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My 1910 Mitchell "parts car" project


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I could claim to have been away from my project for a few days but, in truth, I've been struggling with making the retaining bolt for the center camshaft bearing. This my 4th...and I'm finally satisfied with it.

 

First I made the hex portion... in this case I gave it a deep chamfer on the bottom. My problem has been consistently brazing the threaded portion in place in such a manner that none of the braze got into the threads. This has proved a lot harder to do than to describe. In addition to the deep chamfer, I used a small mandrel to turn a ring of 1/8" bronze brazing wire into a perfect circle...the same technique you would use to make a spring. The wire is springy and it took me 3 or 4 tries to get the correct dimension so that when it sprung out it would be tight on the threaded part of the bolt. The wire now fits down inside the chamfer.

 

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The threaded portion is too long for any of my drills so it was necessary to drill it from both ends. If I'd attached it to the hex piece first, I would not have been able to use the collet to hold it. This worked quite well although its only a 3/16 hole and it was necessary to withdraw the drill regularly to clear the chips in order to make certain it was going in perfectly straight.

 

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The Exact height of the threaded section was calculated and the two pieces assembled, with some brazing flux, on the rotary table using heat blocking putty to keep from getting the table hot.

 

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At just about this point I had a call from a friend who wanted to work on one of his projects so I waited for him and before he began we brazed the two pieces together. We did that by having my friend hold the torch while I turned the handle, rotating the piece so that it got uniformly hot all around until the brazing wire melted.

 

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This technique finally worked although I do have a little clean up to do on the lower surface - though as it doesn't show and doesn't obstruct anything that is more a matter of my own obsessive behavior.

 

I then turned the top end of the hex to the diameter of the banjo fittings I have. This is how it is supposed to look. An oil line will be connected from the pump output line to the banjo fitting giving me oil pressure on the center cam bearing. Depending on how the pieces fit, I may extend that line to the front cam bearing as well.

 

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But, until the engine goes back together it is difficult to plan the plumbing.

Edited by JV Puleo
typos...I hate typos (see edit history)
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You bet...I'm especially at loose ends now since the Baltimore Gun Show was cancelled and the National Archives in Philadelphia is closed, both of which I was supposed to be visiting this weekend.

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This year, with planned shows for the Olds, I figured I wouldn’t get as much done as I wanted. Now it looks like all I’ll be doing is working on cars and no showing. I really want to get the shows out of the way while the restoration is fresh so I can start driving It more.

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Yes... I'm certain that is a disappointment but at times like this I like to remember a saying for the Pirkei Avot that "every misfortune is an opportunity." Fortunately (or unfortunately) I'm a very long way from ever going to a car show. That said, this morning I cleaned up the underside of the hollow bolt I made. It won't make it work any better but at least I'm finally satisfied with the job. The one in the front is the finished item...those behind it have gone into my "mistakes" box.

 

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And, if you were wondering, this is how it works. The projection on the end of the bolt goes through the cap and into the bearing so when it is tightened down the bearing can't move and oil will be delivered directly to the rotating surface.

 

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My mill is still tied up while I try to solve another problem so I decided to make the insert that will screw into the crankcase and provide a seat for the banjo fitting that will oil the center main bearing.

 

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Threading it 1"-20

 

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I then turned it down on the ends. The short end will go into the crankcase but, as the threads won't go all the way to the bottom I put a rebate on it. The other end is turned down to .900 for the banjo fitting. It's still a bit long so I'll trim it down to 3/4" but it's otherwise done.

 

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Monday I'm going to visit the cutter grinding shop and have a 1" end mill taken down to .950 - the hole size for a 1"-20 thread. I'd rather do that with an end mill because I want a flat bottomed hole and I have another fix the end mill will work for so it worth the effort.

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Since I have to get a cutter ground for the job that was in the mill – and that will take a few days – I decided to start putting in the threaded liners. Working on the original parts (as opposed to making parts) is always tension inducing so it took me a while to set this up. The first step was to take a 3/8-16 bolt and put a center hole in it. It was screwed into one of the holes in the crankcase and used to center the spindle.

