Note: Updates are added to the bottom of this section as they happen.
The front axle will be suspended by a pair 1/4 elliptical leaf springs triangulated to avoid the need for a panhard rod. The upper link will be the arm of the houdaille shock which will provide castor location whilst damping. Hopefully this pic will explain what I mean.
Update: had some spare time during lunch so I started on making the 1/4 elliptical springs from the semi spring. I cut one in half removed a couple of leaves and reversed the spring eye. I think a couple of leaves should be enough but I will be able to add others if the suspension needs stiffening up. Length of the 1/4 ellipticals is 13 1/4″ eye to tail.
Update: Managed to get the spindle bosses, kingpins and phosphur bronze kingpin bushes together today. These bosses will be welded to the axle to give some degree of camber.
After looking at the Azusa type hubs I wanted something with a little more beef. Mr Nolan from the Cyclekart kindly sent me pictures of his solution to the problem and they were spot on and saved a lot of head scratching. The original bearings were removed to reveal a 31.5 mm bore. Slide a piece of tube through this hole with a flange welded to it. A similar plate on the other side sandwiches the hub all held together with 4 equi- spaced bolts. At this point I realised that although my kart may end up looking like a Cyclekart , weight, bearings, engine and gearbox use work against me so at a later date I will build another truer to the Stevensons original concept.
What more bearings! A true engineer would never let two metal surfaces work against each other without constant oil/grease lubrication or bearings and I prefer the latter. On the rear the free spinning hub with have bearings. In fact both hubs will have bearings and the facility to lock or unlock them to the axle. I did have a quick look at the peerless differential and maybe that’s something for the future. I will make a spare/ dummy unit out of mild steel and the yep! Out comes the stainless steel!! 😉
So I’m in hiatus waiting on the laser machinists and bearings so I’ll see ya in a week.
Update: hub plates are cut and ready for assy at the weekend.
Update: Cut off the excess and opened up the inner bore to 32mm. Once the hub sandwich plates are machined to a snug fit on the mating faces with a small shoulder to help in centralising location and adding another plane of support the tube through hub will be epoxied in place to increase stiffness in the whole assembly.
Update: Machined the hub plates today. Also added a stiffening ring to support the free side (the brake drum aide) of the hub. I have recently seen a picture of a broken Honda wheel where it has snapped on the free side so I will also do this mod to the front wheels. Next step welding it all together and making the bearing housings for the free running wheel.
Update: Few more pics of the proceedings! I have changed the inner rings for some slightly larger ones with 10mm holes in. Once welded to the sandwich plates these will locate inside the inner hub on its outer diameter and help to create a stiffer setup. To ensure alignment of all holes A little mandrel was turned up on the lathe. Both plates were bolted to it and then using the 10mm laser cut holes as pilot holes the outer hub plates were drilled through. The inner plates will have the bolts welded to them I need now is some M10 x 100 bolts and some tubing for the anti-crush tubes that I will need inside the hubs once I start bolting all together.
Update: made the housings for the bearings on the freewheeling hub. I may do this to both hubs!!! And make a locking mechanism to switch the driving wheel.
Bearings are 25mm id 42mm od taper rollers
Today whilst waiting on some parts for the steering to be lasered I pulled the engine out of storage. It’s a Honda MX 125cc water cooled engine with a six speed gearbox. A quick glance shows that the Tacho drives will mate up however in order to keep rear overhang to a minimum I may need to run the two stroke engine in reverse (alter the timing) and this may affect the Tacho drive!
Nothing done all I have is this.
I fell in love with this on first sight and seeing how kart cockpits are small and one of my sons is a big chap I thought I’ll have a go at making one this coming week using this steering wheel from the parts pile which has the 4 spoke speedway car look.
I was asked a question today about the choice of tube for my axle. I am using 1″ nb 316 stainless steel which has an 33mm od with a 2.7mm wall. If I can get hold of some 1 1/4″ nb tube from the scrap bin then that’s what I’ll use. The brackets and gussets for the springs and shocks will add some strength over the ends of the axle but if I can procure the bigger tube that’s the way I’ll go. The shockers I will be using are oil filled Houdaille shocks from the 30’s. I’ve had these a long time. They were seized but a lot of penetrating oil and work freed them off. They have chambers inside filled with oil and the rotary action of the arm forces the oil through valves that in turn dampen the stroke. I will refill them with lighter oil and see how they perform under pressure. They are quite heavy but I figure the front end assy could do with some weight!
Update: photo of 1930 and 1940 Houdailles
I managed to get hold of some A2 M16 stainless bolts to use as donors to make the spindles and kingpins. I know these are heavier they are also harder to resist wear. I guess I can save weight else where on the body and frame.
I put these in the Lathe and centered them before turning them down to 14.95mm just .05 shy of the internal diameter of the bearings which was 15.00mm. These will have to be sent out! and machined with a 1/2 UNF thread to suit the knock off spinners I want to make.
These will be welded to stainless uprights with steering arms welded to them once the wheelbase is determined and ackermann angle established. The spindles in turn will connected to a 1″ nominal bore 316 stainless tube axle by the axle brackets set at 7 degrees of castor and maybe 3 degrees of camber . The castor should also be adjustable and depending on whether I use a transverse leaf set up and split wishbones aka early Ford…
Or 1/4 Elliptical which are intriguing me as I wonder about castor change on bumps causing handling issues. Maybe I’m overthinking it as I think 1/4 elliptical springs look real cool aka Miller cars…
I have somewhere a pair of 25 1/2″ x 1 1/4″ leaf springs that I traded for a cast Mermaid mirror (Cheers Thomas!) and I shall be looking at them once an offcut of tube for the axle becomes available for free.
Update: after a few questions concerning the use of stainless steel parts on my axle construction I thought it best to test their durability. It took probably the best part of 80kg to get the bolt to bend but not shear!!
All stainless parts will be coated with a very high quality anti seize paste to prevent any issues with the stainless galling on its surface.