David’s MK 1 1947 Douglas

[alwyn]

David has sent in this account and photos of his 1947 T35 currently undergoing an extensive rebuild.

David’s MK 1 1947 Douglas

I picked her up at the Vintage swap shop in August 2004. A poor looking thing but pretty complete so it looked like an easy restoration, as usual that was a mistake should have looked more closely. But then again I was set on buying her so it would not have made any difference.



I borrowed the Ute from work and Nette and I drove up on the Saturday, so after chatting with Barry the shop owner for a while and parting with some hard earned we loaded her up and headed back to Melbourne.


 
The rear section of the guard and the number plate holder came with her no pic’s of it though?
Next step was to join the London Douglas M/C which I did and received a nice joining letter from Reg Holmes telling me that she had been dispatched from the factory in Kingswood, Bristol on the 18th September 1947 to the Douglas agents Bill Mahler of Sydney. The other most important piece of information in the letter was the name of the technical representative Frank Dolman, Who has been a great help especially when I stripper down the wheels to get to the hubs and brakes without measuring the rim offset first!



Frank also identified the seat as being of f a Mk5 the Ferdax optional seat.

I am sure that this is the original Grandfathers bike that was ridden / thrashed on the farm by the grand kids until it did no go any more then just left in the barn for years.
So we started and stripped her down to the last nut and bolt. What did we find, well plenty the frame was broken , right hand down tube just below the steering head and the left hand tube was broken just above the torsion bar lug so off the frame went to Bob Martin Engineering in Ferntree Gully to have both down tubes and bottom rails replaced, they did a fantastic job  not to expensive either.

Both fork springs were broken (you know the square section ones) and the leading link pivot pins were twisted to the point that I had to use a thirty ton press to get then out. I think she had been flown over a few dam walls and the odd fallen gum tree. Luckily a few years ago I had bought a pair of forks from Dave at the Motor cycle Emporium in Maldon, they had good springs in them and the other bits I got from post war spares (Thanks Eddy and Margret).

The electrics were interesting there seemed to have been an event in the headlight shell, something simular to the Chernobyl meltdown I think. The bottom the Light switch was missing and the burnt edges still glowing. no wires of course just a fine copper layer over the inside of the shell on chasing the loom back nothing had survived it just turned to dust at the slightest touch. I would not have believed that a 6volt rubber cased battery could produce so much heat, On the bright side (no pun intended ) Lucas electrics are easy to replace and readily available. So just another job.
Strange things do happen in meltdowns the dynamo and regulator was untouched and intact, totally usable, Clean lube and a coat of paint ready to go again.

Engine, Clutch and Gearbox,

Well what can I say the timing end crankshaft bush had been replaced with the later double cup verity. These had fallen out of position and spun in the case turning the bore nicely oval and allowed the crank to float and destroy the cam gears. The big ends had play and the conrods were bent from taking the thrust loads from the clutch, Speaking of the clutch it was down to the metal, the clutch plate was warped and only had 1/3 of the lining left on one side of it the rest had exploded and were just a clump of oil soaked fibre around the inside of the bell housing, The oil was probably a good thing cause there would have been a lot of asbestos in that material. The gearbox was actually quite good some water damage to the out put gears (which I think we can live with) other than that not bad.
Of course with all this thrust load on the conrods the cylinder were, let’s say, worn out of specification,
Ray out at True line Engineering as got that problem. I’m told that sleeves don’t work to well in the early cylinders so he is going to have them built up using some nikasil process?  And reclaim the old pistons.
I fixed the cases by welding up the timing bore and re-machining the bore to suit the original top hat type bush ----- Twice ----- first time I managed to machine it .010 inch to high. new cam gears sloppy magneto idler gear didn’t fit!!! The engine is not finished yet but the rest of it seems to be just normal reconditioning things. Luckily I have sourced another engine and gearbox from Peter in the ACT. Going to pick it up just after Easter, So if this all fails I have another avenue.

After reading all this you might think I am just another whinging POM, Yes I hail from Erith in Kent, But NOT SO I have had so much fun so far making and sourcing parts that seemed impossible and meeting the nicest and most helpful people from all over Australia and the world I just like to talk about it. Each problem and challenge is just another notch in the comedy of life and just great.

I haven’t told you about the magneto restoration and my foray into nickel plating a couple of very funny things happened but for other posts I think.

