Old Bill

Hi Chaps.

I have been sorting out all the things I put on hold whilst working on the lorry! However, I am getting back to it now. I am not good at instant decisions as I like to weigh the facts and listen to all of the advice I am offered. Even if I don't take your advice, I always appreciate it very much so many thanks to everyone for their suggestions.

In the mean time I have been pushoing on with wing brackets. They are a horrible job and I shall be pleased to see the back of them. I have spent a lot of time filing a bit of shape into them.

Then it was a case of drilling the bolt holes.

Followed by a bit of filler to tidy them up.

They are now in primer awaiting attention from the paint shop.

Something else which didn't quite get finished off was the throttle pedal. Dad had cut it to my sketch but never quite got around to filing the section. In the end, this proved a blessing as I got it a bit too long and had to drill a second pivot hole futher up.

Once trimmed back, the pedal was filed to an elliptical shape to represent a forging.

Another tedious job!

It does make a worthwhile improvement in its appearance, however.

I have finally decided what to do with the pistons and cylinders. The cylinders are to be honed out by a further 0.002-0.003" to clean them up and increase the clearance and this should happen next week. I have been turning the pistons in the Myford to increase the clearance around the top land to 0.017" and that between the rings to 0.012" with the bottom section remaining with a 0.005" clearance. This will increase when the bores are honed.

I have also taken the opportunity to increase the depth of the ring grooves by 0.020" and have opened them out by a whisper to make sure that the rings move freely.

Following advice from here, I shall replace the compression rings on the two pistons which picked up as the originals were scored when this happened. I shan't trouble with the oil control ring. The pistons are all complete now and only await delivery of the new rings.

Now I must return to filing wing brackets, the front ones this time. They don't get any more fun to do!

Steve  

Well, that is a super find! The engine is very nice and will certainly suit it better than the Merc!

I am now eagerly awaiting some comments from Barry and Ben as if anyone knows anything about it, it will be them. Ben, I think, is at Brooklands today with the lorry collecting a well-deserved restoration award. Prince Michael has asked to drive the lorry but that depends on how Ben has progressed. It wasn't driveable two days ago but getting very close!

Good luck with it. We are all here to help!

Steve  

On 5/31/2018 at 8:55 AM, edinmass said:

Steve asked how I found this thread and I didn’t answer. Back in the early seventies a family member had a WW I Renault tank that I use to play on. They had it out in the front yard as a lawn ornament.

Thanks for that Ed. Most interesting! Some lawn ornament! I think we shall have to count that one as one that got away. At least you have a garage big enough for a Sherman tank. You can never have too much space!

Steve   

On 5/28/2018 at 10:15 PM, Richard Farrant said:

Hi Steve,

A thought has just come to me regarding your pistons. I am not sure how long it was between them being cast and when you machined them, but it was well known years ago that iron castings had to lay for a period before machining. I recollect this with motorcycle cylinder barrels. Also cylinder blocks for engines, I have had experience of several types where they were machined pretty soon after casting and then the blocks became out of line when the casting 'relaxed' (probably a technical term for this which I cannot remember).

regards, Richard

I had heard of the weathering of castings by leaving them out in the foundry yard for six months to settle down ('That's not weathering, that's rusting!') I must admit that I hadn't thought of doing so on ours as I thought the effect would be negligible. Apparently not! Our pistons are about a thou elliptical with them being narrower across the gudgeon pin holes. At least I don't have to machine them that way. I just need more clearance in the bores!

Many thanks for the reminder. I shall know for next time now.

Steve     

On 5/29/2018 at 9:20 AM, Tomo.T said:

 

Hi Steve,

Looking at your pics above, your front mudguards appear to follow the radius of the wheels. From the original pictures this was not the case and there should be a straighter section at the rear. This only applies to the fronts, and the rears are as shown. I am unable to illustrate this atm. but you might want to have another look before finishing the brackets ?

Tomo

Hi Tomo.

You are right in that nearly all Thornys have a straighter portion at the rear of the wing. However, if you look , you will find that there are quite a few different patterns in use with some domed and some flat on the top and other subtleties. As ours are domed, I think that straightening out the rear edge is not to be attempted.

