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-   -   Sportster Cycle Wing Brackets (https://madabout-kitcars.com/forum/showthread.php?t=7491)

ChrisS 19th April 2022 09:02

Sportster Cycle Wing Brackets
 
I seem to remember seeing a number of posts in various places about people making up replacement brackets for the cycle wings on their Sportsters. Has anyone got any pictures/drawings they can share? I think the ones I got made for my Sportster, in the absence of any Marlin ones, could do with being a bit stiffer.

MartinClan 19th April 2022 09:51

I used the standard Marlin supplied brackets but there were two versions, one made from solid rod and the other from tube. I had the solid ones and they were fine while I had the car (and still are as far as I know) but the tube ones failed for most people as I recall.

Patrick is the one to ask. He made replacements for his Marlin supplied brackets. I think you will find plenty of pictures on his website. www.msportster.co.uk.

Cheers, Robin

ChrisS 19th April 2022 11:05

Thanks, I will take a look.

Patrick 21st April 2022 18:12

Hi Chris, not sure if you got my reply on my site;

I'm happy with them.

I was recommended to move the wings closer to the tyres over on the MoC forum (https://www.marlinownersclub.com/for...es-broke-again), but they work and took quite lot of time to make. I think if there was a hole in the side of the wing that the metal rod passed through it would be possible to move the wings out a bit and down quite a bit to get that result. However visually that would have needed wings with a larger radius - aesthetically they work quite well where they are now.

I do have a bit of damage on one wing where the wing stays broke last time, but I've not had much luck finding spares the same as these. Carbon mods stopped making them and chucked out the moulds years ago. A lot of the caterham ones are too small for the size tyre I'm using. The bigger ones are often fibre glass instead of carbon, or rather overpriced carbon. I ditched the Marlin wings very early on after the factory wing stays broke within 50 miles of driving - they were very heavy and hazard if they hit anyone. The carbon ones as a pair weigh a good deal less than the originals. I still have the factory ones somewhere I think.

The wings wobble a bit, but much less than the old ones. I'd perhaps make a more solid mounting mechanism than a u bolt, but it works and they've not moved anywhere. Someone with an engineering background could probably design wing stays with angles that resonate less. I modelled the new ones after the design of the Marlin factory item.

Thanks, Patrick

Mitchelkitman 21st April 2022 20:05

From what I've seen of broken wing stays over many years there is a common failure and it's that the tubing breaks at the end of the welds (the heat affected zone). One simple way to avoid this happening, which it has to be said few people appreciate, is to braze the joins. I've had people laugh when I've suggested it (even though my wing stays are still intact), They state that 'welding is stronger. I've even pointed out where they can see such 'technology' which takes huge stresses and rarely breaks.......... Just look at a pair of forks from an old (pre 1980) or a more recent high-quality hand made British bicycle! The forks and the dropouts (where the wheel secures) are brazed together. Consider the force these parts are subjected to when a wheel hits a pothole/ bumpy road - there are bikes 50 years old and more still in daily use. The process of welding can damage the metal, brazing is very unlikely to do that. A cycle frame builder may be able to braze some stays which will outlast the car!

Patrick 21st April 2022 22:10

Can't argue with that logic - welding puts a lot of heat into the metal. Bikes certainly last a long time.

The new wing stays I built have only a single weld each side now where they join to the flat plate that bolts them to the uprights. Everything else in bends with the help of a MAPP torch. The swap from mild steel to stainless will hopefully help too long term.

The original Marlin wing stays failed as they were very thin wall tube, from what I can remember it was about 5cm away from a weld, although that was a long time ago I don't recall the specifics.

They replaced them with solid rod versions, they did have a weld at the end of the rods where they move under the wings. I modified the replacements to work with the carbon wings I got at the time.

Those eventually broke due to rust which is it why I made the stainless ones: https://www.msportster.co.uk/2020/05...nt-wing-stays/

ChrisS 22nd April 2022 06:42

Patrick

Thanks for this. I didn’t get anything back from your blog. So much appreciated.

Would you have used thicker bar if you had been using the heavier original wings?

Chris

Mitchelkitman 22nd April 2022 08:21

Stainless can suffer even more c/f mild steel from heat embrittlement and vibration, so worth keeping an eye on them. One great mod I saw at Stoneleigh years ago was on a lotus 7 type car (IITR it was a Dax, but I may be mistaken) - It had a 'support pair' of stays on the outside of the wing which went to the hubcap of the wheel, incorporating a shielded ballrace! A neat idea to reduce the 'waggle'

Patrick 23rd April 2022 19:26

Quote:

Originally Posted by ChrisS (Post 107629)
Patrick

Thanks for this. I didn’t get anything back from your blog. So much appreciated.

Would you have used thicker bar if you had been using the heavier original wings?

Chris

Possibly, but I figure if 1cm thick stainless can hold an exhaust up it'll probs work fine for the wings. However the originals are substantially heavier so they'd probably benefit from bracing / thicker material. I dont really know much about metallurgy so I've not got data to backup my assumptions.

Quote:

Originally Posted by Mitchelkitman (Post 107631)
Stainless can suffer even more c/f mild steel from heat embrittlement and vibration, so worth keeping an eye on them. One great mod I saw at Stoneleigh years ago was on a lotus 7 type car (IITR it was a Dax, but I may be mistaken) - It had a 'support pair' of stays on the outside of the wing which went to the hubcap of the wheel, incorporating a shielded ballrace! A neat idea to reduce the 'waggle'

Thanks - will keep an eye on it. I'm a bit paranoid anyway and inspect them fairly often given the problems I've had with them.

The sounds like interesting solution adding support on the other side.


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