graemevw

Lunchbox wheel wobble

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It has become apparant im going to need to get my lunchbox wheels running true.

It has 3 issues i can see.

The wheel adapters dont sit square, even brand new ones (axles are straight). This makes the wheels wobble.

The wheels arent true, never have been from new, so this adds wobble.

The tyres are not balanced (i know this is common). 

The combination of all 3 means the new high rpms are shaking it to bits.

 

Has anyone overcome these issues?

I remember seeing alloy wheel adapters somewhere, are they any good?

I can probably straighten the wheels but they will probably go back the same, might try and reinforce them somehow?

I tried taping the tyres to get them balanced but it wasnt working. Has anyone removed or added weight to try and get them better?

I guess i need to stop them balloning too, but i cant get tape in them nicely.

I know a few people are running daft spec lunchies so i cant be the first person needing to sort this.

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I have balanced mine with balancing clay. The tyres I belted with kevlar fabric that I glued to the inside using the type of glue one also use for bicycle inner tube repair. Lightweight, cheap and strong. I have a set of chrome Midnight Pumpkin wheels and they are pretty true. So are the yellow set that came in the box. After balancing it runs very smooth, and the glued in kevlar which covers the whole of the tyre inside, really helps the tyre retain its shape.

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One thing to try that's free is to rotate the wheels 180 degrees inside the tires. Sometimes just that can fix a balance problem, or at least minimize it. If you have a heavy spot in a tire, and it's "in phase" with the wobble of the wheel, the wobble will be more pronounced. If you can move the heavy spot around, sometimes it will cancel out a wobble.

If you're serious about speed, though, eventually you'll have to use something other than the standard Lunchbox wheels. You'll want something stiffer, lighter, and truer-running, with lower profile tires on them. The soft floppy Lunchbox wheels and tires just aren't meant to spin that fast...

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Tire glue and cloth tape is a good call. I could probably use the same technique to try and balance them.

I tried turning them on the wheels but it didnt make any difference. If i can get wheel adapters that actually sit square i think that would make a huge difference. I may even try making some.

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13 hours ago, markbt73 said:

One thing to try that's free is to rotate the wheels 180 degrees inside the tires.

This is a good idea to try out, I've done the same with 2 and 3 piece wheels too, a little "corrective reassembly" to balance out warping a little.

If I had to guess I would say your wheel rims will be the toughest thing to overcome without buying new ones. There's a little wobble on my brushless lunchbox but it smooths out as the revs increase.

One thing, and not to insult your intelligence but is there any dirt inside the tyres? I run mine at a beach a lot and sand gets inside the tyres and then ooo boy the thing shakes like a washing machine with one towel inside! I ended up punching little holes in the middle of the tyres so it can spin back out again, otherwise it get's stuck in there. Especially with the rims glued because it get's in through the air holes and can't get back out again.

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2 hours ago, nowinaminute said:

This is a good idea to try out, I've done the same with 2 and 3 piece wheels too, a little "corrective reassembly" to balance out warping a little.

If I had to guess I would say your wheel rims will be the toughest thing to overcome without buying new ones. There's a little wobble on my brushless lunchbox but it smooths out as the revs increase.

One thing, and not to insult your intelligence but is there any dirt inside the tyres? I run mine at a beach a lot and sand gets inside the tyres and then ooo boy the thing shakes like a washing machine with one towel inside! I ended up punching little holes in the middle of the tyres so it can spin back out again, otherwise it get's stuck in there. Especially with the rims glued because it get's in through the air holes and can't get back out again.

No, nothing in the tyres. Brand new, never been run.

This is ok at half throttle, starts to vibrate after that, then gets so bad i think it will snap the gearbox (no exaggeration).

The axle holes in the wheels are a bit of a loose fit. I think im going to make a jig to hold the wheel square and fill the gap around the axle so the wheel is forced to stay square, then machine the locating lugs perfectly true. That, along with cnc adapters and some tyre balancing may get it under control.

I think the wheel itself may be reasonably ok, just a combination of plastic adapters and slack in the axle hole means the wheel never bolts up true to the axle.

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15 hours ago, graemevw said:

Tire glue and cloth tape is a good call. I could probably use the same technique to try and balance them.

I tried turning them on the wheels but it didnt make any difference. If i can get wheel adapters that actually sit square i think that would make a huge difference. I may even try making some.

What I use to belt tyres is actually not cloth tape. I use actual kevlar aramid fabric. Much lighter, stronger and softer. This is what I use. https://www.fibermaxcomposites.com/shop/aramid-fiber-fabric-br-k220p-p-100135.html You could use an even lighter weave. I just used 220 as I had it on hand. 165 will be plenty for what you're doing.

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If i had any to hand id also use it, but i havent. Ill find something in the garage with no stretch that will do the job. Might try platerboard scrim tape, thats glass fibre, flexible and has no stretch. Just need to glue it on well. I have some tyre glue, lots of rubbery adhesives, silicones, polyurethanes etc. Ill test a few and see what looks like it will work well.

I know some people use duct tape but i couldnt get it neat, or to stick well. I think the tyres need a good internal clean and a scuff up. 

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