I haven't been able to search through the pictures as my new computer won't talk to my back-up drive which is irksome in the extreme!

Steve   :) 

That is one beautiful car, Ed.  'Shiny' and 'refined' are not what we usually see on this forum as 'functional' and 'matt olive drab' are more the norm! However did you find us?

Many thanks for your thoughts. From my measurement of the original piston I think that Thornycrofts probably went for a clearance above the top ring of 0.017", between the rings, 0.012" and for the remainder of the piston, 0.005". If I hone the bores another 2 -3 thou then that would give me a general clearance of 0.008". If I take another 9 thou from the top land and 4 thou between the rings then that would give me something comparable with 'new'. I will take a good look at the rings and replace any that are obviously damaged. I am curious as to why they should have stuck in the bottom of their grooves on 2 and 3 pistons as all were quite free when I put them in. I will have to ease the grooves as well.

In the mean time, I have been pushing on with the wing brackets. They are a horrible job and no fun at all. This is not helped by my welding incompetence so there has been no satisfaction in them being nice. Oh well. They are tacked up now and ready for a proper welder to put them together for me. He is probably reading this and going 'Oh no, not again'!

Steve  

Well, I have found my way to Devon again with the intention of putting the lorry away and then making some more progress. Since I crocked my arm, the lorry has been sitting outside as I have been unable to start it  to back it into the shed. Three weeks later, I am mostly recovered but still cannot start the beast due to the damage. Our pal couldn't make it to help out ( he is moving house!) and our neighbours both have bad backs! The only solution was to push it back. Whilst we were coming to this conclusion I fitted some more bits, starting with the reinforcing strip around the tailboard.

Then the capping strips along the body sides

And the floor strip just inside the tailboard. It was a nasty wet day as you can see.

The we decided to have a go at manhandling the thing back inside. At four tons, this is a bit of a performance. Dad pulled it back with the car to start with and then I steered it forward, downhill on full lock.

I managed to misjudge it and Father had to shift some of Mother's plants.

Then we worked it back in using a pinch bar, 1" at a time. We got there in the end but it was hard work. After that we carried on with some more bits. I trial fitted my floorboard and, much to my surprise, it was right first time.

Then I set in a flush ring to allow us to get the board up.

That was all satisfactory so Father now has the board in the paint shop.

Then, this morning, we decided that the time had come to pull the engine down and have a look.

Now the lorry was in its usual position, the chain block could be installed.

Not immediately too bad.

Some scuffing along number two piston and all of the rings were stuck.

A shiny patch on the wall of number two.

Interestingly, there is a ring towards the top of the bore which can be felt with a finger nail. I can't see how it was formed unless it is just where the piston ring stopped and dragged up the surface, the next time it moved.

Interestingly number four piston is clean where the others are well sooted.

A close up of the damage to number 2 piston

Number four piston was very clean and all of the rings were free.

Number 3 piston is scuffed as well but not quite so badly.

I had a good measure of all of the bores and pistons and find that I machined them all straight with a nominal 0.005" clearance from end to end. Cylinders two and three appear to be a thou or possibly two smaller than one and four and I think that must be the trouble. My plan now is to remove all four pistons and un-stick the rings from two and three. Then I want to set them up in the Myford and take 0.006" off the top lands in each case as well as giving them a polish to tidy up the scuffing. I also plan to get 0.003" honed out of each bore to tidy them up and give a greater clearance. Hopefully, that will sort it.

Then I went on to the front wing brackets. This is a horrible job and I am not enjoying it at all.

More wing brackets tomorrow.

Steve

We are still pottering on but only slowly. There are other things which need doing at the moment! In the mean time, Adrian has kindly welded up the rear wing brackets and I have been filing some shape into them. That is proving to be very tedious and time consuming but I have three down now. I have only to make the front ones to go with them!

For a bit of light releif, I have cut the pedal slots in the floor.

I am a bit concerned about the strength of the item though so I have cut and rebated a strip of steel along the front to brace it.

