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Re: Another 500T

Posted by christian_wyss at September 05. 2018

Hello,

Just had the chance to get a nice 500T. For those interested in records, it has F3T 40283 number.

Engine is running, sometimes real hot (have to learn about how to use manual advance) but the gearbox looks strange. In any case for me.

Gearbox lever is moving a lot up and down and 1st gear won't hold.

Is it possible to find a picture of what's inside (sorry don't know how you call it) the "box" where an axle comes out for the gear lever.

 

Also got some spares for the gearbox.

 

Thank you for your help.

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Re: Another 500T

Posted by George Phillips at September 06. 2018

That's a "doll's head" g/box, Christian.

If you Google "inside a doll's head gearbox" you'll get lots of pics and info.

The numbers put it around 1951 although I'm not sure hat the dollshead was still used then. Perhaps someone knows?

George

Re: Another 500T

Posted by ian_soady at September 06. 2018

The main problem with this box is the exposed clevis joints that connect the positive stop with the camplate (to be seen just to the right of the gearbox in your first picture). These wear badly especially on a trials iron and cause a lot of lost motion.

Congratulations on your purchase - looks like a nice bike and seems to have the correct fork yokes.

Another thing to check is end float on the gearbox mainshaft - that bronze washer in your second photo controls it. It can cause clutch drag as the first part of the clutch pushrod travel is used up pushing the mainshaft sideways.

As I understand it, the dollshead was still used on the 500T as there wasn't room for the laydown box.

Re: Another 500T

Posted by paul_standeven at September 06. 2018

The doll's head gearbox is the pre-WW2 item, but was fitted to the 500T, probably for easier access to the clutch lifter mechanism.

Excess lost movement is what you will have to chase.

As stated above, the doll's head and vertical boxes are prone to wear in the link between positive stop mechanism and cam plate.  That on its own can cause gear engagement issues.

If you have more than a little mainshaft end float, it will affect clutch lift, cause drag, and therefore make selection difficult.  If you have too much, then you need a new bronze thrust washer, or make a steel shim to reduce it.

Bu your first gear failing to engage properly sounds like insufficient movement in the first gear selector, so if it's not the external link, then the layshaft may need shimming to move the kickstart pinion to the left for better engagement..  If the box does not respond to this, then check the selector fork for wear, especially the lug where it engages the cam plate.  That may be the issue.

Once you have sorted those out, you can think about losing some of the lost movement in the positive stop mechanism.....

For the REALLY keen, these early boxes can be given a special up-grade.  The cam-plate is bigger in diameter than on the horizontal box, but the selector tracks are in the same place.  There's lots of excess metal in the perimeter.  It should be possible to grind the indent plunger profile to match the AMC cam-plate, and mate it to a long-travel indent  plunger of similar design.  You will then have a REALLY good Norton box, potentially as good as an AMC (with similar wide ratios) without the clutch lifter issues.  I haven't done this mod (yet), as I don't have a suitable box in a bike.  But I may do it for the hell of it

Paul

Re: Another 500T

Posted by jonathan_newton at September 06. 2018

Previously paul_standeven wrote:

The doll's head gearbox is the pre-WW2 item, but was fitted to the 500T, probably for easier access to the clutch lifter mechanism.

Excess lost movement is what you will have to chase.

As stated above, the doll's head and vertical boxes are prone to wear in the link between positive stop mechanism and cam plate.  That on its own can cause gear engagement issues.

If you have more than a little mainshaft end float, it will affect clutch lift, cause drag, and therefore make selection difficult.  If you have too much, then you need a new bronze thrust washer, or make a steel shim to reduce it.

Bu your first gear failing to engage properly sounds like insufficient movement in the first gear selector, so if it's not the external link, then the layshaft may need shimming to move the kickstart pinion to the left for better engagement..  If the box does not respond to this, then check the selector fork for wear, especially the lug where it engages the cam plate.  That may be the issue.

Once you have sorted those out, you can think about losing some of the lost movement in the positive stop mechanism.....

