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1937 Norton International Build
Part 2

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        Building the Engine - Part 2:                   Last Updated : 25/05/10 (Published 07\10)

Fitting Oil Pump and New Main Bearings
In part 1 of this project I said that originally I was hoping to re-use the original main bearings, as initially they had felt to be in good condition and there was no point replacing them if not required. However, in the process of removing the original bearing retaining plates - which I needed to do in order to get a good look at the bearings (and gave me the excuse to replace these original plates with my own bearing plates), I had found that actually there were tell tale track marks and pitting in the roller bearing, indicating it was scrap.
Even before I had looked at the drive side roller, I had removed the timing side bearing retaining plate, and a potentially more serious problem had manifested itself, in that just heating up the bearing plate with a blowtorch, so as to melt the solder had put enough heat into the crankcase that it had caused the timing side main bearing to drop out.
Normally a main bearing should only drop out once the crankcase had been put in the oven for some time, so this was not a good sign.

Crankcases, with everything stripped, just before blasting.
Notice breather hole in timing case, above lower screw hole, not fitted on all engines
 Old Bearing
As I touched on in Part 1, the original roller main bearing had seen better days, and was just showing signs of having started spinning - see slight marks on outer track
  On close inspection of the bearing wall of the crankcase, there were slight signs of the bearing starting to spin, a faint greyness of the metal, and corresponding marks on the outer track of the bearing. If this was allowed to continue it would soon result in the crankcase journals becoming worn and ruined, then would need to be sleeved and jig bored - a complicated and costly job. In the case of this engine it looks like I might just have caught them in time, but it made the decision to change the bearings very simple.
It will be something I need to be aware of when I run the new engine, because although I think it had only just started to occur, and I will use bearing fit when I fit the new bearings, I need to ensure that this does not continue to happen - as it will soon destroy the housings.
I am fitting the correct 'C3' type bearings, as were originally fitted to these engines, which have a looser tolerence than the standard size bearings and because of ths extra tolerence are less inclined to spin. Anyway before I get to fitting the new main bearings, what about the oil pump?
Oil Pump Refurbishment
It is always a difficult choice when refurbishing these engines, trying to decide if the oil pump should be removed and checked, as this is not always an easy task?, however, I would advise that if there is any doubt as to the condition of the oil pump, or if you are not familiar with the engines history, then this should be removed and checked. It is a good idea first to check if the pump drive will revolve freely, as that will give some clue, but if there is any kind of roughness or locking up, do not force the gears, this might make matters worse - just wait until the pump is removed and then strip it.
Removing the two screws that retain the oil pump. Unfortunately the pump did not then magically jump out and a trip to the oven and a small amount of force was necessary

In the case of this engine, removing the oil pump first meant removing the two retaining screws then placing the crankcases in the oven to get them good and hot. Sometimes once hot the pump will drop out of its own accord, but in this case that did not happen, and therefore further encouragement was required. Sometimes you may be lucky and find the body of the pump has been threaded so that studs can be screwed in and a 1” x 6” placed over the timing case, to act as a puller by screwing nuts along the studs. In this case unfortunately the oil pump was not threaded and even with the crankcases ‘spit’ hot (stick head in oven and spit at crankcases. If the spit bounces back at you the crankcases are hot enough – use thick ovengloves or rags to remove crankcases, they are now very hot!) the oil pump was showing no signs of movement.

