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Rhysn Rhys Nolan
Tamworth, Staffordshire, UK   GBR
Douglas, a Hamblin at Curborough today that explored the limits of grip! Was that you? I tried to catch up with the driver after my marshalling but failed before I was too frigid.

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greggkishline Gregg Kishline
Kenosha, WI, USA   USA
Allow me to offer another option here. There's an inexpensive, slower steering option for these scaled cars, which I used on a 1/2 scale Watson roadster I built a few years back. Standard kart steering was too twitchy, so I searched for something stout and a little slower. I bought this unit from BMI Karts in Ohio. Nice tie rod ends. With commercial kart spindles (and steering arms), I ended up with about one turn, lock to lock. Just right, for me.

They offer a steering shaft and steering wheel flange with the same spline, as well.

Here's a link:

https://www.bmikarts.com/crm.asp?action=contactus


Attachments:
Rack and pinion steering from BMI.jpg    9.2 KB
Rack and pinion steering from BMI.jpg

steering tacked in 3-17-2013 005.JPG    44.7 KB
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assembly 6-28-13 1052.JPG    88.4 KB
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drag link, trailing arms done 4-8-2013 (lighter).JPG    51.2 KB
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Denny Graham Gold Member Dennis Graham
Sandwich, IL, USA   USA
1950 Chevrolet 3600 "Old Blue"
1954 Chevrolet 3600
Rack & Pinion are defiantly a step up in engineering Gregg. But with quite
a bit more added to the budget than the standard go kart type steering, which
can be fabricated at home for penny's. And that's no doubt the reason so many
of the go and cycle karts use it.
Something I noticed in your picture is the cross torsion suspension. Rick used
socket wrench extensions for his parallel setup on the Miller, apparently he
is satisfied with that, Ii seems to me that they would be WAY to stiff and not
allow for any movement at all. Also, I've actually twisted 3/8" extensions
beyond their yield point trying to break loose a stubborn fastener, they
really had no spring or return to it at all.
I'll bet with your background with the champ and dirt cars that you chose
a material for your bars more suited to the task? Also.....how did you spline
the arms?
Thanks
Denny Graham
Sandwich, IL

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greggkishline Gregg Kishline
Kenosha, WI, USA   USA
Denny: This car is not suspended, despite appearances. Front axle is fixed. Built to look like it's damped by faux Monroe Indy shocks. As a tribute car, it was 'decorated' to appear as suspended by T-bars. These cars are eye candy and rarely operate. Example: I sold it as a roller - with a motor-plate only. As for torsion suspension ... you're right about 3/8" tool extensions - rate is much too high. I know nothing of the metallurgy, Rockwell numbers, heat-treating, alloy, and such, but the diameter alone is too great. Think back to plentiful torsion springs, similar to those used on 1/4 midgets - although 1/4 midget springs were custom made and might be light for a CK. The trunk springs of the heavy production cars of the 1950's thru the 1970's were pretty beefy, and most have 90-degree bends in them already. Buicks, Caddys, ... all the GM heavies. That might spawn some ideas. Cheap, readily available, and they were designed as springs. Adjustment stops and attach points can be safely welded on the cut ends. Length would be determined by trial and error, to establish a rate that works for the mass of a CK. A bushed spring could also act as a suspension link. I'd start by looking for 5/16" diam springs in junkers, and start playing.

Built a lot of these. Now that I've tried the rack & pinion, I doubt I'll use kart steering again unless forced to. Even at $75, once you try it you won't go back.



Edited 1 time(s). Last edit at 2018-12-04 05:18 PM by greggkishline.

Denny Graham Gold Member Dennis Graham
Sandwich, IL, USA   USA
1950 Chevrolet 3600 "Old Blue"
1954 Chevrolet 3600
Ah ha!!!! You're foolin' us are ya Gregg! Here I thought you were building fully working
scaled down versions of the real cars.
But....just using some basic backyard figuring, The micro sprints use a bar about
14 or 15 inches, .550 to .600 inches in diameter. My guess would be they are using
something like a 4340 heat treated to about a 45 rockwell C.
With the light weight on the front of these Cyclekarts, for instance, an 18" bar turned to
.500" with 6" arms should handle about 100 lbs. Reducing the section that is necked
down to .4375" would bring it down to a little over 60 lbs. Changes in length and diameter
make for some really large differences.
dg

greggkishline Gregg Kishline
Kenosha, WI, USA   USA
I was simply suggesting something you could adapt from readily available stock. Fabbing and broaching the T-arms is beyond most home-builders ... plus the splines on the bars.... ugh.
We'd soften up torsion bars for (open-wheel) midgets by grinding them down, decreasing the diameter in a lathe, using a Milwaukee 9" hand-held grinder and a micrometer. Your Rockwell "C" scale number (low-forties) rings a bell. Most builders aren't machinists, I'll wager. I'll attach photos of the finished roadster, with its fake T-bar suspension which sat on a 53" wheelbase.


Attachments:
Auction photo- Sotheby-RM 2016 PHX 002.JPG    49.2 KB
Auction photo- Sotheby-RM 2016 PHX 002.JPG

Auction photo- Sotheby-RM 2016 PHX 007.JPG    50.2 KB
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Auction photo- Sotheby-RM 2016 PHX 008.JPG    52.2 KB
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PICT2398.JPG    77.2 KB
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Denny Graham Gold Member Dennis Graham
Sandwich, IL, USA   USA
1950 Chevrolet 3600 "Old Blue"
1954 Chevrolet 3600
Beautiful work Gregg, thanks for the pixs. But I'm afraid we've gotten a wee bit off
course here. Sorry Geoff.
DG

greggkishline Gregg Kishline
Kenosha, WI, USA   USA
I'll echo Denny's apology, Geoff, for the brief detour/distraction ...

I did check the links you offered - thanks for the requested background. Impressive work indeed, and you have a very good eye.

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