Commando motor in solid frame

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Jagbruno said:
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Well dear Jim,

The only thing that could really improve my ride at this stage would be your light pistons, longer conrods and lighter distribution, feel free to sponsor me!

Actually, one of the only Nortons I know which is stronger than mine on the road (I am not talking about full race bikes) is my friend Yves' Seeley with all your goodies inside and fed by a pair of FCR 35's...
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Yves' Seeley below - another Commando motor in a solid frame - it now has several thousands of street and racing miles.

Commando motor in solid frame
 
Mk3 Seeley Commandos are not so common. One of our top guys was racing a Mk3 G50 - told me he thought he could feel the front end walking when he stressed the bike. I've never noticed that with mine, it feels very rigid and predictable. That big loop in the header pipe of the 2 into 1 exhaust is horrible, otherwise the bike in the photo is what a racing commando should be. I believe that Gus Kuhn raced a near standard Commando at first, then moved on to Mk3 Seeley frames. My feeling is that the more common Mk2 is slightly heavier and theoretically better. I believe my MK3 frame was manufactured to accommodate the Commando engine - most were made for G50 engines.- The top mounts are different.
 
This is quite interesting...You have both posted pictures of the same bike...Jim's picture is about 2 yrs old and Acotrel's picture is about 4-5 years old. :D

Yves, the owner, calls it 'The Big Spender'...he never stops improving it'and working on it. He has just installed a TZ 260mm four leading shoes front brake...this is a picture of the bike earlier this week:



Commando motor in solid frame
 
brxpb said:
I reckon Rohan is Carbonfibre in disguise!
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Carbonfibres line was that all Nortons were cr*p.
And had never been near a Norton (?).

I've got a few, inc a project Commando-in-featherbed.
Which I might even get to one day.
I's say that sets us world apart.

Some good ideas here.
Although some seem to be more about being different than improving anything ?
 
The TZ front brake is a very big backwards step - obviously done to suit some race class. I watched one of our A-grade riders out-brake several other guys on similar bikes to his TR3 Yamaha and about 3 of them crashed due to locking their drum brakes on different laps, at the end of the front straight at Calder Raceway. The A-grader had fitted a disc-brake front end off a Yamaha TX500 to his TR3. That drum brake looks magnificent - that is all that is good about it.
 
In the earlier photo, the bike has a single disc with a Lockheed calliper. I tried that and it wasn't enough. I use two Suzuki high speed steel discs with Lockheed AP callipers and the old Ferodo asbestos pads. I tried carbon pads and couldn't get them to become sticky enough.
I notice on that bike that the footrests are lower and further back. On most Seeleys they are an extension of the swing-arm spindle.
 
acotrel said:
The TZ front brake is a very big backwards step - obviously done to suit some race class. I watched one of our A-grade riders out-brake several other guys on similar bikes to his TR3 Yamaha and about 3 of them crashed due to locking their drum brakes on different laps, at the end of the front straight at Calder Raceway. The A-grader had fitted a disc-brake front end off a Yamaha TX500 to his TR3. That drum brake looks magnificent - that is all that is good about it.
Click to expand...

Funny, I don't remember a rash of 7Z250 and 350 riders crashing their bikes because their drum front brakes locked up, back when they were a modern race bike. Must be my aging memory again. From your comments, I assume they must have been dropping like flies :) .

Drum brakes do require a little different technique for heavy braking than disks, but that's something racers at the time had no trouble coping with.

Ken
 
Hi

Alan, I have moved my footrests back on my bikes, nothing to do with my height :D Much.
With the swinging arm set up on these bikes I found the footrest could come undone.
Not good for your confidence.

I believe the headstock angle is the same for the MK2 & Mk3 (must get that confirmed)
Yves bike looks the same as mine. It is deceptive in photographs with the bike on the side stand & no front down tubes to speak of.

Chris

ps Steves 2 into 1 is still the business
 
Seems like I remember tales of Seeley-Norton frames cracking from vibration. Was this something that was corrected over time, or a result of dumping big twins into chassis that were originally intended for singles?
 
I know a fellow who campaigns a Seeley Mk2 (modern replica) and years ago experienced cracks on one of the cross tubes that receives the rear engine/trans plates. It was repaired and may have happened again and been repaired - not sure. This same fellow experienced at least one or two near identical failures on his Featherbed racer, even more years ago. Both bikes had a Commando engine in it and he has not had a hint of trouble for some years now.

I have campaigned a handful of Seeley Mk2 frames (modern replicas and one from the period) with Commando engines without a hint of trouble and I am rather hard on the equipment, especially with the 215 lbs of rider weight. This also includes Mk2 frame with a Nourish eight-valve that runs without a head steady. For reference, my original Featherbed racer developed cracks near the top of the front down tubes once, and I attributed that to a broken head steady and probably running a Combat engine balance factor specified for a Commando frame. :roll: Repairing/replacing the head steady and some spot brazing remedied that problem. I had even cracked my Commando racer frame on both sides just above the gusset plate for the rear isolastic mount. In that instance, my hunch was the isolastics were set too tight.

