David Herbert

I would say so. Well spotted - not the place you would think to look for historic MV photos. Balloon winch 3ton 6x4 too. David

TerryB, Thanks for that, I was pretty certain that would work but it's good to know for sure. As I understand it from Richard Farrant's post Foxes didn't have a speed limiter but I suspect that the module (or more precisely the Luminition base plate rather than the optical module) was identical and the black wire and the fuse were simply omitted. Datadawg, Take the distributor cap off and look inside the distributor. It will either have contact breakers and a capacitor or the Luminition optical electronic unit. See Clive's (fv1609) article 'Ignition Matters' in 'Clive's Corner' section of this forum for nice photos and info. The Luminition unit is relatively unusual for an electronic unit in that it directly mimics the contact breaker system in that it is realy just a switch that doesn't need a capacitor to stop the points burning. You could even adjust the dwell angle by modifying the shutter disk (smaller gaps = more dwell). It seems that the vast majority of CVRT / Fox J60s got the electronic ign conversion fitted well before disposal. Most electronic ignition modules charge a capacitor and release a pulse to the coil when a hall effect sensor is triggered by a rotating magnet that replaces the cam - or nowadays by the engine management computor. The Jolley engineering unit seems to be more like the Luminition one but driven by a hall effect sensor. I could be wrong but I believe it does not create its own pulses but switches the coil as a contact breaker would. David

"I think the red and white sign means they still have beer !" David

Robin, The guide horns are integral with the end conectors on this type of Sherman track. The track links themselves are flat on the inside for the wheels to run on. The end connectors are retained on the track pins by wedge bolts that bolt through the middle of the end conector from the outside, held by a nut on the face of the connector that the sprocket drives - hence the extra cut-outs between the sprocket teeth. The wedge bolts engage with flats machined in the pins but not right at the ends so the end conector is both retained on the pin and prevented from rotation around the pin. Thus when the wedges are in the track has a natural curve of about 5ft radius. To flatten out or bend round the sprocket the rubber bush between the link and pin must flex. In John's photo you can see that some wedges are missing and some end connectors fitted horns outside, as without doing this it would be very hard to flatten the track enough to weld it in place. One thing that concerns me is that the end connectors/guide horns are made of a steel that becomes like glass if welded. They must certainly not be heated to remove them when stuck on the pins. This must have made welding them to the hull a rather unreliable fixing method though I doubt if anyone cared. There may well be additional bits of steel bar hooked between the links that we can't see. As the armour that they are welded to is 1 1/2" thick minimum I doubt that the inside of the hull would even get warm from the welds still less suffer paint burning. David

Do we know if the spark happens when the optical sensor is first illuminated or when the light is cut off by the shutter disk? If the speed limiter is timing the window in the shutter disk there will be a direct linear relationship between the size of the cutouts and the speed. It should be that 10% change in the cutout will change the speed 10%. But is it really that simple ? And which way will it change it ? David

Thanks Clive. One of the things that prompted my interest was your article "Ignition Matters" where you did in fact include some x rayed images of the module. Unfortunately I am not very into electronics so although I am quite happy to replace a component on a PCB, I do not readily understand what I am looking at. Does anyone properly understand exactly how the speed limiter works? It must be reliant on the value of some part of its circuit to set the cut out speed and it may be possible to add a component to one of the accessible terminals that will alter the setting. Alternatively it is possible that the size of the 'windows' in the shutter disk (and thus the time that the receiver is illuminated at each pulse) is what is read by the speed limiter. It would then be possible to make a new shutter disk with the required number of windows but with windows of a different size to get the right speed setting. Also, I believe the contact breaker version of the J60 distributor is a No2 Mk1 but what is the designation of the electronic version? David Clive, just seen your last post which crossed with mine. That I think suggests that changing the window size would alter the speed setting. I just have to put on my thinking hat to work out which way!

I know about the Jolley Engineering conversions to put electronic switching on almost any points type ignition system but I have become interested in using the optical module from a J60 distributor to convert the closely related lucas distributor used on B series engines. Obviously it is necessary to use the original B series advance and retard mechanism and for 4 or 8 cylinder engines a new disk with the right number of cutouts would have to be made but a more technical problem is the electronic rev limiter in the J60 setup. This is, I understand, set to 4750 rpm but most B series engines are limited to 3750 rpm (though safe to 4000). One could simply use the original B series mechanical cut out rotor arm but this is rather crude and good ones are getting very hard to find. Using the J60 plain rotor arm would be a much better option but then the rev limiter is set too high to protect the engine. If the J60 limiter works by limiting the RATE of pulses it would actually limit an 8 cylinder engine to 6/8 of 4750rpm which is 3562.5 rpm which is a little low. Does anyone understand the electronics well enough to suggest how the rev limiter function could be modified? Ideally it might be possible to connect a resister or capacitor to one of the existing terminals on the module to change the rpm ? There must be some electronics experts out there :cheesy: David Ps I do know that J60 distributors turn opposite to B series but the optical modile wouldn't care about that !

