David Herbert

Tony, Do you live in Scotland, they will deep fry anything here, yes including Mars bars. Not heard of corks though. David

Mark, TM9-1750 covers "Power train unit, Three piece differential case, for medium tanks, M3, M4, and modifications". March 1, 1942 TM9-1750B covers "Power train unit, One piece differential case, for medium tanks M4 and related Gun motor cariages", August 16, 1943 I do not have TM9-1750A but I suspect it is just a revised version of 1750. Both these TMs fully cover removal from vehicle, complete dismantling, rebuild and refitting of all parts of the power train forward of the propshaft. The gearbox is virtually the same from the first grants to the last ultimate series Shermans although of course the mounting of the controlled differential and the brakes changed significantly. Also the arangements for lubricating the crown wheel and pinion were improved as time went on so later gearboxes have a built in oil passage from where the return oil hose connects, to the front of the box. The actual gears and shafts are I believe all interchangeable except that the input flange is different on very late boxes to accomodate the tacho drive being moved from the engine to the gearbox. Early boxes were set up for the gearlever to the right of the box as Grants had the driver over the gearbox and he changed gear with his right hand. This stayed the same on Rams and Sextons as they were RHD and changed gear with the left hand. For Shermans the driver was moved to the left of the gearbox so a new linkage was designed but the internals were not changed at all. The gearbox ratios did not change but M40 GMCs, M74 ARV and the 'Jumbo' assult tanks had lower final drive ratios. I am not sure that anyone has found the limits to the power and torque capacity of a Sherman box. There have been many engine upgrade packages for Sherman but the gearbox was never criticised for short life, just for not being automatic. As far as I know the design was not directly used before Lee/Grant but was a major development of the M2 medium tank gearbox with which it shares only its basic concept. I have driven many Sherman family vehicles and as you say many are very reluctant to let you into gear. The worst ever was an Israeli Trailblazer which had had its transmission filled with EP90 on the principal that it was big and that is what you put in big gearboxes! As the syncro and the brakes require friction to work it neither steered or changed gear willingly. The official oil was 50 viscosity (same oil in the engine if a radial) but this took account of it thinning significantly as it got hot. Modern oils, even single grade oils, are far more stable and better lubricants than WW2 oils and you will find that filling the transmission (all of it, not just the gearbox) with a universal 15/40 oil as used in modern tractors will absolutely transform the steering and brakes without any harm to the gears etc. It should be bourne in mind though that the synchro is having to do a lot of synchronising as there is a lot of momentum in the propshaft and clutch to loose. Do not expect to move the gear lever straight from one gear to the next. From neutral, 'lean' it into the next gear firmly, but not forceably. When it has synchronised it will let you in, you can not force it in by pushing harder and if you go back to neutral and try again you will lose whatever synchronisation that you had. Also, when accelerating try to change up early rather than holding out for maximum revs in each gear. There is plenty of torque and the gearchange will be far quicker if changing at lower revs so the vehicle does not loose as much speed while you change. One last thing: if you remove the flange fitting for the oil return pipe from the oil cooler on the top LH side of the box, not the elbow but the actual flange to the casing, you will have to dismantle the gearbox because there is a banjo shape piece on the output shaft that should engage with the piece that you just took off but has dropped down under gravity and is almost impossible to get to re engage from outside. This is not good as there is then no internal lubrication. Good luck, David

Is the guy in front of the three cars trying to hitch a lift ? David

Is it possible that the white paint was a special acid resistant paint? As the champ was designed to wade with the batteries under water some escape of acid would be quite likely. David

I think that the front axles are in their crates which have been opened and then stacked on their sides. If they had invented fork lifts it would have been easier but given the choices of duty in France at that time a sore back probably didn't seem so bad. David

Good grief! I had a Champ as my first car 41 years ago and its chassis was not a patch on yours. I thought it was a good one because the axles held oil and the rear diff pinion was ok. I used it as my personal transport for two years with no real problems but sold it when I got a 1950 Lanchester 10. If you put a modern 10W-40 or 15W-40 agricultural universal oil in the gearbox you will find that the synchromesh works a lot better as long as the synchro rings are still in one piece. Good luck. David

It seems to me that any combustion pressure will reduce the tension on the con rod at TDC and will not greatly add to the compressive load at BDC as the exhaust valve is already open but the TDC between the exhaust stroke and the inlet stroke is almost devoid of pressure on the piston and likewise at the end of the intake stroke there is virtualy no pressure at BDC so at all dead centres the acceleration of the piston is the vast majority of the load. Therefore it seems that as long as the engine is not over revved the load on the big end will not exceed the load at peak combustion pressure which should occur at about mid stroke. I must say that 75psi as max MEP sounds unbelievably low, any modern engine will make that just on compression with no combustion! Since it is almost impossible for you to get engine oil that is not better than original this would sugest that the bearings should cope ok. That leaves the question of the tension load on the con rod at TDC at max revs. Is there any evidence that this engine tended to throw rods or that they never did? I think that I would still like to remove some metal from the inside of the crown and possibly inside below the gudgeon pin but your calculations certainly show less of a problem than I expected. Nice bit of applied physics. David

