In practice higher "colour temperature" LED bulbs will seem brighter for any given input power due to the way they are made. Usual construction appears to be a high efficiency blue LED emitter with phosphors to down convert some of the blue emission to other colours. Nominal red and yellow phosphors seem to be common in headlamp bulbs.
Higher colour temperature specification bulbs let more direct blue radiation through and divert less to the phosphors. There are significant energy losses in wavelength down conversion via phosphors so letting more blue through clearly means more light for the same input power. The blue wavelength is also quite close to the peak sensitivity of the rod cells in the eye. Rod cells are pure intensity detectors and play no part in colour vision. They are very sensitive indeed, almost single photon sensitive in ideal conditions, and do pretty much all the work when the eye is dark adapted. So not only do you get more light power out of higher colour temperature bulbs that power is where the dark adapted eye is most sensitive so things look even brighter at night than pure power calculations would suggest.
Applying colour temperature specifications to LED bulbs is scientifically fraudulent. Colour temperature applies only to incandescent light sources whose output over the appropriate spectral range is adequately close to that of true black body. For quantum physical reasons (Planck's Law) the spectral output power curve of a Black Body is the same shape whatever the temperature. The peak just gets higher and shifted to a shorter wavelength as it gets hotter. http://earthguide.ucsd.edu/eoc/teachers/t_universe/p_blackbody.html Basically just grab the peak of the graph and drag leftwards and upwards.
Can't find good picture of white LED spectra on t'net but plot b "W-LED" here https://www.researchgate.net/figure/237151257_Output-spectra-of-the-colored-light-sources-a-fluorescent-lamp-b-W-LED-c shows the general idea. A sharp blue peak with a hump lower down, mostly yellow & red. Colour temperature is assigned by finding a temperature at which the blue peak and yellow-red tail of the LED output pretty much touch the black body curve.
Really the whole thing only sort of works because of the human brains remarkable ability to interpret the eye output signal so colours and shadow intensities are seen pretty much consistently over a huge range of light levels and source colours. When it comes to apparent colour what you see is along way from what the eye got.
Clive
Ordered pair of those LED bulbs from Powerful as they are now below my £50 "looks OK, give them a try" threshold. Will report back.
Further to those projector style devices I have worked with that style of optical system where a source with projection lens is moved towards and away from a larger block, fresnel or other "patterned" lens to change the output beam shape. Works well if properly designed but I'm told the designing the lenses is tricky. Can't see a one size fits all device being optimum although it may work well enough on some headlights. Bulb flange to headlight lens distance will be the critical parameter.
If you look at the P38 headlight there is a lot going on close to the middle of the block lens. Wet finger in the wind guess is that a projector beam diameter anything significantly more than 2 inches or so diameter where it passes through the lens will have serious stray light issues. Doesn't help that the P38 has a rectangular reflector with the lens tilted sideways.
More chance with the modern type of headlamp having a stepped reflector and clear cover. Especially if the cover is simple and not variable thickness to act as a lens. Probably have to take half the front of the car off to fit one tho'.
Avoid I think.
Clive
Seriously weird beasts. Normally projector lamps go under a simple transparent cover so the lens does all the beam shaping work. I have a pair of the 3" diameter H1 halogen breed on my motorcycle and they work just fine behind the plain glass cover.
P38 headlamps have beam shaping block lenses on the front intended to work with light coming off the reflectors to give the right beam shape. With a normal bulb pretty much all the light comes out sideways and up-down ways to bounce off the reflector. Opaque cover on the end of the bulb stops pretty much all the direct light.
Those bulbs have a very small lens and project a long way into the light unit. Presumably the theory is that the projector lens is pretty close to the headlamp lens and pushes light through only a small section in the middle so the block lens doesn't do much. $64,000 question is how much effective lens the beam sees. If were longer so the projector lens was close up to the headlamp lens I'd be much more confident that it would behave.