For the REALLY keen, these early boxes can be given a special up-grade.  The cam-plate is bigger in diameter than on the horizontal box, but the selector tracks are in the same place.  There's lots of excess metal in the perimeter.  It should be possible to grind the indent plunger profile to match the AMC cam-plate, and mate it to a long-travel indent  plunger of similar design.  You will then have a REALLY good Norton box, potentially as good as an AMC (with similar wide ratios) without the clutch lifter issues.  I haven't done this mod (yet), as I don't have a suitable box in a bike.  But I may do it for the hell of it

Paul

 

I got to say that is one hell of gear lever no wonder you got excess rotation.  Is that how they were or is it a hand  change mounted horizontaly.  Any play in the change mechanism will be magnified by that.  For sure rederess the linkage issues but, as you trials boys rarely change gear on the move wouldnt a short alloy heal and toe changer work.  PS: nice machine, very nice 

 

Jon

Re: Another 500T

Posted by ian_soady at September 06. 2018

I think that's a standard 500T gear lever.

An original 500T like this one would sadly be completely uncompetitive in most current pre-65 events.

Re: Another 500T

Posted by paul_standeven at September 07. 2018

The doll's head and vertical boxes are substantially 1920s Sturmey Archer boxes with a positive stop mechanism tacked on.  It would be very easy to convert any early Norton box, up to the horizontal, to hand change, with a link from the cam plate sector.

Paul

 

Previously jonathan_newton wrote:

I got to say that is one hell of gear lever no wonder you got excess rotation.  Is that how they were or is it a hand  change mounted horizontaly.  Any play in the change mechanism will be magnified by that.  For sure rederess the linkage issues but, as you trials boys rarely change gear on the move wouldnt a short alloy heal and toe changer work.  PS: nice machine, very nice

Jon

Re: Another 500T

Posted by ian_soady at September 08. 2018

I'm not sure why anyone would want to convert to hand change?

Re: Another 500T

Posted by christian_wyss at September 09. 2018

Thank you all for your replies. Like I'm French, it's going to take me some time to really understand all that, but it's part of the game.

 

"looks like a nice bike and seems to have the correct fork yokes"

How can you tell that?
Asking because for me it looks like the "steering stop" on the frame doesn't touch the fork and then it's the fork which can hit the tank.

 

About the manual advance, is it a on/off one, just start and run position, or does it need to be adjusted "all the time"?

 

Christian

Re: Another 500T

Posted by George Phillips at September 09. 2018

With reference to your manual advance query, Christian, it's normal to retard for starting then move it to full advance. I usually retard it a bit when waiting at traffic lights and other hold ups or if slogging up a hill.

George

Re: Another 500T

Posted by christian_wyss at September 10. 2018

OK, always good to know, thanks George.

Re: Another 500T

Posted by ian_soady at September 10. 2018
Previously christian_wyss wrote:

Thank you all for your replies. Like I'm French, it's going to take me some time to really understand all that, but it's part of the game.

 

"looks like a nice bike and seems to have the correct fork yokes"

 

Christian

The standard Roadholder yokes carry the fork legs well forward of the steering column stem. Someone (I believe the McCandless brothers) found that by reversing the bottom yoke it reduced the trail making the steering more suitable for trials.

Maybe you need extended steering stops?

As regards the advance / retard, if you're actually riding in a trial this is a very useful control as it can give you excellent low speed pulling. But on a road bike it's mainly used for starting.

Re: Another 500T

Posted by christian_wyss at September 10. 2018

 

 

The standard Roadholder yokes carry the fork legs well forward of the steering column stem. Someone (I believe the McCandless brothers) found that by reversing the bottom yoke it reduced the trail making the steering more suitable for trials.

 

Maybe you need extended steering stops?

 

As regards the advance / retard, if you're actually riding in a trial this is a very useful control as it can give you excellent low speed pulling. But on a road bike it's mainly used for starting.

 

 

Would try to make some pictures for better understanding. Soon...

Re: Another 500T

Posted by richard_cornish at September 11. 2018

Hi Christian,

   Your 500T looks in very original condition with only a few small parts that have been changed. The 500T frame was very similar to the pre-war trials specification Model 18. This was fitted with the "doll's head" gearbox and so the easiest and cheapest way was to carry on using the same. Also if you look at the rear of the frame you will see the rear tubes are shorter to shorten the wheel base for turning tighter corners which would make the fitting of the lay-down 'box too tight to fit in..

   Inside the "doll's head" section is the positive stop mechanism with a double sided ratchet with a loop spring to return the pedal to it's middle position. As Ian says the external rod linkage wears over the years so may need adjusting. If possible fit a new spring and check if the sleeve isn't missing from the pedal shaft. Remove the top and/or bottom clevis pins and pull the gear change lever up to first gear position. Now pull the bottom cam-plate lever up to first gear position and then set the linkage rod so it fits the length exactly. Check top gear engages fully , if not, the holes could be worn. These are .25" imperial (6.35mm) but you could carefully bore this out to 7mm if you can find 7mm clevis pins.  The lever is longer and heavier than the road-going bikes as the footrests are set low down on this model. 