I'll seccond that ! David

Surely the term "laden" refers to a vehicle or trailer built or adapted for the carriage of goods. If the living van is properly converted rather than being an empty box body with a porta-potty and a camping table and chairs, then it is not suitable for the carriage of goods so can not be tested as such. Its gross weight will require it to have over run brakes up to 3.5T or powered brakes above that, as with any trailer, but if it can't carry goods surely it can not be laden or unladen. David

What an interesting cart. I have no idea what it is, or how old, but I have had hands on experience with German steam locomotives, the most recent of which was built in 1932. All of them had fastenings with metric sized hexagons but inch size whitworth threadforms. Even allowing for the resistance to change of the steam loco builders everywhere I would want to find out when metric threads came into use. Things with wooden wheels were certainly being made into the 40s so it is not impossible that this cart is a bit newer than you think. Still a lovely thing though and in amazing condition. Are you going to do any restoration or keep it as it is, which I think is just great? David

Sorry, been away for a couple of days. I definately agree that the big round castings in the top photo of the foundry are the two main castings of a tyre press. I thought that they were the same with something else leaning against the bottom one but of course that is the location for the steel upright that holds the top up (or down when in use!). Can anyone see what is written on those castings just left of the mounting lug? The press shown in the mobile press photos is possibly surrounded by decking so that wheels can be rolled straight off the trucks that brought them. If the press itself were mounted on a railway wagon I think that it would be rather higher off the ground though it could be a specialy designed wagon rather than a normal flat with the press just sitting on its bed. David

Another bunch of great photos Tim. The amazing thing is that the middle photo could have been a photo of Foden's foundry when I worked in there in the early 1970s, even to what the men were wearing and the junk piled up round the edges. It realy brought back memories! In the top photo they seem to be making the castings for their own machine tools,and quite big ones too. I think the big round things one on top of the other are tables for big radial drills (used instead of box tables for sitting bigger things on). Thanks, David

What super photos, thank you for sharing them. David

[quote=Old Bill: That was my original thinking in adding an extra 1/8" to the crown although it only adds an extra 120cc. I hadn't thought that would let me balance them as well! Steve Steve, If you added 1/8" to the top of the crown but kept the inside where it was your pistons will be considerably heavier than the originals. I would have thought that it was critical that the new pistons were no heavier than the originals and even better if they were lighter. I am thinking about the loads on the con rods and bearings which would not have been exactly over engineered when new. Obviously it is good if all the pistons weigh the same and that the individual compression ratios are the same but this is not exactly a high performance engine and given its low revs and C/Rs I very much doubt that you would be able to tell if they wern't exactly the same. If you must remove metal from the pistons I would very strongly advise removing it from the insides. I would definately keep the higher C/R as modern petrol is a much higher octane rating than the engine was designed for so at the same power output it should run much cleaner and cooler. Similarly you should be able to run with the ignition further advanced with the same benifits, as long as you can still retard it enough to start it. David

Certainly, flakes of metal were a serious danger but I have never heard of flakes of paint hurting anyone. I think that whoever wrote your book has his flakes mixed up! David

Offer them a ride in the country and a pub lunch, that should do it! David

Is there supposed to be a cover over the top of the King pin to keep the grease in and the mud out ? David

Very interesting. This Sherman is not much more than a year old with 1216 miles on it but it has needed a new set of tracks and the steering brakes relining. I find it hard to believe that this would be done unless it was pressing, given the shortages of everything but it could have been because the tank was about to be shipped to be used in action. The engine change may well be because it is relatively easy to swap engines in a M4A4 rather than trying to do serious maintainence in the tank. Interesting too that a 34 mile road test was done. Depending on where they went that is at least 60 gallons (275 Litres for young people) of petrol at a time of serious shortage. It would be fascinating to know more of the history of these three tanks, I wonder if any show up in photos or even still exist. Thank you Ivor for sharing. David

The winch assembly is mounted to the rear of the transverse rear spring and so requires a chassis extension of, I guess, about 18". It also prevents the fitting of the heavy towing pintle assembly that military Bs often have. In the photo above you can see that the chassis is much longer than the body, which would be a bit of a pain when loading and unloading. The winch would have been realy usefull on a gun tractor but not if you had no towing hook! I would think it likely that this one is a military truck that has had the proper FWD winch conversion fitted in its later life and not removed when it was converted back to military trim. David

I see the FWD in the top photo has the rear winch, the drive shaft is visible between the chassis and the body. Does anyone know what this truck sold for and where it went? David

Dennis, Please check your PMs. David

VERY good point ! David

I have been away from the internet for a week but just got on and thought I would check out what had been happening in HMVF land. I am very shocked to find out that we have lost Jack. I never met or even talked to him but seeing his work on this thread I felt like I knew him. My condolences to his wife and family. David

I have been operating vehicles with power steering for 40 years now and never seen or heard of the problem that you have had. Well done for working it out ! David

[quote name=mazungumagic I noticed that when I posted the photo ! I think however that the actions of the fellow with his back to the camera, are possibly more sinister. That may be one of the happy owners, extolled by Gordon. Jack, I must admit that I didn't notice what he was up to, not sinister at all, just considering how to wash the mud off the jeep ? David