 

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You can tell you've got it straight if the center balances on the bolt when you drop the table.

 

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I then used a 29/64 end mill to take the threads out.

 

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And, without moving anything, threaded the hole.

 

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And screwed the first insert in with a little Locktite on the threads.

 

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I ended up having two long phone calls with authors I'm working with so I only got 4 of them done before I decided I'd had enough for the day. There is nothing to be gained by pushing it....all the mistakes come when you are tired.

 

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There are 14 more of these to do and then I have to do the main bearings...so I'll be busy for a couple of days.

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I am still amazed with your solution to a very odd cam bearing design. I wonder what Mitchell was thinking ?  Is the remainder of the engine a better thought out design ?  

A BSA Gold Star motorcycle I worked on years ago had bronze thread inserts in the head. Very similar to what you are doing for your crankcase. Each one had two small diameter drive pins to lock them place once they were installed . Done at the factory so no doubt a very accurately made drill jig to get the position just right.

 

Greg

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The rest of the engine design is just "ordinary." Nothing unusual but the workmanship is often very questionable. I think they were forcing the issue, trying to make the engine as cheaply as possible because they reduced their prices across the board in 1910.

 

I had BSA's when I as younger and remember that. RR also did it. Heldt goes so far as to say that threading aluminum is a poor idea but a lot of people did it to save the added expense.

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I used to work on British Paxman RPH diesel genset prime movers a fair bit. They evolved from a small locomotive powerplant and had quite a few design quirks in order to make them as compact as possible. Not as convoluted as a Napier Deltic,,

but they still took a bit of a knack to get them apart without breaking anything and back together without oil leaks. Lots of external oil lines. Fork and blade con rods that came out through the crankcase doors. But very long service engines , ours had hundred's of thousands of hours on them.

 

 

Greg

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Edited by 1912Staver (see edit history)
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It has been a hectic Monday...I dropped off some end mills to be ground and then went to look at a Blazer. My current truck is tired and needs quite a bit of work. I'd do it but I doubt it will pass inspection at the end of next month in any case. I'm told (and I am almost completely ignorant of these things) that there is a valve in the transmission that is malfunctioning and that it prevents the emissions sensors from setting so my "check engine" light stays on. Replacing the transmission (which may not solve the problem) is just too expensive and, truth to tell, I would rather have something I can fix and that is not subject to the vagarites of electronics. So, I bought an '89 Blazer. I'd like to thank Ted Brito (Christech) for giving some pointers on what to look for.

 

I did get back to the shop long enough to finish the 18 threaded holes for the sump inserts...

 

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I'll put the inserts in tomorrow. The cast bosses in the crankcase are not uniform in thickness and I don't want them to stick up on the top so they have to be done one at the time and, if they protrude on the bottom, filed so the gasket surface is flat.

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I installed the inserts this morning... you can see how some are proud of the surface. This was to make them come out square with the cast bosses on the crankcase which aren't terribly uniform.

 

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Then they were filed flat. I took my time with this because I am not terribly good with a hand file and I did not want to mar the flat surface. As it is, it has plenty of dings and machining marks...it wasn't a perfect surface to begin with but I didn't want to make it worse. Since the sump will get a rather thick paper gasket the little marks aren't important.

 

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Then, just to be sure I set the sump on the crankcase. The holes seem to all line up although it isn't perfect. I suspect that may be the result of Mitchell's lack of precision in their machine work. Fortunately, the ears where the heads of the bolts go are quite large so I may enlarge the holes 1/64... but I'll clean everything up first. As it is, the sump is dirty and that may have kept all the bolts from sliding in perfectly. As a matter of curiosity, the sump is cast iron and weighs almost as much - if not as much as the crankcase. It is not what is illustrated in the original owner's manual and I suspect that, after the fact, the company decided that they needed an iron sump to stiffen the crankcase. They would have been much better advised to make the crankcase of iron and the sump of aluminum but I'll bet the decision to change the design came late in the game.

