Author Topic: Frame Crack Repair (Read 16861 times)

th63ko · « **on:** 24 Feb 2014 at 18:31 »

Too bad:
On my recently bought, just new restored 1913 model, I found a crack in the upper frame tube, see pictures.
Pictures hopefully show that not only the paint has cracked, but also the material under the paint.
From the colour, it is evident that there is braze filler metal under the paint which also cracked.
I must assume that the frame tube cracked as well.
Question: is there any proven, lasting repair method for such cases?

My best option is to fabricate a split ring from 3mm sheet steel (or two half shells) and silver braze this OVER the cracked area.
Will this repair stand the stresses?

I have just contacted the seller of this bike, who is a semi-professional dealer and hope that he finds a good way forward.
He sold the bike as a new restauration to me and I have just unloaded it from the trailer.
He has a reputation to loose, so we might find a way.
I just like that specific bike and hope that a suitable repair method can be found.

Is this a known frame problem?

Many thanks for your comments.

Dave@NZ · « **Reply #1 on:** 02 Mar 2014 at 07:03 »

Hi,
One possible repair would be to have the frame bead blasted then the crack tig welded up depending on how that goes an external 1/2 shell brazed over the area similar thickness as the original tube.
A high quality tig weld should return the tube back to original strength.
Dave.

Eddie Doc · « **Reply #2 on:** 02 Mar 2014 at 19:14 »

That's such bad luck, my first thought was not the repair but the reason the crack came about in the first place.
I think the first reply you had to have the frame TIG welded was spot on, what is important though would be to clean all traces of brazing as this would have an effect with the TIG process causing gassing and porous weld finish ending with a suspect weld.
It may also be a good idea to anneal the part of the frame to be welded as this section has work hardend and caused the material the become brittle and break. Also try to find suitable weld rods that would be recommended for dissimilar material if the weld is good there may be no need to cover with a shell.
Hope this helps in some way.
Eddie.

eddie · « **Reply #3 on:** 02 Mar 2014 at 21:16 »

Hi,
The crack looks to be at the joint between the headstock lug and the top tube of the frame. Short of actually parting the joint to enable the tube and lug to be cleaned and rebrazed, the best way would probably be to 'V' out the joint and then braze it again using a good quality 'silicon bronze' rod.

Regards,
Eddie.

th63ko · « **Reply #4 on:** 10 Mar 2014 at 20:16 »

many thanks for your comments!

i made contact with the guy who sold this bike to me and he thinks that the frame is not actually cracked, but the same as eddie assumed regarding the headstock lug.
makes sense to me.
tig welding is another option, but only when there is no braze metal around.
will keep you informed about the outcome of the repair attempts, which will hopefully be successful.

best regards

cardan · « **Reply #5 on:** 10 Mar 2014 at 21:01 »

I'm afraid it is cracked. I'd scrape all the paint off for a couple of cm either side if the crack, then give the area a good clean up with emery tape back to bare metal. That way the damage and the repair method required should become more obvious.
Good luck!
Leon

th63ko · « **Reply #6 on:** 17 Mar 2014 at 08:11 »

I have carefully removed the paint and performed a penetrant crack inspection, see pictures.

as can be seen, the crack goes nearly around the tube and it seems that someone in the past already tried to braze this. I have removed the paint carefully with ScotchBrite and sandpaper, so all deeper marks and dents had been there before.

I see the following repair options:
1. Braze the cracks: Will not help for long, the braze metal is less strong than the steel tube.
2. TIG weld the crack: May be problematic due to the braze filler that is present in many areas.
3. Cut out a portion of the tube (20mm or so) and TIG weld in a new piece of tube. I believe that this is the safest repair.
4. Two half shells brazed over the cracked tube. This might work, but the repair can easily be seen forever.

From the earlier comments I have seen that this forum has some real experts.
May I ask these experienced guys to assess the pictures and post their related repair proposal, please?

Many Thanks again

eddie · « **Reply #7 on:** 17 Mar 2014 at 10:18 »

Hi,
As I said previously, the crack looks to be at the joint of the top tube and headlug. From some of the photos taken in the Douglas factory, it looks as if Douglas used an early form of gas welding on this joint. With this in mind, I would suggest that it would be a good idea to 'V' out the crack - firstly to remove any of the old 'braze' - as you don't know what grade of rod was used, and secondly, to get full penetration with the new weld/braze. If this process leaves you with clean steel right to the root of the 'V', you may be able to get it TIG welded but it is likely that the weld may end up porous due to impurities in the parent metal caused by the original gas welding operation. I still prefer the idea of a brazed repair - if you are worried about the strength, you could use a Nickel bronze rod instead of silicon bronze - these rods are about twice the price and not often available in small quantities.
Whilst you have the bike dismantled, it would pay to check out the lower top tube for any similar defects. Should another crack be found, it might pay to saw on round from the cracks so that the frame can be sprung open to insert sleeves into the tubes to reinforce the repairs.
As always, repairs on 100 year old motorcycle frames can throw up unexpected surprises, but good luck anyway.

