Frame blueprinting

I am going to start work on a 73 750 fairly soon.
I have read the 'World's Straightest Commando' numerous times.

The question for me is how far do I want to go and how much do I want to spend?

My question for the forum is, who out there has had some experience with frame blueprinting? Has anyone out there done the full 'Ken Augustine' treatment?
Is there any other info regarding Norton frames?

Ken has a list of gotta do's in that article and I know many who have done them. Mainly head steady work. Here in mid Michigan we have Dan clark who builds many Commando's among his many machinist customers a way was found to true the ends of the iso tubes, gentley facing them off to flat, they are always .015 out of wack. If you do this and some sound swing arm work you will be happy. There is a man in Germany goes by Ludwig on B.B. com that has gone the full ken treatment. It sure can't hurt the bike but after that kind of effort it's hard to get a subjective opinion out of anyone. Commando frames are very light and bend real easy. I would be checking any bike with bent forks with a jig on a plate. The frame bare is 20 pounds Triumphs and BSA's go 36-38 pounds. So it's no wonder that they don't do the ton without a little wiggle here and there. If you like doing 90MPH and holding it there for miles then by all means go for it. By the way Iam one of those guys.

Although the Commando frame is light, it's not because it's weak. For a structural design that pre-dated finite element analysis, it's quite a remarkable piece of work. I personally tested both bending strength in the vertical plane (between front and rear suspensions) and torsional strength between the headstock and the swing-arm axis (trying to twist the front wheel out of alignment with the back wheel).

The tests were done on bare frames (no engine/transmission or Isolastics installed) and compared to the same tests on an Atlas Featherbed frame. From memory, the torsional strength was about 8 times better and the bending strength about 5 times better.

The only real weakness on the Commando is that the two downtubes can get splayed apart by braking forces. With the original Italian (Campagnolo?) TLS front brake that was never a problem!

I need to get Mick Duckworth's book to find out more about what happened to the Commando after I left N-V. I guess that's the next use of a gift certificate to Amazon.com.

Frank the most common bend is right in the strongest part and is easy to find. Just lay a straight edge on the top of the main tube. If it's humped it's been bumped. If it took a hit that bent the forks you better check it. Don't get me wrong I love the 20 pound advantage on the other bikes and being able to see in the mirrors is good too.

My 750 was a pretty solid handler even before the resto so I didn't worry too much about all that stuff. I replaced the fork tubes (old ones were bent), upgraded to Norvil vernier isos and an 850 headsteady, new Hagon shocks, needle bearing conversion on the swingarm, and that's about it. Did not have the isos faced but I probably should have. Rear wheel is offset about 1/4 inch to the left but I'm not planning to do anything about it.

I'll have to put a straight edge on the main tube one of these days. I did check the triples - they were straight.

The bike feels fine up to 80 or 90 mph, which is about as far as I feel like flogging the "antique touring bike". If I want to go faster than that I take my Ducati!

Debby

You should also check your swing arm. Mine was bent - one "arm" was bent upward relative to the other one, very strange.

Jason

frankdamp said:

Although the Commando frame is light, it's not because it's weak. For a structural design that pre-dated finite element analysis, it's quite a remarkable piece of work. I personally tested both bending strength in the vertical plane (between front and rear suspensions) and torsional strength between the headstock and the swing-arm axis (trying to twist the front wheel out of alignment with the back wheel).

The tests were done on bare frames (no engine/transmission or Isolastics installed) and compared to the same tests on an Atlas Featherbed frame. From memory, the torsional strength was about 8 times better and the bending strength about 5 times better.

The only real weakness on the Commando is that the two downtubes can get splayed apart by braking forces. With the original Italian (Campagnolo?) TLS front brake that was never a problem!

I need to get Mick Duckworth's book to find out more about what happened to the Commando after I left N-V. I guess that's the next use of a gift certificate to Amazon.com.

Click to expand...

Frank, check out this link http://www.vintagenet.com/phantom/wsc.html

Cost of blueprinting a frame?

Has anyone had this done, as described in the article that MichaelB mentions? Does anyone know of an East Coast shop who could do the
job to a similar standard?