Looking through my notes, I made a decent sketch of the original pistons in 2013.

Apologies for the drawing clarity or lack thereof. However, assuming that the bore was 4.500" originally and that there was no wear on the piston, the clearance above the top ring is 0.017", between the rings, 0.012" and for the remainder of the piston, 0.005". Once we get the top off, I will have a measure and see what I actually did!

I am sure that I gapped the rings in accordance with what was on the packet.  I would quite like to do some sums to check so can anyone give me a feel for how much hotter the rings could be than the bores? I am guessing at 150°C but I would value your views.

Steve   

On 5/14/2018 at 1:35 AM, edinmass said:

Steve, The earliest car we have serviced is 1897, .....

Thanks for all of your thoughts, Ed,  and everyone else's contributions. I think the next step is to tear it down, look for evidence and measure what we actually have. I don't really want to skim the pistons if I can help it but we shall see. It may be very obvious where the problem lies so we just have to have a look. That will be part of the task for the next visit.

An impulse starter is definitely on the cards. The difficulty is that very few magnetos have the holes to mount the trigger plate. I have a variety of impulse bits so I think I shall have to put my thinking cap on and make up a 'special' to suit the lorry. I have a similar problem with the Dennis but space is very tight in that case and another special will be needed but this time, anti-clockwise. I must go and get the bits out and study them.

Steve  

Thanks for your kind comments Ed. I am very interested to hear your experiences of piston clearances. Are these for alloy pistons or iron? I am very keen on doing the job as closely to how it was when new as possible so we have made iron pistons for it and fitted the rings we could get. I really don’t want to go to aluminium pistons even though they are so much better! If memory serves, I gave them a five thou clearance along the length with 0.009” above the top ring and simply turned them circular.

Another of our forum friends in South Africa has very kindly sent me these experiences of a local restorer

‘He used Model T pistons as an example as those were the most recent pistons he had worked on. (3 3/4 bore.)

1. The pistons were machined perfectly round and 4 thou clearance with the bore size.

2. Pistons were then tapered 30 thou from the crown to the oil ring. (Crown expands more due to higher temperature)

3. He then machined a dolly to hold the piston and clamped it in a 4 jaw chuck.  It was then off-set 5 thou on the one side and then on the other side to allow 10 thou total ovality. The thrust side will expand more due to heat build up.

When you remove the first block on your engine, you should see scoring marks on the piston and possibly the bore. The scoring on the piston will indicate where the material will be removed to make the piston oval.’

These views are similar to yours. Also, I was reading the FWD Model B drivers manual, as one does, and found this:

‘The clearance between the cylinder and piston, at the skirt, is 0.003” to 0.004”, under bottom ring 0.006”, at the third land 0.008”, at the second land 0.009” and at the top land 0.012”.

They don’t write drivers’ manuals like that any more!

All of this suggests that I am going to have to set the pistons up again and skim them, a job I don’t want to do! Oh well.

Steve    

Well, Brighton was a week ago and things are returning to normal. In other words, cooking, gardening and earning a living! This is how close we got to succeeding:

It was a bit disappointing not to go but I am consoled by the fact that the traffic was terrible and it would have been a miserable drive. In the mean time, we didn't stop during the week but carried on without the pressure. We cut and fitted the tailboard hinge pin.

And then went on to the wing brackets.

I tacked them up ready for a proper welder to stick them together. Even my tacking is dreadful! I can't seem to get the weld to stick to both halves of a fillet at the same time. More practice needed I guess.

Four rear brackets ready for welding. Once properly attached, I shall spend some time with the angle grinder and files to give them some shape.

We had various friends around when we attempted to test-run the lorry and they have kindly sent me some photos.

This is the somewhat daunting sight to be met coming out of Dad's driveway. I have to trust that I set the brakes up correctly!

I mis-judged the corner, however.

Fifty yards further on, it stopped.

Return to base.

Steve.

Thumbs.db

Well done Ben! Hows the starting handle arm? Or did it go first time?

Steve

Hi Scott.