I cannot dispute nor support any tales of the Seeley-Norton frame cracking from vibration .....except vaguely hearing or reading about the original Colin Seeley frames using a lighter gauge tubing but I never confirmed this. I believe the modern replicas are coming to the States from across the pond in a steel tubing meeting a T45 spec, so perhaps there was an alloy change from the originals but I am hunting on this one. Anyone else, feel free to correct this as I am going from recollection.

As for the Mk3 frames and a feeling of vagueness or twisting of the front end as acotrel mentioned, I have heard that before from a few others including my friend Nigel who campaigns a PUMA in a Mk3. I would never seriously campaign a Mk3 racer for that reason.
 
My friend Mick Ofield campaigned a Seeley Commando racer for a number of years, and had a series of frame cracks. He believed that they were just the normal results of fatigue from hard racing with a frame built for light weight, and not uncommon in purpose built racing frames of all sorts. After multiple repairs, he eventually decided to replace it with a new frame, and went for a new Rickman frame. To his surprise, it also developed cracks in the frame tubes almost immediately. He repaired it and welded in some reinforcing tubes, and it was raced successfully for many years by him and later by Scott Fabro, who only recently decided to retire it. I think the moral of this is that any frame built light enough for competitive racing has a limited fatigue life, and particularly those with big 4-stroke singles and twins.

Ken
 
lcrken said:
acotrel said:
The TZ front brake is a very big backwards step - obviously done to suit some race class. I watched one of our A-grade riders out-brake several other guys on similar bikes to his TR3 Yamaha and about 3 of them crashed due to locking their drum brakes on different laps, at the end of the front straight at Calder Raceway. The A-grader had fitted a disc-brake front end off a Yamaha TX500 to his TR3. That drum brake looks magnificent - that is all that is good about it.
Click to expand...

Funny, I don't remember a rash of 7Z250 and 350 riders crashing their bikes because their drum front brakes locked up, back when they were a modern race bike. Must be my aging memory again. From your comments, I assume they must have been dropping like flies :) .

Drum brakes do require a little different technique for heavy braking than disks, but that's something racers at the time had no trouble coping with.

Ken
Click to expand...
Theguys were crashing becaust they were trying to brake as late as the disc-braked bike. In the races you watched all thebikes probably had drum brakes. Themix is dangerous for the unsuspecting.
 
There are lots, and I mean LOTS of drum braked racers on the UK CRMC and BHR scene.

Pile ups on track due to locked drum brakes, like you describe Alan, just don't seem to happen here.

Your guys must have been very unlucky.

Or very skint....

Apart from minor lockups when using AM4 linings without a proper warmup, the only proper drum brake lock up I ever suffered was when the cam went 'over centre' and locked up the brake. This only occurred cos I was too tight / skint and had run the shoes past their minimum thickness, allowing the over centre situation to occur.

We know you don't like drum brakes Alan, you've mentioned before (about once per month I think), but others do, and most seem to survive the experience.
 
In Period 3 in Victoria, only drum brakes are permitted because the mix is dangerous. The only serious racing injuryI ever received was when an idiot mate popped in front od me ans used the disc brake. Personally I don't have aproblem with the mix, the young guys do. I raced AllpowersC grade in the 60s when both types of brake were used. I am not easily caught out because I am aware of the problem
 
Alan, not sure why you deem mixing disc brakes with drum brakes while racing is dangerous, I race in a mixed field of both drum and disc brakes to keep the grids fuller, drum brakes for pre 1963 class and a mix of both for pre 1976 class under our NZCMRR rules.
I have seen both types causing crashes, locked fronts on both types for what ever reasons, and there is sometimes broken cables, burst hoses, brake fade etc. Although rare.
I use a single Norton Lockheed (standard) caliper and disc on the front of mine, kitted M/C and a drum brake on the rear (the pedal is somewhere to rest my left foot) and the guys using big double twin Grimeca's or Fontana's (what ever the brand ) can certainly out brake my set up.
Whats your point?
Regards Mike
 
When you race with a drum brake, the distance you can safely brake up to a corner is usually less than with a disc brake. And how many ways can you wrongly set up a drum brake compared with a disc brake. With discs, the only problem I've ever had was when I left the rubber bellows out of the master cylinder and the piston took a gulp of air. With my 7R drum brake, I was forever working on it trying to get it right. The simple fact is that if you are racing on the limit, the front brake needs to be one-finger operation and when you use it, you need to know what it is going to do. The problem with mixing disc and drum-braked bikes in historic races comes when you pop in front of someone and out-brake them - if the are using a drum brake, it is odds-on that they will lock it because they cannot possibly brake as fast as the disc-braked bike. That is the way I copped the only serious injury, I ever got from racing and the only time I ever thought I might have been killed in an accident. As an old now-deceased friend of mine used to say - ' BE TOLD' !
Grimeca brakes are not too bad, an Oldani is as probably as good as you can get. The Fontana brake is what that TZ brake is. The front brake issue is one of the things that makes Period 3 Historics in Australia too expensive for the average guy. For something decent, you are probably looking at about $5000 - a more effective disc brake you can buy for about a tenth of that. I would not like seeing Manx Nortons with disc brakes, however how important is staying alive ?
 
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