

cheers, I found this replacement filter on eBay, but its circular, not in a bowl shape - any idea if it's the right one? The description is : HKS Super Power Flow Air Intake Replacement Filter Element Dry 3 Layers 200mm G cheers Mike

cheers Josh, I'll have a look Mike

Hi guys, just discovered the foam in my HKS pod filter has died. I've got an R33 GTST with the usual mods. Have done a search, which pointed to avoiding the HKS as it doesn't filter that well, and to avoid oiled as it can affect the AFM (and may be illegal?). The search results were all very old, so I'm not sure what current products are recommended. I realise the standard airbox is fine (but my car came with the Pod), and that a pod should be airboxed (which mine is not), but right now I'm just looking for the best option to get back on the road with minimal cost and modifications. options: 1) replace the foam in the HKS Pod (maybe they're better now? - I read triple layered somewhere) 2) replace with a dry filter of similar dimensions (not a lot of room there - I could go another 50mm longer than the HKS mushroom) Recommendations on where to get the new kit would be great also (I live in Brisbane, but happy to buy online) I've attached a photo of the current HKS pod in the engine bay. cheers Mike

cheers Carbon34 I'll keep the forum updated on progress. great idea for the charger output to charge the iPhone. Thanks for all your input/links etc. Carbon would be sooo good, but beyond my manufacturing abilities. thanks Mike

cheers Carbon 34, valid points - I wouldn't think of going 24dB passive - way too power hungry and way too hard. If I went 24dB it would have to be active - otherwise I'll go 6dB and use iron core inductors as you suggest. Happy to consider a ported box for the woofers - especially since I'm not planning to run a sub, just stereo 2 way. lol I haven't pulled out the loudspeaker cookbook in years, but it is a good read. If you can suggest any sites on ported box design that may be more appropriate with modern drivers that's simple to build, and don't make the boxes too big that would be great. I'm not so hung up on SQ that digital amps aren't suitable, basically they're essential whichever way I go (active or passive) for battery life. I just love the sound of an active setup, but the simplicity of a 6dB passive has huge merit for a portable system. If there's design options for small ported boxes (ie not much larger than a sealed box for the same driver) it would be the go for the extra dB as you suggest. I'm happy to go for a more esoteric cabinet (ie isobaric etc), but as you say - I don't want to need a crane to carry this thing around. So Active - twice the amps, more electronics, higher cost (?), better sound Passive - fewer amps, simple Sealed box for woofers - simpler box, smaller boxes (? based on 20 year old thinking), not as much bass, more weatherproof Ported box for woofers - harder to design, larger boxes (? based on 20 year old thinking), more bass, easier ingress for sand etc Leaning towards passive and ported. Thoughts? Mike all the reasons you mention (ie more dB

cheers Carbon34, great tips...though using an iron core in a coil ? - unthinkable where I come from (home diy hifi) - any core increases inductance but then includes significant distortion as the core saturates. Any coils will be air cored or I'll go active. Your idea of dumping the head unit means less current draw to allow a 2 way 24dB/octave active crossover into a 4 channel (or 2 stereo channels or whatever) D class amp/s. I like your thinking on running the amps inside a port - very clever, but I'll probably just run a sealed woofer and accept less bass (shock horror). I'll seek out a low Fs high Qts bass driver that will work ok in a sealed box and not have to worry about the driver unloading below the box resonant freq, larger box size required for ported alignments, and the design specs changing as the driver ages. Your ideas on isobaric bass boxes are again worth considering - but I have no idea what a "reverse isobaric in a double reflex box" is. Reverse Isobaric implies to me the drivers are in phase (I'm probably wrong) - which means you need to double the size of the box - and if they were facing the same direction you'd get major suckout (ie no bass)....If reverse isobaric is the drivers mounted back to back (or front to front) then that's just normal isobaric to me, and if the double reflex ports are the ports not venting the common space between the drivers I understand. A normal rear firing Isobaric will just annoy other people in the campsite - assume anyone listining to music is in front of the stereo. I want to avoid vented enclosures, as there's too many problems (as mentioned above, plus the extras you've mentioned - sand/water etc) - being an active enthusiest, if I thought the bass drivers could handle it I'd add a linkwitz transform to get more bass rather than ports. Assume I only want to go 2 way (tweeter + 8" woofer and no sub/mid etc), 2 way active, Can you recommend any brands of: - active crossovers, - digital amps - drivers (tweeter or woofers) greatly appreciate your input so far - I've chnaged direction based on it already, plus got me thinking cheers Mike You're right on marine ply being heavy, and I'll probably go with MDF and just seal it with epoxy etc - sealed boxes are easy in that regard. Again good call on the tweeters

cheers guys, great call Troy on not needing a head unit - hadn't thought of that, just use iPhone straight into digital amps using the analog out of the iPhone. Food for thought on simple 1st order passive crossovers - a decent poly cap in series with the tweeter and a coil in series with the woofer (or resistor in series and cap in parallel to avoid the coil). I don't plan on running a sub - how can you get more bass from a 6" unless ported? - I'd prefer to stay with an 8" in a custom box - ports are a bigger slot to get sand in, and will unload at high volume and pole the driver. Carbon/Kevlar boxes would be great but beyond my manufacturing expertise - pity you're not in Brisbane. I'll likely go marine grade formply, heavy but waterproof. cheers, Mike

