The mounting points are slotted, so the whole fender can be raised or lowered for a more precise fit just above the tire, neat!
This new bracket is also slotted so I can align the silencers until they're level; much better.
Monday, March 25, 2019
Fender stays & exhaust bracket
Marcellini strikes again, this time with a cool set of stainless steel fender stays for the smaller aluminum item I had previously on my Fastback.
It was originally fitted with a pair of very classic 'Y' shaped brackets, that were cut to size for a 3.60 K81 Dunlop:
However when I switched over to the uglier, but better handling Avon, those brackets ended up being too short and I had to temporarily fit a big heavy original-type mudguard from an 850 Commando:
These new stays, designed entirely by Marcellini (I gave them carte blanche) help save considerable weight and make the whole front end look more svelte and less like a 1930s Auburn.
The mounting points are slotted, so the whole fender can be raised or lowered for a more precise fit just above the tire, neat!
Another thing they made for me is a new bracket for the RH silencer, specifically to replace part number 06.1721, not that there was anything wrong with the one I had in terms of manufacture, but it just wasn't lining up properly and the two silencers were not at the same height, which from the back looked just horrible.
This new bracket is also slotted so I can align the silencers until they're level; much better.
The mounting points are slotted, so the whole fender can be raised or lowered for a more precise fit just above the tire, neat!
This new bracket is also slotted so I can align the silencers until they're level; much better.
Monday, February 25, 2019
Isolastic - part 2
At long last, I was finally able to get back to this and make some progress.
Yes, I know the sprocket has nothing to do with the Isolastic, but this was the typical "while you're at it" scenario, and I've been meaning to improve the gearing on my bike for a while now. More often than not, that would mean fitting a larger sprocket, but this time we're going for a smaller one.
The retaining nut measures a whopping 1½″ across the flats (AF) or about 37.5mm. Because the mainshaft is in the way, a conventional socket just won't work, and even a deep well type may not be enough to reach. You need a tube wrench, but then the issue becomes finding a tommy bar that will hold up to the torque needed to undo the nut...
I ended up using the thumb and index finger of my left hand... because, shockingly, the nut was completely loose. I find this alarming and I've been wondering how this could be, so I've thought about it a bit and this is what I reckon:
1) the nut cannot come off if the locking plate is on; that, it was, and the securing screw was nice and tight.
2) I dug around my archive of photos taken during the rebuild many years ago, and found that I must have installed the sprocket, locking plate and screw, before handing the bike over to someone else who then finished the primary and other things for me.
3) What I think happened is that, at the time, I fitted the sprocket but didn't have the right wrench to properly tighten it (and the rear chain wasn't on, so I couldn't lock the wheel either), so I must have thought "I'll do this later" and then forgot.
Obviously this is a big deal and something like this should not just go overlooked. In those heady days there was a lot of activity but also long delays in getting from one stage to the next, so this must have been one of those things that fell between the cracks.
On the plus side, it has never been a problem and there is no damage to be seen anywhere, so all in all this was not as bad as it could have been.
Here's a very large spanner (thanks dad) that was perfect to get this done - remember this is a left-hand thread nut.:
One tooth may not seem like much but it was enough that I had to remove one link from the chain for a proper fit.
This is now done and I can move on to...
☆☆☆ Refitting the primary drive ☆☆☆
First things first: the crankcase has to be clean and free of any bits of old gasket or sealant:
I thought this would be an ideal opportunity to check all the various fasteners in the sub-assembly, that is to say the through-bolts that secure the engine and gearbox in their cradles. Shockingly, they were all loose, at least two of which dangerously so. I tightened everything down as it should be and I reckon that between the new Isolastic kit and this important bit of maintenance (for sure to be added to the yearly service before the riding season gets under way), this motorcycle should show a noticeable improvement in terms of handling and vibration.
I have high expectations from this upgrade, perhaps I shouldn't but I really want this to turn out well.
