Mike Macartney

REPORTS ON A 1914 HUMBERETTE RESTORATION

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Thanks guys for all the information and thoughts. I need to check the clearance I have to 'play with' on the outside and inside of the flywheel faces before I decide what to do. I have found a company in the UK that seems to stock various shoulder bolts.

 

https://www.accu.co.uk/en/564-ultra-low-head-socket-shoulder-screws

 

 

 

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9 hours ago, mike6024 said:

There'd be nothing wrong with shoulder bolts though. Just saying I don't believe they are really needed for locating purposes. In this case the holes in the flange would be sized to fit the shoulder snugly, and the thread would be cut into the holes in the flywheel.

 

I'm certain that is correct. I only suggested shoulder bolts because of the low head and the nut being a smaller size, not knowing what clearances Mike has to deal with. Also, even if the diametrical clearance isn't critical there is nothing to be lost by overdoing the precision.

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If you want precision and certainty, you need shoulder bolts or similar that fit the holes. If you use friction bolts (i.e. smaller than the hole and rely on tight nuts) there is always the possibility a loss of friction will allow movement. We are not allowed to bolt chassis together for this very reason, or at least to replace a rivetted part such as a cross member with another bolted in.

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RR chassis are all bolted together - or at least the ones I'm familiar with are. I've mostly only worked on pre-war cars. The technique was to drill the holes undersize then line the parts up perfectly. I assume fixtures of some sort were used but they didn't rely on the drilled holes which would almost certainly be a tiny bit oversize or not in perfect alingment. After everything was lined up, the holes were reamed with a tapered reamer, known today as a car reamer or a bridge reamer. Then they were bolted together using the reamed holes. Years ago I read that they used tapered bolts so when I had a rusty RR chassis in the shop I purposely took some bolts out...they aren't tapered and I'm guessing that the writer knew about the tapered reamer and just assumed the bolts must be tapered as well.

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I agree that shouldered bolts, used on 'more modern' flywheels, would be fine - BUT - "'Houston we have a problem!"

 

1912.thumb.jpg.98b2ae65c3654a8127d5277b650990cf.jpg

 

There is not a lot of room here for a bolt head.

 

1914.thumb.jpg.eb636e2bd762ba77dca32e186dd9054e.jpg

 

There maybe some room if I could find some conrods were "fork-and-blade" style. I wonder what length conrods they used in the Rolls Royce Merlin engine?!?

 

I wonder if the hammer marks are somebodies idea of tightening the bearing?

 

1908.thumb.jpg.ded978ed75d65bb406d262a8ec65fddf.jpg

 

The thickness of this flange at the end of the main shaft is only 5mm thick, less the 90 degree 'chamfer' for the rivet. In this photo I am checking the runout on the shaft where it goes through the cast iron flywheel. It is virtually zero. Next job is to check if there is any runout on the flange face that sits in the recess in the flywheel. Any discrepancy here will be magnified by the time it is gets to the outer edge of the flywheel.

 

1909.thumb.jpg.68640a2306a73e0e36ca48ab079af621.jpg

 

On the inside of flywheel recess there are these marks. Presumably due to the slight movement between the surfaces with loose rivets? I'll have a look at the shaft flange to see if it is the same on that.

 

1910.thumb.jpg.8ff4f03d3ff632086f7455c14e4b0f58.jpg

 

This was a photo I took of the flange after I had cleaned it, at the time I hadn't thought of looking for any marks. I will inspect it more closely latter.

 

1911.thumb.jpg.07239e145e4241d1c2c3f39d973c7687.jpg

 

The bight marks in the chamfered holes must be where I just kissed the cast iron flywheel with the 8mm drill I used for drilling out the rivets. The heads of ultra low head socket shoulder screws are only 2mm thick so possibly these could be used if there is room to get nuts or a plate with threaded holes on the other side.

 

This job certainly gets the old brain box working!

 

Thanks again for your thoughts and comments, they are appreciated.

 

 

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I see a couple of possibilities. One would be changing the connecting rods, something that is already under consideration. Another would be reducing the width of original rods, added to counterboring for the heads of the bolts and then facing the bolt heads off to a slightly lower profile. Was there a thrust washer on the inside? And yes, these problems can be real mind-benders. I have a love/hate relationship with this kind of problem. On the one hand I think they are a PIA - on the other hand I am drawn to them and derive satisfaction from solving them.

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Or... use flat head shoulder screws. I tried copying the link. It didn't work but they are made. You would just have to clean up the chamfers for the the rivets a little for the heads to fit perfectly. It would take a little calculation to get the depth just right but it looks to me like the best of both worlds.

