Sunday, 26 April 2015
Tuesday, 21 April 2015
-JdK- Dan in the UK found this 1929 Norton Model 18 in Essex and took it home. The previous owner John Lee advised it was raced during and prior to his ownership and that the engine was built and tuned by Stan Johnson.
Monday, 13 April 2015
Updated 13th April
-JdK- One of the most annoying nuts on a Carroll OHC engine must be the nut holding the bevel on the camshaft. I may be 'teaching grandmother to suck eggs' but it took me two weeks to tighten this nut so here's the story.
The best way to assemble a Carroll cambox may be to first fit the bevel to the camshaft and tighten this nut. Then the camshaft can pushed through the bearing in the cambox, and spacer, cams and roller bearing fitted whereafter the nut on the other side of the camshaft can be tightened. The problem is that this is a left-hand nut. The camshaft is locked with a spanner using the nut at the bevel side but as this one is a right-hand nut, when one nut is tightened the other nut may come loose and vice-versa.
So the nut holding the bevel should be very tight. The 'square' at the end of the camshaft is easily damaged and cannot be used; further, the camshafts are made from unhardened steel like EN8 and can be easily twisted and damaged when you apply brute force.
The best way seems to be to just grip the bevel between two pieces of wood (shaped like in the photo above) in a vice. This looks brutal but the teeth on the bevel will be embedded in the wood and the torque will be spread over a large part of the bevel. It won't damage the bevel.
When doing this I found out the bevel needs to be gripped very tight in the vice otherwise the wood will splinter. I used good quality Meranti hardwood and a one-meter length of steel pipe to tighten up the vice. This was required because the nut needed 200 Nm torque (that is a lot!) before it was tight enough to allow the left-hand nut at the other side of the shaft to be torqued to 50 Nm. This is probably because the nut at the bevel side hardly moves once torqued up to around 40 Nm. It needs a really good pull with a very long spanner before it moves after that!
(Ian Bennett and Dr George also use this method and around 200 Nm to tighten this nut. Others suggest to just fit the cambox the engine, lock the crank and then tighten the nuts on the camshaft; that means putting a lot of torque on the teeth of the bevels. Perhaps the engine may withstand such abuse but it doesn't feel right to me.)
Update by Dr George on the 13th April: "I was inspired by this article and decided to upgrade my tired old lead jaws. Below is my new tool; it's two alloy plates with two thicknesses of roofing lead. It works perfectly!"
Saturday, 11 April 2015
Friday, 10 April 2015
-SG- Here's an uncommon shot of Bennett and his 1925 Senior TT Works Norton. Interestingly another photo popped up that was made seconds before or after the other one.
The oil pump adjuster is visible on the oil pump cover (it was simplified in '26 and onwards) and one can see the drooping footrest - damaged when Bennett had a minor 'off' during the event. Note also the front brake - still very small but with brake arm pointing forward. Small or not, I can tell you from personal experience this makes otherwise rather useless small Vintage brakes infinitely better!
Sunday, 5 April 2015
-JdK- While checking over my 1927 Model 18 last summer I discovered that one of the valve springs was broken. Rather annoying as they come in a different size compared to the later OHV models and are difficult to find. I managed to buy a few sets but as all the original Norton stock is now gone they are all replica and -not surprisingly- all different. I sent them off to Viktor for a closer look.
|Dimensions of the 1920s Model 18 valve springs and the recorded data. In blue the old/used spring; in green the replica spring from Czech Republic. In purple and red the two replica springs from the UK.|
Viktor does everything with great care and took a scientific approach. The tension of the springs was measured at 41 mm; that's how far the springs are compressed when the valve is closed. And at 30.8 mm; that's the compression at full lift when using a standard W7 Model 18 cam.
The outcome is that the strength of the springs differ a lot, see the summary in the table above. Both UK replica springs constantly apply around 10 kg extra pressure on all the delicate parts of your Model 18 valve train and this is bad news; it will result in a lot of extra wear, especially on the cams and the followers.