I am quite certain that those wheels are not from a tank. The wheel disks and six very small studs would be far too fragile for AFV use where there are very high side loads from turning at low speeds. Also the sides that you show have no provision for the wear from the guide horns of the track. If the hidden sides have extra metal to rub against guide horns, and the wheels can be bolted back to back leaving a gap between the rims of an inch to inch and a half then I am wrong but I doubt it. There were of course Dunlop factories in Germany in WW2 so one does see German tank tyres with Dunlop written on them but again I don't think that is the origin. If the size is right for your truck I think I would think myself lucky in your position. David

The really flash way would be to get the turret to land on the beach making recovery much easier and saving the hire of a boat with a crane. Can I watch please? David

You could build it into your house and have it as a feature wall to the lounge, with exotic fish swimming around it and a full size diver called Rick in there too. David

In the UK we have largely standardised on the metric course pitch standard - to the point where "M8" is recognised as a single standard. However there is also a metric medium pitch and a metric fine pitch. Looked at quickly, the medium pitch is similar to BSF and the fine pitch looks like UNF, but they are not compatable with either. Metric medium is very common on VW vehicles but almost nowhere else that I have seen. I would have thought it very unlikely that BSF would have been used on anything built or modified after 1982 but we had not then properly settled into metric course as the British standard so anything is possible. David

To lift the side plates, I made a device out of a piece of 10mm x 80 x 200 mild steel with a hole for a lifting hook at one end and an old 5/8" bolt welded very securely into a hole in the other end. this was cut to length and a cross hole drilled so that if the side plate was eased only 10mm away from the tank, the device could be pushed through a bolt hole and an 'R' clip used to secure it. The weight of the plate can then be taken while the last fixing screws are removed. I found that this worked very well and has the advantage of being much easier than threading strops down a small gap. Hope this helps. David

Hi Danny, Don't know about everyone else but I can't see the photos, just get a message about "invalid atachment" if I click on the links. Very odd! As for the Bedford: engine oil is much thinner and blacker than gearbox oil. Stick your finger in the drips and you should be able to tell quite quickly where it is coming from. If gearbox (and not from the top cover) it must be from the front (input shaft) housing, the PTO flange, or the back cover. All are easy to make new gaskets for - I have used the cardboard from breakfast cereal packets with a suitable oil resistant sealer like Hylomar. To do the front one you will need to remove the gearbox but that is really a very easy job. It is heavy but still liftable by one man so once you remove the floor plate above it, the prop shaft and the four bolts to the bell housing you can stand above it in the cab, hold the gear lever with both hands and wiggle it backwards out of the bell housing. If you have put a couple of pallets under the truck first, you can then lower it through the hole in the floor without being pulled through yourself. To get it back in you realy need another person under the truck to push it forwards while you support the weight by lifting it with the gear lever as a handle. Alternatively you could just be pleased that it won't go rusty ! David

Hi Phil, They didn't ! Mechanicaly there were no changes, not even to the winch. I am a little suprised by the references to front tyre wear. The extra weight of the jib when folded is entirely in the front axle but it is not very heavy (I guess 1/4 ton) which is not a great proportion of the standard load. All the stuff in the back is carried on the tracks so doesn't add to the front axle load. Of course when using the jib there is a lot more weight on the front axle but movement would be very limited and slow so that would not be a problem either. Kevin, They would be well within rail loading gauge. In service they were almost treated as medium size trucks, certainly able to keep up with a convoy as they will cruise at 45 mph if you don't care about petrol consumption. Track wear was not a problem as the rubber hadn't gone brittle then. I should add that I have driven one of these halftracks (empty) on the road. Apart from having almost no cushioning from the suspension and of course no power steering it was quite fun. Did get sworn at though for drifting it round a roundabout in the wet. Sorry no photos though. David

I agree with you Tony. Even though I have a mag drill, I would have done it the way you did because there was a very limited area to 'stick' a mag drill to, and that is not very flat. usually you would get round that by clamping a bit of steel plate on to give you a firm base but in this case the rivet heads would be a problem. As I said in my post above, trying to use a hand held power drill with a rotabroach type bit would most likely result in breaking the bit (particularly with the other hole overlapping). A bunch of 1/4" holes followed by a file doesn't take that long anyway. But the job got done, some more bits bolted on . David