Other issue is whether you can actually get them into the P38 headlamps without removing things to make way. They are effectively about 5 times as long as a normal H4 and the business end pretty much fills the hole so probably need to be slid in straight on. I always tilt the halogen bulb to get it in or out.
I see that Powerful UK have their simple halogen replacement LEDs back in stock. £45 the pair - https://www.powerfuluk.com/vehicles/range-rover-full-size/p38/exterior-accessories/h4-led-4000-lm-headlight-bulbs-white-pair.html - at least we know they work OK with acceptable beam pattern.
Clive
Know exactly where you are coming from Chris. Not had seal leaks either but I have had things tighten up seriously due to corrosion under the seals and seals swelling from old age. Albeit mostly motorcycle applications. But all the calipers I've re-sealed, usually for other folk, needed a good clean out in the seal grooves.
Really really can't be doing with seized or snapped bleed nipples mid job.
Clive
Objectively I'm somewhat overdue for brake fluid replacement and bleeding. But I'm less than confident that the bleed nipples will shift. Realistically it makes sense to do the flex-pipes too whilst I'm in there. Had the rear axle pipe done when I got the car but thats all the serious brake work its seen in the last 4 or 5 years.
So do I get a set of decent looking used callipers and overhaul them with new pistons and TRW seal kit or just push the boat out with a set of decent brand calipers. Island list TRW calipers at £100 and £60 + VAT for front and rear respectively whilst a pair of seal kits and OEM standard pistons come out around £60 + VAT. A set of adequate condition calipers to rebuild can probably be found for around £100. In round numbers by the time I've finished the job probably £500 with new TRW calipers, against £300 or bit less with home rebuild. Me being me I'll probably replace the mud shields whilst they can still be got so there goes another £100. Probably still solid enough to blast and paint tho'. I can blast and paint the carriers but at £20 (ish) a pop new is it worth it. Bolts, pins and screws were all new when I did the brake disks and pads over the last couple of years so they should be fine. Anything else I've forgotten given its year 2000 and approaching 100,000 miles.
So which way to go. £700 ish new-new just bolt it all on, £300 ish maximum DIY or somewhere in between? Generally I'm reasonably careful with money but skimping brakes is verboten. Especially as Madame Leadfoot is visiting for November & December so we may be sharing driving, (no way am I slumming it behind the wheel of her L322).
Anything else I've forgotten that should sensibly be done whilst the system is drained down?
Clive
RutlandRover wrote:
Aren't the washer pumps accessible with the bumper in place?
Tried that first. Not with foglight fitted. Not enough room to get your hand round to pull clear and wiggle out. Especially as the wrist angle is all wrong when working on the floor.
Clive
no10chris wrote:
what grief just to change a washer pump, grrrr,,
??? Hardly. Easiest one I've ever done.
As I recall it took around 15 minute tops from opening the Snap On box when I did the rear screen washer pump on mine. Including scrambling inside to pump the suspension up to highest level.
Of course I'd had the bumper off t'other year to do the air-con radiator so everything moved. No need to take it right off. Just pulled it forwards a bit and slewed it to make room. Jack under slewed corner to support it if need be. Probably disconnected the foglight that side too but really I don't remember if I did or not.
Clive
As Sloth says just flip the clip and slide the bumper out. Its heavy. ideally two person job but I have put mine back on my own using a jack fitted with cross bar to support it. Easiest bumper to shift that I've ever seen.
Usual trap is if somebody has fitted the wheel arch liner with the front flap inside the bumper return edge instead of outside as it should be. Right pain wiggling things out then unless you pull front end of the wheel arch liner. Which of course I didn't as that was far too much effort.
Clive
The most correct anti-freeze is probably the official BMW stuff sold under a BMW part number. Dirty green-blue colour if I remember correctly and about 3 times the price of a normal good brand. But that particular car was being quite seriously tuned and the folk doing the job insisted that only the BMW jollop was up for it. My only involvement was earache from owner moans about the price!
