Jim Lee Commando

mdt-son said:
If you intend to use the frame on the street or at the track, consulting an expert frame builder is advisable.

- Knut
Click to expand...
Maybe the one who built the bike is an expert? Maybe?

Maybe looking at a couple pics on the internet has not given you enough insight to holler that the sky is falling? Maybe?

No flame job here, Sir, but maybe it'll be just fine, as it's proven itself to be for the last 40 years. Maybe?
 
If indeed it has been ‘modified‘ by persons unknown at some point, then there is justification for suspicion IMHO.

But if, by researching other frames and pictures, it can be concluded that this is actually how Jim Lee made the frames, then considering A) he was an expert and B) the frame has proven itself, then I would personally leave it be.

FWIW, to my very untrained eye, it looks like that’s how Jim made ‘em.
 
t ingermanson said:
This is flat out wrong.

An engineer you may be, but a fabricator you are not.
Click to expand...
You are right on that account. With all respect and out of curiosity, please send me sketch or picture how you make a uniform sleeve across an angular joint, where one member is curved as well.

- Knut
 
Last edited:
The frame is, as original. The man who built the frames for Jim Lee confirmed this. Im hopefully at Pembrey on the 10/11th of June & will get it looked at. Personally Im happy with it.
My Jim Lee 8 valve had the lower frame rails sleeved & pinned by Pat French MRD as he wasnt happy with them being butt welded. So far I have not see anyone else do this. Although I have onlu had 2 stroke frames to look at. Mine will be a rare 4 stroke exception. lol
 
t ingermanson said:
Maybe the one who built the bike is an expert? Maybe?
Click to expand...
An expert? I would question the expertise of someone designing a butt welded joint like this, proviso it's original.

An exerpt from an auction advert for one of Jim Lee's creations gives the impression of a skilled racing guy and homegrown entrepreneur who has ideas and enthusiasm but doesn't care much about the details, and going by the what Chris posted, didn't actually fabricate the frames himself !

Jim Lee of Batley took up racing on his Norton in the early 1950's as an enthusiastic Clubman at the Isle of Man and local short events such as Oliver's Mount. He gave this up to concentrate on motor cycle repairs, selling out to Padgetts in the early 1960's. He then set up again, making race components in Moor Lane, Birstall, very much a family affair.
By 1966 he was making his own frames for customers, normally drawn out with chalk on the floor of his workshop. His frames had various engines fitted depending on the customers desires, such as Paul Dunstall who had a Norton fitted; this bike, ridden by Ray Pickrell won at Crystal Palace, Thruxton and Brands Hatch in 1969. Mick Grant started to work and ride for Jim in 1970, building Dalesman frames during the week and racing a Gold Star engined machine at the weekend. Commando and Yamaha TR2 engined machines followed for the 1971 season and Mick won some 30 odd races. Mick signed for Padgetts in 1972 and the bikes were sold on. During the 1980's Jim's began working on Formula Ford and Formula Three race cars and won more than 100 races by the 1990's. Jim passed away in 1996.

- Knut
 
Last edited:
t ingermanson said:
No flame job here, Sir, but maybe it'll be just fine, as it's proven itself to be for the last 40 years. Maybe?
Click to expand...
It will take some more research to find out for how long this particular frame was raced. The bike has been in storage for years, maybe even decades.
Being a survivor is hardly proof of anything, is it?

Pictures do lie, but after examining pictures of 3 (different?) frames carefully, including the one Fred Broadbent raced, the frame detail we are discussing has no consistent design, IMHO.

- Knut
 
To say Jim Lee wasn’t an ‘expert’ I guess depends on one’s definition of expert Knut.

In terms of being a man who designed and campaigned successful race bikes, and launched the careers of people like Mick Grant, who respected Jim so much he ALWAYS wore the Jim Lee logo on his helmet throughout his career, would pretty much make him an expert in the eyes of those who value the old saying ‘when the flag drops, the BS stops’.

Meanwhile, back in Chris’ shed, he’s already stated he’s gonna enlist the advice of a professional and take it from there.
 
mdt-son said:
You are right on that account. With all respect and out of curiosity, please send me sketch or picture how you make a uniform sleeve across an angular joint, where one member is curved as well.