Hi guys, I have a project to build a portable stereo, and I want to use as many off the shelf car stereo parts as possible. The unit will comprise car speakers mounted in removable boxes to get some stereo separation, and a head unit and a small sealed gel cell car battery in the main box. My requirements are decent sound (not hifi), decent volume, reasonable portability, reasonable battery life - say 4 hours at decent volume before a recharge. The plan is to fit an off the shelf battery charger (suitable for a sealed gel cell) inside, and run a separate linear power supply when running on 240 volts to be able to simultaneously charge the battery whilst listening to music. I'll use relays to disconnect the battery power so it charges properly while running on 240V. Each speaker will use a car tweeter and woofer (ie 2 way). The woofer will probably be an 8" to get reasonable bass, in a sealed box of appropriate size to get a total Q of about 1 to get a little bass boost. Happy to go smaller box and higher Q. The head unit needs to support CD (incl MP3 on disc) plus input for iPhone and USB input. I haven't decided whether to use an active or a passive crossover between the woofer and tweeter - it will depend on what's available off the shelf. My home stereo is a 3 way active crossover (ie tri-amped), and I'd prefer to go active crossover if achievable. Most of my experience in stereo is home stereo. My one foray into car stereo was years ago when I built 2 active crossovers - one for the front tweeter/woofers and one for the rear woofer/sub crossover. My questions are: - are head units available with say 4 x 50W outputs where you can get access to the output of the pre-amp and input to the individual output amps (ie in a 2 way active crossover setup I plug the output of the pre-amp in the head unit through the active crossover and feed back into the individual (ie 4) power amp stages in the head unit? - are 2 way active crossover units available at reasonable cost? I can build some for around $100 but there'll be more design work to get op-amps that will work with the low voltages - say +/- 5V after some voltage droop in the battery - I'd prefer to buy off the shelf. - if I go passive, are decent passive crossovers available off the shelf for say 2nd order (12dB per octave) slopes at reasonable cost? cheers Mike

based on a search it appears my original question has been answered - R34GTT 6 spoke rims will fit an R33 GTST, but it would be useful for many to know what standard rims fit which cars. I found bits of info across numerous threads...but more often questions eg whether R32 GTR wheels fit R33 GTST etc etc without answers It would be useful to build a reference of what standard wheels can be interchanged with different models assuming stock brakes and tyres. (edit : formatting doesn't work - I'm trying to show a table of what wheels will fit other models) standard wheels (fit) R32 GTST (???) R32 GTR (????) R33 GTST (???) R33 GTR (???) R34 GTT (R33GTST, R32GTST (with 3mm spacers)) R34 GTR (???) Stagea (??) GTS models (??) If people provide the info I'm happy to collate into a table. cheers Mike

The car now handles beautifully: -doesn't skip over bumps -much better traction especially out of corners, especially if it's bumpy -more ground clearance - easily goes over parking blocks -far more comfortable ride -I no longer hit my head on the roof going over the bumps at the end of the main straight at Qld Raceway -I dropped 1 second on my lap times at Qld Raceway

agree with the above posts - when I replaced my Cusco coilovers with bilsteins I had to get the standard tops. SK provided all 4 for $250

and the pressure plate bolts to the clutch cover? all the clutches in the magazines look like a pressure plate and cover in one, unless the cover goes over that again?

a few noob questions but I'm a bit confused after all of Noel's drama... I've only ever replaced 1 clutch and the things I bought were the clutch plate, pressure plate and throwout bearing. The clutch cover was never mentioned. Does that mean that they used the existing clutch cover? and is that because clutch covers typically don't wear out? (other than catastrophically in Noel's case ) All those steel fingers on the inner part of the clutches you see in the magazines, is that the pressure plate? cheers

there's the possibility that the wiring from the cigarette lighter to earth has melted before the fuse blew. That means you'll still have 12 V to either side of the fuse, assuming the negative probe of the multimeter/test lamp goes to a proper earth.

yes - sub boxes need to be strong and the correct size for the speaker/driver. Decent drivers usually come with a spec sheet that will tell you the right size for either a sealed or a ported enclosure. If you're putting 2 drivers in the same box just double the volume, assuming you wire the drivers the same way (recommended). The least risk is to mount the 2 drivers on the same side of the box as close to each other as possible (but try to include a brace to strengthen the box in between the drivers). Getting fancy and mounting the drivers at each end of a box can lead to un-predictable results - could sound great, could sound cr@p. It's the same for mounting the drivers on either side of the boot facing each other, they could add to each other (constructive interference) or cancel each other (destructive interference or "suck out"). You mention it doesn't sound as good as cheaper systems you've heard - they may have been working against each other. Getting the box size right for a sealed enclosure is not as critical as a ported box