   The engine getting too hot is either the carburettor running too weak or the ignition running too retarded. When started the bike should run fully advanced or fully retarded, if not adjust to which ever way the engine cuts out.   

Regards,  Richard.            

Re: Another 500T

Posted by christian_wyss at September 11. 2018

Thank you for those precious details Richard, it's sweet music for a newbie.

With your instructions it would now be a real pleasure to take care of the external rod linkage. And check about springs and bushes inside.

I would check both, carburettor settings and timing. And try to remember about timing while driving.

Like I believe oil tank was not cleaned from a long time ago, I'm planning of doing this first now before riding it too much.

What kind of engine oil would you recommend? Straight 40?

 

Still willing to learn more and more, what, or why is the stop mechanism "positive"?

Regards, Christian

Re: Another 500T

Posted by richard_cornish at September 11. 2018

Hi Christian,

   When you are happy the timing is O.K. most of your riding can be done at full advance, although retarding is good for very slow running. Yes SAE40 should be good for all conditions and is better than multi-grades as these need a fine element filter. The mono-grade oils trap the contamination in their sludge as you will probably find in the bottom of your oil tank when you clean it. SAE50 is needed for the gearbox, not EP transmission types.

   The positive stop design is controlled by the ratchet teeth in the unit which means the gear lever will only move one tooth at a time. The position of the ratchet teeth is equal to the indents on the cam-plate so it stops at the right place for the selector to move each gear into place. Before this design came in (around late 1920s) it was a series of slots on the petrol tank gate to control the position of the hand lever, or you just found the gear by feel.

Hoping you get it sorted,    Richard.

Re: Another 500T

Posted by christian_wyss at September 14. 2018

Hi Richard,

I like the relation with the timing and my happiness. Might work with my wife also, who knows?

 

You said:

Your 500T looks in very original condition with only a few small parts that have been changed.

 

Would you please list me the parts that you see that have been changed. I think the rims and the rear spokes, seat springs, license plate, side stand and  tool box looks recent. What else?

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Re: Another 500T

Posted by christian_wyss at September 14. 2018

Here is a picture of the the steering stops on the yoke. On the frame, where the yoke gets in touch with when I'm turning to each side limits.

Doesn't look for me that the screw on the frame is touching the yoke at the good place.

Or does the yoke really hit only the head of the screw? On all 500T?

Saying that also because the fork can sadly hurt the tank when steering full left or right.

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Re: Another 500T

Posted by christian_wyss at September 14. 2018

Opened the doll's head cover to discover a few things:

Gear lever splines are very good

Gear lever bush in the cover have a little play (O,3mm) with the shaft.

Bush in the cover is a little crooked, but could be factory signature, no?

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Re: Another 500T

Posted by christian_wyss at September 14. 2018

The linkage rod doesn't have that much play.

The gear lever shaft does have a lot of play, behind the ratchet.

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Re: Another 500T

Posted by christian_wyss at September 14. 2018

And after dismantling for cleaning, I'm wondering how to adjust this part:

 

Thanks for your help.

Regards, Christian

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Re: Another 500T

Posted by George Phillips at September 15. 2018

These are the "pawls", Christian. When you remove them check that the faces which push against the ratchet plate (with all the notches in it) are not worn. If they are then replace them along with a new spring. Both pawls should fit firmly on the ratchet plate with no free play. They are instrumental to a good gear change.

George

Re: Another 500T

Posted by ian_soady at September 15. 2018

Christian - something pointed out elsewhere that you may not have realised. The oil supply line seems to have a (non-standard) tap in it. This will be to prevent the oil draining down from the tank into the crankcase when the bike is unused for a while (known as wet sumping). Make sure you ALWAYS check that this is turned on before you run the engine.......

Re: Another 500T

Posted by christian_wyss at September 15. 2018

Previously George Phillips wrote:

These are the "pawls", Christian. When you remove them check that the faces which push against the ratchet plate (with all the notches in it) are not worn. If they are then replace them along with a new spring. Both pawls should fit firmly on the ratchet plate with no free play. They are instrumental to a good gear change.

George

OK, thanks for that George.