Clive
Did they charge you for the OEM Dunlop one? If so some-one mucked up and put wrong one in your box so get on to Island and ask for the wright one.
I'm surprised that they would be happy selling such sensors without warranty. Especially as the price difference relative to OEM is so small.
Saying that there is huge variation in price between suppliers. Most seem to want more for Britpart than OEM let alone a better aftermarket brand. Island price for OEM is very good.
Clive
Great job.
Don't see a major worry if the sound comes on OK if you turn the beast on separately rather than have it come up automatically when switching the ignition on. Or does it have to be set up for automatic turn on so memory settings aren't lost?
Personally I don't like auto start on audio systems. Probably because I don't use radio all the time.
Looks like that will be next months P38 presents.
Clive
Morat
If you've not ordered more Delrin yet drop the offcuts in the post to me and I'll trim them to length on one of the lathes. Only need about 1/8" for parting tool so could get the two 35 mm ones out of a 75 mm length in perfect safety. Even easier if you have two pieces longer than 35 mm.
Clive
Something I have to do for mine too.
But given that a Lemfoder drag link assembly cost me £46 + VAT from Island 4x4 back at the end of May it hardly seems worth battling with an old one. Joints are bound to be well worn too and I've seen similar broken during the hit, heat and heave with added scaffold pole process. Just what you want on Sunday afternoon when you need the beast to get to work on Monday!
However I tend to price my time out at around half garage rate and figure I'm ahead if I spend less than that on new parts. So usually plenty of wiggle room for new "not necessarily essential but so much easier to handle" than the "rusty but serviceable" bits that came off. At my age do it once, do it right and do it fast is attractive.
Different if its just tweaking recent replacement of course.
Clive
Agree that fan draught and under-car airflow sweeps minor oil (and water!) leaks all over the place so its hard to locate the source. Point of deposition has more to do with swirls and eddies in the flow than anything else.
Similar cable and pipe oil wetting on mine seems to have pretty much gone away since I changed the front crankshaft oil seal and, of necessity, re-did the sump joint a couple or three years ago.
Clive
Electric control bit doesn't really matter as its a simple DC motor. Take supply out of an always live when ignition is on feed with the usual bi-directional power on / power off drive and job done. Retracts when the ignition goes off, swings out when it goes on. Basically a change-over relay and two diodes. Need an over-ride for servicing of course.
A potentially hairy issue is if Disco system lacks limit switches relying on seeing the stalled motor current spike to detect end of travel. Still do-able in a retro hack but a pain in the behind to get always reliable right without risking motor burn-out. Correctly done a computerised system can detect difference between hard stop and sticky movement so motor overload is unlikely. Not so easy with a simple retro-hack where stalled current spike has to be greater than maximum overload. I've built such limit stopless drive systems in pre micro days with safe stall current and short overload motion capability but it gets tricky.
3D printers sound like good idea but its a shedload of work to get properly up to speed for real world jobs. Need good one too if the results are going to be strong enough. That said if you do get a good one folk will be forming a queue for good quality sunroof guide bits! Better to design properly and go to a bureau service. Looked at the whole 3D thing more than a few times but as I still can't be arsed to get my CNC mill going ....
Clive
Had similar effects and marks with cast iron disks on my Norton Commander. Supplier sent replacement disks saying they had had some material issues. And told me off for upgrading calipers from standard two piston XJ900 ones to 4 piston FJ1200 ones which should have had a slightly different material. Dammed if I can recall if they made me a special pair from the right material or not but 70,000 miles on were still working fine.
Clive
Before you start make up an O ring sorting stand to keep the new ones in order before you fit them and the old ones in order as you take them out. I bang some thin nails into an off cut of melamine faced chipboard. Plain wood or ordinary chipboard will do fine but needs smooth plastic face, half a freezer bag for example, to nurse the new O rings aren't damaged.