6" will struggle at 80Hz and more likely to pole at high volumes (ie hit the limit of their excursion). Better to keep the crossover Hz the same on both at 100Hz - the sub will cope with 100Hz better than the 6" will cope with 80Hz. I agree completely with Doof regarding the importance of the box for subs - especially if ported (ie they have a tube or port allowing air in/out of the box). A badly tuned ported box can sound very ordinary. Ideally you should set the gain on individual amps so that a reference signal (such as a test CD with a pink noise track) gives the same volume from each amp (ie have only the sub amp turned on, run the test track, and measure the volume on a sound level meter, then do each amp in turn and adjust the gain to the same reading on the sound meter). This is difficult to do without the sound level meter, as each amp is producing a different frequency range and the ear will have difficulty comparing. I use the Jaycar unit ~ $100. Given the fact that the sub is in the boot, and the other speakers are in the car, and the car itself provides "gain" at different frequencies, it's very difficult to predict what gain settings you should use to get the smoothest response across the frequency range.... ....or just crank up the sub until it's too boomy then back it off a bit

I agree with the posts above - a better head unit will provide better sound, as will better speakers, amps, crossovers etc You'll hear better sound if you play normal CDs also rather than a CD filled with MP3s. The specs you've provided on the different units don't provide any indication on quality (and they rarely do). Typical quality specs include Total Harmonic Distortion (%), Signal to Noise Ratio (dB), Total Intermodulation Distortion (%) etc, but even these depend very greatly on the test methods the manufacturers use. Ignore the 20kHZ vs 22kHz upper limit in the frequency response - if you've been listening to loud music for a few years you'll be unlikely to hear above about 15kHz anyway. Audio (ie what you can hear) is typically regarded as 20 Hz to 20kHz. Your dog may get benefit from ultrasonic information at 22kHz but you won't. Interesting that the crossovers are specced the same for each unit at 12 db and 18dB per octave. I assume this means that the woofer low pass rolls off at 12 db/octave (2nd order) and the tweeter hi pass at 18dB (3rd order) (ie a steeper rolloff). Tweeters are more sensitive to being provided out of band information, so they need the steepest possible crossovers to avoid damage. Personally I'd prefer matched crossovers (ie low pass and high pass are both 18dB/octave) to minimise phase issues and ensure that each woofer/tweeter pair adds together properly. This mis-match may be common in car audio to save on components and size in the passive crossovers. Only look at rms power not peak. As others have said go and listen.

having fuses blow does not relate to the cables being too small, although the fuse size should relate to the cable gauge so that the fuse blows before you melt a cable (that's what fuses are for - it's very frustrating when expensive cable sacrifices itself to save a $1 fuse:( ) If the tweeters aren't distorting when listening normally, then they're not broken. If they're clicking when the music is loud then they or the amp may be clipping, and if they click for long they'll soon be dead. Tweeters tend to zot themselves quite quickly when mistreated. If the amps are clipping then you'll be sending more power to the tweeters via compression than they'll be able to handle - turn the volume down.

you may also have performance pads which tend to squeal more. if you don't use your brakes hard, try putting standard pads back in, but expect pad fade when they get really hot

I run my tyres at about 35psi cold on the street and a bit softer on the track, about 35psi hot. Some people have told me to run higher pressures on the track to reduce sidewall flex on a street tyre (and reduce the risk of peeling a tyre off the bead), but I found I lost a lot of traction running them around 39psi hot. Read what the sidewall of the tyre says and stick close to that.

I agree with the above post - the fuses are there to protect the wiring, and also amps under short circuit conditions. Provided you have no fault like a short circuit causing the fuse to blow (which is unlikely since your fuse blows when you wind the wick up), then check that the cabling can handle additional current and put bigger fuses in, or separate your power feeds and individually fuse them.

Thanks guys. Is there no easy way to take them off without cutting/cold chisel etc? A cold chisel could potentially damage the hub assembly wouldn't it?

Took my front rotors off to get them machined, only discovered they're at their limit so put them back on while waiting for new rotors. The front right now appears to lock up (ie trigger the abs) quite easily, although the car still pulls up straight, so the other side may also be activated by the abs at the same time. Are there speed sensors in the brake assembly I could have knocked? I didn't disconnect any brake lines in taking off the caliper/rotor so there shouldn't be any air in the system. I'll take the wheels off and check for fluid leaks and that all the bolts are still tight this afternoon. Any ideas ? - could it be slight changes causing more bite as a result of removal and re-install? Have I f&*(*d something to do with the abs? my abs light comes on on start up and then goes out as normal. Mike

As mentioned above, where is the best place to cut the stoneshields? I've attached a photo of the stone shield with a line drawn where I think they should be cut - just want to confirm before I pull out the angle grinder. cheers