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Mick

  Registered Users Last seen online, 1 week ago
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  • Mick uploaded a new video
    Really cool video about cyclekarts by eGarage which perfectly captures what cyclekarting is all about.
    Cyclekarts
    The cyclekart community is a small but widespread band of eccentric builders and racers. Centered around a love for creating, budget racing and having fun th...
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Recent Activities
  • Picked up the wheels today, very stoked with how they have come out. I had the rims blasted and powder-coated in satin black and then had some new tyres fitted. The wheels have been the most expensive part of the build so far, but then there are...
    Picked up the wheels today, very stoked with how they have come out. I had the rims blasted and powder-coated in satin black and then had some new tyres fitted. The wheels have been the most expensive part of the build so far, but then there are four of them and I had refurbishment costs on top of the purchase cost of the rims and tyres. I'm not entirely sure if I have ended up saving money by going down the path that I have, which was my original goal, but none-the-less, I'm very happy with the final outcome, as to me they look more 'vintage' than new or shiny wheels would have.

    For anyone else sourcing rims, I think that the cheapest option is probably to start off by purchasing better condition rims with good usable tyres to avoid the refurb and tyre replacement costs but it might take a while to find two pairs for a reasonable price, and then there's always the risk that you are going to end up with miss-matched tyres. I could have probably shopped around and got some cheaper tyres or ordered some online and got them fitted locally, but it was convenient to use Don and such convenience has a cost.

    New 17" rims with knobbly tyres are about AU$180 on ebay, but those are moto-x fronts and not postie bike rims and so have knobbly tyres and a bit more of a modern look to them. It does look like some of the fellas in the US are using these however so they are another option.

    So if you're just getting into collecting parts for your build, wheels are going to be the big ticket item so it is worthwhile keeping in eye on Gumtree ads or finding someone who parts out postie bikes.

    So what was the cost? Here's the final tally (excluding my machining work)

    $50 - Initial purchase price (Gumtree)
    $80 - Blasting and powder coating (Aluminium hubs were wet blasted)
    $125 - Supply and fit tyre (including valve / rim tape + spoke repairs)

    In total this has worked out at $255 per rim.

    I used Associated Gritblasters in Edwardstown for the blasting and powder coating. 83741979. They came under recommendation and I was not disappointed. I'll definitely get the chassis and suspension parts done there when I'm ready. It's worth noting that they have a surcharge for EFTpos so cash is king with these fellas.

    Don at DC Motorcycles sourced and fitted the tyres as well as fixed some broken spokes. He's in Marion. 83775566
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  • Mick replied to a discussion, Chassis design plans
    Some more plans courtesy of Steve Vinson

    69175787_981872908828427_3329609066203840512_n.jpg 70092368_981872938828424_1150306277545476096_n.jpg 69999082_981872962161755_3801471134168252416_n.jpg
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  • Got the front suspension kinda mounted up. I welded on the front spring hangers and made up some keeper plates for the U-Bolts. I did a bit of a test fit (even though I didn't get to finish the rear hangers) it looks pretty good and also looks...
    Got the front suspension kinda mounted up. I welded on the front spring hangers and made up some keeper plates for the U-Bolts. I did a bit of a test fit (even though I didn't get to finish the rear hangers) it looks pretty good and also looks like the axle line is higher than the centre of the chassis, which is great as it means that I can mount the rear axle above the chassis to help get the C of G down lower.

    To mount the springs up I had to fabricate some eyelet bushes. I decided to make these from some rubber radiator hose and a metal spacer. It's not the most elegant of solutions, but should work okay. If I come across some urethane bar stock I'll make some new ones but I recon these will do just fine.

    I need to make up some steel spacers to weld into the chassis rail to take the rear spring hanger pivot bolts. The rear spring hangers need to be bolted in relatively tightly as any play will result in the spring flopping around and a loose front axle. Given that this is 1930's technology we are playing with, it can use all of the help it can get. Handling is expected to be poor at best.

    The rear spring hangers have been cut, I just need to profile the ends and drill a couple of holes, then that's it for the front suspension.


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  • Managed to scrape half an hour on the cyclekart this arvo.

    I pressed the old bearings out of the front hub on one of the wheels. Well I tried to drift them out but there was no purchase on the inside so I ended up punching the seals and bearings...
    Managed to scrape half an hour on the cyclekart this arvo.

