Third bearing conflicting info

Hi all
I need advice on 3rd bearing fittment. When to use or lose. Kart is an exprit noesis.
Thanks in advance

Running the same kart, we keep it loose as our baseline setup, and rarely tighten it.

Tightening will effectively stiffen the axle. This will reduce flex in the rear of the kart and eliminate some of the inside rear wheel lift. If the kart is hopping from being too soft in the rear, the 3rd bearing is a good quick adjustment to help eliminate that.

We usually use it as a quick test adjustment to see if we need to go stiffer on the axle. If we tighten it and the kart gets better, then we know that we should probably go to the next stiffest axle if the track continues to grip up.

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Thanks for quick reply.
What would you suggest as a base setup?
Rotax, dunlop DFH, 165kg (364lb). Tracks low to med grip.
Trying to free up off the turn.
Thanks

Like I said, we run it loose as a base. I believe that is the OTK recommended setup as well.

I always start with the OTK baseline setup and rarely stray too far from it.

If the kart turns in well but isn’t getting off the corner properly, I would take a look at reducing some caster. If the kart isn’t free off the corner, the inside rear wheel isn’t staying lifted long enough. The lifting action is happening too quickly. Reducing caster will help slow down that lifting action and keep the inside rear up longer, helping the kart roll off the corner better.

There are several adjustments you can make, but I would start there. Any time you can reduce caster and keep the front end working well is good.

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Welcome @Marin_Vujcich!

Don’t be afraid to experiment and try changing one thing at a time.

Thanks for the responses

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Hey Marin,

Did you do some more testing yourself on this? I’d be interested in hearing your findings/thoughts on running the bearing loose vs tight on the rotax senior application

Yip have done.

In short the 3rd bearing in on the OTK makes the inside wheel drop to quickly and more likely to get an exit push.

Never run it now. Might be ok in the wet, but havnt experimented with that.

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Thanks for that, i am going to experiment with it loose on my 30mm birel chassis. Is there any difference to running it in place with zip ties vs having it completely removed?

No difference. (20 char)

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As far as loose or zip tied, our club rules specify if it is not secured with bolts it must be zip tied or wire tied. Not sure why though. Not like it could fly out. I’m pretty sure I’ve seen the same rule for other events also.