At this point, if you're undertaking a complete rebuild of the bike from scratch, you ought to check that the crankshaft and mainshaft are in alignment (i.e. actually parallel to each other). In this case, I hope I'll get away with having refit everything as it was, seeing as I didn't disturb anything other than the primary chaincase during disassembly, and didn't move the gearbox at all. It looks ok, I'll find out for sure when I actually get to ride this thing.
New sealant goes on, then the new gasket and then the inner primary cover.
Alessio had noticed a big ugly hole in the inner chaincase and was wondering what the hell had happened; this was back when I had to replace an engine mounting bolt but didn't want to dismantle all of the primary chaincase, and obviously something I was only able to get away with because I run a dry belt drive with no oil. I tidied it up with a reamer and sealed it with a rubber plug; much neater now.
The locking tabs come already pre-bent to help you during final fit; neat!
The front pulley, rotor and stator go back on without a hitch, I just replaced the woodruff key for the rotor with a new one, as the old one was showing some signs of wear.
Before reinstalling the belt, I cleaned it and inspected every tooth looking for tears or damage: all looks well. The clutch basket also got a good clean and I put everything back in place, with a new tab washer for the center nut.
In closing, a word of gratitude and appreciation for the late Bob Trigg, who passed away recently and whom every Commando owner will always thank for his brilliant contribution to this fantastic motorcycle.
Monday, January 28, 2019
Dangerous.
You think motorcycles are dangerous? You don't know what dangerous means until you've ridden one of these!
"the brakes are about as good as a strong headwind"
Wednesday, January 2, 2019
Isolastic
Rivers of ink have flowed for half a century (not to mention the countless bytes within the virtual world) to describe the Norton Commando and its revolutionary Isolastic system, arguably mankind's greatest achievement of all time.
I would hazard that any article written about this bike mentions it at least in passing, often flirting dangerously with plagiarism of what's come before...
So, since you already know all there is to know about the Isolastic, I will instead tell you about my machine.
As you may know, I got this bike as a... well, the word that actually best describes the state it was in, is the French épave.
The restoration effort we undertook was very thorough and not without its hurdles, however the result was well worth it. At some point with these endeavors you can reasonably claim to be finished with the restoration, and begin actually using the damn thing in the real world.
This is where we enter a much more subtle realm, that of maintenance and improvement: since the whole thing actually works, it becomes easier to isolate (no pun intended) those areas that can be improved, and it's usually possible to be far more surgical and focused. This is where my motorcycle has been for a good while now, and whenever I do bring it in for maintenance, it is for very specific and relatively easy things.
There is a vast repository of knowledge available when it comes to the Norton Commando, and most problems have already been encountered and solved by someone else, so you're hardly ever in uncharted territory.
Of all the things that have been said of the Isolastic, in my opinion two in particular really capture the feeling of a properly set up system: it has been described as a "magic switch" (source unknown, but a common enough idiom among Commando owners) and as "floating drive" in Cycle magazine's September 1969 test of the 750 'S'.
There is a point in the rev range, usually when hitting 3.000rpm, where all perceptible vibration simply vanishes. What's important is that this is not a progressive, gradual thing; it is a sudden (but predictable) on/off magic switch, unmistakable and impossible to ignore, it just never goes unnoticed by the rider. The next thing you immediately realize is that no other motorcycle in the world behaves this way, and by the time you're done thinking that, you're usually tearing through the gears and accelerating hard, surfing a tidal wave of torque and horsepower that is, in a word, addictive.
That surge is entirely down to the Isolastic being in perfect shape, otherwise the ride will be mediocre at best, and downright dangerous if not addressed quickly.
During my rebuild I decided to fit the vernier upgrade, as I didn't want to faff around with shims, especially for the rear unit which is harder to service. It seemed like a good idea at the time...
What I didn't know, was that the kit I ended up fitting was a poorly made reproduction using a very hard rubber compound, and just bad engineering at its core. Repeated attempts at setting the right clearance never seemed to produce much of a difference, and I feel it is now time to get back in there and sort this out once and for all.