    I pressed the old bearings out of the front hub on one of the wheels. Well I tried to drift them out but there was no purchase on the inside so I ended up punching the seals and bearings out of one side so tat I could get a drift to them. The new bearings are a perfect fit (6202.2RS Bearing - 35x16x11)

    I note that the shaft is a little longer than it really needs to be. This was simply the only 5/8" UNF bolt that my local hardware store had in stock so that's what I ended up with. I need to turn down some spacers to get it to fit properly. Need to figure out the wheel spacing from the king pin. It seems logical to me to have it as close as possible, but need to confirm this. Aesthetically they would look better a little spaced out but will see.

    The only other thing I managed to get done was drilling some holes in the spring hanger brackets. I also spent a bit of time searching for something suitable to make spring bushes from. I think some rubber radiator hose and a spacer will do the job. Just need to find or make a suitable spacer.



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  • Mick unlocked the badge Journalist
    Journalist
    Loves browsing photos. To unlock this badge, you need to browse more than 150 photos on the site.
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  • Managed to get a few hours this arvo to finish off the front beam and suspension, I'm pretty happy with how it came out.

    The leaf springs needed the leaves tying together. I think that normally they are drilled and pinned but as the springs I...
    Managed to get a few hours this arvo to finish off the front beam and suspension, I'm pretty happy with how it came out.

    The leaf springs needed the leaves tying together. I think that normally they are drilled and pinned but as the springs I made are only 1" wide I decided not to drill them for fear of weakening them too much. Instead I ran a bead of weld along the outside to hold the leaves together. I then bent some flat bar around the spring to both cover the weld and hold the spring together. I think they've come out pretty good, I'm very happy with them. To finish them off I welded up the eyes on the end to give them some extra strength.

    The beam and kingpin mountings that I had made previously just needed to be welded together. To do this I had to set everything out so that the kingpins had some castor angle and a little bit of camber. The caster angle is what helps the steering return to the centre and a little bit of camber helps with grip.

    After laying everything out on the welding bench and setting the angles I tacked everything together before welding it up. I added some spring perches to the bottom of the beam to allow the springs to sit correctly. The width of the chassis puts the springs directly on the edge of the lower bends on the front beam, which would have made them impossible to bolt on properly. So to fix this I welded some small lengths of angle iron so that they sit parallel to the ground. This give the springs a nice flat area to mount to.

    All I have to do now is make some keeper plates for the U bolts, turn down some bushes, weld the spring hanger brackets to the chassis and then I can get the beam mounted up. There's still the steering arms to sort out, but I will not be able to make those up until the rear axle is in place and the steering column has been made.

    When the front beam is mounted I will be able to see how the axle sits relative to the chassis, which will then tell me where I need to mount the rear axle. Would be good to finally get it on four wheels and rolling.

    There's a bunch more photos in the gallery if you are interested in how I made the beam and leaf spring.

     https://cyclekarts.com.au/build-pages/1-micks-cyclekart-build/albums/23-suspension-and-steering



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  • Managed to squeeze a few minutes build time in yesterday. Drew up some front spring hangers and made a few cardboard templates to figure out a design that I liked. This is what I ended up with. Now I just need to make another three.
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  • Had a bit of time this arvo so decided to take a look at the front spindles today. The basic design uses 5/8" UNF bolts for the spindles along with 6202.2 bearings. The bolts are generally welded to some pipe or tube which pivot on a high tensile...
    Had a bit of time this arvo so decided to take a look at the front spindles today. The basic design uses 5/8" UNF bolts for the spindles along with 6202.2 bearings. The bolts are generally welded to some pipe or tube which pivot on a high tensile bolt or pin. Pretty basic stuff really. You can of course buy these, but as I like to make things, that's what I did.

    I decided to make the vertical links out of 1" bright bar to fit the M12 high tensile bolts that I'm using for the king pins (plus I already had a length of this that I bought to make the rear axle from). By making them to fit I could ensure that there was minimal play in the king pin, and I could also machine them to length so that they fitted perfectly within the hangars I had previously made.

    I set the length so that two thrust washers would fit above the vertical link. These washer will help reduce friction and make the steering a little easier to turn.

    After stamping the hangers and vertical links with 'L' & 'R' so I knew which one went where, I then cranked up the TIG and welded them up. Hopefully they are strong enough.