 

jp

 

 

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Maybe we are overthinking this... how about regular grade 8 flat head socket cap screws with a fine thread? Holes measure just under 8mm so get the bolts and measure them. Then see if you can get an under size reamer that will allow about .001 clearance (I have no idea how that is measured in the metric system)... ream the holes and replace the screws one at the time. The bolts would be so much cheaper than the low profile shoulder screws that this is probably the less expensive alternative. Of course, this is dependent on clearance on the other side. Fine thread will allow a higher torque setting. I'd use Locktite too.

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20 hours ago, JV Puleo said:

Was there a thrust washer on the inside? And yes, these problems can be real mind-benders. I have a love/hate relationship with this kind of problem. On the one hand I think they are a PIA - on the other hand I am drawn to them and derive satisfaction from solving them.

 

There are no thrust washers to the insides of the flywheels to the big end of the conrod. There is only one thrust washer on the main shafts and that is to the rear flywheel, between the flywheel and the bronze bush on the rear engine casing. I agree with your sentiments completely 'PIA', but when overcome the problems successfully you do get a great sense of achievement.

 

20 hours ago, JV Puleo said:

Or... use flat head shoulder screws.

 

As you say these maybe the better option as the flange they fit into is only just over 5mm thick (0.203"). It would be best if I could find some with a short shoulder that would fit snugly into the 'flange' and a . I could then thread the flywheel to accept the screws. This was what I was thinking of:

 

s-l300a.jpg.522ceb3cde947a03d3680f536b8f6ac1.jpg

 

But were you thinking of this type?

 

Flat-Head-Hex-Socket-Shoulder-Screws.jpg.ded21363d8214ab3d7a1ba694e68508d.jpg

 

The only problem that I can foresee is that the existing hole in the cast iron flywheel is 7mm (0.276"). If I use 7mm as the tapping drill size the nearest thread size is M8 x 1. I may get away with M8 x 1.25, the tapping drill for this is 6.8mm.

 

Another possible problem, that I will have to check out, is the diameter of the heads and the diameter of the shoulders too large to fit OK into the flange?

 

20 hours ago, JV Puleo said:

Maybe we are overthinking this... how about regular grade 8 flat head socket cap screws with a fine thread? 

 

Yes, we are overthinking this problem! I should have read all your posts before I started replying to them!

 

If I can find something like this with a bit of a shoulder, more of a bolt rather than a screw, it should work OK.

 

producttech-din7991.jpg.5fabd2ffd4927f8366b054e0094a0aad.jpg

 

Thanks Joe, for all your help and thoughts.

 

I've heard nothing from Australia about the Humberette with the Harley conrods. I may try a 'general post' on this site to see if I can find someone who knows some details on the sizes of conrods they used.

 

1892.thumb.jpg.76445557b11281cbde7784af484b74f1.jpg

 

This is the front casing. There was no thrust washer on this side of the flywheel. Just the flange with the rivet heads? My measuring should find out if there is space for one and maybe, it had been left out when the engine was assembled?

 

You may not hear from me for a few days as I have an article, on the Poppy Flyers, to finish for a cycling mag. I have said to myself "I must finish it before I go out and 'play' in the garage!"

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Posted (edited)

I think we have a solution.

The hole size for a 5/16-18 screw, in cast iron, is .277. You wouldn't even have to ream the holes - just tap them. The only machining operation would be to enlarge the holes and clean up the countersink on the head end. I think it is a 60 degree taper and should be the same as metric.  See if they are available in the UK. If not, I can get them from McMaster Carr and send you a box along with a tap. It should be a perfect fix. McMaster won't ship out of the country - some years ago they were fined for selling nuts and bolts to a would-be terrorist. The fact that there was no way to find out if the party was on that list was apparently immaterial. Apparently, the list is a secret. Another example of government stupidity.

 

 

Edited by JV Puleo (see edit history)
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Hello Mike,  It appears that you have a good and solid modern engineered update for your stock riveted flywheel connection.  You should, by all accounts, end up with a solid connection that should not flex or move.  Have you contacted anyone, in the Harley Davidson world, to get some information on the V twin connecting rods used.  You should be able to get the dimensions you require to see if a retrofit is possible and if the eye to eye measurement will work depending upon your chosen CR and pistons available, (even if you have to go with custom pistons).  The Indian enthusiasts might also be a second good source for information on pistons and rods.  The fork and blade style rods may allow you to have a bit more room for the bolt up connection that is currently an issue for you.

Al

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Posted (edited)

I did some more figures last night and now see that 8mm may be just as good as 5/16. Just figure the hole for a coarse thread. You don't want to use fine threads in cast iron. When the SAE threads were agreed on the coarse pitches were intended for castings and the fine threads for strength in steel. Coarse threads are better in soft materials (which iron qualifies for even fhtough it really is hard). I'm guessing that when you finally do this you'll be saying "why did it take so long to figure this out"?

 

Good quality cast iron threads very easily so you can safely use a slightly smaller hole than is often recommended for ferrous metals. I'd probably use the fine thread hole size with a coarse thread tap.