☆☆☆ Disassembly ☆☆☆
The first thing to do is to study the original Norton Workshop Manual thoroughly, and then peruse the excellent accessnorton forum if there's anything that's not quite clear.
Overhauling the Isolastic (plus a little extra, bonus task while you're at it - more on that soon) is a fairly big job in terms of the amount of stuff that needs to come off the machine; you also need a couple of special tools and pullers, possibly an air/impact wrench or a very long breaker bar.
That said, it is absolutely doable for the home mechanic.
Let's get started!
Yes, it's a wee little breaker bar and it worked a treat. After all, as Archimedes famously said "Give me a lever and a place to stand and I shall remove the crankshaft nut."
Needless to say, keep all the parts neatly stored in clean containers, don't lose anything and pay attention to woodruff keys and various shims and spacers throughout. I won't get too specific here because if you're thinking of doing this on your Commando you really need to read the workshop manual.
Once the alternator and the actual primary drive have been removed, all that's left is the three retaining bolts around the crankshaft: these are threaded directly into the crankcase, so take a moment to control your breathing, visualize the parts moving as you undo them, and treat everything with respect. Gentle hands, ok?
And that's it, that's the primary chaincase removed, easy, right? Actually, provided you have all the tools available and you know what you're doing, getting to this point is lightning quick; LIGHTNING QUICK, you guys.
Some of these parts look a bit dirty, I'm going to give everything a thorough clean and it's going to look like new in here when it's all back together.
If removing the primary drive is a relative breeze, what follows is a descent into madness, as you remove more and more parts from the motorcycle (gas tank, complete exhaust system, at least one Z-plate and both side panels) and a balancing act worthy of a Chinese acrobat as you lift and move the powertrain and the frame, then the frame and the powertain, up and down, back and forth, sideways and oh crap it's gonna fall! Have someone there to help you. Thank you dad.
We can now remove the front engine mount. You'll also note that the head steady and the air filter will come off to gain some wiggle room.
There's nothing else left to remove around here, so it's time to stop procrastinating, bite the bullet and get stuck in with the rear mount.
The rear Isolastic housing is now visible but still not fully accessible, so we have to either lower the sub-assembly in the main frame, or lift the main frame off the sub-assembly. Oh, and the rear shock absorbers may need to come off for this part, just to keep things interesting.
Once the old Isolastic rubbers are removed by whichever method you see fit, it's important to clean the housings and use a lubricant that will not damage the rubbers: this is crucial or your nifty new kit will perish within a short time and you'll have to start all over.
In my case I first lifted the front engine mount out of place (not without difficulty I must add) and clamped it in a soft jaw vice, then bashed the crap out of it to get the old kit out.
For the rear, since the gearbox cradle stays where it is, I rigged up a puller using part of the clutch tool and some bits of rubber to protect the frame. Surprisingly, it worked well:
☆☆☆ Defects of my kit - comparison with Andover Norton parts ☆☆☆
I now want to bring your attention (if you're still reading, that is) to a comparison between the badly made kit and the proper new one by Andover Norton.
The metal tube itself is shocking, it's a crappy seamed pipe that I wouldn't use for a toilet roll hanger.
By contrast, the one in the Andover Norton kit is fully machined and a proper fit for the retaining bolt:
Another glaring difference, and perhaps the most important, is the hardness of the rubber compound:
The inferior quality kit is definitely harder and even the shape of the rubber bushes, and the overall finish is just off.
Andover Norton's is soft and squishy at the front, a little firmer at the rear.
☆☆☆ Reassembly ☆☆☆
I started by fitting the new rear unit, it is obviously a tight fit and you have to compress the rubber to get it started, but with careful use of a flat blade screwdriver, it is possible to guide the first bush into place (this is where some grease is also essential):
Once in place, the end caps, PTFE washers and rubber gaiters go on:
Getting the front Isolastic in the housing is a lot easier:
After installation, it's just a matter of lowering the main frame on the powertrain and bolting them together using just three bolts: front, rear, and head. Although the image below is very familiar to Commando owners, when you see this in the flesh metal it's really striking, to see that this motorcycle has been engineered and built like this, a very gutsy move by the Norton team, and one that will never cease to impress me, and that I'll never cease to praise:
Before bolting too much stuff back on, this is a rare opportunity to give this bike a deep clean, something dad did using a compressor-assisted sprayer with kerosene/gasoline. It's essentially one spark away from being a flamethrower, ok?