 

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The threaded hole in the front of the sump is how you check the oil. This engine pre-dates the invention of the dipstick. You poured oil in until it came out of the hole. The raised section on the bottom of the sump is an oil galley. I'm guessing there were petcocks there to drain it but why were there 2? In any case, it is a handy ting to have because I am going to have to think of a way to drain oil from the timing gear case. Mitchell made no provision for lubricating the timing gears aside from packing the case with grease. Since centrifugal force with throw the grease against the inside of the case that is a poor idea at best and I'm going to have to think up a way to get oil in there and out again.

Edited by JV Puleo (see edit history)
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Hi JV, I hadn't noticed it before but the two photo's above show a lot of similarity's in the design to that of my Teetor. . The front and rear cam bearings use the same sort of separate , bolt in housing for the bearing. And the general 

design of the sump is likewise very close.  I put a couple of new scans into my engine woes thread yesterday, they show the bottom of my engine fairly well. As I have mentioned before the Staver family and the Mitchell family had

reasonably close ties. One of the Teetor family cousins was Staver's plant engineer. Perhaps he dabbled at Mitchell as well ?  I will have to look closely at all my engine printed material and see if Teetor used a center cam bearing similar to yours.

With the exception of your engine being a I.O.E. design vs the Teetor a T head with the second camshaft they are extremely similar when viewed upside down.

I am going to re- read all of your posts from the beginning , it never twigged on me before just how similar the bottom half of the two engines are.

 

Greg

Edited by 1912Staver (see edit history)
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Well...I'll be happy to help in any way. Perhaps I should measure the crankshaft so you can compare it to yours.

You might also try to find some photos of a Jackson engine...it used the separate mountings for the cam and it has internal timing gears. I have a crankcase here and I'll take a photo.

 

Oh... and the Mitchell is actually EOI - the exhaust valves are in the cages. They made no provision for valve guides so when the valves - or the guides wore it just leaked.

 

jp

Edited by JV Puleo (see edit history)
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Here is the Jackson crankcase. It's a bit heavier than the Mitchell and, I think, a bit more robust. The camshaft goes in on the side where it is resting. Notice that the gear that drives the camshaft, and the gear that drives the magneto are inside the case. There is no timing cover, nor is there it big intermediate timing bear.

 

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I started on the Mitchell today by chasing the threads in the original holes for the main bearing studs. This is just so that the centering tool will screw in easily. One of the reasons I'm doing this (aside from the fact that this old aluminum is not very strong) is that the Mitchell method of securing the studs was to cut a slot in the end and, after they were in, to spread them with a chisel. They were a bear to take out and in doing so it was clear that unscrewing them was damaging the threads. Would they work? probably - as there are 4 of them on each cap but I really didn't like it and I know I'd be worried that they might come loose.

 

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I put the crankshaft in the case to see how it fits. Converting this to bronze shells is a fairly complicated job and I wanted an idea where I was going. I's probably been close to 8 years since I took it apart. This is the front bearing, the only one I'm really concerned with because the hole is rather close to the edge. I must have measured this thing a dozen times but, ultimately, decided to go ahead.

 

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Before I started on the case I drilled a hole in a piece of aluminum to test the end mill and the tap...just in case I made an error somewhere. It's better to find out now before I damage an otherwise unobtainable part.

 

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It seemed fine so I went ahead with the crankcase. In this case the centering fixture is a flat head socket cap screw that has been center drilled. I used this to line the hole up with the spindle.

 

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I then bored it with the end mill, threaded it without moving anything and screwed the insert in. By the end of the day, I'd done 4 of them, including one of those I was worried about.

 

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So far, so good. I should finish this tomorrow and then make the studs that will hold the caps down.

