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#Post#: 5412--------------------------------------------------
King pins et.al.
DIR By: David F-R
Date: February 7, 2022, 4:04 pm
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I'm trying to work out the mechanical design of the kingpins.
I'm a total newbie to vehicles and Cyclekarts but quite handy in
the workshop.
This what I've come up with so far _
kingpin 15mm dia. x 72.05mm, bored 10mm
pivot bolt 10mm dia. x 100mm
housing 30mm dia. x 60mm long, drilled 16mm, recessed each end
to take bearings.
bearings 15mm x 24mm x 5mm type 61802
bottom thrust bearing 15mm x 28mm x 9mm type 51102
top bronze washer 30mm x 3mm x 15.1mm hole
grease nipple in housing
'C' shaped axle mounts from 31.75mm x 3mm (1.25" x 0.125")
Should this be thicker??
Stub axle M15 socket head bolt
The kingpin is nipped by the long bolt between the arms of the
'C' and rotates in the main bearings in the housing. The housing
is welded to the bent main axle (from Gemini Karts).
Now - have I got this right???
Please, please correct me where wrong and advise accordingly.
Thanks.
#Post#: 5413--------------------------------------------------
Re: King pins et.al.
DIR By: Mark Under
Date: February 7, 2022, 4:24 pm
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I have no idea what other people have done but I didn�t put
bearings on my kingpins, I just made up some nylon bushes.
I am hoping that there is so little weight on the front that
bearings will not be needed although you now have me worried.
#Post#: 5414--------------------------------------------------
Re: King pins et.al.
DIR By: David F-R
Date: February 7, 2022, 5:05 pm
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[quote author=Mark Under link=topic=733.msg5413#msg5413
date=1644272667]
I have no idea what other people have done but I didn�t put
bearings on my kingpins, I just made up some nylon bushes.
I am hoping that there is so little weight on the front that
bearings will not be needed although you now have me worried.
[/quote
Don't get worried Mark. I have a habit of over-engineering
things. I think that oilite bearings have been used and plastic
'top hats' both remove the need for kingpin bearings and thrust
bearing. I may yet re-think but I wanted to get feedback. Thanks
for that.
#Post#: 5416--------------------------------------------------
Re: King pins et.al.
DIR By: StefanN
Date: February 8, 2022, 1:38 am
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There�s a bit of info about the Gemini axle here
HTML http://www.cyclekartsgb.com/tech-forum/turnkey-dropped-front-axle/msg1184/#msg1184.
#Post#: 5417--------------------------------------------------
Re: King pins et.al.
DIR By: ChrisS
Date: February 8, 2022, 2:12 am
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Nylon bushes are fine but mine wore over time and I've now
replaced them with bronze. Yet to see how well they wear.
#Post#: 5418--------------------------------------------------
Re: King pins et.al.
DIR By: StefanN
Date: February 8, 2022, 2:23 am
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Your kingpin set up sounds about right and is pretty much the
same as the Gemini one. Can�t remember how thrust is carried on
theirs -will look later.
As Chris says, nylon or bronze work. My first axle needed a
little fettling to make a longer kingpin so that when the bolt
clamped it to the yoke, it didn�t lock up the joint.
15mm stub axle might be a bit small. Pit bike wheel takes 17mm
and I think Honda is normally 20mm, but I�ve not used them so
others can confirm. Attaching the stub axle to the c shaped
yokes needs a little care because it can be a weak spot.
#Post#: 5419--------------------------------------------------
Re: King pins et.al.
DIR By: RhysN
Date: February 8, 2022, 2:42 am
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Just a couple of amendments to what Stefan has said.
Pit bike wheels come standard with 15 mm spindles. They are a
bit on the light side, 17 mm works just fine (Refer to Chris
Brown bearing chart)
Honda wheels as standard are 12 or 15 mm. The same applies.
Again, check that OD of the bearings, I have had some with 32mm
OD bearings, Learn from my costly lack of knowledge!
If using Gemini stub axles, both varieties are 17 mm (Honda or
Pitbike), the difference is in the length, at least the ones
they sold me on each occasion that was the difference.
I have used plain steel on the 10 mm kingpin, also used bronze,
and also kart spindles with bearings and 8 mm king ins. All have
worked OK for me. These cyclekarts are not a fit and forget,
just make it so you can change things readily along the way.
David F-R, your method sounds like an engineering masterclass, I
suspect that very few would feel the need to go as exotic as
that.
#Post#: 5420--------------------------------------------------
Re: King pins et.al.
DIR By: David F-R
Date: February 8, 2022, 4:15 am
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All really helpful advice. Thank you everyone.
Definitely 17mm stub axles - can't think why I put 15mm.
I'm also considering using flanged oilite bearings top and
bottom for the kingpin - they're certainly a cheaper solution.
#Post#: 5421--------------------------------------------------
Re: King pins et.al.
DIR By: StefanN
Date: February 8, 2022, 4:23 am
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--- Quote from: StefanN link ---
>
> Pit bike wheel takes 17mm and I think Honda is normally 20mm
--- End Quote ---
�.When fitted to a Cyclekart
#Post#: 5422--------------------------------------------------
Re: King pins et.al.
DIR By: David F-R
Date: February 8, 2022, 4:49 am
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--- Quote from: StefanN link ---
>
> [quote author=StefanN link=topic=733.msg5418#msg5418
date=1644308582]
> Pit bike wheel takes 17mm and I think Honda is normally 20mm
--- End Quote ---
�.When fitted to a Cyclekart
[/quote]
I'll have a look for bearings. I usually buy bearings from
Bearing Boys and they don't seem to have 20 x 35 - I'll look
again. [Found some]
20mm stub axles definitely better.
I like the pics of the Gemini turnkey axle. 5 or 6 mm thick yolk
more meaty, bending will be fun.
The boss on the end of the stub axle gives a better joint to the
yoke too.
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