Oil Pump Stripped
The pump finally removed and stripped to its component parts
  Getting it Out . . .
As with many Inter crankcases, there was a hole drilled behind the oil pump to assist with removing the pump, if all else fails, this allowed me to use a small drift, to tap the oil pump out from behind. It was actually in quite hard and therefore I had to use far more force than was ideal, and with each bang of the hammer I had visions of the gears crunching, or the monkey metal body deforming, as the steel punch drove home. Luckily, I could see there was a brass plate behind the pump - a common thing to find, it stops the backgears wearing against the crankcase wall, and hopefully this would take the brunt of the force
Eventually, after what seemed a long and painful period of time, the pump had loosened off to almost drop out the last half an inch and I breathed a sigh of relief. As expected the punch had done a little bit of damage, just catching one of the back gears, but this was not serious and was carefully bought back to shape with judicious use of a swiss file. I was pleased to find no serious scores or gauges in the body, and although the gears had a slight sharpness on one end, they also looked in generally good condition with no nasty notches or damaged teeth – so often the case when a piece of foreign debris has made its way through the pump.
On that subject, a mildly amusing story comes to mind. A few years ago I saw advertised a collection of oil pump parts. The price was not excessive so I took a punt and bought them without seeing them (I should have known this would be a bad move, as I had an idea who the seller was and thought this might be their cast off’s). When they arrived there was a collection of oil pump parts that would originally have compromised approximately 8 – 10 pumps. Of these 100 - 150 parts, I don’t think there were more than 2 to 3 of them that could be in any way classed as usable! Of the others, I have never seen such a rotten collection of scrap in my life. Every pump body showed heavy score marks and gauges in the areas surrounding the gear wheels, where lumps of debris had been forced round the pump under duress! The gears were all chewed and even some of the shafts looked bent. What it does illustrate is that you should not take it for granted that the pump will be ok, even if it is capable of turning. If the body is badly chewed, or the gears damaged, it will seriously reduce the efficiency of the pump.

In the case of this engines pump, I could see that the pump was actually in very good condition, and as can be seen from the photographs, there was no heavy scoring to the body. My normal process for maintenance of an oil pump is first to meticulously degrease and clean it, then loosely re-assemble it with clean oil.
Oil Pump Stripped
As can be seen, the sidewalls were in good condition and relatively unmarked, which was nice

As is often the case, I found that the gears would not turn freely, even after cleaning, so I spent the next hour very carefully running a swiss file round each gear removing any signs of burrs or high spots. By the way, it is important when stripping pumps to ensure you note which way the gear sits, relative to the pump body, so you reassemble in the same plane as you stripped it. The reason for this, is that you can find that the gear occasionally ‘flattens’ at the end it touch’s the end plate, and therefore the gears become ‘sided’. I confess I forgot to do this in this case, so had to be extra careful when I re-assembled until I figured out which side went where (you can sometimes see matching wear marks on corresponding gears – I tend to use an eyepiece to check). After what seemed a very long time, the gears were able to slide back into the pump far easier and gently revolving the pump drive with a suitable drive tang (an old oil pump drive plate is good for this) gave that lovely satisfying feeling of gears revolving smoothly together. The last step of the refurnishing process was to take the brass side plate (the plate that the drive shaft fits through) and remove the score marks where the oil pump gears have been revolving. I first of all put this plate (carefully) on my linishing machine, using a fine belt, until all traces of the scoring are removed. I then put it on a surface plate using fine wet and dry (with light oil sprayed on it) for the final clean.

Having washed all parts again in the degreaser (and put an airline on them all), I carefully reassembled for the last time, using lots of clean castor oil. The oil pump body is in two parts, with the small set of pump gears sitting in the smaller side. These two bodies are clamped together with two screws. When re-assembling, I just screw them together finger tight then spin the gears again, while final tightening, to ensure everything finds its proper place, to give the best operation. The final result was an oil pump that felt totally different to the one that first came out, and was lovely and smooth in operation, with lots of gurgling castor oil passing through it – very satisfying!      
Oil Pump brass cover
I forgot to take a 'before' photo, but there were heavy score marks in the brass cover, made by the pump gears. They were removed on my linisher, before final wet\dry polishing on a surface plate
Oil Pump Complete
Final re-furbished oil pump, ready to go back in crankcase. Old brass shim (bottom) was replaced with new steel shim (right)
Re-Fitting Pump and Main Bearing – Timing Side
Obviously, the thing to get right when refitting the oil pump is to ensure you get it in in the right location, as it is cylindrical and there are no guiding channels. As this pump was so difficult to remove, I also knew I would only get a couple of seconds before the heat in the crankcase transferred to the oil pump and everything locked up! To help with this process I use a very simple tool, this being a shaft the same diameter as the securing screws, with a thread on one end and a slot for a screwdriver at the other end. I screw this into one of the threaded holes in the crankcase before I place the crankcase in the oven, so it provides a guide for the oil pump to slide down, and ensures it must locate correctly – simple. Once the oil pump is fitted, this can then be removed and the proper securing screws can be refitted. This should be done with the crankcases still hot, to ensure the pump is fully bolted home, before the crankcases have cooled and ‘shrunk’ around the oil pump, locking it.