The next phase will be refitting the primary drive, actually adjusting the Isolastic, then refitting exhausts and bodywork; that may have to wait until February (!) but this post will surely keep you busy until then...
I would hazard that any article written about this bike mentions it at least in passing, often flirting dangerously with plagiarism of what's come before...
So, since you already know all there is to know about the Isolastic, I will instead tell you about my machine.
As you may know, I got this bike as a... well, the word that actually best describes the state it was in, is the French épave.
The restoration effort we undertook was very thorough and not without its hurdles, however the result was well worth it. At some point with these endeavors you can reasonably claim to be finished with the restoration, and begin actually using the damn thing in the real world.
This is where we enter a much more subtle realm, that of maintenance and improvement: since the whole thing actually works, it becomes easier to isolate (no pun intended) those areas that can be improved, and it's usually possible to be far more surgical and focused. This is where my motorcycle has been for a good while now, and whenever I do bring it in for maintenance, it is for very specific and relatively easy things.
There is a vast repository of knowledge available when it comes to the Norton Commando, and most problems have already been encountered and solved by someone else, so you're hardly ever in uncharted territory.
Of all the things that have been said of the Isolastic, in my opinion two in particular really capture the feeling of a properly set up system: it has been described as a "magic switch" (source unknown, but a common enough idiom among Commando owners) and as "floating drive" in Cycle magazine's September 1969 test of the 750 'S'.
There is a point in the rev range, usually when hitting 3.000rpm, where all perceptible vibration simply vanishes. What's important is that this is not a progressive, gradual thing; it is a sudden (but predictable) on/off magic switch, unmistakable and impossible to ignore, it just never goes unnoticed by the rider. The next thing you immediately realize is that no other motorcycle in the world behaves this way, and by the time you're done thinking that, you're usually tearing through the gears and accelerating hard, surfing a tidal wave of torque and horsepower that is, in a word, addictive.
That surge is entirely down to the Isolastic being in perfect shape, otherwise the ride will be mediocre at best, and downright dangerous if not addressed quickly.
During my rebuild I decided to fit the vernier upgrade, as I didn't want to faff around with shims, especially for the rear unit which is harder to service. It seemed like a good idea at the time...
What I didn't know, was that the kit I ended up fitting was a poorly made reproduction using a very hard rubber compound, and just bad engineering at its core. Repeated attempts at setting the right clearance never seemed to produce much of a difference, and I feel it is now time to get back in there and sort this out once and for all.
☆☆☆ Disassembly ☆☆☆
The first thing to do is to study the original Norton Workshop Manual thoroughly, and then peruse the excellent accessnorton forum if there's anything that's not quite clear.
Overhauling the Isolastic (plus a little extra, bonus task while you're at it - more on that soon) is a fairly big job in terms of the amount of stuff that needs to come off the machine; you also need a couple of special tools and pullers, possibly an air/impact wrench or a very long breaker bar.
That said, it is absolutely doable for the home mechanic.
Let's get started!
Because the Commando is essentially made up of the main frame and the powertrain sub-assembly, you need to support both independently at different times. You can do this with a jack underneath the lower cradle tubes of the main frame, and the centerstand which is bolted to the gearbox cradle on '71-on machines. You may need another jack to support the front of the crankcase when the front Isolastic mount is removed.
The primary drive has to come off, no point dancing around this. Get stuck in there and remove the crankshaft nut, remove the stator and rotor, then dismantle the clutch and pull the whole basket off.
The tinfoil was a precaution in case there was any oil, but since none seemed to have seeped past the crankshaft seal, I will use it to make a hat, as the one I'm currently wearing is a bit tattered.