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Done. I tried all the caps and they fit just fine but this was a serious tension inducing job. Now I'll make the studs. Interestingly, I had a bit of a search to find grade 5 castellated nuts. The grade 2's are available everywhere but it is desirable to match the nut to the stud or bolt. I'm making the studs out of Stressproof which has just about the same tensile strength as grade 5. With four 7/16 studs on each cap there is no need to go to grade 8 - the original bolts were about as hard as soap.

 

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The only holes I'm not putting inserts in are those for the studs that hold the blocks and the lifters. In both case there is room inside the engine for a lock nut...those will be castellated as well.

Edited by JV Puleo (see edit history)
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Great progress ! , I have been re - reading from the start. I had forgotten just how much work you have done up to this point and how detailed you have been writing it all up. Quite remarkable. 

Thanks for the Jackson crankcase photo.  My crankcase would be quite similar with regards to the built in timing chest. Except Teetor uses a rectangular sump like your Mitchell.

I had also forgotten that your car also used a sub frame. Interesting that there is not as much distance between the main frame and the sub frame as I am used to seeing.  

 

Greg

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My default setting for finding odd industrial products is ebay. In fact, it's about all I use it for these days. fortunately, a lot of the stuff I'm looking for has a very limited market so you can find some bargains. A week ago I searched for a 1"-20 bottoming tap...which I need for exactly 1 hole. The cheapest was 14.20 + shipping, a very good buy. I wondered if the person who listed it made a mistake though because they seemed to be offering 6 of them for that price. I bought it...thinking it was cheap for even 1. This is what I got...

 

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So if anyone needs one... I've got extras.

 

I planned to make the studs for the main bearing caps today. Much to my surprise - because it isn't like me, I forgot to get the materials. I went ahead and made 1 as they are a bit fussy and it might be a good idea to work the dimensions out ahead of time rather than make 12 and then decide aren't right.

 

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The tricky part is drilling a hole for the split pin in exactly the right spot. I was thinking of making a tool and remembered I had one - made some time ago when I was making the rockers.

 

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I think I got the hole a bit too low. I can adjust that but I'd better wait until I have the nuts and washers.

 

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Hello Joe,

 

Great progress! Good idea in regards to the threaded inserts. A few years ago 

I talked with a gentleman that at one time was involved with the Burrowes automobile in the Maine State Museum.

He said that one of the problems was the studs pulling out of the aluminum which was of questionable quality.

 

Again, great to see progress!

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I think the early car makers were madly in love with aluminum. Given the low power of early engines saving weight was critical. My pre-1900 Panhard had a number of aluminum parts, including the transmission case. Looking at it with hindsight, it was very poor quality material - of course not to them but it simply hadn't been available in commercial quantities long enough for anyone to have a good idea how it would stand up in use and, of course, no one, then or now was building a car to last 100 years. It's interesting that by 1912 it was acknowledged that it was a poor material for holding threads and makers were encouraged not to use it that way. They did, but for reasons that had nothing to do with long-term reliability. I'd be more critical were it not that I've had a couple of experiences with modern cars (i.e. built in the last 10 or 15 years) that did exactly the same thing, with the same results, and that is with the advantage of hindsight and modern metallurgy.

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19 hours ago, 1912Staver said:

I had also forgotten that your car also used a sub frame. Interesting that there is not as much distance between the main frame and the sub frame as I am used to seeing.  

 

I thought to measure the sub-frame as I was leaving yesterday and realized it it 21" wide so it does not follow the SAE guidelines - which explains whey it looks to be closer to the main chassis rails. It is!

 

 

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Since I'm waiting for the materials to make the studs for the bearing caps I took the water pump apart for, hopefully, the last time to clean out as much of the lapping compound as I could and put in new seals. I doubt the old ones would have leaked but it is hard not to damage them when prying them out and they are relatively cheap so it seemed the prudent thing to do.

 

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I then greased it with the water pump grease I bought in England and plugged the front grease hole with a 3/8-16 grub screw.

 

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I now get to put it on the shelf and forget about it until I assemble the engine.

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Yes. I think that might be the first component that is completely done. If it isn't, it's one of the first.