Glad you have been enjoying it. Yes, the tension was certainly there this time, more so than with the Dennis. We were much further on with that one at this stage. It is very disappointing but was quite a big ask to be 100% right first time after such a big rebuild. We did put it on the road on the day we promised though!

Starting the thing is always an issue with these old vehicles and not many of my friends can swing it. I think it is technique as much as anything. I must say that there is great satisfaction in a hand start but sooner or later I may have to give in. At least one of my friends has rigged up an electric start on his bus but has managed to do it without drilling any holes in the chassis. The intermediate stage is to fit an impulse starter and I certainly plan to do that. The Thorny isn't actually too bad when it is free. I hurt myself trying too hard on a stiff engine but have now learned that lesson! I don't think an impact driver has enough torque to turn it but it is a good idea. I have seen a starter rigged up using a chainsaw engine and gearbox attached to two long bars and engaged in the starting dog. It worked but took two people to hold it!

I need to start the thing again this morning so that we can put it back in the shed. I shall be more careful this time.

Steve  

Thanks for all of your thoughts Chaps. I am still pondering at the moment as I am not much good at instant action I'm afraid. We haven't run it today as I pulled something yesterday and now have blue biceps! Driving a desk isn't good practice for this hobby! In the mean time, we have been gently pottering along, making capping strips and edging strips for the tailboard. I have also fitted some reflectors as a concession to modern traffic.I shall have a go at the floor tomorrow and then the wing irons. I am not really looking forward to them but they need to be done.

The sump plug is not magnetic. However, the pump draws through a strainer so major lumps of metal shouldn't get in. The fine stuff will so we will end up with another oil change soon, I guess.

Steve    

Thanks Chaps. To be honest, it was quite a successful day really. We did take it on the road on the day we planned. We just didn't get very far!

Today, our old friend Dave came and had a look. He is a retired motor mechanic and keen rebuilder of motor cycles. He has helped us a tremendous amount over the years with advice and assistance and we value his opinion very highly. We ran the lorry for him and it started very easily. We seem to have that bit nailed now anyway! It was very smooth and nice and, when switched off just ran down as you might expect rather than stopping sharply with stiffness. I started it again and, although stiffer than when cold, rotated OK. His considered view is that it is almost certainly tight in the bore and he thought that it should have nearer 0.008" clearance. However, rather than pull it down for the moment, he would keep it running for a few hours at a fast idle and see how it goes so we plan to do that. Failing that, he has the appropriate honing equipment and would be pleased to have a go at the bores for us if we drop them off with him and handle them.

We have run it for another hour today until the fuel ran out. I put some more in the tank and then tried to swing it but after those few minutes, it had tightened up a lot and I couldn't turn it. In fact, I have pulled something trying so I thought that a good moment to stop! I have a couple more days of holiday so we will run it again and see what happens before putting it back into the shed.

In answer to Andy's comment, it is running rich now due to my oversize jet. I shall make some more, when I get home, of slightly smaller bore. In the mean time, we are doing some bits of the body ironwork before going back to the wing irons. I would like to finish off the floor shortly as well. It is interesting watching the clutch operate beneath one's feet but I should hate for someone to put their foot through it!

Steve   

1 hour ago, Surveyor said:

Steve

Just seen this, every day a school day, many thanks for this

Richard

It is just that I have a head full of useless information. I still don't know why British tyres were metric!

Steve    :) 

Well, once we had finished cancelling all the arrangements, we had quite a nice steady day. I started off by cutting the tailboard hinge pin to length and drilling for split pins. I also fitted the tailboard catches leaving only the pins to make.

I also took the bonnet boards off and fitted the rearmost bonnet catches  so they are now secure.

With the lorry out in the sunshine we could see the faults in the paintwork so Dad has been touching up and finishing off. I am amazed at how well father does in such a cramped shed in the dark. It still narked him to see the odd patch of primer showing through!

Then our pal, Mark D turned up with the cab straps. Mark is an amazing craftsman and can turn his hand to anything. He previously made up the leather drive shaft joints for us and very kindly offered to make the straps as well. I gave him the measurements but he was keen to see them fitted in person so that he could adjust them as necessary.