Some of these parts look a bit dirty, I'm going to give everything a thorough clean and it's going to look like new in here when it's all back together.
If removing the primary drive is a relative breeze, what follows is a descent into madness, as you remove more and more parts from the motorcycle (gas tank, complete exhaust system, at least one Z-plate and both side panels) and a balancing act worthy of a Chinese acrobat as you lift and move the powertrain and the frame, then the frame and the powertain, up and down, back and forth, sideways and oh crap it's gonna fall! Have someone there to help you. Thank you dad.
We can now remove the front engine mount. You'll also note that the head steady and the air filter will come off to gain some wiggle room.
The rear Isolastic housing is now visible but still not fully accessible, so we have to either lower the sub-assembly in the main frame, or lift the main frame off the sub-assembly. Oh, and the rear shock absorbers may need to come off for this part, just to keep things interesting.
In my case I first lifted the front engine mount out of place (not without difficulty I must add) and clamped it in a soft jaw vice, then bashed the crap out of it to get the old kit out.
For the rear, since the gearbox cradle stays where it is, I rigged up a puller using part of the clutch tool and some bits of rubber to protect the frame. Surprisingly, it worked well:
☆☆☆ Defects of my kit - comparison with Andover Norton parts ☆☆☆
I now want to bring your attention (if you're still reading, that is) to a comparison between the badly made kit and the proper new one by Andover Norton.
You can see that the old kit's metal tubes are far too big for the bolts, and only held by two abutment pieces, but only one at the front/left and one at the rear/right... not even one on each side for each mount! Supposedly, the torque setting would bring the whole thing in alignment and somehow work... This is just complete lunacy and it clearly cannot work.
To confirm my suspicion, I then found this: https://www.accessnorton.com/NortonCommando/isolastic-conversion-kit.5053/The metal tube itself is shocking, it's a crappy seamed pipe that I wouldn't use for a toilet roll hanger.
By contrast, the one in the Andover Norton kit is fully machined and a proper fit for the retaining bolt:
The inferior quality kit is definitely harder and even the shape of the rubber bushes, and the overall finish is just off.
Andover Norton's is soft and squishy at the front, a little firmer at the rear.
☆☆☆ Reassembly ☆☆☆
I started by fitting the new rear unit, it is obviously a tight fit and you have to compress the rubber to get it started, but with careful use of a flat blade screwdriver, it is possible to guide the first bush into place (this is where some grease is also essential):
Tuesday, January 1, 2019
2019 riding calendar
I'm sure everyone is hard at work in their garages getting motorcycles ready for spring, but just in case someone is lacking motivation or a clear goal, I've put together the basic ingredients for a good riding season:
As for my bikes, in order of priority this is what I have to get done with extremely limited free time to wrench:
Fastback: overhaul the Isolastic and replace the gearbox sprocket.
Triumph: get the damn thing to start.
Sportster: fix the gearbox, set up the suspension properly, blueprint the carburetor.
(For all of the above you might as well add "anything else that comes up during maintenance and that will require more parts, more tools and more swearing".)
Nothing to it but to do it; let's go!
- The season opener will be for British motorcycles mostly, back to the forest, by a brook (25/26 May);
- Pathfinder 3, in search of a new itinerary for the CMT, I'll probably do this one solo on 15 and 16 June;
- Old Irons (27/28 July);
- either another Majella tour, or a return to Fiastrone, or an apéritif in Villetta Barrea - or a combination of all three! (9/10/11 August);
- I will try to squeeze in a Pathfinder 4 on 24/25 August; and
- finally, the Campotosto Mystic Trip 5 will be on 14 and 15 September.
As for my bikes, in order of priority this is what I have to get done with extremely limited free time to wrench:
Fastback: overhaul the Isolastic and replace the gearbox sprocket.
Triumph: get the damn thing to start.
Sportster: fix the gearbox, set up the suspension properly, blueprint the carburetor.
(For all of the above you might as well add "anything else that comes up during maintenance and that will require more parts, more tools and more swearing".)
Nothing to it but to do it; let's go!
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