The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: tlmark on 25.10. 2021 10:36
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Hi Guys
I was just upgrading the headlight bulb to LED one at the weekend.
when I noticed the lower two mounting bolt hole sections had cracked, also a crack was running up the side of one side.
have any of you seen anything like this before?
My mate is going to try welding them back on, and when he looked at it he said it looks like it has happened before and been repaired on the opposite to the main split.
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I've suspected for a while that the A series front downtubes are the frame part which vibrates in harmony with the engine (given the propensity for them to fracture close to the headstock). Could this be another manifestation?
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yep, mine is the same, re re repaired.....
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I'm interested to know how you get on with the led bulb on these machines - I've always "heard" that led's cant handle variable voltages, that they end up flickering???
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I'm interested to know how you get on with the led bulb on these machines - I've always "heard" that led's cant handle variable voltages, that they end up flickering???
I've heard that although LED headlights are bright they don't have a penetrating focused beam.
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When I tried an LED headlight, it lit up everything except the bit of road I needed to see.
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Hi Guys
I was just upgrading the headlight bulb to LED one at the weekend.
when I noticed the lower two mounting bolt hole sections had cracked, also a crack was running up the side of one side.
have any of you seen anything like this before?
My mate is going to try welding them back on, and when he looked at it he said it looks like it has happened before and been repaired on the opposite to the main split.
Those cracks are annoying, but commonplace, I have had to weld mine up too.
Going a bit off topic, I am in the luddite camp and have a 6v headlight, it’s not blown a filament yet, I don’t use the headlight in daylight and I rarely ride at night and keep the speed down if I do, generally I am all for improving safety by buying good tyres, brake linings etc but ultimately these bikes cannot be made anywhere near as safe as modern bikes so each of us have to draw the line somewhere.
If I did fit an LED it would be an additional “driving light” and on all the time. The headlight LED are not legal in NZ anyway and they usually get picked up by the beam testing machine at WOF (aka MOT) time. I’m thinking a really bright parking light LED in the reflector might work, if a 6v one was available.
I have not looked much into it but there are some oddities in the NZ laws eg driving lights must be on all the time and not switchable on/off. No parking light is required (on bikes anyway). A while back I watched a modern honda owner go livid when the WOF inspector basically passed his bike, but then asked if he could demo the extra driving lights he had fitted could be turned off, he turned them off and promptly failed the WOF *problem*
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Weld the broken bits to a mudguard washer ( or smlilar then weld it to the cowl, trim where necessary then paint or you will be re-repairing the re-repair of a repair
Welds are castings and as such nowhere near a s strong as the original .
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My welding course instructor stated that a good weld is stronger then the surrounding metal. It's the surrounding metal that will give you problems.
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May be a trick if the light, but that hole for the speedo looks a little different. Great shame that any hot repair will ruin the finish. From scratch a gas weld (a true fusion weld) to the sheet metal and a braze on of support reinforcing washers would be my choice. Tack welding with mig won't give the same strength, but could save the majority of the finish. Bolt on hidden subframe is an alternative. I used a cross bar here to mount a modern horn.
As to the cause, there are support washers under the cowl, and the lower mounts are slotted, all in order to ensure the cowl is mounted without strain. Make sure the repair lies flat against the lower yoke with the forks finally set straight, again to avoid any strain on the cowl as the lower yoke bolts are tightened.
Swarfy.
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Interesting, but not surprising that the break occurred right along the circumference of both washers. When welding back together, I believe it would be a good idea to distribute the stress over a wider area, maybe by putting down some braze after the weld. I will now wait for more weld-savvy members to correct me.
Richard L.
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To me that has all the hallmarks of a vibration fracture, and I would fit a thin nylon or rubber washers either side of the cowl when refitting it to reduce the chance of it happening again. My A65 mudguards were prone to cracking around the mudgaurd stay holes, I fitted rubber washers either side of the mudguard and they have been good now for about 10 years.
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To me that has all the hallmarks of a vibration fracture, and I would fit a thin nylon or rubber washers either side of the cowl when refitting it to reduce the chance of it happening again. My A65 mudguards were prone to cracking around the mudgaurd stay holes, I fitted rubber washers either side of the mudguard and they have been good now for about 10 years.
When I removed the front guard on my bike I found the (presumably original) squished remains of a rubber packing between the underneath of the guard and the U shaped bracket it bolts to. I used some large tough rubber washers to replace the original packing. The idea seems to have worked so far.
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The LED is a projector type and is
6-12 volt compatible also positive or negative earth. I’ll post some pix in another thread tomorrow.
I think I’ll try some sort of rubber isolating once I have it repaired
Sadly I think it is powder coated so once it’s fixed I’ll have to have it blasted and re coated
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The headlight LED are not legal in NZ anyway and they usually get picked up by the beam testing machine at WOF (aka MOT) time
Fully legal in NZ if you fit an entire assembly and not just a bulb, it's to do with the reflectors not working with the led bulbs hence the incorrect beam pattern
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... Fully legal in NZ if you fit an entire assembly and not just a bulb, it's to do with the reflectors not working with the led bulbs hence the incorrect beam pattern
Is that why LED headlights are reported as not throwing a good beam of light?
