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Leopard has run a few times now. At militracks we has wet conditions but we had to stop on Sunday as 26 of the 28 road wheel tyres had loosened or fallen off.
Wheels were shot blasted prior to being painted, rims were masked so no paint got on them. 480 Loctite was applied to cleaned rubber and cleaned wheels ( panel wipe). Tyres were then applied and zip tied to hold them in place and left for 24 hours.
What did I do wrong?
I think the bonding area is too small basically just the outer rims, also the tyres are a loose fit. I also think that the 480 is too fast. I have seen others use gorilla epoxy and uhu. I think that a filler type is needed to bridge the gap between the dished rim and the tyre so maybe sikaflex or similar maybe worth a try.

Any suggestions.

Also investigating torsion bars, the leopard has 5mm bars but I want stronger bars. Any supplier recommendations for 5.5 (king tiger uses this size) or maybe 6mm.

Torsion bars are just spring steel round rod, these are commercially available. a quick look on ebay 265697799507

To show what I mean, the tyre was held to the wheel, and shows how loose it is when clamped.
Also the tyre turned inside out against the rim show the contact area available and the void.
The glue seems to have stuck to both surfaces but the stress has pulled it apart.

Thanks Mark for the link, I did look at that one but the rod is stainless and I wasn’t sure.

Good points and ideas. Good Luck in finding what glue works as it sounds like your install method is good.

Good Luck as I see this problem happening to others.

Later Tim

I have been using hysol epoxy for airplanes and have found it is very strong and pliable. It works well on wood and plastics. It gives long work time and mixed with a special tool. There is a 5 minute version too (680) I have started using the 5 minute version instead of green loctite for slip fit parts and now that I see your report I think I will use the hysol for tires and give it a try. It is more expensive but may also have the added benefit of being mixed with micro balloons for filler. I’ll have to check on that with my friend. You could try some experiments. Last maybe cut the tire and remove a small amount of material for a tighter fit? This would create a seam but I think that would be preferred to a gap. I will say once you start using hysol that old traditional epoxy does not really seem appealing at all. I agree 480 is one of the hardest adhesives to work with and brittle. Will have to test the hysol to see if it binds with rubber.

Model Shop Leeds have a good selection of piano wire:

https://www.modelshopleeds.co.uk/catalo ... ords=piano

Adrian.

Paul the gap between the tire and the wheel is too big,the contact surface is too small there is no force to hold them together. There is no glue that will work with this huge gap maybe AT will say more

It doesn't look like there's any glue residue on the steel, so the glue stuck to the tyres better than it stuck to the wheels.

More abrasion on the wheels ?

Adrian.

Adrian Harris wrote: ↑

Thu May 30, 2024 6:24 pm

It doesn't look like there's any glue residue on the steel, so the glue stuck to the tyres better than it stuck to the wheels.

More abrasion on the wheels ?

Adrian.

Adrian, that wheel has been cleaned with a wire wheel to remove the rubbish and rust (lots of rust very quickly).
Pretty sure the problem is the bonding area and the loose tyres.
I could cut some steel strips, weld to the rim and fill the inside space before bonding again, but Id rather not do that.

Hi Paul,
I think the issue is not a glue problem but a surface area issue. The recess in the middle of the wheel can cause the rubber tire to deform and crack the joints. There isn't enough surface area for bonding too.

If you have access to printer perhaps you can print an insert to fill the gaps?

Also of importance is have a clean (paint free, burr free, rust free) surface to bond too.
-Bob

Due to the problems I have had in the past with super glue bonding to quickly I have been looking around for a slower acting super glue.
Has anyone tried using UHU all purpose adhesive super?
It is a super glue that gives you around 20 seconds for adjustment before it bonds so it is not instant and gives you time to aline the rubber tire and get a more even spread of glue by moving it around before setting.

David.

Hi Paul,

the loctite 480 is one of the best Cyanacrylate glues for the rubber to metal surface. Highest performance and still flexible.
Most other glues are to brittle after curing

One key thing to take care is the cleaning operation ! NEVER use any kind of VOC cleaner, thinner however you call it to clean the surfaces. This will kill the bonding performance !
Respect some lift off time after cleaning with just a little bit wet cloth or similar, wait some minutes before glue application.
Cyano glue is nothing else than a 2K system with humidity as second component.

The gap in the rims is indeed not perfect but can be easy filled up e.g. with some rubber stripes glued in the bed as first step, followed by the rubbertyres on full surface in the second step. Just an idea so ...

Hope you can find the cause and get it fixed.

cheers Uwe

David Merritt wrote: ↑

Thu May 30, 2024 7:58 pm

Due to the problems I have had in the past with super glue bonding to quickly I have been looking around for a slower acting super glue.
Has anyone tried using UHU all purpose adhesive super?
It is a super glue that gives you around 20 seconds for adjustment before it bonds so it is not instant and gives you time to aline the rubber tire and get a more even spread of glue by moving it around before setting.

David.

On my Panther G wheels I used UHU Epoxy Ultra Strong

https://www.uhu.com/en-en/products/uhu- ... ener-blist

Loads of time to adjust and hardly any mess.

Time will tell how well it works.

If mine were like that I would fill the gap solid with something like All Metal which is a form of bondo with actual metal shavings in it, then I would use a rc tire glue, the good stuff will rip the tire before the glue lets loose.

Paul Sparkes wrote: ↑

Thu May 30, 2024 2:07 pm

To show what I mean, the tyre was held to the wheel, and shows how loose it is when clamped.
Also the tyre turned inside out against the rim show the contact area available and the void.
The glue seems to have stuck to both surfaces but the stress has pulled it apart.

Thanks Mark for the link, I did look at that one but the rod is stainless and I wasn’t sure.

Paul, have the tires (sorry tyres!) always been that much larger than their rims or did that occur after some while running?
I hate to say it but that tyre/rim combination would be a tough nut to crack especially since the rim has essentially a void
in the center limiting the contact area.

It almost seems as if a silicone based adhesive with filler capabilities might both support the tire and bridge the gap between rim and tire
however with the tire fitting loosely as you described it would need a fixture to assure proper alignment concentrically.

I hate to think the tyre became loose after running, that would bring into question as to the state of the rubber.

Ideally the tyre would have a center rib section molded in that would better engage the rim circumference - center portion.

I second the opinion of loctite 480; I learned the hard way that regular Ca adhesives cure too brittle to hold rubber to flexible parts;
my M2 halftrack project proved that to my annoyance... and the jury is still out for the final assessment.

Jerry