A brief moment of doubt when he thought they were too short! However, Mark's work is spot on and when I pulled the canvas tight, they proved to be perfect first time.

And then the other one.

The straps pull out the canvas and the lorry is looking really nice.

I think we will have a look at the valve plugs tomorrow and see if we can seal them up. Two were blowing, one quite badly, so it would be nice to fix them before we try the engine again. Then I want to finish the floor and start on the wing irons.

Steve  

Good morning one and all!

Well, the phone was red hot last night and again this morning. Many thanks everyone for your thoughts and suggestions. We have just discussed our options and have decided not to go which is a great disappointment. However, it really needed everything to be spot on yesterday for us to be able to finish the rest off in time and the hours are just not there to fix it. It would be a great shame to get there and fail or, worse still, bust a rod and do catastrophic damage for the sake of lifting a block and having a look. We shall carry on this week and have a day out in Brighton to watch our friends come in.

Thanks to everyone who has been rooting for us.

Steve 

Today has been one of mixed successes. Not a bad one for a new lorry but not quite as good as I had hoped considering our timescales. This is what we have been up to.

We started off by fitting the seat cushions. I first drove the Dennis with no cushions and every time I tried to steer, I slid around rather than turning the lorry and I didn't want that to happen again.

We drained some more water from the sump which, to be honest, is causing us some concern. I took a side cover from the crank case and then poured water over the top whilst Father looked in with a torch. Water could plainly be seen coming in at quite a rate so that is where it is coming from. The best solution will be to seal up the water hoses and stop the leaks  at source. At least we know how it is getting in there now.

We then filled the radiator with water and the sump with oil.

Time for a swing!

It didn't want to know so one of our guests, a young and fit student type had a go and, of course, it went.

It idled for a while but didn't want to pick up very much. However, I decided to move it out which it did nicely. The clutch works anyway!

I had a bit of a go at manoeuvering and it was OK but it would not rev and the engine kept dying on me. We decided to stop for a bit and fit the hood and tailboard whilst there was plenty of manpower about. and then have a think about it.

It idles quite nicely but any move to open the throttle and it fades and pops and bangs through the carburettor. If we choked it a bit and tried to open the throttle it was much more responsive so we diagnosed a weak mixture and I turned up a new main jet. The original had a number 56 drill through it. Our 55 and 54 were missing from the rack so I used a number 53 which is 0.012" bigger. That was a much bigger step than I intended but we fitted it and it was much improved so we decided to have a go.

Coming down that hill certainly proved that the brakes work!

We were away!

Unfortunately, fifty yards up the road we came to a sudden stop as the engine stiffened up and seized. I could not turn it. We sat there for ten minutes whereupon it freed itself and I could re-start it. We reversed to the bottom of the hill and then started to drive back up whereupon it seized again. Another delay whilst it freed up and then I drove the rest of the way back. That hill start was fun! We then parked it in the driveway and left it idling for two hours which it did very smoothly. I did try to accelerate it just before we shut down but it was very sluggish and then stiffened up again and stopped. We are hoping that it is only a running in issue and that perhaps I made the pistons a bit tight. We intend to idle it some more during the week and see if it frees itself up. In the meantime, there are still the straps for the hood, the tailboard catches, the wing irons the cab floor and the hood frames to do. Fortunately, I have the week off!

TIm has some clips which he will post when he gets home.

Steve   

We have had another good day with plenty of progress. It is feeling a bit relentless at the moment though! We started off by finishing the bonnet catches and fitting them to their new mountings. That all went well and I drilled the holes in the bonnet boards for the front ones without issue. However, the rear ones are so positioned that they are right over the chassis rail. I am not drilling a hole in that so I will have to take the boards off and counterbore them so that the nuts sit inside the timber. One for another day as we are pushing to be ready for the test run tomorrow.

The front one does look quite nice though.

Then I spent the rest of the morning setting up the footbrake linkage and pedal. Nothing very interesting to see, unfortunately, but we do now have a working footbrake.