Lots of O rings in the packet and its easy to miss one if you aren't organised. I know I guy who did and wondered why it didn't work properly! Having done a fair bit of similar keep it it order stuff in the past I thought I could just lay them out on the bench. Nope! Pride'n falls'n all that.
Collets push in easier with a U shape tool pushing on two sides than with a screwdriver operating on one. I copied my memory of the fancy one that Newport used to put in the box with air spring leg optical tables as those use the same collet fittings.
Clive
Probably just heat exhaustion!
Or in my case just heavy duty solitaire trying to make room to get my car lift installed in the garage. Taking forever! One of those six deep have to do this before I can do that so t'other can be done ..... thingies.
Plan A. Just clear out back of garage, pull bike lift out to make room to swivel pallets and unload, put bike lift back in middle of car lift. Rewire for 220 volts three phase from 415 volts. Hook up VFD, thats the really easy bit. Sort out a baby compressor to release the air locks. Build or buy that is the question. Oh and stick mirrors on back wall whilst I'm at it to add light.
Actual. Most of stuff in back of garage has to go up in workshop attic. So sort workshop attic out first. Except insulation under metal roof is falling down so sort that first. Freaking hot and very difficult to do working round all the stuff flat on back. Half done but most of the stuff to be re-homed over the workshop is moved. Remains has to go in house loft so gonna make sone decent shelving first, fed up with the standard pile. Need to reposition the scaffold hoist so it swings over the middle of the trap rather than from one corner. Which means I need a longer scaffold pole so weld two bits together. Which is where we got to yesterday evening! Now the scaffold hoist pivots need re-engineering so it goes full circle ....
Am I gonna get it done before (new) builder turns up to shift a couple of walls old builder put in wrong place when doing the extension!
Oh joy. Now Bridgeport head is rattling like mad over most of the speed range. So that will have to be done in-between. Hate futzing with varidrives!
But my life is now complete. Just paid gas and electricity bill before noticing the old supplier had used well wrong, estimated, readings instead of the ones submitted when I closed the account and switched suppliers. Like you can use negative amounts of electricity -800 odd KWHh in this case. Another hour or more gone on website battles.
Where's my chefs hat, time to cook dinner.
Clive
Once you get used to the noise it'll be a proper pussy-cat. Just make sure its tied down properly before you use it and that you have firm footing. Like (nearly) all machines you just have to be firm and confident to show it who is the boss.
Clive
That saw looks excellent value. Pity they cheaped out by only providing one clamp although there are four receptacles for it in the base. Looks pretty much like the SIP one I got 14 years ago to build my workshop. They all seem to use the same design of base casting. But I got two clamps.
Frequently a bit more controllable to make cut by bringing the head down and sliding it rather than a vertical chop. I often use a combined movement to reduce the chance of lifting but thats not a novice technique as getting it wrong can make things worse.
Clamp the part to be cut firmly down into the corner between base and fence. Use a stop to set the length as there is no satisfactory way of marking the stuff. Measure twice cut once of course.
If you have a set of grip palm work gloves, either leather or PU faced cloth, you may be able to hold the main body down into the corner between fence and base. Use the heel of your hand. Not your thumb! Cut the longer spacers first. Free end will dance around quite wildly until you get it down to 500 mm or so. It will almost certainly try to escape as the cut goes through. Just had a quick play holding some offcuts down on mine. 40 mm Ø no problem, 25 mm Ø too small, no 30 mm Ø to try. Depends on your hand size and how well your gloves fit. I have small hands and use the stretchy PU faced cloth work gloves from LiDL. Cheap, comfy and made in my size.
Of course having done a couple or three sets got the knack and nailed down what it feels like when all is going well you'd dump the clamp(s) and do it free hand. Like wot Chris does and as I would. Albeit with a block of wood having a Vee out of one corner to help hold the material down.
Last thing. Chop / mitre saws are really, really noisy. I pretty much levitated first time I turned mine on!
Clive