Splat Rat

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The colors match up well, so I'm stopping where it's at before it looks overdone. The Splat Rat will look just about the same. I'll do the same to the rims (without taking them apart I hope) and handlebars. I may leave the forks and chainwheel chrome.
 
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A layer of clear coat and it's done.
test clear coat.jpg
 
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I looked for some scrap that might work instead of buying a piece of metal and getting some new hardware and got lucky. I have everything I need already. Two matching plates that were meant for brake mounts will be modified to be the upper and lower plates. The long bolts I need and plenty of locknuts were in the big bag of leftovers. I even have the chrome cap nuts I needed. The shorter bolt for the center mount also is there. I just need to drill some holes larger and trim the edges.

top parts springer.jpg
 
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I have a bag full of springs. I wondered about smaller springs on top for return, so I googled it. "Recoil springs on monark springer"

I'm going to give this a try, seeing as I have an extra 2 inches of bolt to work with.

recoil.jpg
 
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@Wildcat, I appreciate many of your build threads. They illustrate a particular determination that's quite motivating. Excellent documentation as well.

I was about to ask if you've considered any sort of rebound dampening. I'm searching for a primitive solution myself.

If my reactions are absent, it's not because I don't like.
 
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I have no engineering background or any other mechanical ability to brag about. Everything I come up with that works has been preceded by a dozen ideas that didn't make any sense in the end. :crazy:
My add on to this homemade thing for rebound is two weaker and smaller springs from a bike seat. I have to widen the ends to slide the 1/4" rods through and that should be it. Sounds too easy, and usually is. I just got home from getting some new drill bits and will get back to work when it cools off a little. Nothing to do now but take a nap.
 
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This is where I ended up today. I remembered the motorcycle seat springs I had and used them as they are just the right size and as strong as the bigger springs. I may not need the top plate but I'll have to figure that out as I try out the fork.

springer 5.jpg
 

metalchewy

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I used motorcycle seat springs on my hard eight build. The had a lot of side to side and front to back play. With the threaded rod up the center you may have some better luck.
 
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I think having 2 springs also will help with stability. A lot of things depend on how it acts in use.

My challenge now is to figure how to straighten the fork legs with what I have in my shop. Maybe my vise can handle it.

I was going to use them as is, but the front wheel would be too far forward, making the bike steer funny. The bike has to be a good solid rider.

I need to keep the trail as close to normal as I can. As the forks get longer the angle of the head tube changes which also affects the trail.
1636331322619.png


The travel of the fork must be in line with the fork angle, so the flanges I make (or get made at the shop) must place the axle right below the leading fork. The flanges should be similar to a Monark springer. I'll need some height to give the tire clearance but not too much on the flange so the travel will be vertical, or nearly vertical. The location of the mounting holes depends on how it all lines up when I bolt it together.

rocker_w-_brass.jpg
 
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All my drill bits are dull, so I couldn't drill the last two holes in the top bracket. I'll have to get another set. This is as far as I got today:

I was about to drill my rear dropouts yesterday when I realised that my 30 year old 10 mm drill had lost the corners - I think I should buy some new drills as well...

I see that the spring bases of your big-spring version have nice seats, and I look forward to seeing whether that is enough to keep the springs apart. Do the springs have any significant pre-compression when there is no rider on board?
 
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Turns out the bracket was stainless and the drills weren't that bad. I used a grinder attachment on the dremel to finish the two holes.

I've changed the config yet again, now using 4 ordinary seat springs, and no top spring. Like this standard Monark springer. Just locknuts and caps on top.
1636367574251.png


The spring ends have an opening that is just large enough to loop over the bolts, so they are secure when added in. I'll post up a pic tomorrow, already locked up for the night. There's no room for them to slide around so I like this setup the best so far.
 
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This shows the 4 springs mounted. The loops on each end of each spring are just the right size to fit over the bolts. That will keep them in place. The holes in the bottom plate and top bracket are 1/4", just enough room for the bolts to pass through, so that will help in stability also. The locknuts on top determine how much tension is on the springs. As they are tightened, it will bring the fork end upward and change the geometry of the wheel somewhat.
I'll trim the bottom plate to look better. I will also keep the fork legs curved, straightening them won't really make much difference and might make them weaker. I'll design the bottom flanges next.

springer7.jpg
 
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This shows the 4 springs mounted. The loops on each end of each spring are just the right size to fit over the bolts. That will keep them in place. The holes in the bottom plate and top bracket are 1/4", just enough room for the bolts to pass through, so that will help in stability also. The locknuts on top determine how much tension is on the springs. As they are tightened, it will bring the fork end upward and change the geometry of the wheel somewhat.
I'll trim the bottom plate to look better. I will also keep the fork legs curved, straightening them won't really make much difference and might make them weaker. I'll design the bottom flanges next.
Ah, those springs are so neat, curling around the fixing bolts like that :)
 
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I am still on the hunt for a cottered spindle, no luck online or at the bike shop. I borrowed the one that was on my previous build, just for a mock up. The arms on the cottered cranks are a tad longer than the 170 new sets I have, and a lot longer than the normal cottered set.
chainwheels.jpg

That's ok, as I should have plenty of ground clearance with the height of the fork, once it is done. The weld on the bearing cap seems to be ok and the cup is lined up well. Someone must have cross threaded it when new , not knowing it had left hand threads.
BB weld.jpg

I have to trim the plates further and use both plates on the bottom now, because one wouldn't be strong enough after cutting it down to size. But they can be smaller because they will work together. I tried a different fork as the main fork, but it didn't have enough threads. I see the need to straighten both forks, so maybe the machine shop will get some business from me. This mockup doesn't show how high the front will be, but was just to get an idea.

mock 1.jpg
 

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