    Next up I need to drill out the hangers for the king pins and weld some retaining tabs to the pivot bolts to retain them in position. I'll also add some grease zerks so that they can be lubricated, once I've figured out the range of movement.
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  • Managed to get the tyres off of one of the wheels. I tried (and failed) to do it the old fashioned way with tyre levers as I don't have the strength in my arms any more. In the end I cut the bead with some bolt croppers and cut the rubber with a...
    Managed to get the tyres off of one of the wheels. I tried (and failed) to do it the old fashioned way with tyre levers as I don't have the strength in my arms any more. In the end I cut the bead with some bolt croppers and cut the rubber with a sharp knife. Work smarter, not harder as they say.

    With the tyre removed I could finally mount one of the wheels up on the lathe to check if it fitted. Fortunately there was a few mm to spare. With the wheel mounted in the chuck it was only a few minutes work to face the hub off and remove the spigot so that the hub flange I made sits nice and flat. I'm pretty happy with how it has turned out.

    I still have the other hub and wheel to finish off. Then I can look at making the front hubs up

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  • Mick uploaded a new video in Mick's Cyclekart build
    Machining my Cyclekart Wheels
    Facing off the hub on the rear wheels to mate to the axle flange. Just about managed to squeeze the wheel onto the lathe with the tyre removed and the gap be...
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  • Picked up some smaller flat bar to make up the leaf springs from. The local steel supplier had a bunch of 25 x 1mm offcuts in the rack so I grabbed a handful. Unfortunately they did not have spring steel in the width I needed so I ended up with...
    Picked up some smaller flat bar to make up the leaf springs from. The local steel supplier had a bunch of 25 x 1mm offcuts in the rack so I grabbed a handful. Unfortunately they did not have spring steel in the width I needed so I ended up with mild steel, but having already experimented with the deflection of a mild steel leaf spring in my last experiment, I knew that it could be made to work.

    Having already figured out the process, making the new springs did not take too much time at all. I modified my design a little, shortening the distance between the eyes and adding more leaves to compensate for the narrower mild steel. I also made the diameter of the eyes a little smaller so that the overall dimensions look like they are in scale.

    I still need to bind the leaves together and do a little tweaking here and there, but I'm pretty happy with the results. Considering that it cost me $10 and an hour of my time, it's a win-win.

    Testing out the 'springiness' (that's a technical term by the way lol) they seem to work very similar to my original test. The original spring I made was 50mm wide but only had three leaves, the new spring is 25mm wide and has six leaves. I can easily put a majority of my weight on the spring and it deflects an inch or so and then returns back to shape.

    If you are interested in making one the dimensions I used are as follows:

    25" - Overall length of unformed flat bar (18" eye to eye + 1" for curve + 3" for each eye)

    I then made several leaves of the following dimensions - 18", 16", 14", 12" & 10".

    NOTE: The 18" leaves are designed to tuck in between the eyelets of the main spring.

    I will probably stitch a weld along the side to hold everything together and then wrap a band around to cover the weld and make it look more like a regular leaf spring.

    I measured the position of the front spindles on the car taking into account the leaf springs and axle. The spindles are approximately level with the top of the chassis rail (front axle has an 8" offset.). I expect that the finished height will likely be a bit lower when the weight is on the wheels. This means that I might just be able to mount the rear axle above the chassis rails to lower the chassis a little. Will have to see how it all fits together.
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  • Did a bit more experimentation today. After yesterday's success, I decided to try and turn my curved bit of flat bar into an actual leaf spring with proper rolled eyes

    I initially started out trying to figure out how to make a simple former, but...
    Did a bit more experimentation today. After yesterday's success, I decided to try and turn my curved bit of flat bar into an actual leaf spring with proper rolled eyes

    I initially started out trying to figure out how to make a simple former, but then struck on the idea to simply clamp it in the vice and bend the eyelet around a bit of bar stock (with the help of a large hammer). I had to re-grip the work a few times, bending it around and then rotating the whole thing in the vice so that I could bend it into a full circle, but it was surprisingly easy and the results came out pretty good. A definite proof of concept. If you are going to have a go yourself, make sure that your flatbar is square to the vice by using an engineers square or protractor.

    The material I used is 3mm thick by 50mm wide, a little wider than I want to use for my finished spring, and the length ended up a little too long as well (600mm eye-to-eye), but it turned out pretty good. It also allowed me to do some spring rate testing. The spring is obviously not heat treated and is only actually mild steel, so the elastic point (Youngs Modulus) is a lot less than it would be if it were say heat treated 5160 spring steel, but it still does have an elastic limit and so would actually work as a spring provided that it doesn't get bent past that point.

    What I found was the spring was fairly weak and easy to bend by leaning on the upturned spring on my welding bench. I could easily deflect it 100mm and it would still return to its original shape but bending past this limit caused the spring to permanently deform.