Regards,
Eddie.

th63ko · « **Reply #8 on:** 17 Mar 2014 at 17:20 »

Thanks Eddie for this hint!
I was wondering anyway, how they joined the headlug with the upper tube.
As there is no ordinary "plug in and overlap" braze connection (as on the other frame joints), your explanation of an early torch welding seems plausible to me.
I will discuss this repair option with the guy that sold me that bike.
If the "simple" TIG weld should be our favorite, I will do the repair at home by V-ing out the crack and have a certified aircraft welder do the rest.
Will also investigate about the special braze metal that you have mentioned.
Is this the filler that Rickman used to "braze-weld" their frames from high strength steel?

Best regards

eddie · « **Reply #9 on:** 17 Mar 2014 at 17:58 »

Yes, I believe this was the rod used by the Rickmans and most other frame builders here in the UK. A pal of mine has also produced several replica frames for BSA motocross machines - he will happily admit that he is not the greatest welder, but has never had a joint fail using these rods.

Regards,
Eddie.

cardan · « **Reply #10 on:** 17 Mar 2014 at 23:37 »

Eddie has excellent suggestions, and since you're planning to use an experienced welder it should go OK. If in any doubt after the vee-ing out, you can always cut though both tubes and sleeve as Eddie suggests for more personal security. It's your neck at stake, so go for an option you consider very safe. Maybe just a light coat of paint afterwards so you can keep an eye on things. Good luck.

Leon

th63ko · « **Reply #11 on:** 19 Mar 2014 at 13:08 »

Many thanks again to all.
I can get that braze filler metal from a German source easily.
However, the TIG weld repair is still my favourite option, since the braze metal has only about half the strength of a mild steel.
This might be more than sufficient on a joint with some overlap, but with this butt joint ??

Anyway, I will make pictures during the repairs to illustrate the outcome of all this.
Might take some time, my job keeps me very busy indeed.

This bike is meant to be driven by my lady, because it is real low and an easy starter.
That is not the case with her other bike, which is a direct drive/no clutch single cylinder.

Best Regards

th63ko · « **Reply #12 on:** 30 Jul 2014 at 17:35 »

just to keep this topic updated:
i had the cracked area x-rayed. what was to be seen was quite disgusting: there was an older repair attempt to be seen, with a flat steel inserted into the frame tube.
all that stuff had one thing in common: cracked.
seeing all this, i made the definite repair decision: two half shells will be used to form an overlap braze joint. these shells will first be joined with each other by welding when in position over the cracked tube. after this, the joint will be brazed with silver based braze filler.
all this is to happen sometime in august and i will report here with pictures.

brazing will be performed by an experienced craftsman (not myself).

lets hope for the best! many thanks to all for your continuing support!

cardan · « **Reply #13 on:** 30 Jul 2014 at 22:40 »

Great that you've decided how to fix it - your plan should work fine. Personally, I don't have a problem with a visible repair, and in this case the option is to cut and sleeve all three frame tubes...

When the external sleeve is made, it should be tapered at the ends to reduce the tendency to crack again where the tube enters the sleeve. Good luck!

Leon

desmobikes · « **Reply #14 on:** 30 Jul 2014 at 23:14 »

The best repair in my opinion is a sleeve inside, this can be done by cutting out about 3 mill from the frame, spring the longer part to one side and insert the tube, I also make the tube overlap the joint by at lest 40 mil each side and drill 2x6 mill holes back 25 mill on each side of join. Once lined up you move the sleeve into the other side with a sharp pointed tool through the 6 mill holes( you can put saw cuts in sleeve before assembly) Once all is lined up tig weld all around and importantly tig weld up the 6 mill holes so that the weld takes to the sleeve in these places, I also stagger the 6 mill holes at 90 degrees to each. I have repaired frames in this way and had no failures yet. Bob

cardan · « **Reply #15 on:** 30 Jul 2014 at 23:25 »

I agree Bob, but in this case there are remains of an earlier repair inside the tube already. Messy. I suppose you could cut out an replace a good length of the top tube to get at and tidy up the inside of the head lug - or cut through all three frame tubes to clean up the inside of the head lug properly. I think the external repair is reasonable in this case.