My 1927 Model 18 has been tuned with a high compression piston and IT cams, it goes like stink and it likes to rev. It does so on the softest springs I could find; the old/used springs in the table above. So I suggest there is no need at all for stronger springs in a flat tank OHV Norton.
If you have ever new springs made you could probably ask the supplier to use the data as presented in the figures above.
Do realize that the 41mm/30.8 mm dimensions are for a c1927 Model 18. For other models/years valve stem length, position of the collets and dimensions of both the top and bottom collars etc. may differ which may affect spring pressure.
Friday, 3 April 2015
Saturday, 28 March 2015
-JdK- Juergen in Germany has SOLD these wheels
Sunday, 22 March 2015
-JdK- Malte recently sold his 1939 Model CS1; an interesting machine as it has seen little modification since it left the factory. In Malthe's own words: "This bike has not been restored. Most details are as when it left the factory. All numbers match. The only new parts are new (old stock) Dunlop rims fitted in the 1970's. It has had three owners from new and all are related (two friends and 1 son-in-law). I partly dismantled the machine years ago to give it a thorough cleaning. 99.9% of the nuts and bolts are still the original dull plated and undamaged items. When you then add the original cloth cables and electric wiring which is very, very brittle, very brittle rubbers for the tank fitment, original levers, original ammeter, clips holding the wire to the rear mudguard, dull chrome petrol and oil pipes (which were almost black from oil and petrol, before I cleaned them up) etc. etc it suggests to me that this bike has not seen much, if any modifications.
-Richard- This one indeed looks very original. It does have a left hand (nearside) front brake plate; also notice that the speedo drive gearbox is in the wrong place. The brake will still work O.K. but it will put undue stress on the fork leg as the correct plate puts the pressure vertically up the fork tubes. This plate will put a horizontal force on the fork tubes. Perhaps it was replaced when the original one got lost and a right hand brake plate could not be found?
Malte does point out that the 1939 Norton parts catalog actually lists this brake plate (part number 3650) as fitted as correct for the CS1; see the copies from the catalogue below! We suggest the catalogue is outdated and that any wheel with a right hand brake should have a 3651 right hand brake plate or similar; like the Models 30 and 40.
Another small feature is the chromium dome on the front of the primary chain-case. This chaincase is chromium plated all over and then painted black only to leave the dome and edge plated. We understand from the records that the machine was delivered with a chromium plated chaincase so this should be the original item. It's a very minor and confusing detail but black chaincases with a chrome plated dome (thus no chrome underneath the black paint) were a feature for one season (1945/6 ) only.
Tuesday, 17 March 2015
-Richard- Some photo's to identify Norton girders. The pictures of the forks in-situ (above) are 1946 Model 16H type. The main points are the four headlamp lugs (Inters never had these) and the off-side brake anchor. The four small headlamp lugs were only used on the post war girders. I have seen a couple of Inters fitted with (modified versions of) these forks in recent years.
|Inter', left; 16H/ES2 etc right|
The other photo's show the forks from my 1939 Model 30 Inter' (left) alongside a set of blades from circa 1933 16H/ES2 type for comparison (on the right) as these are the same dimensions as the 1946 ones. All Norton girders have the same dimension across the top spindle but the difference at the bottom spindle is half an inch wider on the splayed 1946 type which has the interchangeable wheels.
Also notice the brake plate anchor which is oval on the Inter' instead of round and the position of the cable fitting lug which is separate and much higher than the standard forks. These features were used from 1936 to '39.
Splayed girders from a Model 16H etc. can be modified to resemble Inter forks. There are three levels of craftsmanship to do this:
- Cut the bottom forging of the blades and remove material and then braze back together and line ream the forging and also reduce the width of the headstock bottom yolk all of which is best done by someone with the relevant skills.
- Heat the fork tubes below the bottom forging and bend the tubes to a suitable pre made jig, bit of a bodge but it would work.
- Bend the tubes cold and hope no one notices (AARGHH !!)