Well that’s what we started with. Where are we now these pictures say more than words? It’s not finished but she is starting to look good.



Yes I know the front guard is strange but I don’t like the “Peckker” look of a standard replacement and I haven’t found an original yet so this will do. If anybody id interested it is a Harley guard I cut 2-1/2 inch out of the middle and welded back together again. (All with an angle grinder and oxy torch)



I am going to repaint the tank it was painted 2 years ago and in that time the paint has changed colour. In the picture it is a light blue but in the sun it is very purple, when I put it on it was close to the right colour I don’t know what happened?



Recovered seat plasticised leather wont get to soggy in the wet.



Some of my Nickel plating and restored gauges. (not the fuel cap)



A question about the stand? All of the other Douglas Mk bikes I have seen have had cast aluminium stands. This one as you can see is oval chrome molly (I acid tested it) tube. Is it original or has someone spent a whole lot of time making it?

Well that’s about it for this post now all I have to do is get it onto the web. Maybe one last comment, why did I choose to restore a Douglas MK motorbike?  Because of my old art teacher from school Mr Michael Foxley unfortunately many years deceased, from a motorcycle accident. He owned Douglas’s a Mk3 and I think a Mk5 both of which were in appalling condition but took him from Dartford to Erith every day. The sound and looks of them have just stayed with me. Mick was a pretty big influence in my life too but that’s another story, I believe he was a member of the KENT chapter of the London Douglas MCC, somebody might remember him, early 1970-73.

Cheers

David H


 

[Reg]

David,
               Lot of work gone in so far. Look forward to seeing it complete. With regard to the centre stand, this is an original item from the T35 (Mark 1) before the cast alloy items were produced.  Good luck,   Reg

[alwyn]

........The electrics were interesting ...... no wires of course......

David, I have a wiring diagram I can pass on if you need it.

I haven't told you about the magneto restoration and my foray into nickel plating a couple of very funny things happened but for other posts I think.

I will be interested to read of your experience with replating the dynamo casing as I have just recently replated mine.

Well that's what we started with. Where are we now these pictures say more than words? Its not finished but she is starting to look good.

I have to agree David - however without wishing to criticise the splendid job thus far there's one or two observations that I will pass on in the interests of authenticity as I am sure your wishes are to rebuild the bike as closely as possible and in good faith with the original.

Yes I know the front guard is strange........

Actually, the profile of the front mudguard isn't that far out in comparison with the original - the height of the guard above the wheel circumference is exaggerated in the photograph because there is no load on the front suspension - it won't look so bad when the motor is in the frame and the load is fully applied to the suspension - compare it with the side on view of my T35 here - it has a similar appearance as the load is off the suspension and the weight is on the stand. Yours maybe could be improved if you can have the section of the valance forward of the forks shaped to match the radius of the wheel instead of it being straight and tangential to the wheel. A replacement guard may be the better solution - you may be lucky and pick up one at a swap meet somewhere? - or you could advertise for one here on the forum - best of luck!

I am going to repaint the tank it was painted 2 years ago and in that time the paint has changed colour....

There has been much discussion on the forum about modern equivalents for Mk series Douglas colours - this post by our mutual friend Peter Davey in particular will give you a lead as to the paints required - I can vouch for the result - Peter's bike is spot on - you can view the finished job here.

When repainting the tank take note of the slight curve in the line between the black top and chrome strip - they were never straight and parallel like you have them at present - the curvature can be seen in this photo I could attempt to make a tracing of the lines and side panels for you if you wish - and yes, the strip between the black top and the black and blue tank sides was chromeplated, not silver painted.

In regard to signwriting on the tank, so far as I am aware, the name Douglas was never in stylised script writing but in a serif font as is seen in the photos linked above and almost exactly as in my avatar at the left (including the full stop!). The nearest standard font I was able to find for this purpose is 'Courier New' (emboldened) but the 'g' has to be customised slightly to match the original.

Some of my Nickel plating and restored gauges. (not the fuel cap)

A comment about your handle bar - the original handle bar (at least on the '48 and later models) was much straighter having just a moderate curve and no grip offsets - this can be seen in these photos.

A question about the stand? All of the other Douglas Mk bikes I have seen have had cast aluminium stands....

Reg has answered this one - my '48 T35 has the cast alloy stand that Reg refers to.