    I then decided to make some additional leaves for the spring and increase its strength. As these were offcuts that I had kept from a previous job, I already had another identical bit of flat bar in the scrap pile. So I rolled another curve and cut a third off of it to give me an additional two leaves of staggered dimensions. I clamped these to the first leaf in the centre and redid the test.

    I found that with three leaves I could place a majority of my weight on the spring and it would deflect by approximately 100mm and still spring back into its original shape. It worked that well that you could almost forego the heat treating and just use mild steel.

    Just for fun I punched the dimensions into the excel spreadsheet I made up yesterday to see what the extra 25mm of width did to the results. It pretty much doubled the results, which is unsurprising given that they are twice as wide.

    I'm keen to get some 25mm wide flat bar and make up some proper springs now. I may even go for a thinner gauge of steel so that I can make it up with multiple leaves as I think that this would be kinda cooler than a single large spring.

    Another consideration is using pre-treated 4140. A while back I was planning on making up an anti-roll bar for my car and read about a fella who made his from pre-treated 4140. He just heated up the ends to form the bends he needed and then re-quenched and tempered the steel. Given that there is not a lot of deflection in the area of the eyelets on a spring, it's probably not super important to get this area back to the same hardness / temper. The only thing I'm not 100% sure of is if it can be cold rolled to form the ellipse. I guess given enough force, anything can be bent.

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  • So I popped back into our local spring makers yesterday to get a quote on some small leaf springs. The last time I was there I wasn't 100% sure on the dimensions, so this time I was armed with a bit more info.

    What I wanted was 500mm eye to eye,...
    So I popped back into our local spring makers yesterday to get a quote on some small leaf springs. The last time I was there I wasn't 100% sure on the dimensions, so this time I was armed with a bit more info.

    What I wanted was 500mm eye to eye, 25mm wide and a thickness suitable to support about 50-75 kg. Unfortunately the largest flat stock they can handle is 19mm by 2.24mm thick, which is probably too light to take the load of a cyclekart and driver. I did manage to get a quote, which was $80 for a pair plus heat treatment (minimum $80) so the price ended up more than ordering them from the US.

    Figuring that I could probably make them myself and then get them heat treated, when I got home I did some calculations to work out exactly what was needed.

    Assuming that the weight of a driver and karts is somewhere around 200kg all up, the front wheels, will take just under half of that weight, and that will be split between the two front springs, which gives us roughly 50kg per spring. I know that the weight is more split towards the rear but decided on an arbitrary value to start with.

    The springs should also be 25mm wide so that they are easier to fit to the chassis (also 25mm wide), which means that to end up with a spring rate to support 50kg we need to determine the thickness and length of the spring.

    This was pretty easy using a formula in excel that I found online as it allowed me to easily and quickly try various sizes until I found one to suit.

    Here's what I ended up with:

    25mmm wide
    1 Leaf
    6mm thick
    500mm long
    This gives a rate of 65kg / inch deflection

    Note, this is a bit of a nonsense unit of measurement, simply as the original formula was in imperial measurements, but for me it's easier to understand. What it basically means is that for every 65kg you place on the spring it will deflect 25mm (1")

    I then decided to map out what this might look like for various combinations of spring thickness and length and ended up with a table that looks like the attached image.

    What you will note is that the shorter the spring, the higher the spring rate. Likewise a thicker spring will also result in a higher spring rate. By playing with these values it is possible to build a spring to suit. The greyed in areas are the 'might be suitable' combinations.

    So next up I decided to take a look at how I might make the spring. I made a quick test on rolling the ellipse, which was pretty simple on my bench mounted roller. This only leaves the eyes to make.

    One method is to make a former and then heat the flat bar to bend it into shape - a bit like making ironwork scrolls. The second is to make up a hossfeld style bender, which will allow the eyes to be bent cold. Each option has advantages and drawbacks.

    I quite like the idea of making up a hossfeld bender. It's a little bit of work but I do have other jobs that I could use it for, plus I figure that with a minimum charge for heat treating I might as well make up a few sets of springs and the bender would definitely be better for making multiple sets.

