Austin 7 Special

Hoopla hoopla! First weld. Got a Unimig Viper 120 (they're tiny!). Had to fill in one hole in this 60T sprocket, as I have to drill another hole that overlaps that one. Decided to try welding it in. First weld (oh, OK, so I did drill three holes in a practice piece and tried those first ... and it kind of worked!). Like me - not pretty but should do the job. Have fun! Simon

The wheel adapters look like being a success. That's more than I can say for the ebay buggy axle, which was poor quality and not even true; about 3 - 4mm runout in the centre. So I sent it back. So I am now looking to source a 25mm dia 1000mm long axle with a 6mm keyway and circlip grooves on the ends. Any pointers, anyone? Alternatively, I could have one made. I doubt I could make one myself. Have fun! Simon

https://www.amazon.com.au/gp/product/B082PYT33D/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

OK, so I made my first part! Well, kind of - it's a wooden mock-up of the pair of adapters I'll make for my $90 wheel/tyres to fit the 25mm rear axle I'll use. The mock-up shows that it works but that I'll have to countersink the bolts coming through from the back of the adapter and into the wheel hub. I chose this side (92PCD) of the wheel rather than the other side (100PCD) to attach to the adapter because the wheel hub is clearly stronger on this side. To be clear, I'll be changing the two existing 15x37x11 bearings in each rear wheel, and substituting four 25x37x7 bearings in each wheel (two each side), so the adapter does not carry any weight load, only the driving and braking load. Have fun! Simon

Got springs today. $25 for a pair. I hope to use them as front quarter-ellipticals. Each leaf is 45mm wide and 6mm thick. I ground off the retainers and pulled the 3 leaves apart ... and figured I'd used a ~400mm long section of the middle leaf. So I set up a test rig, clamped one spring to the bench and carefully measured the deflection at the point where my axle will be, for a given load at that point. One spring sagged exactly 6mm for 5kg load. So with 2 springs it will sag half of that: or 3mm for 5kg. If my Kart weighs, say, 240kg all up (excluding the unsprung front wheels and axle) and if say 1/3 of this carried by the front axle, that's 80kg on the front axle or 16 x 5kg, so the springs (and body) will drop 16 x 3mm or ~48mm from its unweighted position when at rest, and drop a further 48 mm from a 1G "bump". Putting it another way - if someone about 80kg leant down hard on the front of the kart, they'd lower the front by about two inches. So I think I'll run with that and not chop the leaves in half lengthways. It seems to me that, using a spring as a cantilevered quarter-elliptical effectively halves its effective stiffness, compared to using it as a full semi-elliptical, supported at both ends. Makes sense because only half the spring is present and working.