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The headlight LED are not legal in NZ anyway and they usually get picked up by the beam testing machine at WOF (aka MOT) time
Fully legal in NZ if you fit an entire assembly and not just a bulb, it's to do with the reflectors not working with the led bulbs hence the incorrect beam pattern
Quite right, I left out the word “bulb” as I thought it obvious that was what we were talking about, an LED bulb being fitted to a “BPF” type reflector, which I believe to be “illegal” in NZ but I don’t actually know the technicalities on why *eek* it’s just what a WOF tester told me, and they aren’t infallible!
Fitting complete (internal) assemblies has been done for decades eg sealed units, halogen reflectors/bulbs etc and as far as I know has not caused issues at WOF time, anyway, a quick google brought up this info.
Can the hella product (easily) be fitted into a std A10 shell?
https://www.hella.co.nz/en/products/driving-headlamp/7-round-headlamps-and-housings/7-round-led-headlamp-highlow-beam-insert.html
https://www.classicbritishspares.com/blogs/news/bpf-headlight-bulb-testing
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My welding course instructor stated that a good weld is stronger then the surrounding metal. It's the surrounding metal that will give you problems.
Unless you are using a higher strength rod than the parent metal there is no way that a weld which when you think of it logically is just a casting can be as strong as the sheet mtal with a grain size 1/20th of the weld grain size
This is why most welds are not dressed smooth to the surface and you leave beat to increase the cross sectional area which is similar to using thicker material to start with .
Add to that a flame weld will render the joint softer than the original while an arc weld will make it stiffer .
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... Fully legal in NZ if you fit an entire assembly and not just a bulb, it's to do with the reflectors not working with the led bulbs hence the incorrect beam pattern
Is that why LED headlights are reported as not throwing a good beam of light?
I would suspect that is the case but I don't know enough about them to be sure
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... Fully legal in NZ if you fit an entire assembly and not just a bulb, it's to do with the reflectors not working with the led bulbs hence the incorrect beam pattern
Is that why LED headlights are reported as not throwing a good beam of light?
A filament globe throws off light as a full sphere
So some gies directly ahead while the rest hits the reflector and is bounced forward
An LED is a flat element that only throws off light in a forward direction
Add to that the foreward only facing cone can be anywere as small as 15 deg to as wide as 120 deg
So to work for a headlamp you need a deep conical shaped columnator rather than a parabolic reflector
What most LED globes try to do is put the LED in tha smae place withing the reflector as the element of the globe would be but facing backwards into the reflector to get the full beam spread that a std globe would get
However the LED generates heat that has to be removed using a heat sink and that hea sink asts a shadow of itself in the middle of the beam of light so you get a sort of ring of light, bright at the edges and dim in the middle which is the exact opposite of what a normal globe does which is bright in the middle and dim on the edges
This is why you will hear LED globes being acused of throwing a "hollow" beam
The high light output type of LED ( there are lots of them ) usually used in globes is the CREE which are 3 V
So for a 6V system, 1 for low ( 3V ) and both for high ( 6 V )
The smae globe is used for 12 V systems but as they have 12 V then they can use 2 for low + 2 more for high so the 12 V British prefocus globe works really well in the standard reflector.
And because they use so little power it is viable to pop a 12 V regulator on a 6 V dynamo with a 5 Ah battery and all LED globes .
The 4 element LED globe draws 0.5A so a 5 Ah battery will power it for 10 hours running total loss ( no dynamo )
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soooo, going back to my original question then, an LED globe, DOESNT get affected by voltage variations or??
the reason for asking is that I know of a no. of people who have (tried) converting to led's on old cars but have had issues with flickering, even on/off, which "apparently" is due to insufficient voltage stability........
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My mate dropped the welded up cowl back today looks good.
I'm going to have to get it re powdered coated hopefully that won't take to long.
He thought some noise deadening might help with reducing metal fatigue from vibration?
what are your thoughts?
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Not sure 'noise deadening' will achieve much. To address vibration one needs to either remove the source (re-balance engine) or alter the part that is in harmony by changing its length or mass.
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Not sure 'noise deadening' will achieve much. To address vibration one needs to either remove the source (re-balance engine) or alter the part that is in harmony by changing its length or mass.
Noise deadening material will change the mass
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Noise deadening material will change the mass
I appreciate that, but discounted it on the grounds the item is small, so any deadening material is likely to be light and of insignificant mass. Hardly the place to fit lead-lined foam.
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My friends idea was to use the self adhesive sound deadening used on car panels
The cowl is at the powder coaters now
We. Have to see when I get it back
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Will not make a wrinkled rats rectum of a difference
It has taken 60 years to fracture the first time .
If he added some bracing as I suggested then it will go another 60 years standing on it's head
If he just welded it then it will depend upon the thickness of the deposit & what alloy he used .
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Cowlback fro the powder coaters
happy with how it looks if you didn't know you you'll never see anything.