Leon

Douglas52 · « **Reply #16 on:** 31 Jul 2014 at 00:58 »

If there is evidence of a failed patch type repair then perhaps the best solution is to cut out the damaged portion and replace. The problem ares will be the connection of the new tube to the old. The old tube is showing signs of distress as evidenced by the bronze filling of small cavities. Using TIG to weld a butt type joint may result in a stress discontinuity which may cause the new sound weld to tear away from the old metal. Anyone who has tried repairing an old exhaust system will know about this. By having an internal spigot type connection and using a brazed joint will enable a much greater weld interface area, and lower stresses at the new/pold interface. Attached is a rough sketch of one way to approach the repair. If the TIG joints in the new tube are used to simplify assembly then they should be made first to prevent damaging the brazed joints. Careful selection of the brazing material and flux and fastidious cleaning should result in a permanent fix.
Cheers
Steve

Doug · « **Reply #17 on:** 31 Jul 2014 at 03:10 »

There might be a problem with slipping a reinforcing tube inside. Some of these earlier frames were reinforced with a pair of d-tubes arranged back to back. See sketch for cross section.

This may even be the inner 'repair' that you are seeing on the x-ray.

-Doug

graeme · « **Reply #18 on:** 31 Jul 2014 at 10:17 »

Agreed Doug

I have two frames that have just such an internal flat strap inside the tube. I hadn't thought about it being two D shaped tubes inside another tube, but it certainly makes sense.

Doug · « **Reply #19 on:** 31 Jul 2014 at 11:57 »

Graeme,

I saw it on several tubes of a 2-3/4hp that had rusted in two, but not sure when the practice started or stopped.

-Doug

th63ko · « **Reply #20 on:** 04 Aug 2014 at 17:42 »

thank you doug and graeme for the info about inserted d-shaped inner tubes!
today, i took a second look at the x-rays and indeed yes, that stuff inside the cracked outer tube are the d-shaped tubes. cracked as well...
so, no earlier repairs, just bad factory design...

next saturday is scheduled for the repair. will take some pictures.
cross fingers, please.

p.s.: this is a great forum, real knowledgeble people.

best regards. h.k.

th63ko · « **Reply #21 on:** 26 Aug 2014 at 16:00 »

Here is what happened in the meantime:
The frame was brazed.
The craftsman proposed not to weld the two joints for half shells, but instead use brazing for the longitudinal joints as well.
I liked this idea, because such repair could have been performed even in 1913.
For the circumferential fillet joints, a copper based braze filler was used, while a silver braze made the longitudinal joints.
Lots of silver filler diappeared in the joint, indicating that capillary forces did their job.

I have spent some hours to grind and file the joint.
It is my intention to reach the impression of a factory made overlap joint, as can be found on other 1913/1914 Douglas frames in that area. Still, there is some more filing required, see picture.

However, I hope that this joint will be a lasting, durable repair. Fingers crossed.
In the meantime, some specialist is turning, hardening and grinding a set of new steering bearing shells.
Next report and pictures hopefully when this bike is on the road again.

Many thanks for your comments and support.

H.K.

th63ko · « **Reply #22 on:** 22 Sep 2014 at 16:07 »

Made only little progress in the meantime, due to business travelling and vacation.
Presently waiting for new steering head bearings.
When visiting the Beaulieu Motor Museum, I spotted a 1913 Douglas 2 3/4 HP.

Guess what the frame looked like (see picture).

Seems that the 1913 frame has a severe problem with cracking.

Best Regards

th63ko · « **Reply #23 on:** 26 Jan 2015 at 15:38 »

Finally, the Douglas is in one piece again, waiting for the official registration (see pictures)
Also, the winter weather in Germany might keep me from test riding for a while.
Too much snow and salt on the road. Or lots of rain as an alternative.

According to documentation provided, it has first been registered in England on May 6, 1913.
Frame and engine number is 74xx, hope this fits.

May I encourage the experts to examine if these data correspond to the bikes appearance, please.

Thanks for continuing support, great forum, great people.

Best Regards H.K.

P.S. Have later also attached the fuel line to the tank.

th63ko · « **Reply #24 on:** 24 Nov 2017 at 08:57 »

Just to give my experiences on the above repair (2 summers later):
The bike performed well in several pre-1915 runs on the continent.
It is a good runner, quite faster than my 3hp nsu from the same year.
Had spray painted the repaired area to give a very thin paint layer, but no signs of cracking have appeared until now.
Fuel consumption is a bit higher than on my other motorcycles from that era, roughly 5 liters per 100 kilometers.
But the fuel cock was slightly leaking, adapted a new one for the next season.
Thanks to all that have helped me with good information.
Can watch me and many more on youtube: Search for "rondom gees"
Best regards hk