Thanks.

norbsa48503 wrote that "if it's humped it's bumped."

I have bought a new frame for my bike, which I did so after checking the straightness of the original (new to me) frame, after I found that the long back tube was slightly bent!

On checking the new frame, it is the same as the original as the long backbone tube also is not absolutely straight. It bends almost identically to the original. From the rear bracing plate to the forwards angled downtubes it is straight, but deviates downwards by 3mm by the time it has reached the headstock.

Therefore do they build them bent, or is 3mm within tolerances, and if so, does anybody want to buy a secondhand (bent by 3mm) " normal" frame, which is not actually bent, if that makes sense, as I have a spare in my garage. The new frame was purchased from BSA Regal by the way.

Reggie

Yes they are bent from welding stress from new. If you have seen a crashed Norton the bend goes way beyond 3mm. Hoping you didn't buy a new frame based on my post. It was pointed out to me at the rally in Michigan that this 3mm bend could be used to con a little old lady from her Norton for cheap because it's been wrecked. That is not my intention nor to mislead anyone.
If you have had a crash that has bent the lower triple tree but not the top. This will not bend the frame in the ones I have seen. If the top triple tree was also bent check the top rail for more than 3mm of bend.

No norbsa48503, it was nothing to do with your posting that I bought the new frame as I have only just found this site.

I also found a very slight indentation across the top of both down tubes which were in-line with each other and about 2.5" below the headstock, which at the time thought was conclusive evidence of a bent frame, and with the top tube slightly out of straight, but on reflection, I think that this could have been where a steering damper may have been clamped across quite tightly, with the "u" bolts coming across the front of the down tubes.

I'm not that bothered at having purchased a new frame as at least I know it should be straight, and any future handling problems will not be caused by the frame!

Reggie

I fitted a new Andover/BSA frame to my Mk111 in 1997/98. I know that the old one had damage as I was on it when it T-boned. It does show some deflection on the top tube, as did period frames that I checked but seems to be in line.

The damage was bad enough to push the down tubes into the head fins, corrugate the top tube and put an S-bend into the gearbox cradle.

Needless to say, I replaced everything (except the back wheel) with new parts or in the case of swinging arm and cradle with original parts that I had removed and replaced with newly stoved items years before.

Sadly, the blasted thing just doesn't handle like it used to and although it sometimes seems to have better days, that might just be me. I would certainly hesitate to say that a new frame is a guarantee of good handling.

I have checked and re-checked everything that I can think of and am now in the process of putting my 750 PR project back as a Roadster to try to make a comparison again. If it's OK then I will start swapping components individually.

I am totally in awe of the level of engineering sophistication shown in the link.

Perhaps Bob Trigg and his merry men who designed the Commando frame structure were aware of these micorscopic idiosyncracies, but I'm absolutely sure the people building the frames (which may have been an outside supplier, but I'm not sure) had no idea how small tolerances would have built up to screw up the basic design.

Quite honestly, Norton-Villiers, for all its posturing, was not much removed from the gas-pipe welders who made other 1950's British bikes.

There's an interesting story from the time Norton was taken over by Associated Motor Cycles. The entire Norton enterprise was moved to Plumstead, in the east end of London. Many of the old timers took retirement and left AMC to figure things out.

The new owners found a serious inconsitency in the drilling of the holes in the crankcase for the cylinder hold-down studs. Finally, in furstration, they got in touch with the previous machine operator. After agreeing to a handsome fee for his services he asked "Did they take my bit of wood?"

It turned out that the bearings of the main spindle that drove the multi-head drilling machine were so worn, that the only way to get the repeatability was for the opeator to push a big piece of wood against the spindle to set it at one side of the clearance.

This is the type of "high-tech" craftsmanship that was typical of the UK motorcycle industry in the 1960's. Is it any wonder the Japanese ate us for lunch?

It's a testament to the basic design of the Commando that there are people willing to re-invent the manufacturing technology that shoould have been applied. Maybe the technology wasn't well known in the middle 1960's?

