LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Nothing exciting, more documenting posts I re-did the steering, I'd managed to weld one of the carriers slightly higher than the other which caused a rock in the chassis, plus I wanted a little more width at the front as it turns out the Mini Scamp has a slightly wider front track. Cut it all off, measurements, jigs etc  I finished my exhaust as well. Decided the baffle tube probably wasn't great as it came of a 50cc and had smol holes, so I've gone with some drilled tube inside and packed with course wire wool. Should be pretty quiet, the pitbike exhaust had no packing whatsoever and we checked Ians GX engine exhaust and that was the same, just offset tubes into an expansion chamber, so...  I've bought a large tin of VHT black to paint this and the engine, the bit of tube sticking out the back is chromed (it's just filthy atm) although I may look for something a bit prettier |
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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More steering It's tight, Karts are a good 40cm wider First thing was to make a steering column, just a length of 20mm tube and an 8mm steering arm. There's an M8 bolt welded into the bottom, this fits into a rose joint, just as it is on racing karts. If it works for them, it works for me.  Here starts the next issue. As you can see here there's very litte room between the steering arm and the spindle arms, probably 3.5inches, 88.9mm or 1 Pixel 6 width (not Pro) I could use them, at this length, but I would have to cut down the rose joints as they have long tails on them and I think it would just get messy and when you turn the angles change and things might bind.  There was talk about having the arms at the purple angle, but I feel this would make the steering heavier. So the easiest thing to do is to cut the arms off the spindles and flip them over (red) and have the arms at the blue angle So a bit more work, but worth it I believe |
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Apr 12, 2023 11:32:47 GMT
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It probably won't make much odds at the speeds you'll be doing, but the arms are angled in for a reason. It's to ensure the inner wheel follows a tighter radius when steering. Google "ackerman angle"
Apologies if I'm telling you something you already know
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Apr 12, 2023 11:33:41 GMT
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Turns out I've spelt Ackermann wrong!
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merryck
Club Retro Rides Member
Posts: 480
Club RR Member Number: 9
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Apr 12, 2023 12:13:43 GMT
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When I did my son's hot rod I made my own steering arms with threaded rod. They were even adjustable, using left hand thread, with one side welded into a nut. They were only M6 rod/rose joints, but dead simple to make up and doing something similar would save you cutting up what you've got. forum.retro-rides.org/thread/209897/finns-tot-rod |
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Apr 12, 2023 12:27:13 GMT
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mr2fc, I'll drill some flat bar i've got and try it in the current position If I can get full steering and the angles look good i'll just whip some off the end of the rose joints, would save me a load of hassle merryck, I bought these complete track roads for £11 of eBay, can't beat that for a price. They're adjustable like you mention. I'll just have to shorten them to my required length then re-tap the right hand thread
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Apr 12, 2023 12:35:07 GMT
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Bit more done over lunch I sat where I need to sit and decided the steering wanted a slight bit more angle than I could currently get, so I notched the dash bar. This will get a fillet welded in and ultimately will be covered by the dash panel.  Racing karts use a plastic block to hold the top of the column, but I managed to buy a plummer bearing for the same price, so this got fitted here  So once the track rods are sorted I should be able to steer... Well, I need a steering wheel first  I shot the completed exhaust in some matt VHT paint the other day, so that's another bit completed  |
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merryck
Club Retro Rides Member
Posts: 480
Club RR Member Number: 9
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Apr 12, 2023 21:49:37 GMT
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What are you doing for a steering wheel?
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Mole grips on the column mate.
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Steering wheel?
I want a small one, a really small one, but I can't find any.
Well no, I like the Grant 829 classic, but it's way out of budget
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merryck
Club Retro Rides Member
Posts: 480
Club RR Member Number: 9
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Apr 13, 2023 11:57:41 GMT
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I'm not promising anything because when I made the wheel for my son's hot rod I nearly lost a finger, but if I get some time at the weekend I'll have a play and see if I can make something similar to a Grant 829 classic.
It'd just be out of mild steel, and I'm not sure I've got anything to finish it with, but I'll post up some photos of whatever I come up with and you can decide if you like it or not.
