Author Topic: Pit Bike Wheel to Rear Axle... are you receiving me?  (Read 722 times)

Graham Hill

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17” pit bike wheels are now commonly accepted as an alternative to the increasingly elusive Honda C90 wheels. I am demonstrating a simple method I have used here, for attaching to a standard 25mm kart rear axle to produce a fixed wheel solution.
Components:
2 off. Standard karting mono-alloy 3-stud rear hub. Typically £17.00 each online. Plus key steel.
2 off. 3mm steel ‘CycleKart adaptor plate’, newly available from Gemini Karts in their shop section. £2.80 each plus VAT
4 off. Flanged Oilite bushing OBF253516. Bearing Boys £3.88 each plus VAT
14 off. M8 x 25 Stainless steel socket button set screws. Toolstation Code 11982. £6.29 for a pack of 50.
2 off. Standard 25mm locking collar. Typically, £3.00 each online
2 off. External circlip. Less than £1.00 each online
Method:
1.The three 8mm studs require removal from the kart mono hubs. Mine unscrewed easily after carefully heating.
2.The standard 17” rim hub will require a couple of simple alterations. Remove the existing 35x15 bearings from both sides of the wheel by simply knocking out. The wheel hub has a raised flange to the disc carrier which is best removed flush and this can be achieved with an angle grinder, abrasive flap wheel or a hand file. See photo. The inside diameter of the wheel hub will most likely require a small amount of additional filing to remove casting flashing and allow the 25mm axle to pass clear through (this does not have to be accurate).
3. The Oilite flanged bushings are OD 35mm and ID 25mm and will press fit snuggly into both the inside and outside face of the wheel hub (in place of the original 35 x 15 bearings). These bushings are used as reducing spacers only and do not rotate on the axle.
4. The mono hub is fitted utilising the axle keyway. The 3mm steel adaptor plate is now bolted to the mono hub using three button head set screws, using thread-locker. Note, button head type screws are the best fit here but will still clash slightly with the wheel hub. This is remedied by cutting a small section off the outside of each screw head. See photo. This does have the advantage that they cannot back-out unseen.
5. Finish off by fixing four more set screws between the adaptor plate and the wheel hub, (photo shows a standard bolt in this instance) .Then a locking collar and a circlip.

NOTE. Each wheel has three separate attachments to the axle. The locking mono hub, the external locking collar and the external circlip. Individuals should ascertain for themselves the security of this suggestion, however I have yet to experience any issues.
See also my previous article on the tech forum utilising pitbike wheels with a front axle. ‘Turnkey dropped front axle’ 14.08.19
« Last Edit: 15 Jun 20, 10:00 pm by Graham Hill »

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Chris Brown

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Re: Pitbike Wheel to Rear Axle... are you receiving me?
« Reply #1 on: 15 Jun 20, 02:50 pm »
Thanks for setting that out Graham, the adaptor plate is particularly handy, not worth making them at that price.

jim

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Re: Pit Bike Wheel to Rear Axle... are you receiving me?
« Reply #2 on: 15 Jun 20, 06:19 pm »
That looks really good Graham and I will use that method myself the next time I use pit bike wheels.
If you can drive round corners, you're not going fast enough.

Graham Hill

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Re: Pit Bike Wheel to Rear Axle... are you receiving me?
« Reply #3 on: 15 Jun 20, 07:06 pm »
Thanks, I did spend some time with Gemini Karts developing the budget adaptor plate for general sale.

guest274

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Re: Pit Bike Wheel to Rear Axle... are you receiving me?
« Reply #4 on: 14 Mar 22, 10:53 am »
Whist following the procedure suggested by Graham Hill when fitting hubs to pit bike wheels, which was very useful, I had to amend slightly what I did. The 8x25 stainless steel screws used to fit the adaptor plate to the hubs had to be shortened to about 13mm to allow them to tighten. The 8mm studs that were in came out easily using two locking nuts. I didn't grind down the flange on the wheel hub. Instead I used 8mm washers flush with the flange.   Other than that, it went as described.

RhysN

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Re: Pit Bike Wheel to Rear Axle... are you receiving me?
« Reply #5 on: 14 Mar 22, 10:57 am »
I do understand that at least you have taken some measure to deal with the disparity of the surface, however, as I have broken one of the lugs myself (of course it then became a front wheel) it's a matter of very few minutes with a flap disc to take the lip off, and the the disc has a full contact surface.
End of the day, it's your call. I now do it always, lesson learned the hard way :)
We must avoid torturing our brains with false problems, it occupies but it can annoy. In jest!

guest274

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Re: Pit Bike Wheel to Rear Axle... are you receiving me?
« Reply #6 on: 14 Mar 22, 01:50 pm »
Thanks for the info.

Tinworm

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Re: Pit Bike Wheel to Rear Axle... are you receiving me?
« Reply #7 on: 31 Aug 22, 05:26 pm »
That looks really good Graham and I will use that method myself the next time I use pit bike wheels.

Jim, in your workshop you have a kart which you didn't build (I think you said), which has retaining bolts at the ends of the rear axle (tapped M12, I believe?). Have you tried Graham's method now and if so, do you think that a circlip is just as good?

I have been setting up my pillar drill to do an end hole, but if the circlip works fine, I may not bother (except that it might make it possible to have brass detailing later).
I don't want to bore you all with the details, here. But if you are interested, have a look at my blog https://peteskart.blogspot.com/

-Peter

Tinworm

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Re: Pit Bike Wheel to Rear Axle... are you receiving me?
« Reply #8 on: 31 Aug 22, 05:28 pm »
Thanks, I did spend some time with Gemini Karts developing the budget adaptor plate for general sale.

Graham, has a wheel ever come off using this method - especially the circlip? Has anyone lost a wheel through the circlip failing?
« Last Edit: 31 Aug 22, 05:53 pm by Tinworm »
I don't want to bore you all with the details, here. But if you are interested, have a look at my blog https://peteskart.blogspot.com/

-Peter