simonr Posted January 28, 2006 Share Posted January 28, 2006 Do any of you happen to know the thread size used to screw the viscose unit on to the front of the engine? Also, what is the distance between the end of the threaded portion of the unit which attaches to the engine and the mounting face of the fan itself? Lastly, do all the fans for different vehicles with viscose fans have the same mounting holes / style? If you happen to have a fan, could you measure the diameter of the hole in the middle and the distance between the centres of each of the four mounting holes? Why you ask? Well, I have an electromagnetic fan clutch design on my cad at the moment. It would be ideal if it could be made to fit all vehicles - or as many as possible. This has to be the ultimate answer to the electric or mechanical fan question as it gives you the best of all worlds. You can switch it off in water or on the motorway for a few extra BHP and switch it on continuously off road or towing for a bit of extra cooling. the rest of the time leave it controlled by a thermostat. I believe that the fan can sink up to about 7kw of energy from the engine rotating it. It seems to me that it will be hard for any electric option to compete in terms of raw cooling. Just for a taster: Red = Bearings Green = Electromagnet Grey = Clutch Plate and magnetic ballast Brown = Electromagnet Mounting Blue = Fan mounting boss Gold = Engine mounting boss I'm going to start making it tomorrow! Si Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 28, 2006 Share Posted January 28, 2006 Very neat idea I am pretty sure the 300Tdi and 200Tdi ones are a different bolt spacing for the 4 bolts, both are 32mm spanner size but I am fairly sure the viscous units aren't interchangeable. But I know an older V8 one fits a 200Tdi because I put one on my old 200Tdi Discovery when I had it. Later 3.9 V8s are different again with a 36mm spanner to fit the thread. I am busy tomorrow morning but I should be able to lay my hands on a 200Tdi and 300Tdi one at work tomorrow afternoon and I have a dud 3.9/4.0 V8 one in my garage so that will be the main 3 types there are, so if nobody else comes along in the meantime, I will measure them and post the measurements tomorrow afternoon/evening Quote Link to comment Share on other sites More sharing options...
white90 Posted January 28, 2006 Share Posted January 28, 2006 the hole that in the fan to cover the centre would need to be in excess of 50mm from the end of the threaded mounting to the front of the viscous is 50mm, but the fan mounts on the rear(engine side of the viscous unit) thread size I'm unsure sorry Quote Link to comment Share on other sites More sharing options...
simonr Posted January 28, 2006 Author Share Posted January 28, 2006 Thanks Tony (and Steve). Didn't realise the fan mounted on the back of the viscose unit. That makes it a little more tricky - but only in terms of running the wire for the electromagnet out. Not impossible though! Just had an interesting idea! If the electromagnet were allowed to rotate with the fan, I could use a bearing as a rotating contact to apply power to the coil. That would simplify the design no end. Si Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 28, 2006 Share Posted January 28, 2006 Si Another thing to bear in mind is that some are LH thread hubs (300Tdi for example) and others are RH thread (some V8s) don't know what the thread is though Will measure later when I get back from the airport, still on my first coffee at the moment then have to go! Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 29, 2006 Share Posted January 29, 2006 Woops Sorry I forgot to go and look at a 200 one today (but I think you have a 200Tdi SV don't you?) but can confirm from what I have here that the 4 bolts holding the fan onto the viscous are the same spacing on a 300 one (as per pictures posted by Tony - the ERR2266 viscous unit), as on a later 3.9/4.0 V8 (ERR4996 viscous unit). The difference between them is that the 300 uses a 32mm spanner size LH thread onto the engine, and the V8 uses a 36mm RH thread. The 200 viscous unit (ETC7238) I think is the same thread onto the engine as a 300 (32mm LH) but different bolt spacings onto the viscous, and this also fits earlier 3.5 V8s IIRC. Let me know if you still need one measured. I think the 200 viscous unit also does earlier ones like TD's, so there appear to be 3 basic types if you ignore the very latest stuff like a Td5 (which is different again, the fan/viscous can only be purchased as a complete assembly on those for £stupid) and probably also Discovery 3s and things. Quote Link to comment Share on other sites More sharing options...