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Apr 13, 2023 13:00:13 GMT
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That would be lovely, thank you
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Apr 20, 2023 13:13:10 GMT
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Lets talk steering No, lets talk steering when you're making a kart that's 550mm wide using components from something that's normally 1200mm ish wide. I've been reading up on akkerman angles, lots of calculations and all that jazz, but I basically figured out you're in the right ballpark if your steering arm holes fall on to a line drawn from the centre of the rear axle to the pivot point of the steering.  I flipped her over, laid out a long steel ruler and came up with the correct location to gain correct akkerman. I then went and welded some plate to the side of the arms so I could redrill the holes  Made them look pretty, then bolted them to the kart, happy. I altered the length of some kart steering arms, fitted one side, then turned the wheel. I was upset to find that due to the short length as you got near full lock, the arm on the column would flick forward which just would'nt work.  So I did what any self respecting engineer would do when faced with such a thing, got angry, drilled some more holes where I knew it would work and frankly Mr Akkerman can go f........ himself   So I now have steering, it will probably push on tight turns at low speed but meh, I have steering |
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Apr 20, 2023 14:45:51 GMT
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Oh, I threw on the steering wheel from an old mower, still a bit large, but it will have to do for now Chucked the seat on as well, I think I might not use this as it's a bit big.  I'm thinking of just a seat pad, then a pad as a back rest on the cage???  |
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mylittletony
Posted a lot
Posts: 2,419
Club RR Member Number: 84
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Apr 20, 2023 14:47:06 GMT
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I'm no dynamics expert, but your Ackerman looks a bit off in that pic ^^
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Apr 20, 2023 15:26:22 GMT
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I'm no dynamics expert, but your Ackerman looks a bit off in that pic ^^ Don't know what you're on about chap 🤔  |
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zipgun
Part of things
Posts: 109
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Apr 23, 2023 15:07:34 GMT
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It might work with a straight track rod joining the 2 kingpin arms, and a drag link from the column to another hole in one of the arms ?
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Apr 23, 2023 15:13:00 GMT
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Would an aluminium snow shovel or similar work as a backrest?
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Apr 25, 2023 12:57:22 GMT
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I really wasn't happy with the steering. I decided the issues all stemmed from the fact the column was behind the axle line. I don't know how I decided this or why, but it led me to cutting out the centre of the axle   This allowed the steering arm to pivot more inline with the arms which in my head was just jolly. I welded up some more holes in the spindle arms, shortened them and redrilled them to get this Which now works flawlessly, so much lock now that the wheels hit the frame front and back - which is a good thing, I just need to add stops now  I've moved the brake slightly up, which meant drilling the current holes oversized then making up a location plate  Exhaust is now complete and fitted, supported it in 2 locations, it's nice and solid   I've fitted the shortened Forward / Reverse knob, it's out of the way and as tight to the engine as possible  I need to tidy up where I've cut the centre out the front axle and do some bracing. I have the battery now which I plan to fit as low and far forward as possible as the front end is light comparted to the rest of it. I have a choice of a plastic fuel tank which requires a pump, or and old Atco cylinder tank, which needs some repairs I can't be fair off firing her up really - oh, I have to sort the throttle / brake out, but I think i'm going for a simple 1 handed affair just to get her to RRW. Talking of which, I doubt the bodywork will be done for RRW either |
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LowStandards
Club Retro Rides Member
Club Retro Rides Member 231
Posts: 2,716
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Apr 30, 2023 19:02:36 GMT
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I've done a lot. Well, me and barstoolracer have done a lot But it doesn't look at a lot But it took a lot of time So a lot... I really wanted my throttle and brake to be foot operated. There was talk about hand controls under the steering wheel the same as Army'Geddon , we also toyed with a push pull arm meaning one handed steering. But it turns out being clever there was enough room to have foot operated controls The brake master cylinder was where we started as it's the biggest piece of the puzzle.  We managed to slot it into a gap where I could lose a little bit of the inner mudguard  Next I thought about the pedal itself and how it would operate the cylinder. I made a couple of these (actually 4 as you'll see later)  I used a bit of leftover 20mm tube, bit of welding, a bracket to match the pivot point of the cylinder and  A working brake pedal. It's both comfortable on the foot, operates the cylinder smoothly and has enough give to hold your foot up, yet work with slight pressure. Throttle next. Hmmmm, the brake works so well, might as well replicate it  This doesn't return to it's original position or even have an original position (the cyclinder arm limits forward travel on the brake) Stopping it moving forward was easy, a little tab was made and welded in Looked around for pull springs, had a few, but they're all long and pretty weak. I did find something that resembles a valve spring, no idea where it came from mind. I drilled through the chassis and welded in a cap head bolt that fitted snuggly inside the spring, then welded a tab on the pedal  So there you can see the stop and the return spring, it all works great, again, great foot feel (that's a thing right) Finished up mounting the battery. All the weight is at the back so far, so I stuck this right up front. Just a simple flat bar bent round it then welded to the chassis. This is just going to be held in by a cam buckle strap - why make it difficult?   Really getting there now - What is it? 3 weeks till RRW. She should be going, in a non-complete fashion |
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