The studs to hold the bearing caps are proving to be more off a headache than I'd anticipated. It turns out the material I wanted to use isn't available as 7/16" rod. So, I went back to my 1926 SAE handbook and looked up what they recommended for this purpose. It turns out that Grade 5 is probably the right thing so tomorrow I'll see if I can get some bolts that I can make the studs from. I have found matching castle nuts, albeit rather expensive (for nuts)...I guess 7/16 is a size that isn't used much any more especially in the fine thread.

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This post is a question for Edinmass... or anyone else with experience doing this sort of thing.

These are the bearing caps. They have a projection on each side...

 

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When they are bolted down, the projection does not touch the crankcase leaving a gap between the two halves of the bearing.

 

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Presumably, this was to allow the bearing to be shimmed and tightened up by removing a shim or two but the result is that the two halves of the bearing are not in contact. I plan to bore these out and fit bronze inserts that will be Babbitted - the original Babbitt is very thick – almost 1/4" – so there is room for that. But, I don't like the idea of having the two halves of the bearing not in contact so I'm wondering if I should include a provision for shims...maybe removing the projection from the cap and surface grinding it flat. If it was then bored with the shims in place the hole would be round and there would be a small amount of adjustment. Ideally, I think I should dispense the shims but I'm not certain. It would then be necessary to do a perfect job of boring the main bearings leaving no room for adjustment.

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Hello Joe,

 

On the Wisconsin there is a thick shim and a series of thin ones. The Thick shim actually has babbitt tabs

that have to be machined when the bearings are bored.  

 

The shims are actually not as wide as the face by about  1/16"(?) so there would be a gap with the exception of where

the babbitt ends are. The gap or relieved area was there to help lubricate the bearing along its entire length and to collect

grunge or other things that could harm the bearing. I have heard it referred to as a "mud pocket".

 

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Edited by Terry Harper (see edit history)
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RR used those thick shims with a Babbitted edge as well but there we no additional shims. I notice that the Wisconsin uses dowel pins to locate the caps perfectly. I wonder if I should do that too. I don't think that with modern oil and an air cleaner the bearings are apt to wear enough to ever have need for the shims. Were I to put them in it would only be to adjust for my boring...never having done that before I wonder if I can get it perfect on the first try. But, I plan to make a st of aluminum bearings as a practice run and to use them to hole the crank when I'm working on the connecting rods so I'll get a chance to see if I can hold a tolerance of less than a thousandth.

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I have an opinion, but don’t believe I have enough experience for you to rely on it as a definitive answer. I have been in this hobby a long time, and I only know three people who have made modifications to a block, designed, machined, installed, and successfully driven on their new main bearing shells. The one engine I had my fingers in was a 1910 Pope Hartford, and the work was based on Dyke’s engine books from the 1917-1921 era. Basically it was the same concept as what you are planning. Getting the caps, shells, and crush set up correctly is not easy. One thing I would certainly do, is make multiple pieces for each spot. You have plenty of experience in the machine shop......which is what is most important. And making a trial run is a good idea. With today’s modern oils, and the fact that it’s a low horsepower engine turning rather slowly, I’m sure you will be fine. Using the correct bronze for the shells, and the correct finish for proper Babbitt adhesion is also critical. I would not run any shims. Also, bearing operating temperature and heat transfer between the bronze and aluminum crankcase needs to be looked at, understood, and planned BEFORE you machine anything. Oil failure(lack of oil) is only one thing that causes bearing problems........heat transfer is another. I think reading several different publications from the era, as well as sources today would be prudent. Also, understanding the final thickness of the Babbitt in relationship to the shells also must be understood. Where on the crankshaft do you adjust for thrust? 😎 As all the changes you are making may affect what you do there also. Detailed photos of the crank, and flywheel would be helpful. 👍

Edited by edinmass (see edit history)
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I believe the thrust has to be on the center bearing. I think it was there from the visible wear and that bearing gives me the largest amount of leeway for adjusting the width. I've yet to discover what the optimum thickness for the Babbitt should be but I'm thinking between .040 and .060. I've seen this figure somewhere but at the moment can't remember where. As to heat transfer...that is closely related to how tight the shells fit the bored crankcase. If contact is very good, the heat transfer will be. Thankfully aluminum dissipates heat very well so it may not be quite as critical were it an iron crankcase but putting in a slip of paper to shim up a shell is a big mistake since it acts like an insulator.