simonr Posted January 29, 2006 Author Share Posted January 29, 2006 Cheers Steve, I have a new design which is much smaller and overlaps the bit that screws on to the engine (the thread is inside the coil & clutch). It's hard to fit everything in place when the distance between the engine and fan is so small - I reckon no more than 40mm to play with - but I have a plan - which looks good on paper. I've done a quick calculation of how much force the mag clutch on an AC pump applies to squash the two plates together and it's almost a ton. This may prove to be over the top - but I'm going to start with that. The bit which screws on to the engine is a fairly small part of the assembly and should be easy to make more than one version. Likewise with the plate to which the fan bolts - and that could have several sets of holes for different fans. I'm starting to realise why nobody has done this before (as far as I know) - it's quite a difficult and technical problem! I'll do some hunting at sodbury for different fans and viscose units - they are too expensive to buy all the combinations new. I would have imagined all the fans would have a left hand thread to stop them unwinding while the fan is running - but the laws of physics are different for Land Rovers I believe! Si Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 29, 2006 Share Posted January 29, 2006 I have a 300viscous.I might be able to lay my hands on a 200 but not sure what happened to that one. I'll be at Donnington if you are. Any help?? I eat rat poison mike I can cause trouble in an empty house. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted January 29, 2006 Share Posted January 29, 2006 Simon, Interesting. I have a V8 one lying about somewhere should you wnat to borrow it.... In the meantime I have enclosed a range of screen dumps from Microcat Defender, Classic RR, P38 Late and early, Disco 1 and Disco 2 variants, the LR in question shows in the blue header at the top of each screen dump.... The parts numbers showing shoulsdallow you to work out / have a better idea the options etc for full range.. ? Nige Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 29, 2006 Share Posted January 29, 2006 I would have imagined all the fans would have a left hand thread to stop them unwinding while the fan is running - but the laws of physics are different for Land Rovers I believe! Si, When I go out later I'll check but I'm 99% sure the fan on the 4.0 Thor engine turns the opposite way to a 300Tdi one because of the belt/pulley arrangement, hence the RH thread to stop it spinning off. So I assume the 3.9 in my old Disco (which also used the ERR4996 viscous unit) and 3.9 RR (which I know uses the same p/no as well, at least some of them do) also had the same belt layout to give a fan spinning in that direction. I also remember being able to wind up somebody at work who b****red up a fan spanner trying to get one off my old Discovery because he assumed it was a LH thread same as a Tdi (there aren't many V8s here) - took a bit of getting off afterwards too Hadn't thought about all the VMs, 2.8 BMWs etc, but I think a lot of those in the Microcat listings are hot climate spec ones (hence the "(-GB)" which means all except GB) and a lot of the numbers are duplicated as well. On top of that I think if you check measurements you would find the thread will be the same between a lot of them - maybe the on/off temps are different or something? I know that I fitted a V8 one to my old 200Tdi Discovery, though I can't remember which V8 one it was exactly. I still think the 3 to go for at the beginning would be the 3 I listed above, 200Tdi (which will fit some V8s), 300Tdi and 36mm V8. If you get it working I may well be interested - I am on my 3rd viscous unit in the 90 (all under warranty ) and I noticed when I took the fan off the other day that the bearing in that is on its way out already - only been on there about 4 months I think Quote Link to comment Share on other sites More sharing options...
simonr Posted January 29, 2006 Author Share Posted January 29, 2006 Mike, Nigel & Steve, Thanks for the help. That catalogue looks good - easier to navigate than a shelf full of parts catalogues anyway. I share Steve's opinion that first off, go for 200, 300 & V8 although there are a lot of V8 variants out there, so I guess go for 3.5 & 3.9 V belt types. Sadly, I'll not be at Donnington - even though I had an invite to go & do show & tell with TBR UK. Sarah has other plans for me that weekend! If one of you happens to have either a micrometer or a thread gauge to hand, I'd like to know the pitch and either outside diameter of the stud on the engine or inside diameter of the female thread on the viscose unit. To measure the pitch, measure the distance between the tops of the peaks of the thread. Measure distance between say 5 peaks & divide by 5 to give good accuracy. I have a very handy thread lookup table of the measurements of every size of thread - which makes it easy to identify by measuremet. Si Quote Link to comment Share on other sites More sharing options...
simonr Posted January 29, 2006 Author Share Posted January 29, 2006 After a few hours slaving over a hot computer: Key: Gold = Engine mounting boss Green = Coil former Red = Bearing Grey = Magnetic Ballast / Core Purple = moving cone-clutch plate Light Grey = 4 x M6 x 20 stainless cap bolts to retain fan Blue = Fan mounting plate (on radiator side of fan) Fan bolts in between Purple & Blue Clutch plate slides on 4 cap bolt heads (only moves 1mm) Assembly held together by M10 x 50 bolt which passes through Grey and into Gold. 7mm of the big nut which holds the thing on to the engine protrudes - probably enough to get a spanner on it. The distance between the left hand end of the gold bit and the engine side of the fan centre is 30mm Max outside diameter 120mm A bit of meccano will need to be attached between engine block and the green coil former to stop it rotating and to carry the wires (from the coil). Assuming my calculations are correct (and there are a lot of assumptions) it should be capable of transferring about 5hp with a current draw of 4A to the coil. Si Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 29, 2006 Share Posted January 29, 2006 OK here you are From left to right: 200Tdi ETC7238, 300Tdi ERR2266 with fan, 3.9/4.0 V8 ERR4996 Measurements 200Tdi one Overall diameter of unit is 152mm Hole spacing between 2 opposite holes 99.32mm 32mm spanner size LH thread Internal diameter of female thread on unit 22.41mm 300Tdi one O D 166mm Hole spacing 82.66mm 32mm spanner LH thead Internal dia 22.44mm 4.0 V8 one O D 166mm Hole spacing 82.3mm 36mm spanner RH thread Internal dia 28.42mm Quote Link to comment Share on other sites More sharing options...