Christian

Re: Another 500T

Posted by christian_wyss at September 15. 2018

Previously ian_soady wrote:

Christian - something pointed out elsewhere that you may not have realised. The oil supply line seems to have a (non-standard) tap in it. This will be to prevent the oil draining down from the tank into the crankcase when the bike is unused for a while (known as wet sumping). Make sure you ALWAYS check that this is turned on before you run the engine.......

 

Thank you for bringing my attention on that Ian. I've seen it, it's the same tap that on the tank. There is a little sticker/reminder on the speedometer and I'm leaving something on the kick starter to remember also. From there, cross fingers...

Re: Another 500T

Posted by richard_cornish at September 17. 2018

Previously christian_wyss wrote:

Hi Richard,

I like the relation with the timing and my happiness. Might work with my wife also, who knows?

 

You said:

Your 500T looks in very original condition with only a few small parts that have been changed.

 

Would you please list me the parts that you see that have been changed. I think the rims and the rear spokes, seat springs, license plate, side stand and  tool box looks recent. What else?


Hi Christian,

   Sorry for not getting back to you earlier. Although most of the parts you list may be replacements they are very near to the original specification. The obvious new parts are all the handlebar controls have been replaced for more modern parts, also the petrol taps. The prop-stand fitted below the rear brake lever looks to be original or a good copy. The bracket (arrowed in your picture) is the prop-stand bracket from the road-going models, but this was never fitted to the 500T. Overall, your bike looks to have all the original major parts which is good after 67 years! If you can find a copy at a sensible price, the book " Norton Singles" by Roy Bacon ISBN 0-85045-485-9 has a chapter on the trials models with some original pictures and some technical information.

Regards,  Richard.

Re: Another 500T

Posted by christian_wyss at September 18. 2018

Hi Richard,

Thank you for the details, always appreciated the connoisseurs' gaze. About the book, was lucky enough to just found one for 10£ delivered in France. Can't wait to read it.

 

Regards, Christian

Re: Another 500T

Posted by paul_standeven at September 18. 2018

The 500T fork yoke is a highly desirable part for any iron-lug frame, and consequently lots of 500Ts have been robbed of them.

When the McCandless brothers developed the 500T, they realised that it needed lots more trail.  What they did was cut the platform at the rear of the lower fork yoke which supports the steering stem off, and weld it onto the other side.  For standard road bikes, the rings which surround the fork stanchions are ahead of the cross yoke.  The modified lower yoke has the fork stanchions further back.  The upper yoke has to be bent to match the new alignment of the stanchions.

Soon after the 500T yokes were developed, the road racing team discovered that the trials yoke made the works racers handle better.  So racers in-the-know bought a 500T, swapped the yokes, and sold the trials bike on to an unsuspecting buyer.  Of course, it begs the question - since Norton knew that the trials yokes made a better-handling bike, why didn't they make it a standard part on all the bikes?  It's a bit late to ask.

I don't know of anyone offering repro 500T yokes.  So if you have one which has been pillaged, or want your rigid, plunger or s/arm iron-lug frame to handle better, then you will have to do what the McCandlesses did - take the yoke off, cut the lower platform off, and weld it onto the other side.   But do make sure your welder knows what they are doing.  A fracture here does not bear thinking about......

Paul

Previously christian_wyss wrote:

Thank you all for your replies. Like I'm French, it's going to take me some time to really understand all that, but it's part of the game.

 

"looks like a nice bike and seems to have the correct fork yokes"

How can you tell that?
Asking because for me it looks like the "steering stop" on the frame doesn't touch the fork and then it's the fork which can hit the tank.

 

About the manual advance, is it a on/off one, just start and run position, or does it need to be adjusted "all the time"?

 

Christian

Re: Another 500T

Posted by ian_soady at Wednesday 10:55

Another book which is well worth getting hold of if you can find one at a reasonable price is "Classic British Trials Bikes" by Don Morley. It has an excellent (though short) section on the 500T.

One here for £40 but I think that's overpriced.

https://www.ebay.co.uk/p/Don-Morley-Classic-British-Trials-Bikes-UK-1st-DJ-1984/1116275843

Re: Another 500T

Posted by christian_wyss at Wednesday 18:57

Very interesting Paul and Ian, thanks.

Always willing to learn more about the bike, history and more. Prices for the book are going real crazy, more than 80$ some times... Will keep on looking.

Here is a picture of the fork, what kind of fork is it?

 

Because cutting and welding the lower yoke could have been possible, but bending the upper yoke!

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