 

The flywheel is conventional, bolting to a flange on the crank. It is very large as the car has a cone clutch so not much can be done about lightening it. Actually, I think it has already been skinned because there are no timing marks on it and there should be.

 

[EDIT] Interestingly, some time ago I discussed this with a friend (a Packard guy) who has many years experience with engineering and machine design. He suggested that, with good lubrication, the correct clearances and given the relative slowness of the engine, it would probably work with just bronze bearings. I've actually seen period references to engines made that way but it isn't something I'm prepared to experiment with...maybe some day but I've too much time invested in this to be trying an experiment like that.

Edited by JV Puleo (see edit history)
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Hello Joe,

If you want to dive into the calculations (I have them somewhere) the formulas for calculating plain bearing heat etc.

Its interesting to think that in the mechanical engineering world a shaft supported by three bearings

is considered to be a major no no. yet its so common in motor design.

 

Correct, A rule of thumb is that your shells need to be .001 larger than the bore they fit into to get crush.

The crush helps the shell to fit tight to the bore and to maximize contact with the crankcase to

maximize heat transfer. If your bearings run over 250 degrees than..... well. Lets just say it won't be good.

 

In regards to babbitt thickness I found pretty much the same .020"  to .060" Like almost anything in engineering its a trade-off.

Reading an article on the Liberty V12, At first they used shells with rather thick babbitt. Then they figured out that by thickening the shell

and using a thinner layer of babbitt the bearing was much stiffer and minimized distortion and cracking of the babbitt and held up

much better. Now, babbitt can only entrap particles that are equal or less in size to the thickness of the babbitt. The thicker the babbitt

the larger the particles it can entrap.  However, babbitt is one of those materials that runs counter to "if some is good, more must be better".

Its strength actually decreases with thickness. The thicker the babbitt the less it will withstand distortion. That's why in heavy

machinery they have thick babbitt but its backed by very, very, heavy rigid shells.

 

Its kinda of strange that here you have a material that is soft enough to entrap small bits of metal etc. yet is so brittle.

 

 

Edited by Terry Harper (see edit history)
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I'd be interested in calculating the heat but ultimately there isn't much I can do about it since I'm not designing the engine – just trying to do the best job I can rebuilding it. The options available are limited by the dimensions of the parts. That said, I've worked on enough good quality engines of the period to have a feel for them so I doubt that whatever the final dimensions of the shells are they can be far off. One of the reasons I wanted an oil filter (actually all I have is a very fine screen) as well as an air filter is to get away from the obvious problem these cars had when made, aside from those that weren't helped by the lubricants of the period or the very common practice of putting used oil in a settling tank and re-using it. I have several period plans for such tanks and you can bet that many of these cars got the used oil as soon as they were "old and worthless" - which came a lot sooner then than it does now. I did just order a book... Bearing Design and Application by Wilcox and ? (I forget the second author) published in 1957. Hopefully it will have some worthwhile data.

I'm more concerned about getting the crankshaft thrust right. The crank does not seem to have very substantial thrust surfaces and, because they are radiused, it will be difficult to measure. But, we keep chipping away at the problems and eventually it will come together.

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I did a little reading on bolts last night, looking up the SAE recommendations in the 1926 handbook. The steel recommended for bearing studs and bolts had a tensile strength of 80,000 PSI. According to the McMaster Carr catalog, the tensile strength of grade 5 is 120,000 PSI so I think I'm safe using it. Finding the appropriate rod stock was, however, difficult so I decided to make the studs out of grade 5 bolts. Fortunately, I had 10 so I went out and bought a few more. I cut the heads off first.