- Knut
Click to expand...
You never said uniform.

There are myriad ways to sleeve it well enough to be good enough, which is all it needs to be. It needs only a small amount of overlap to be stronger than the tube surrounding it, and it's very easy to feed rod into a gap. Personally, I wouldn't design it this way, but it has proven itself to be good enough. And, yes, surviving is proving. Why else would things be fail tested?

Early on, I noticed the weird tube incongruous to the radiused tube, and thought it was sub-optimal, but it's a race bike, and things get tweaked all the time. This could have been a fix for a failure of the original tube at the terminus of the web. It could have been a modification to adjust cornering clearance or squat/anti-squat. Somebody may have forgotten to "carry the one", or anything we'll never know.
 
Last edited:
Fast Eddie said:
To say Jim Lee wasn’t an ‘expert’ I guess depends on one’s definition of expert Knut.

In terms of being a man who designed and campaigned successful race bikes, and launched the careers of people like Mick Grant, who respected Jim so much he ALWAYS wore the Jim Lee logo on his helmet throughout his career, would pretty much make him an expert in the eyes of those who value the old saying ‘when the flag drops, the BS stops’.
Click to expand...

When it comes to all sorts of racing, there are so many tales, and the validity of a phrase may become extrapolated into absurdity.
The old phrase you quoted says nothing but "the whole package has to work well for the duration of a race to be successful". It takes more than a good (and enduring!) frame to win a race. In the mechanical and structural departments, all preparations have to be meticulous.

As for Mick Grant, the author of a Wikipedia article wrote about him: "He usually raced with number 10 and carried the initials JL on his helmet, even after retirement from competition, as a tribute to his early sponsor – mechanic, fabricator and frame-builder Jim Lee of the 'Dalesman' marque."

Being a former employee, a sponsored rider and probably a friend, it's easy to understand his desire to pay tribute to the man who helped him launch his racing career.

Unless you heard him say so, I think you stretch Mick Grant's tribute too far by implying a testimony to the quality of JL's engineering work.

- Knut
 
Another shed of light on Jim Lee's business (copied from the "Yorkshire Ferret", January 2017)

Jim was clearly born with a welding torch in his hand, but had a wonderful ability when it came to all aspects of fabrication. His skill was not only in the actual joining of the parent metal, but also in the visual effect of the finished product. It had to both ‘look right’ and be easy on the eye. Unless requested by a customer to do things differently, the former qualities gave his work a distinct feel and have left a signature for all to see.
By the mid 1960’s Jim had fabricated racing frames suitable for a huge variety of race engines. In fact it was his ability and willingness to take on ‘one-off’ jobs that had attracted his services to people such as Reg Orpin, Peter Williams, Dave Simmonds, Bill Bancroft and Paul Dunstall to name but a few. These frames were made using 17 SWG Renolds 531 tubing and were fillet bronze-welded at the joints. Jim used a gas-fluxer fitted in the acetylene hose to the torch and it is fair to say he was generous with the bronze fillet applied. The frames were generally of a simple duplex design and as Jim used a thinner gauge tube than the accepted norm, were considerably lighter than proprietary units. Jim’s constant quest to save weight resulted in him using brackets and gussets that were minimalistic in design and in many cases barely up to the job required. As a consequence his frames suffered badly over time, with fatigue and fracture cracks limiting their useable life. It is often said that no two similar frames are identical, as Jim did not use a complete frame jig, the tubes being bent to chalk markings on the workshop floor.
Jim had taken the brave step to invest very early in MIG welding equipment and was one of the first of the ‘bespoke’ frame makers to go down this route. Primarily it was because he wanted to increase the production of frames for Dalesman and Wassell. Following a series of tensile welded-sample tests carried out at Aston University, it was clear that Renolds 531 could not be reliably MIG welded. This prompted the move to Cold Drawn Seamless Tube as the frame material to be used with this welding technique. Mick Grant assisted in the jigging and welding of these frames. [1970/71 seasons]

- Knut
 
Last edited:
Chris,

I was looking at some of your pics posted, in particular post # 2 that show the gearbox mounting plates.