The other thing I had to do before finally fitting the pump was to make a new ‘backplate shim’. I am not sure if these were fitted by Norton’s originally (I have seen crankcases with gear wear marks on the backwall, so presumably they were not), but it is not unusual to find them fitted, which to me seems a good idea, and means the shim then takes any future wear, rather than the crankcases itself (Not sure really why Norton’s themselves did not design the oil pump to have a plate on both ends). The one I removed from this engine was the normal brass jobbie, but as I mentioned earlier, because I had to use a punch to remove the pump, this shim had been badly deformed and where the punch had hit it, there was a little circle of brass that was almost broken away. I did not have any brass (used normally because it is relatively soft), but did have some shim steel of the same thickness, so got my scissors out and soon had a new shim made that slotted in to the oil pump recess nicely.
Fitting pump locating pin
Before placing crankcase in oven, I screw in the oil pump locating peg and drop the shim in to the base of the pump housing
Crankcase in Oven
And finally, place crankcase on a baking tray and cook at full temperature until nicely browned, or spit bounces off . . .
(just kidding)
Refitting Pump
Having dropped the pump into the hot crankcases, a firm tap with an alloy drift ensures it is seated and fully home
I then placed the oil pump in a freezer bag and placed it in the freezer, next to the main bearings I had already put in there a couple of hours before. I don’t know about you, but I often get a nose turned up, when I mention this to friends – particularly friends wife’s! Similarly, when I talk about placing crankcases in the oven to make them expand. I explain to them that my engine parts are normally cleaner than the oven I am putting them into, but this bit tends to fall on deaf ears!. Luckily, I have a long suffering wife who is used to such things (as was my mother, with my father before me), and her main bugbear is that invariably I leave oily fingerprints on the freezer or oven door!
  So with the timing side crankcase final cleaned, to ensure it was spotless, I then put it into a really hot oven, while I prepared the work surface of the bench, with suitable alloy drifts, hammers and the large spacer rings I use to rest crankcases on, to provide a firm surface to press against. Once the crankcase half was at a suitable temperature it was just a case of working fast and methodically. First the assembled oil pump was dropped in, ensuring the shim was still in place and that I had got the orientation correct (it is still possible to get the pump 180 degrees out, even with a locating pin in place). I was pleased to feel that the oil pump dropped almost all the way down immediately, into its well, before I need to apply a light tap with a large alloy drift, which ensured it was touching the back wall. Then quickly I removed the guiding pin and replaced the two oil pump screws that lock the pump to the crankcase body – job done. Final step is to just quickly revolve the oil pump drive gear again and ensure the gears still turn, again, do this with the crankcases still hot, just to let everything seat correctly.
Fitting the Timing Side Main Bearing
This only took a couple of minutes, so I tested the crankcase and found it still very hot, so a quick dash to the freezer again and I retrieved the timing side ball bearing and carefully removed it from its protective packaging. As I knew the original bearing had started to spin in its journal, using a Bearing Fit compound on reassembly would be an essential. I quickly and carefully smeared the outer face of the new bearing with this, ensuring it was evenly coated across the full surface, then lined the bearing up square above the crankcase journal, holding it by its inner race – and dropped! I was rewarded by seeing it drop instantly all the way into the journal, and hearing a slight clink as it hit bottom. Just to be sure I placed one of my wide bearing drifts (i.e. the drift only touch’s on the outer bearing race, not the inner) on the bearing and gave it a quick tap with a mallet, ensuring it was definitely seated fully home and square. Job done.