 

IMG_2797.thumb.JPG.6d26f7ee47ab2db93adacd2f40b61a5d.JPG

 

Then set them up in the lathe to turn the threaded portion of the bolt down to the length of the longer part of the prototype stud I'd made.

I set a stop on the lathe bed and used the nut you see as both a stop and to smooth out the burrs on the end after turning them.

 

IMG_2798.thumb.JPG.6f49fec382859fe04dbd57887cb172f0.JPG

 

With that done, I marked each one with a cut off tool and then sawed off the extra metal. These are too long, of course, but tomorrow I'll trim the ends and, hopefully, thread them.

 

IMG_2799.thumb.JPG.08ff957b8ce077a4d5311746fe1fbb9f.JPG

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The studs trimmed to the final size. After I did this I also put a chamfer on both ends.

 

IMG_2800.thumb.JPG.fa0a3e5092916d54d7a325ff2449c9a9.JPG

 

Then I put each of them back in the lathe and cut a groove at the end of the thread. This material is too tough to thread with just a die in the die holder. The pressure needed to turn it makes the stud slip in the collet. My idea is to single-point them about 3/4 of the way and then finish with a die. It doesn't thread smoothly either so I'd have to run a die over the finished part just to get rid of the burrs.

 

IMG_2801.thumb.JPG.5ae66a0a970c8b3b7f7330c2ea984e6c.JPG

 

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I cut the threads on the first one .020 deep and used the die holder...

 

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It worked but it was very tough going. On the second one I cut them, .025 deep which is very close to what is supposed to be the finished thread depth. This time it worked perfectly with the die taking off just enough to smooth the threads up.

 

IMG_2805.thumb.JPG.6944bbddbf762abe9579885044332125.JPG

 

You can see the two finished studs at the bottom.

 

Edited by JV Puleo (see edit history)
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While looking at the crankshaft as it lays in the crankcase, I think this engine will offer a challenge to try and improve on the thrust surface of the crankshaft. It looks like the front main is the best place to try and do it, but with such a small crank, it will twist and deflect that far away from the flywheel. I think in the end you will end up using both the front and center main to control the thrust. It looks like that is what the initial design was doing. I have another idea, but would need to see the flywheel first. I think it’s just a case of an inexpensive engine design, that was meant to only last a short time. With all of your upgrades, I expect it will last several lifetimes when your done with rebuilding it. I’m looking forward to it’s “coming out” party..........maybe next year?🤔👍

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3 hours ago, edinmass said:

... just a case of an inexpensive engine design, that was meant to only last a short time. With all of your upgrades, I expect it will last several lifetimes when your done with rebuilding it. I’m looking forward to it’s “coming out” party..........maybe next year?🤔👍

 

I hope it's next year...making the connecting rods will be a challenge but they are the last major component I've yet to start and I've given the process a good deal of thought.

I'm in complete agreement with your assessment. I suspect the major problem was that the company was committed to a price and had to cut every possible corner in order to meet it. Only the fact that they had limited choices for materials has left us with something to work with. If they had pot metal they would have used it everywhere.

 

Mitchell-Lewis claimed to "make everything themselves" but I seriously doubt it. Some of the chassis components, notably the axles and rear end are quite well made and I know they didn't make the springs because the maker's name is on them, albeit in a place where you would never see it unless you took them apart.  The frame itself is very conventional and, to my mind, a bit flimsy but I think that can be addressed readily enough.

 

Tomorrow I'll get some pictures of the flywheel and the mounting flange.

Edited by JV Puleo (see edit history)
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 I know my Staver used Sheldon axles { same as Michigan used } a very robust unit and Warner gear transmission. Very few car makers made their own frame at this time . A.O. Smith and Parish Brothers were the two big names in vehicle frames. 

There was a definite stigma against  " assembled  " cars but many of the smaller makers were indeed assemblers of bought in components even if they claimed to the contrary in press releases and brochures.