Certainly, Norton-Villiers wasted a lot of development money chasing intangibles without the necessary data to back up their decision-making. I was there and watched it happen.

frankdamp said:

Perhaps Bob Trigg and his merry men who designed the Commando frame structure were aware of these micorscopic idiosyncracies, but I'm absolutely sure the people building the frames (which may have been an outside supplier, but I'm not sure) had no idea how small tolerances would have built up to screw up the basic design.

Quite honestly, Norton-Villiers, for all its posturing, was not much removed from the gas-pipe welders who made other 1950's British bikes.

Click to expand...

Norton frames including the Commando and Featherbed models were made by the Reynolds Co. (I'm surprised you didn't know that Frank?), so I doubt that any shortcomings in the build quality was due to any lack of expertise!


But I suppose that like all mass produced goods Commando frames had to be made 'down to a price' or the Norton Company would simply have bought them elsewhere, which they did for a while when they started buying them from an Italian manufacturer (Verlicchi).



And it should be remembered that it was Ken Sprayson of Reynolds that found a cure for the early frame breakage problems, (as I think Mr. Sprayson predicted that it would break-and said so!) but the early Commando frames that Reynolds built for Norton was what they required so that is what they made. I believe Reynolds also corrected many faulty Italian made frames, apparently making more money from doing that than they would have done if they had built the frames in the first place!

frankdamp said:

The entire Norton enterprise was moved to Plumstead, in the east end of London.

Click to expand...

Plumstead isn't in the East End of London-more correctly South East London I think, the factory address (at that time) being:

Plumstead Road,
Woolwich,
London,
S.E.18

I guess it's old age or passage of time. I remebered that the frame used Reynolds materials, but I'd forgotten that they actually fabricated the frames, at least in the days I worked there. Does anyone remember if Reynolds also did the AJS Stormer frames?

As someone from "up North" (born and raised in Leyland, Lancashire), the fine detail of waht was where in the London area was about as intelligible as Arabic! I did visit Plumstead a couple of times, but don' remeber exactly where it was.

If I've offended any Plumstead folks with my Lancastrian ignorance - please accept my apologies. Micro-geography was never a stron suit!

Frank,

I shouldn't worry about getting confused in Woolwich. I grew up to the south-east of London and I don't think I could find my way anymore.

What you're actually dealing with is the original North-South divide - Norf and Sarf London. For some reason the East End can only be north of the river even though you only have to hop through a tunnel to get there!

Wasn't the AMC factory compulsorily purchased for the South Bank Poly or some such monstrosity ?

The Commando frame must actually be quite a clever piece of design. That a motorcycle with a hinge in the middle can even be ridden down the road, let alone win production races is something of a miracle. By rights, it should be something for circus clowns

frankdamp said:

Does anyone remember if Reynolds also did the AJS Stormer frames?

Click to expand...

Quite likely I would have thought (up to the point where Fluff Brown took over production at least?) the tubung I believe was Reynolds 531 and the frame was designed by Dr. Stefan Bauer?
Ken Sprayson (Reynolds) was also reported to have built the earlier AJS Starmaker racer frame apparently?

Dr. Bauer was the head of the Wolverhampton operation, where all the design and development took place for the AMC group. A very clever and erudite gentleman, but I thought out of his depth in an industrial organisation which was supposed to make products for profit. His specialty was combustion chemistry, I think.

When I was there, we were down to just Norton and AJS on the market, along with the Villiers range of industrial engines. We did make one "oddball" Matchless, a trials version of the Starmaker motocross machine for the ISDT in 1968.

Bob Trigg headed up the design team on both the Commando and the AJS motocross/trials bikes, sold in the US as the "Stormer". I believe the design was sold to a division of Bombardier (KTM?).

There was a strong family resemblance between the two frames, the only differences on the AJS being the way the top tube joined the headstock and no Isolastics. We had real problems with fatigue failures on the top tube.

Gentlemen, Regarding the article "The World's Straightest Commando", allow me to point out that Ken Augustine wrote the introduction and did the welding and machining after I did the measuring and assembly. The referenced list of "must do items" is by the author, not Ken. As the author, I'm pleased you got something out of the article. I'm now working on a second Commando.
Stevan Thomas

Hi Stevan Thomas
Do you have an up to date link to your article?
TomC in Ohio