If we are going to drive it tomorrow, we need some half-shafts. Dad has cleaned these up so it was just a simple fit, or so we thought. Nothing is ever quite that easy!

After clearing enough space to swing it, the half-shaft was pushed home

I don't remember it being that rusty but the back of the garage is a bit gloomy!

The 5/8" bolts are fed through from the rear. The holes are very close fitting so the bolts had to be tapped into place which was quite tricky considering the limited access.

Then the hubcap was fitted and the bolts tightened a little bit at a time until everything was in contact.

They were finally done up with my 3/4" drive Chinese socket and tommy bar.

Then the other side. As has been noted here before, space is a bit limited. We had to push the lorry forward until the axle aligned with an empty shelf!

Then it was a case of simply bolting up as before. The flange on this half-shaft is very loose on the spline and has obviously been working over a long period. I think it will be OK in the short term but we will have to make another sooner or later.

The brake setting up brought the pedal into line with the clutch. This looks nice but the stroke is a bit short so we will have to be careful about keeping it properly adjusted. I have no doubt that the shoes will bed in very quickly so we will probably have to stop to adjust them on the run itself. With the padel in its final place, I can now see what I am going to have to do with the floor board.

After setting the clutch springs and bolting up and pinning the coupling between the clutch and gearbox, I fitted the outer floor panel.

And then the footstep.

We put oil in the differential and I moved the lorry back into the garage by winding the handle with it in reverse. So far so good! Just water and oil in the engine and we will be away tomorrow. Let's hope all goes well and it will drive back up the hill into the driveway!

More tomorrow.

Steve   

Good luck with that. We shall follow with interest!

Steve

Dad has been busy whilst I have been at work. He has finished off the footstep and also fitted the rear licence plate as well.

That is another tick in the box. Tomorrow is going to be busy if we are to have a test run on Sunday. I need to set up the footbrake and clutch, oil in the engine and back axle, fill all the greasers, fit bonnet catches, fit the step and also the cushions. The cushions are actually quite important as we test ran the Dennis without them and whenever I tried to turn the wheel, I just slid around on the seat without maneuvering the lorry. With the narrowness of our roads and the steepness of the drive, that is one variable I could do without!

Steve  

British solid tyres were specified in metric dimensions from the very early years and the Government Subvention scheme required that those on the front would be 720x120mm and on the rear 880x120mm twins. Both our Dennis and Thornycroft have these. The AEC Y-type was not approved for the scheme but, very sensibly, had the same sized tyres all round but 850x120mm. The American trucks coming over had imperial sizes so our FWD has 36x5" tyres all round. The Peerless also has imperial tyres but I can't remember the sizes offhand.

This seems to be another little quirk of history. Do you think it might have been the French influence which led to metric tyre sizes being adopted?

Although these are 850mm tyres, I don't think they are AEC as the hub cap is too square. I shall have to look at some more photos and see what other suggestions I can make. An interesting find, nonetheless.

Steve  

We are still keeping busy. Dad has been cleaning up the half shafts and has found that one of them is loose in the flange. I am sure that this wasn't whatstopped the original lorry from running so we will just live with it. If we get into trouble in the future, we will just have to make another.

He has also been busy painting the lamp brackets at a coat every twelve hours or so. These are now complete and fitted, complete with a splendid side lamp found by Tim.

Front number plate is on as well.

In the above picture, you can just see the bonnet catches lying on the bonnet boards because they have no way of attaching them. Looking through our collection of catches, I found this one with the mounting arrangement. If this were longer, it would be ideal so I have turned some up.

They can go on over the weekend.

Finally, I have just turned up an 1/8" BSP plug to go in the oiling hole in the top of the steering column.

Not a lot more I can do from here now. It is so hard being 200 miles away when I want to get stuck in! Oh well. We still intend a test run on Sunday. That is causing me some trepidation as well!

Steve  

We haven't balanced the shaft. The rotation depends on how well I drilled the leather so there will be some variability in it. Hopefully, there won't be a problem but if there is, then I will have to get it done. No time left at this stage!

Dad is still pressing on and has sent this report:

Thanks John. Now it looks the part!

Steve