Even the very large makers often bought in things like castings and forgings and alloy steel parts. It didn't pay to re - invent the wheel  if there were specialist producers who already had the basic major equipment to turn out high quality components at a 

volume price. As auto makers became huge industrial entity's they sometimes bought up the specialist subcontractors but much was still sub contracted.

 

Greg in Canada

Edited by 1912Staver (see edit history)
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Here's the flywheel end of the crankshaft. In looking at this again (it's been years since I really looked closely at it) I suspect the thrust should go on the rear bearing.

 

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With the cap in place.

 

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And the flywheel itself. It's massive... 16" in diameter and I think it weighs about 75 lbs.

 

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The clutch surface on the inside of the flywheel.

 

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I did get some work done as well. The cap studs all threaded. I now have to drill the holes for the cotter pins and they are finished.

 

IMG_2810.thumb.JPG.3f4a603496f38c36c7775aeb2d605f46.JPG

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High speed steel. I use carbide very rarely because my lathe is far to old to go fast enough for carbide to work correctly. I find grade 5 difficult to machine. I don't know that I'd even try threading grade 8 but I've successfully shortened bolts and faced them off.

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Your going to have to control thrust on the crank with the rear main. Looks like it’s going to be tight......which means challenging and complicated. I would resist the temptation to change or alter the flywheel. Too many people want to “lighten it up” but with such a small engine turning low rpm’s the flywheel mass is an important engineering design addition to make the car drivable.  Your much better off trying to save weight on the custom body your planning on building. Every single pound added to the car is going to drain off performance and speed. I can’t remember, were the rods splash lubrication? I’m having trouble wrapping my head around the entire oiling system. Oil leaking / control on the rear main is not obvious to me in the photos. Also, if the car has splash rods, your going to need to figure out how to keep oil in the pan and windage area for the dippers without running them low with the pump. Whatever was there initially may not be able to handle the pump you built. Maybe a “focus “ on the oiling system with photos would help. I’m not seeing the big picture, and it’s possible to work your way into a corner on the oiling system that you may not be able to work out of. Thoughts? Also, do the main caps have enough material to accept the bronze shells? Or are you planning on making new ones that are larger........then oil pan clearance issues come into play.............”it’s just an old car...........it can’t be that complicated!” 🤔

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The caps are thick enough to handle the shells. It looks as if they may not have done more than a rough boring of the main saddles and used Babbitt metal to make up the difference. The bearings are almost 1/4" thick.

 

As to the oiling... the pump is on the back of the engine and draws oil up from the sump. Because it's a vane pump it has good suction - unlike a gear pump but if the system is dry from standing a long time I've incorporated a hand priming pump. In operation all it does is replicate the original box oiler which probably generated a higher pressure but much lower volume to the mains. I have eliminated the oil line to the rear of the camshaft since that bearing is now inside the oil pump but I've added a line to the center bearing of the cam. Aside from that, the lines run where they originally did they just get their oil from a different pump.

 

I'll make a drawing of the rear main bearing I'm planning...it will be easier than trying to explain it. Essentially, it will have a large flange on the back end (facing the flywheel) which will serve as a thrust surface and provide a place to put a rear main seal. To install it I'll have to mill away about 1/2" of the width of the bearing cap and crankcase - a scary job and once that I'll have to think about very carefully before I do it.

 

The rods are splash lubricated. There were no scoops on the original rods, just a big hole in the big end cap at the bottom and two feeding the top half of the cap with oil pockets. I've yet to give that aspect of the job much thought. I don't think there is room for a windage tray but I will have to take some measurements when it is possible to put more of it together. There will be very change of the internal arrangements aside from forcing oil to the bearings.

 

Oh...and I've no intention of mucking with the flywheel. I suspect  the business of lightening them is overdone. As it is, if the cone clutch is precisely made and balanced it should be smooth and positive. I think about 98% of the complaints about cone clutches are  the result of wear and poor adjustment. The SG had a come clutch that worked perfectly but it was extremely well made.

Edited by JV Puleo (see edit history)
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