Incidentally, I found I had to cross drill and wire the head of the the stand mounting bolt to prevent it from unscrewing in use and another point, the stand return spring is attached to a small weldment on the battery carrier and just a word of warning, the stretching of the spring to engage the weldment on the stand is a herculean task! - I found I had to attach both ends of the spring (to the stand and battery carrier, the latter before bolting the carrier to the gearbox casing) before offering the stand up to its mounting position and then position the stand and push the mounting bolt through - it's a 2-man job!

Finally, I reiterate, none of the above should be construed as criticism of what you have achieved thus far David - I merely pass on my observations in the interest of authenticity for the finished job at hand.

Alwyn

[Doug]

In regards to the "Douglas" logo on the tank, the LDMCC regalia section has the correct style transfers, as would the VMCC in the UK, I imagine. Easy enough to get sent by post, and no skilled sign-writing with enamel and dagger brushes required!

However they may now be water slide transfers, as I think folk no longer want to mess with, nor it is as easy to re-stock, the original style varnish affixed transfers. I used the varnish transfers on my Mark 3 Sports, and I did not find the process difficult. I think the water slide transfers might well be a slightly thicker film, and that might be a problem on compound curves of the petrol tank (especially towards the front.) Hot water might help.

Just a thought if you do go with a repaint.

-Doug

[pjondeck]

I used two-pack paint on my tank. The LDMCC provided the water-slide transfers. The curvature was not a problem if the transfer is rolled with a rubber roller to exclude almost all of the water. I used one of the new plastic wine "corks" to do this job. I then did a clear two-pack over to finish the job . I was pretty nervous about this but found that after four or five fine misting coats and a final "wet" coat after flash-off the result was fantastic. Same deal with the tool box transfers.
Bon chance
Peter

[David H]

Hi Alwyn

A wiring diagram would be much appreciated it will make the exercise a lot easier, as for plating the dynamo housing. I chickened out and painted mine, I have tried before but because of the very high iron / ferrite content of the housings I did not think it would stay there. But I do not really know, so let me know if yours works and I might give mine a go to.
I have had a look at the picture of your T35, and very nice it look to, I think you could be right and the profile is not that different, Would it be possible to give me a number of  flange heights taken from the centre of the crown to the edge of the side flange

 
I have advertised for one some time ago no luck though but I will keep looking one will turn up I am sure.

I am going to re paint the tank and Peter has given me the line offsets he used for this tank layout so that will help a lot, you say the tanks were chrome plated ? Were all the T35s chrome, I am 99% sure that this tank has never been plated. I had to cut the tunnel out of it and repair rust / dents etc. I though at the time it may have been straight black painted when new. Maybe I should check with Frank and ask if there were any colour scheme variants in the very early bikes?
As for the Douglas script through work I have access to a scanner and film cutter. The Douglas script came from the front cover of the 1948-1951 Maintenance Manual, when I have the tank painted correctly I will put the right script onto her.

The handle bars came from the Bendigo swap meet for $5 don’t know what they are off but Aussi made and 1 inch diameter so probably meant for a Harley. The originals are the same as Peter has on his Mk3 but again 1 inch not 7/8 They have unfortunately fallen fowl of my De-Chroming bath (more about that later) A friend of mine is going to recreate a set when he gets time, hopefully not to long.

Thanks for the warning about the stand spring; the original battery carrier is almost non-existent so I will have to make a new one from scratch. Sounds like I should not go to skimpy with the metal thickness, Do you know if the springs are available from post war spares?

Thanks for all your comments they are appreciated.

Cheers
David H

[pjondeck]

Dave
I believe from when I was researching paint colours etc that all of the Mk tanks were not chromed. My understanding was that it was an option. I think that where mine is chrome it could have been silver.
I'm sure someone can confirm that.
Peter

[David H]

Hi Peter

I had a look at the John H Mark manual and he suggests that the early Mk1 tanks (single fuel tap no bridge) same as mine were in fact silver paint and that the colour was Douglas royal blue not the lighter mid blue of the sports models, I did get this verified by Frank Dolman, He suggested that the modern colour alternative was Ford ambassador or Granada Blue or Vauxhall Empress Blue. I have uploaded a picture of Frank’s Mk1. The tank layout is correct, it also shows the flat bars which as Alwyn pointed out are much finer than the ones I currently have.

Cheers
David H

Frank Dolman's Mk1 - Img 1



Frank Dolman's Mk1 - Img 2



Frank Dolman's Mk1 - Img 3

[alwyn]

A wiring diagram would be much appreciated...