 

By way of explanation, since you've see me using fine threads in aluminum, this is only on parts that are not intended to be taken apart.

Edited by JV Puleo (see edit history)
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Thanks for your posts and offers of help and assistance, I do appreciate it. I have spent this week trying to finish an article on our quest for the human power vehicle land speed record, with the 'Poppy Flyer' machines, that we designed and built. So far, I have written four episodes or chapters, but writing the fifth, and hopefully the last, is proving bloody hard. Trying to remember back to the early 1980's, and writing it up, seems even harder with attempting making it sound interesting. At present I have got to our record attempt at the American Air Base at Greenham Common, in the UK and then have to describe our trip to the Indianapolis 500 Speedway to compete there. When I get back in the workshop I'll check how much room I have for the screw heads. I'm trying to be strict with myself to finish the article before going back to the Humberette. Sometimes, like now, I wonder why I volunteered?

 

In the meantime here are some photos of the inline thermostat I bought to fit in the top radiator hose.

 

1834.thumb.jpg.e1c3d43032b31fe48f7a7520fe47f9ab.jpg

 

The large diameter that seals the rubber hose is 44mm.

 

1835.thumb.jpg.256c8f9a1d8b4a78635641e572acf760.jpg

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Joe, I have found these in the UK. Do you think they would be suitable? The company is ACCU

 

SSK-A2_md.jpg.77e6b3d25da010d6874abcc4ecc41ab4.jpg

https://www.accu.co.uk/1536-imperial-socket-countersunk-screws#elasticsearch_id_feature_710702=710702_1&id_elasticsearch_category=1536&orderby=ranking&orderway=asc

 

Hopefully, the link will work for you. I will need to buy a countersink drill, but before that I will need to find out the angle of the countersink from the ACCU. Is A2 stainless material OK to use for this application. My knowledge of materials is very limited. Thanking you again for your help and advice.

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The trouble with fully threaded bolts is the bearing on the hole is much less than half and the threads can crush, allowing movement. They also tend to be undersize.

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I agree, but I am having a problem trying to find these countersunk socket headed fixings as bolts rather than screws.

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Posted (edited)

I'd prefer grade 8 to stainless but I doubt the stress on that flywheel requires them. Remember, the original rivets were very soft. Yes. I think those will work. What length are your looking for?

Spinny... since they just go through the flange and thread into the flywheel I suspect they have to be fully threaded. They probably aren't going to be  1" long.

Edited by JV Puleo (see edit history)
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I thought I knew a fair bit about nuts and bolts, how wrong I was! I have been trying to find the head size of a 5/16 UNC countersunk socket head cap screw. Eventually, I found a BS2470 table of measurement's for UNC screws with all the details but no drawing, showing me what measurement was what. After some searching I have found a drawing. I now have all the information I need. The thing that concerned me was that the large diameter of the countersunk head would stick out slightly at the side of the flange outside diameter. It seems there is just enough room. Below is a photo of the conrod side of the main shaft flange.

 

1913.thumb.jpg.3605c609225a443dead3f4da4ad6a72e.jpg

 

Outside diameter of the flange 55mm (2.160")

PCD of the 6 x 7mm holes 40mm (1.575")

Maximum diameter of the head of the 5/16" UNC countersunk socket head screw 11.1mm (0.437")

Thickness of the main shaft flange 5mm (0.197")

Thickness of the cast iron flywheel where the screws will be threaded into 10mm (0.394")

Therefore, maximum outside diameter of heads of screws is PCD + 1 screw head 40mm + 11.1mm = 51.1mm (2.012")

Therefore amount of metal at the outside of the flange is (55mm - 51.1mm)/2 = 1.55mm (0.061") Which should be enough?

The length of the 5/16" UNC countersunk socket head cap screw need to be 5mm + 10mm = 15mm (0.591")

1/2" long screws are 12.7mm long therefore length of thread in flywheel will be  12.7mm - 5mm = 7.7mm (0.303")

 

I will have to be very careful drilling the holes and the countersink to match the screws. I think the angle is 82 degrees, am I correct? I had better buy a new countersink as the ones I have are very old and I don't know the angle of them. I do have 5/16 UNC taps.

 

As an aside, the thread on the main shaft is strange. It appears to be M19 x 1mm pitch. I have never come across M19 before. When I first measured it I thought it would have been 3/4 UNF but that should be 12 TPI it's more like 18 TPI.