I then carefully removed the crankcase from the workbench and placed it on a clean spot on the garage floor to let it cool down a bit before I went back to put the bearing retaining plate on. This is a difficult choice, as the retaining screws need to be soldered to stop them from coming out, and to do this needs the crankcases to be quite warm, as they act as a heatsink, stopping the solder flowing freely, but I also wanted to give the crankcases enough time to cool and ‘grasp’ the main bearing, before moving on.
I used the few minutes while I was waiting to place the drive side crankcase in the oven, to repeat the process.
Bearings in Freezer
To ensure the main bearings are as cold (and shrunk) as much as possible, place them in the freezer at least a couple of hours before fitting them
Preparing Workbench
Drive side crankcase has just come out of the oven and is placed on large steel spacer that supports the bearing housing while bearings go in
Bearing Spacers
Drive side spacers, that fit between ball and roller bearings. Note large dished washer which is very rare to see
Bearing Fit Fluid
Before dropping each bearing in I applied a liberal smear of Bearing Fit Fluid to the bearing outer wall. Apologies for blurred photograph but I was in a bit of a hurry!
Drive Side Bearings
For the drive side, fitting new main bearings is pretty much straightforward and relatively simple. The only points to be aware of, are to ensure that the outer and inner spacers are fitted between the ball and roller bearing. The ball goes in first (I do it with the writing on the bearing facing me, not sure if this makes a difference, but I remember being told many years ago this was the face you should hit, if having to drift the bearing in). Then the outer bearing spacer, with the holes drilled in it (to ensure oil flows to the outer bearing in operation), then carefully and quickly place the smaller inner spacer on the inner race of the ball bearing.

Finally the roller bearing is removed from its packaging and dropped in, ensuring the lip is innermost (you are using a lipped roller aren’t you??, I have stripped a few engines where these have not been used, but they should be). Final step is again to use the bearing drift to ensure the bearings are fully seated and square, and again I was rewarded with that slight metallic sound, telling me the bottom bearing was touching the bottom face of the crankcase journal. Good stuff.
Again, with both bearings I had decided to be safe and use Bearing Fit compound to ensure the best possible chance against spinning the new bearings.
As with the timing side crankcase, I now placed these onto the garage floor and put a small piece of clean cloth over the bearings themselves, to ensure no bits of crud got in while I was working on the other crankcase.
Mains Fitted
Drive side bearings now fitted. There is something about the look of brand new bearings smothered in hot, clean castor oil that cannot be beaten!
Fitting Bearing Plates
Fitting new bearing plates and screws. I am using a screwdriver with the facility to take a spanner, to give extra purchase
Fitting the Bearing Retainer Plates
Once the bearings have been fitted in the drive side crankcase I can revert my attention back to the timing side crankcase, which has now cooled down sufficiently for me to touch it without a cloth, although still quite warm. First of all I check the bearing by lightly spinning its inner race and am glad to feel that although still far from cool, the outer bearing race looks to be quite firmly held. Now for fitting the bearing plate, which is held by 3 countersunk screws. Even though the bearing plate is brand new, I still degrease it and remove any trace of dirt, ditto with the screws themselves, which I also just put up against my rotary wire brush (despite advice from my old friend Arthur, who tells me this is not good practice for soldering.
Anyway, the bearing plate is fitted, with each screw being loosely screwed in first, to ensure there is no chance of cross threading any of them, before tightening each in turn. I use a screwdriver which has a facility for a screwdriver to be put on it, to get them in quite hard. Finally, I give each screw a tap with an impact driver before soldering over the heads.
For those that have tried this process, you might find it is quite difficult to get the solder to run freely on the heads and bearing plates. I have found this is invariably because the crankcases are not hot enough and are just absorbing heat. Having already warmed the crankcases up, and using new plates and screws, I found the solder ran quite freely and easily. I use a good quality soldering flux and place a bit of this on both screw and plate corner first.

The other thing to be careful of when soldering is to ensure that once the solder has flowed and you have let it cool, you are very careful to remove any loose solder that has spattered, so it does not go into the bearings or any of the oilway’s, this is much easier to do than you may think. By the way, I have tried soldering irons to do this task, but have never had much luck, so I use a butane torch, which seems to work well.
Soldering over the screws
Final job is to solder over each bearing plate screw, so they cannot work loose in operation
Well, that about does it for the main bearings and oil pump. I have to say, I am always pleased when I have got these two jobs done and I can relax a bit. Next stage will be to complete the bottom end assembly, shimming the crank and fitting lower bevel housings etc, and I will cover this in my next update shortly.
For the moment, I need to go and fettle the doubleknocker ready for my annual trip to Mallory 1000 Bike Festival, so it may be a little while until this engine gets another look in.


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Initial Stripdown and Crank Balancing
'37 Norton Inter Part 1


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37 Norton Inter Part 3


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