Here's the wiring diagram David. It's drawn for the Mk5 but to the best of my knowledge it's useable for the T35's - at least it's worked for mine.

...as for plating the dynamo housing. I chickened out and painted mine, I have tried before but because of the very high iron / ferrite content of the housings I did not think it would stay there. ....

I zinc plated mine and it looks OK - time will tell about the durability.

Would it be possible to give me a number of  flange heights taken from the centre of the crown to the edge of the side flange?

Otherwise occupied for a few days David - and bike is garaged away from home still - will get to this for you asap.

....., you say the tanks were chrome plated ? Were all the T35s chrome, I am 99% sure that this tank has never been plated.

Only that stripe between the tank top and sides was chromed - see again the photo here. Mine is a 1948 production and it's possible there was a difference from the '47 model but I can vouch for the fact that my original T35 bought new in Adelaide in 1949 was chromed in the same manner as my curent bike. I have an inkling that there may have been 'Deluxe' versions that carried the chrome strip?

.... the original battery carrier is almost non-existent so I will have to make a new one from scratch. Sounds like I should not go to skimpy with the metal thickness...

Is there enough of it left from which you can determine metal gauge and general dimensions/details?

Do you know if the springs are available from post war spares?

No - but I'm sure Eddie Turner would tell you if he has stocks or at least provide the spring specs. for you.

Alwyn

[eddie]

Hi David,
               LDMCC Post War Spares can supply both the stand spring and the battery carrier for a Mk1 - prices as below (all +P&P)

      SA1590      Battery Carrier                              £14.95
       29705       Strap for battery carrier                  £2.00
       29706       Trunnions (2)                                  £1.10 pr
       29707       Nuts (2)                                          £1.00 pr
       27612       Spring for stand                              £5.30

Regarding the finish on the petrol tank: for several years after WW2, there were quite severe restrictions in Britain concerning luxury finishes like chrome plating. So some machines (probably the export models) could have had chromed tanks whereas models for the homemarket just had painted tanks - so both finishes can be considered correct for this model.  Also, during the years the Mark series were produced, there was a change from positive to negative earth - but the wiring diagram remained the same apart from reversed terminals on the battery.
                Good luck with the rest of the rebuild,
                                                      Regards,
                                                                  Eddie.

[David H]

Hi Eddy

Thanks for the prices and availability of the Battery carrier etc I will send an order through soon There are some other bits you maybe able to help with as well.
The information on the restrictions on production of luxury finishes is interesting I will have to do some research on the net, there is so much about the after effects of WW2 that I am unaware of.

Cheers

David H

[David H]

Hi Alwyn

Thanks for the wiring diagram it will be very helpfull I can even use the colour code, without that the colours would have been red and black. Once I have the loom made in PVC I will talk to the VINTAGE WIRING COMPANY and see if they would make a loom up in modern cotten price will be the issue with that I think.
No rush with the front guard offsets I've got a few other things to keep me going. When ever you can find the time. The more I look at my guard the easier it will be to radius it.
Hope to post something about my plating endeavours this weekend.
Thanks for all your help

Cheers

David H

[David H]

Much sadness ans frustration with the Mk1 on sunday. tried to fit th engine into the frame, It wouldn't fit!!!!! when the frame was repaired they managed to refit the Lower front frame Lugs on the wrong side so the torsion bar anchor bolts are facing inward not outward. causing the timing case to hit. More problems is that the firm that repaired the frame in 2004 has closed down. So does anyone know of a good frame man around Melbourne?

[eddie]

Hi David,
               What a downer!!  There isn't an easy way of rectifying this without drastic surgery. Getting the frame apart again is going to be the biggest problem. Last time, it had already started to self destruct, so half the job had already been done. Getting the bottom lugs off without doing irreparable damage to the tubes or lugs by overheating, is going to be the biggest problem - bearing in mind the fact that these lugs can become quite brittle with repeated heating and cooling. I know it sounds drastic, but it may prove better to accurately measure and cut the downtubes and bottom tubes, so that the lugs and stubs of tubing can be swapped side for side. The joints should then be chamfered prior to getting them TIG welded together again. As I said, it sounds drastic but the new tubes are likely to be more tolerant to this remedy than the lugs will be to a second re-brazing. I would suggest the downtubes should be cut about 2" above the lug, and the bottom tubes about midway between the lug and the front engine mount. To line up the tubes for welding, get a couple of bits of angle iron to clamp to the sides of the tubes (they make good, cheap,expendable 'V' blocks). Cutting the tubes will also mean the repair will only require localised heating, so less damage will be done to that super paintwork. Something else to bear in mind is the fact that the bottom tubes have a wall thickness of about 1/8", so the torsion bars only just pass through the tubes. it will probably pay to slide a piece of 3/4" dia copper tube into the bottom tubes while they are being welded. This will prevent any weld penetrating into, and obstructing, the tube but the weld will not actually take to the copper, so they will be removable when the job is completed.
                   Good luck with the repairs,
                                                       Eddie.