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Posted (edited)

3/4-18 is a real size, just not commonly seen. None of the "standards" we use today were agreed upon in 1914 and there were many threads in use that we don't see much today. During WWI the US Army had huge logistical problems associated with fixing the large number of motorized vehicles it acquired. Part of the solution was to create mobile field machine shops. The British had the same problem and, more or less solved it by assigning each service a specific maker. Vauxhall supplied the Royal Flying Corp, Buick supplied the British Red Cross, Armored Cars were always either Rolls Royce or Lanchester etc. After the war the US informed the motor industry that they would have to agree on standard fasteners before the government would buy their products. That is when the SAE standardized their threads although none of the sizes were "new". Usually they were just the most popular. So, where you had 1/2-12, 1/2-13 & 1/2-14 you now had just 1/2-13. Some makers, like Cadillac, made many of their own fasteners - early Cadillacs use a 12 pitch thread everywhere they can regardless of diameter. This facilitated easy threading and kept them from having to alter the set up on their change-gear lathes for different pitches.

 

You can always turn the head down a little. I've done that. I've also ground them using a valve grinder to reduce diameter and thickness while preserving a nice sharp finish.

Edit: This is the reason threading is such an important skill when working on pre-1920 cars. Many of the fasteners and the parts were not made using currently, readily available thread sizes.

 

Yes. The countersink angle is 82 degrees.

Edited by JV Puleo (see edit history)
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Very interesting information re early thread details.

Cadillacs use a 12 pitch thread everywhere they can regardless of diameter

That is presumably why BS Bicycle threads were all 20 TPI. Most of my early motorcycles have lots of these threads.

 

Thanks for the information on the countersink angle.

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Mike, sorry if I was absent with comments for a long time. We are now in vacation; yesterday, the temperature was above 44°C. The best place to stay was at the beach!

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No problem Roger, enjoy your holiday, you have certainly picked a warm time for you vacation. Anyway, I thought everyday was a holiday for us retired people!

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Yet more engine problems to overcome!

 

1916.thumb.jpg.bbc17e25a74e85b5cf2d8fd87aee40db.jpg

 

Because I was a little worried about the surface where the main shaft flange sits into, on the cast iron flywheel, I coated the flange face of the main shaft flange with engineers blue and rotated the flange in the hole. As you can see in the photo above virtually no blue transferred to the casting.

 

1917.thumb.jpg.ad5d8bf3acd81c0f9ff63eb64d8144fb.jpg

 

On rubbing my finger from the outside of the recessed part to the hole in the centre it was very uneven, with a lot of wear between the bolt holes. The centre around the hole in the middle was also raised a bit. Now to think how to machine this surface flat, when the flywheel is loo large a diameter to fit the chuck on my big lathe? With my newly gained knowledge from Joe's 1911 Michell posts, I sat down and drew out a jig that I hope will work to mount the flywheel, to enable me to machine the face flat. A lot of work just to take off a few thou off the flywheel.

 

1915.thumb.jpg.a5adf26ce84006e21614652739e89932.jpg

 

I am hoping this will do the trick. I can then bolt the flywheel onto the jig and machine the face flat again taking off just the minimum amount of metal.

 

1918.thumb.jpg.0c51686bc856630b28e24b503b218b87.jpg

 

The only relatively large diameter bar I have is rusty steel, saved from being sent for scrap. I got the bar as near as I could to running straight and turned it clean, so I could put that end in the lathe chuck.

 

1919.thumb.jpg.7160b811465c282b895ec387de76f352.jpg

 

Then started machining the other end which now was running only a few thou out. It would be nice to be able to leave this in the chuck until I have machined the flywheel, but that will be impossible, because I will have to drill the clearance holes for the socket head cap screws that will screw into the 5/16 UNC threaded holes that I will tap into the flywheel. I can have a think about this while I clean up the rusted surface of this bar.

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I think I'd try putting a little grinding paste between the two faces and turning the shaft against the flywheel under light pressure. The Idea would be to lap the tow surfaces into each other while removing the smallest amount of metal. It would have to be perfectly straight, maybe with the flywheel on  the table of a drill press and the quill gently pressing on the shaft. You'd have to make something to use as a handle to turn the shaft so as not to mark it up. I'd be tempted to use a lathe dog with a piece of brass or copper between the tightening bolt and the shaft. It would be slow going but guaranteed to give a true surface and you Can't accidentally remove too much material.

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Posted (edited)

Oops. I think I'm looking at this backwards. It looks like the heads of the attaching bolts are on the flat side...so in order to lap the faces you'd have to turn the shaft from that side. That's a little more complicated. I'd think in terms of a flange with a pin or pins to pick up the holes (but not go through) with some sort of extension to turn from. I'll draw it and post a picture. It's hard to describe.

 

jp

 

This is what I have in mind... You could turn it by hand with a brace. With really fussy fitting like this I prefer to use the old and slow methods, especially with original parts.. If they take more time they also preclude making a bad error. The pins don't have to fit the holes perfectly. They are only there to drive the flange under light pressure.

 

360741908_newwaterpump-4.jpg.b3ea87aa8c34f107980f622e6205e11e.jpg

Edited by JV Puleo (see edit history)
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