There might be an easier / less intrusive way to add strength to the area concerned…

Make plates that fully envelop the gearbox, might take potential stress out of the equation. Kinda like this:

af6a97ef-dd32-4a71-87b4-c4b25580b67a.jpeg
Jim Lee Commando
 
Last edited:
.Nige you read my mind! I have a 4ft by 400mm slab of 10mm alloy sheet. I told the engineering shop I brought it from that I wasn't going to replicate the old plates as I prefer to build the engine & gearbox in one side at a time. I have no need facilitating easy gearbox removal.
 
Chris said:
Yes banking on the Donington meeting as I never got the call from Goodwood lol.😂
Might take a run in those black leathers Nige! The least I can do when we meet up is try them on & see if they fit.
Click to expand...
Wearing new leathers is like painting the fairing on your bike - they help you fall off. It is a psychological effect - like fitting new tyres. That also works well. Get your mate to ride it - they have immunity.
 
Chris said:
10 weeks later & I have a painted frame. Unfortunately they didnt do the headsteady, so I am no further forward as I need to mount the engine by this to make my engine plates.
The "pattern" I was given isn't rightView attachment 107843.
Click to expand...
There should be bosses on the inside of the frame tubes to hold the ends of the head steadies. I use two short pieces of tube with rose joints at each end, the forward ends are held to the top of the motor with shoulder bolts so the threads are all in shear. Theoretically, my motor can rock sideways, but it cannot jump under load. I also use a piece of gusseted chrome/moly pushbike tube in front of the motor, instead of the ladder, It stops the MK3 frame from walking when stressed in corners.
I will measure where the top of my motor is in relation to the frame tubes for height and the distance back from the steering head, if that would help you. You need the motor to be well forward - it affects the way the bike handles when you gas in corners.
 
Last edited:
acotrel said:
There should be bosses on the inside of the frame tubes to hold the ends of the head steadies. I use two short pieces of tube with rose joints at each end, the forward ends are held to the top of the motor with shoulder bolts so the threads are all in shear. Theoretically, my motor can rock sideways, but it cannot jump under load. I also use a piece of gusseted chrome/moly pushbike tube in front of the motor, instead of the ladder, It stops the MK3 frame from walking when stressed in corners.
I will measure where the top of my motor is in relation to the frame tubes for height and the distance back from the steering head, if that would help you. You need the motor to be well forward - it affects the way the bike handles when you gas in corners.
Click to expand...
I think my Mk3 Seeley frame was set-up for the Commando motor. It is genuine - not a replica. It was brougt into Australia in the late 60s, by an A grade rider. None of us duds would have known about Gus Kuhn, back then.
 
acotrel said:
I think my Mk3 Seeley frame was set-up for the Commando motor. It is genuine - not a replica. It was brougt into Australia in the late 60s, by an A grade rider. None of us duds would have known about Gus Kuhn, back then.
Click to expand...
The centre of the crank of my 850 motor is 44 cm ahead of the pivot and 36 cm below the point where the frame tubes cross over. It is on s slight forward lean.
When I made the engine plates, I just stood it there and used cardboard and scissors to make the pattern, Then I went to work with a jig saw and 8mm aluminium plate .
You need a belt linisher and a pedestal drill, and a piece of 3/8 inch rod with a point to position the holes.
 
Hi Al
If you read the original posts you will see that the frame has tube brackets welded on. The engine is suspended via the cylinder head & the engine plates via void bushes in these tubes.
That relationship cant be changed.
As to handling we will see! However Mick had a great season on it in 71. Jim Broadbent told me it was a really good package.
 
Al Ive still got race bikes out on loan with mates. I never let anyone ride my bikes until I am happy with them. Likewise I will be the first to ride this one.
The leathers are second hand black ones I brought for Goodwood to look classic in. Although thankfully I have manage to put a stone on, which has helped my health immensely. Unfortunately its all gone to my midriff lol which is why I quipped if the fit.

The void bushes are Norton featherbed swinging arm bushes so pointy 9/16 rod.
 
You must log in or register to reply here.
Back
Top