[alwyn]

What rotten luck David!
As Eddie points out there's considerable risk of terminal damage to the lugs if they are subjected to more brazing and his suggested workaround I think is the way to go. There's a report here of my own experience in repair of my T35 frame - I had sound advice on that occasion from both Doug and Eddie and I suggest there may be some relevant tips there that may help you further - worth a read anyway!

Good luck with the rework.

Alwyn

[David H]

Hi Eddy and Alwyn

Thanks for the information, They really confirmed my own fears that trying to remove the lugs again would be Iffy at best. Had a talk with the boiler makers at the Uni where I work they were of the same opinion except they suggested that the front down tubes be internally sleeved and that the lower tubes be cut further back and then rejoined with an external tube which had been fish mouthed at each end to spread the load. The only problem I could envisage is the external tube getting in the way of the waffle box muffle.  If it were cut just under the carby it would miss everything I think.

Can either of you see any problems with cutting the tube behind the front engine mount?

Cheers
David H

[eddie]

David,
          Internal sleeving is obviously possible on the down tubes, but not on the bottom tubes as they have to accommodate the torsion bars. As I said in the previous posting, originally these had a wall thickness of about 1/8" - so should be amply strong enough when welded. Cutting the bottom tubes behind the engine lugs would probably be better, but would entail having to remove the engine lugs and re-braze them to the other side of the tube. Bottom tube failure only happens at either end, due - I believe - to frame flexing because there is no bracing tube running back from the bottom of the steering head. If you examine, in detail, frames that have been involved in a head on 'coming together', you will find that not only do the top tubes and downtubes get bent as the forks get pushed back, but the swinging arm lugs also get tipped forward - bending the bottom tubes in the process. The whole frame ends up leaning forward something like a parallelogram. I think it's a pretty safe bet that butt welds in the middle of the bottom tubes will not fail - so for the sake of originality, personally, I would not sleeve them.
                                        Regards,
                                              Eddie.

[Doug]

David,

The lower frame tube is of fairly heavy wall, so if notched and welded with full penetration, there really is no need for external gusseting. Your boilermaker friends have the right idea for the ultimate strength, but it is overkill for this application. Others have welded the lower frame tube and dressed flush, and then gone on for many trouble free miles. To spread the transition of the weld zone, rather than a square cut butt joint I have used a 45 degree cut or scarf butt joint. If done by a qualified welder, the joint will likely be stronger than the tube, due to the better alloy in the welding rod compared to the soft mild steel tubing the frame is made of.

While there is more room aft of the engine mount to make the splice, it can be done between the engine mount and the front lug. This avoids disturbing the mounts and the distance between the front and rear engine mounts. If you cut aft of the front engine mount, make up some sort of fixture (or use a stripped down engine) to maintain the original spacing/alignment. Do not forget the appropriate spacers and shims!

Nothing that is impossible to do, but what an aggravation! I never spotted the lugs being reversed when you first posted the pictures of the frame restoration. I think one and all were distracted by the paint scheme on the petrol tank!

-Doug

[alwyn]

Hi again David,
In my previous post I referred to my experience in repairing my own T35 frame – I have tonight reread that saga and am reminded that there is a link there to a another webpage that I prepared to detail further the modus operandi adopted under the invaluable advice of Eddie and Doug – the page is copiously illustrated with photographs. You will find the webpage here.

It strikes me that the task you are now confronting practically mirrors the one I faced, the difference being that you have both lugs and the down tubes to contend with whereas I was dealing with just one fractured bottom tube - but I suggest the method has been demonstrably proven and worthy of emulation for your job.

Basically, I see your initial task as recovering the lugs by cutting them free from both the bottom and down tubes flush with the face of the lugs and then drilling out the tube from within them. There is a description in the webpage of how this was achieved and about the tools used.