simonr Posted January 29, 2006 Author Share Posted January 29, 2006 Thanks Steve, Any guess what the pitch is? The core diameter looks most like 1" UNF or UNC Thread Dia/ Dia/ Pitch/ Pitch/ Core Core Depth/ Depth/ Name Inch mm TPI mm Dia/" Dia/mm Inch mm 1 ADM 1.0000 25.400 12.0 2.117 0.8933 22.689 0.0534 1.355 1 BRASS 1.0000 25.400 26.0 0.977 0.9508 24.150 0.0246 0.625 1 BSF 1.0000 25.400 10.0 2.540 0.8720 22.149 0.0640 1.626 1 UNC 1.0000 25.400 8.0 3.175 0.8466 21.504 0.0767 1.948 1 UNF 1.0000 25.400 12.0 2.117 0.8978 22.804 0.0511 1.298 1 WHIT 1.0000 25.400 8.0 3.175 0.8399 21.333 0.0800 2.032 And what is the diameter of the hole in the middle of the 300 tdi fan? Cheers, Si Quote Link to comment Share on other sites More sharing options...
nas90 Posted January 29, 2006 Share Posted January 29, 2006 Simon, the NAS (MY 1995) being Disco 3.9 with coil and distributor is LH thread, a bit later engines changed to RH thread and I think it was when LR switched to the one continuous serpentine belt driving all ancillaries? perhaps someone could confirm that? Did the 300 TDi use the serpentine? 1995 was about switch over from 200 to 300 TDi? If I can find an old coupling I will measure thread and pitch. I remember it well since I told someone to knock the coupling clockwise looking from front of vehicle and they nearly smashed the engine cos' it was RH thread! Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 29, 2006 Share Posted January 29, 2006 Don't know and it isn't really possible to measure inside the fan hub with any accuracy to get the pitch from that, I don't think there is room to get the external calipers onto the front of the engine (too close to rad) and anyway it would be hard to see to get it accurate. However I would say it is UNF rather than UNC if those are the two choices, as its quite fine for the diameter, I would have said UNF or fine metric but it may be a non standard thread pitch nas90 certainly my 1996 Disco used the same RH thread viccy unit and it was a serpentine 3.9 - you're probably right and I suspect the early V8s used a 32mm spanner size LH threaded hub same as a Tdi is. Hole in 300 fan is ~67mm, can't get the internal calipers into it but that is measured with the external ones and within about 0.5mm Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 29, 2006 Share Posted January 29, 2006 Tomorrow morning it will be light [i hope]. There is no fan on my 300Tdi so I will measure the diameter of the thread.I'll see if I can find what pitch it is as well. I thought the pitch looked to be finer than UNF.More like a metric fine. I eat rat rat poison mike I can cause trouble in an empty house. Quote Link to comment Share on other sites More sharing options...
simonr Posted January 29, 2006 Author Share Posted January 29, 2006 Thanks both of you. Si Quote Link to comment Share on other sites More sharing options...
JST Posted January 29, 2006 Share Posted January 29, 2006 Si, havent read the whole thread (it looked too long) plus as soon as saw two keyboards Cordell i thought it was going to be over my level....................... anyway i have a 200tdi and td5 viscous fan (both knackered) that you can have if required for measurements etc, can bring them to slindon next weekend. Quote Link to comment Share on other sites More sharing options...
simonr Posted January 29, 2006 Author Share Posted January 29, 2006 Si,havent read the whole thread (it looked too long) plus as soon as saw two keyboards Cordell i thought it was going to be over my level....................... anyway i have a 200tdi and td5 viscous fan (both knackered) that you can have if required for measurements etc, can bring them to slindon next weekend. That would be good - Cheers James! Si Quote Link to comment Share on other sites More sharing options...
rick Posted January 29, 2006 Share Posted January 29, 2006 Mikes right, a 300Tdi hub is a 1.5 pitch x 24mm from what I can measure. Screw pitch gauges are handy little buggers. edited to add, definately LH thread. I just whipped my fan off the front of the engine to measure. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 30, 2006 Share Posted January 30, 2006 Mikes right, a 300Tdi hub is a 1.5 pitch x 24mm from what I can measure. Screw pitch gauges are handy little buggers. edited to add, definately LH thread. I just whipped my fan off the front of the engine to measure. I've just measured mine. rick is spot on 24mm x 1.5mm pitch. I eat rat poison mike I can cause trouble in an empty house !! Quote Link to comment Share on other sites More sharing options...
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