In the UK these are often referred to as Mag - Drills. I agree with Andy that an ordinary HSS Rotabroach type cutter is quite happy to cut a partial circle but you must go very gently, especially at the start. It is after all just a hollow end mill really. I am not sure about the idea of driving them with an "ordinary drill" though. An ordinary bench mounted drill press - yes, but a hand held drill is very hard to hold steady enough and although these cutters will drill hundreds of holes without sharpening they won't survive shock loads. It is just too easy to break them, particularly as they break through at the end. David

Thanks Sirhc, I stand corrected but it's still bl***y heavy ! David

Matt, Did you know that a Centurion clutch weighs almost the same as the engine ? I don't have the exact figures available but it needs a crane to install it. You would certainly be building a quite substantial bed to mount the engine and as you say, extending it backwards to support the back of the clutch would not be too dificult. A dummy gearbox input flange and a big self aligning bearing in a pillow block would do it. Have fun ! David Correction, see next post - the clutch is actually 1/3 the weght of the engine but still very heavy. Sorry !

And some quick shots of Loyd carrier + 6pdrAT, Churchill ARV1, Ram Kangaroo, Archer. Nice bit of film, thanks for posting it. David

Sorry, I had assumed that the main flat bit of the hinge would be single thickness and the part that is bent round the pin had to neatly butt up to it without the 90 degree bend and extra inch or so. All clear now. Looking good too. David

The whole gun cradle is a bronze casting - more resistant to fatigue cracking than the steels of the day and steel casting capacity was in very high demand vs. bronze. My feeling is that German tanks were very sophisticated - sometimes too much: British tanks were just complicated ! The hard chrome plated rod is supplied finished ground for repairing hydraulic rams in inch and metric sizes and you just machine the ends as required. They doo look good though :thumbsup:. David

Robin, Are the four little tabs on your new cage nuts actually part of the nut itself or is the cage in two pieces with the nut trapped between ? If the former you probably need to be quite precise in fitting it but the end result will be much stronger. Definately worth greasing the bolts when you reassemble it all. I do like your SOP of photocopying any pages of the manual and only the copies are allowed in the workshop. David

With rubber bushed track like CVRT or FV432 it is possible for the rubber bushes to fail. When they do they deteriorate very quickly and the whole hinge between adjoining links goes metal to metal and eventually you get wear between the pin and the actual link. As a result that pair of links go over pitch and won't run smoothly over the sprocket. You can easily spot dead bushes by looking at the inside face of the track (where the wheels run) and compare the gaps between each link and the next. If bushes have failed the gap will be 1/4" or more bigger than normal. If you have a few gone it makes a real difference to track tension and is really not very safe at more than walking speed. Obviously if you are going to remove a link, first check that the bushes are all ok on the rest of the track. Move the vehicle so the link you want to remove is under the sprocket and break the track there. This allows you to use the parking brake to keet the tension on the top run of the track giving the track clamp an easier time. With a CVRT it is possible to pull the ends of the track together with a ratchet strap but the proper track clamp is much better. Similarly the correct tools for removing and replacing the pin make life easier and save damage to pins. The reasion that track should be condemed if 15 links have been replaced is only that if that many have needed replacement the rest are not long for this world. More important is that you don't go below the minimum number of links allowed, and that you have exactly the same number on each side of the vehicle. Have fun, David

I am sorry to say that most museums see themselves as the only proper custodians of historic objects and actually selling unwanted items to mear enthusiasts as a form of prostitution. After all we might sell them on and make more than we gave them (obviously the cost of restoration doesn't count !) or actually play with them. From their perspective we are just a bunch of hooligans who should butt out and leave history to them. Please don't think that I have strong views on this but the above is a paraphrase of what I have actually been told on more than one occasion by employees of two significant museums in our field. To be fair to the Batterie Todt museum the tank was in a dreadfull condition. It had been in the sea for a very long time and the salt had got into the structure of the metal. As soon as it got into the open air it just started crumbling away and parts that had looked quite good initially turned to flakey rust. Even I had to admit that it couldn't be saved but why couldn't it have been offered to the open market ? If anyone has seen the SS Great Britain on display in Bristol, that was refloated as part of its recovery from the Falkland Islands but now has hundreds of significant holes that wern't there when it got back to the UK. They got very concerned and finnished up making a glass 'sea' surface at the water line so they could have a very big dehumidifier keep the humidity down to a very low level both outside and inside the lower part of the ship. This has helped but it is an ongoing problem. If you are in Bristol I thoroughly recommend a visit. David

If there is no phase change, how does the annealing change the aluminium ? Sorry to be thick ! David