Having recovered the lugs, the frame tubes must then be reinstated – you can see by reference to the photos and notes on the webpage that this was achieved, in the case of the bottom tube, with the use of a short tube passed right through the lug and scarfed and butt welded to the bottom tube at a point midway between the lug and the first engine mount - I think Eddie is still of the opinion that this is an appropriate location and we should ask him if he agrees that a similar location for the joint in each of the down tubes would also be appropriate, in fact looking back I see he has already recommended placing the weld about 2” above the lug – as Eddie has also pointed out, it is not possible to strengthen the joint in the bottom tubes with an internal sleeve because the full bore of the tube is needed to pass the torsion bars: this is not a problem however with the down tubes which I suggest might well be strengthened at the weld with internal sleeves and Eddie or Doug might make comment upon this for us.

In Eddie’s post above he refers to the use of V-blocks for aligning the tubes for welding – I found that a mandrel of aluminium bar turned to a clearance fit within the new tube spigots was sufficient for both tube alignment and weld backup and little effort was required to extract the mandrel post welding.

A final point, I also expected the existing frame tubes to have been 1.00 ” o/d x .75 i/d but on measurement of the recovered cut off portion it was found to be of considerably thinner walled welded seam tube the dimensions of which are noted within the webpage. I am unable to check until the weekend but I believe I have sufficient new tube to restore your frame - I will check and advise asap.

Regards,
Alwyn

[eddie]

Hi Alwyn and David,
                              I have just had a look in my scrap box and found some bits of old Douglas frame tube (some with remains of lugs) and can assure you that the bottom frame tubes were originally 1" O.D. x 1/8" wall. Alwyn, if your frame has thinner wall, welded seam tubing, I would think that it has already suffered a previous repair. I have repaired quite a few postwar frames and don't remember ever coming across welded seam tubing on any Douglas. If yours had previously been replaced with thinner wall tubing, it would be doubly weakened because of the thinner section and the fact that welded seam tube has a lower tensile strength than the equivalent solid drawn tubing. Also Alwyn, I think you might have misunderstood my advice regarding the repair on David's frame. I am not suggesting that the tubes should be cut out of the lugs and then new bits brazed in. Rather than subject the lugs to further heating and cooling, I would carefully measure and cut the 4 frame tubes above and behind the lugs so that they can swapped side for side and then get the tubes TIG welded together again (without disturbing the brazed joint between the tubes and the lugs). For the sake of a little careful measuring and cutting, this method would give the same end result, i.e. the lugs on the correct side and 4 welded joins in the tubes, but without further heat stresses to the lugs. I feel this would be better than chancing the lugs becoming brittle due to repeated heating. As I stated previously, the bottom tubes tend to crack due to the frame flexing. The down tubes are also prone to cracking but usually a couple of inches below the steering head lug. This is caused by Mr Douglas's attempt to strengthen them. For some odd reason, the internal sleeves were produced from bar with the lower end still blank (presumably to assist with driving them into the tube). The result is a concentrated stress build up at the solid end of the sleeve, causing the tube to crack. When I made a replica frame for my Comp, I fitted open ended sleeves that were taper bored at the lower end to spread the stresses. This seems to have worked, as 25 years of using the bike in trials hasn't resulted in any frame tube damage.
     By all means, use sleeves to strengthen any joints, but remember abrupt ends to the sleeves will only concentrate the stresses - get the ends taper bored if you can.
                                 Regards,
                                          Eddie.

[alwyn]

Hi all,
Thanks for your further comments Eddie - seems I went off track somewhat and don't wish to confuddle your advice to David.

......I have just had a look in my scrap box and found some bits of old Douglas frame tube (some with remains of lugs) and can assure you that the bottom frame tubes were originally 1" O.D. x 1/8" wall.

That's an interesting (and slightly alarming!) revelation Eddie - I still have the piece I cut out and will measure it again at the weekend but quoting from my recorded notes "when the existing tube was cut it was found to have a bore diameter of 20.6 mm indicating a wall thickness of 2.4 mm compared with the expected 3.0 mm - "moreover and surprisingly, the tube was found to be welded seam tube and not drawn tube as expected. The replacement tube was turned out to match the bore dimension of the existing to avoid having an internal step at the weld."