    As usual with most projects, it's a case of two step forwards and one backwards
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  • So I picked up some steel and the 5/8" UNF bolts for my front axles. On trying to fit the bearings, I note that they are too small to fit onto the bolts. It seems that the 6202 bearings (15mm ID) are not correct. What I need are 16mm ID. These...
    So I picked up some steel and the 5/8" UNF bolts for my front axles. On trying to fit the bearings, I note that they are too small to fit onto the bolts. It seems that the 6202 bearings (15mm ID) are not correct. What I need are 16mm ID. These are 6202.2 bearings. I will update the parts sources with the correct info
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  • Mick unlocked the badge Story Teller
    Story Teller
    Loves sharing stories. To unlock this badge, you need to post at least 30 different story posts.
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  • Mick uploaded a new video
    Some cool helmet cam footage from one of the Tieton HP races
    Who did I see in the Grand Prix asked the Godfather
    Let's see who I come across while running in the 2019 Tieton Grand Prix.....
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  • Mick uploaded a new video
    Tieton GP pits walkaround
    A look at some of the entrants to the 2019 Tieton GP
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  • Mick replied to a discussion, Chassis design plans
    Some additional chassis plans. I used these along with the original Stevenson design plans for my build.

    These plans are good in that they contain details of the front beam and also a plan view of the chassis so it is a good reference from which to determine the width of the chassis and axles.
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  • Mick replied to a discussion, Chassis design plans
    Some GX200 dimensional drawings including overall dimensions, mounting pad dimensions and shaft position
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  • Mick started a new discussion, Chassis design plans
    Chassis design plans
    Thought I'd make a sticky post where we can share some basic plans to help new builders.

    These are plans that I have come across on my search for all things CycleKart, so I do not necessarily own the rights to these. Hopefully the copyright owners are happy for me to share (in the spirit of furthering CycleKarting of course).

    Please feel free to add any designs and plans you may come across.
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  • Mick started a new discussion, GX200 power upgrades
    GX200 power upgrades
    Stumbled across this GX200 upgrade info whilst checking their website for parts.

    Removing the governor - this will allow the engine to rev over 3500rpm. There are some caveats to this - mostly that there is a risk of the cast flywheel 'exploding'


    GX200 upgrade kit - takes power from 6.5hp to 10hp

    It's not a cheap kit, but does look fairly comprehensive and even includes and uprated fuel pump.

    To be honest, if you are chasing some bolt on power this kit is probably the way to go.
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  • Mick uploaded a new video
    tieton gp 2019
    Start of the 2019 Tieton GP CycleKart race
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  • Spent a bit of time this arvo having a bit of a measure-up.

    The rear wheel needs two differently sized steel discs to mount it up on. One on the inside and one on the outside. The two discs need to be 130mm & 123mm.

    The front wheel does not...
    Spent a bit of time this arvo having a bit of a measure-up.

    The rear wheel needs two differently sized steel discs to mount it up on. One on the inside and one on the outside. The two discs need to be 130mm & 123mm.

    The front wheel does not need a disc / hub as it can be mounted directly to a spindle, however the standard bearings will need to be replaced with bearings that have a larger ID as the standard ones are only 10mm.

    The dimensions of most go-kart stub axles appear to be 5/8" which equates to 15mm for the imperially challenged. (Big thanks to Ken for the previous links).

    So after a bit of googling I found that a standard 6202 bearing is 35mm OD and 15mm ID which is about perfect. It is ever so slightly larger on the OD than the original bearing (34.5mm) but I can machine the hubs to suit. There are some 34.5mm taper bearings available, but they are pretty expensive so machining the hub seems to be the best option to me at this time.

    The rear hubs will also need to be machined to get a flange to fit inside as the bearing housing protrudes past the rest of the hub. I checked on my lathe and with the tyre removed from the rim and the gap bed removed from the lathe I think I can just squeeze it in without having to disassemble the wheel.

    Happy days
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  • Mick started a new discussion, DIY Leaf Springs
    DIY Leaf Springs
    Found some info on the heat treating stages required for making leaf springs so leaving it here for later...


    • Steps in making a leaf spring without special equipment
    • Anneal the steel strip raw material - Heat to approx 800~850°C (cherry to bright red) and allow to cool s-l-o-w-l-y in air.
    • Cut, machine and form and shape the individual leaves.
    • Test assemble the complete spring assembly.
    • When satisfied, disassemble the spring again and harden the leaves (individually). [Heat to approx 820°C (bright red) and quench in oil].
    • Clean the surface with steel wool or similar to see the colours clearly when tempering (next).
    • Temper the leaves. [Heat to approx 320°C (dark blue/grey) and quench in oil].
    • Clean the leaves, and paint or apply final finish if desired.
    • Assemble the spring.
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