It would not be a surprise however that a repair pre-existed - so many frames of the bikes imported here (to Australia) suffered from the problem, my own new Mark1 c 1950 a case in point.

Also Alwyn, I think you might have misunderstood my advice regarding the repair on David's frame.

I am not suggesting that the tubes should be cut out of the lugs and then new bits brazed in.

Rather than subject the lugs to further heating and cooling, I would carefully measure and cut the 4 frame tubes above and behind the lugs so that they can swapped side for side and then get the tubes TIG welded together again ...

Sorry - didn't read it very well did I?  A much wiser solution and I commend it to David. - I suggest the use of an internal mandrel to align the tubes for welding, even as an additional precaution to using v-blocks and as backup for the welding.

Will be watching your progress with great interest David - please keep us posted.

Alwyn

[tommy]

Hi David,
This looks like a big setback and problem, but given time you can overcome this.
I would suggest in order to keep your pecker up and the project going forward, that you source a replacement frame for the time being.
They are very cheap in bare form and you can blast/paint and get on with your build.
I presume you are trying to preserve the frame number, but you can shelve and do later?
Anyhow, it is all good and part of the learning curve!
I have a bare MKIII frame that you are welcome to for free. It needs repair but is easily do able.
Problem is the postage from UK.
I am sure you will find a member over there that can sell/donate a frame, even if it is a later MK.

Good luck and keep going.
There are people here can and will help, so shout if you get stuck, but don't try and take this frame mod to your head right now.
Get the thing on the road and enjoy. The rest can follow later.

Tom

[David H]

Hi Tommy and everyone

I am really taken back by all the words of encouragement, advice and offerers of help. It shows what a wonderfull group of people you are Thanks its just great.

Tommy I probably won't take up your offer of the MK 3 frame just yet although I might come looking later on I seem to be acquiring Mk parts at a steady rate and might have enough to make up a Bitser some time in the next couple of years. After reading Eddy's, Doug's and Alwyn's posts I don't think it is going to be such a big deal, Very annoying and frustrating but I am over that. What I intend to do is follow Eddies advice and cut the tubes above and behind the Lugs and get the boiler makers at Uni to re-weld them, as Eddy suggested. No doubt it will cost me much beer but so-wot.  One thing I haddent mentioned is that when Bob Martin repaired the frame we used 4130 CrMo tubing not realising the original was drawn mild steel. I am still a little concerned about the welds cracking due to thermal stress. I've seen what happens on light aircraft frames through poor welding techniques which is why I would only get it welded by professionals. If it were normal steel I would be sorely tempted to do it myself. Anyway this week end I will be making up a jigging system and cutting the lugs out If I get it to the welders on Monday they say it will be back by the middle of the week, repaint the frame the weekend after and I'm back in business. easy when you say it quick. The Pictures on Alwyn's post of his frame repair are very helpfull I will make up a Plate Jig something like Alwyn used but modify it a bit so will hold the frame from springing out of shape as obviously all four tubes will need to be cut at the same time leaving only the top tubes to keep it all aligned.
So the plan is 3 weekends and I will be putting the engine in again this time it had better fit!!!
Thanks everyone will keep the posts going.

Cheers
David H

[David H]

.........I never spotted the lugs being reversed when you first posted the pictures of the frame restoration. I think one and all were distracted by the paint scheme on the petrol tank! -Doug

Hi Doug
I think one and all were distracted by the paint scheme on the petrol tank!

That petrol tank seemed to take everybodys attention, I did'nt mean to cause a fuss, I just painted it one Sunday for something to do. If nothing else this frame business will give me some time to repaint it standard - but before I do I will fit a anti-flex strap, like the later Mk tanks have. It looks like it has had several cracks repaired already.

Cheers
David H

Edit 01/05/2008: Quote tags and formatting adjusted.  A.

[alwyn]

... I am unable to check until the weekend but I believe I have sufficient new tube to restore your frame - I will check and advise asap.  Regards, Alwyn

Hi David,
I have a 400 mm long piece of 1.00" o/d x .125" wall (0.75" i/d) drawn steel tube (new condition) which should be sufficient for your repair. If you would like to have it, send me a PM with a receiving address and I will forward it on to you. It was was quite difficult to find at the time and I would ask that if you don't happen to use it all and there's a piece left over that may be useful for another repair would you return it to me please, not that I'm that pessimistic about suffering another break but, well you know, just in case! - I'm an inveterate hoarder 

Alwyn