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#Post#: 8077--------------------------------------------------
Indespension Spring
By: StefanN Date: January 19, 2023, 6:34 am
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In the search for cheaper springs I experimented with an
Indespension leaf spring - mainly because they are about the
right size and reasonably priced. The cost has gone up now to
£38 but still not crazily expensive and discounts might be
available.
HTML https://indespension.co.uk/1200kg-7-leaf-spring-eye-to-eye
I dismantled the spring to get the long leaf from the pack.
It's about 585mm (23") eye to eye, 50mm wide and approx 6.85mm
thick. The camber from the eye down to the outside of the
spring is 78mm.
Deflection with 83.2kg (183lbs) was 14.5mm (would be higher if
no friction between eyes and workbench). That’s a spring rate
of 320 lbs/inch
I cut 9mm off each side with a 1mm cutting disc. I burned
through 4 cutting discs (£3.50) and it took less than an hour.
By doing long cuts rather than concentrating in one spot, the
spring didn’t get much above warm to the touch so the heat
treatment won't have been changed.
Deflection at 32mm wide = 24mm = Spring rate 194 lbs/inch
Switching to metric
CK + driver approx 180kg
say 35:65 weight distribution gives 63kg on the front.
As a transverse spring this would deflect about 18mm at rest
Or 9mm as a pair of longitudinal springs.
The eyes are a bit oversize (visually).
I hope we might be able to test the spring out on a cyclekart.
#Post#: 8080--------------------------------------------------
Re: Indespension Spring
By: ian.lang Date: January 20, 2023, 7:08 am
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Stefan, I was thinking what else uses light springs and than had
a thought - pony carts! - see attached pic. I have dropped him
an email and he had come back already asking for some pics and
dimensions of what we want. Please can you kindly do a sketch
and take a pic of your set up and I will go back to him. Many
thanks. Ian
#Post#: 8081--------------------------------------------------
Re: Indespension Spring
By: Ian F Date: January 20, 2023, 12:24 pm
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Thanks Stefan for posting all the dimensions and resultant
spring rates. I will be looking at building a second cycle kart
as soon as my current project (class 7 classic trials car) is
finished. The new CK will have a transverse fron t leaf spring
and I will be looking for about 120 lbs/ inch spring rate, so.I
now have good idea from your measurements. I am currently
thinking about making my own leaf springs and bolting on the eye
ends as the loads are lower on A CK
#Post#: 8083--------------------------------------------------
Re: Indespension Spring
By: StefanN Date: January 20, 2023, 1:25 pm
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[quote author=Ian Lang link=topic=1042.msg8080#msg8080
date=1674220118]
Stefan, I was thinking what else uses light springs and than had
a thought - pony carts! - see attached pic. I have dropped him
an email and he had come back already asking for some pics and
dimensions of what we want. Please can you kindly do a sketch
and take a pic of your set up and I will go back to him. Many
thanks. Ian
[/quote]
Hi Ian,
They look interesting. There’s a drawing on this post
HTML https://cyclekartsgb.createaforum.com/where-to-get-stuff/leaf-springs-492/msg3894/#msg3894
Can I suggest you have a word with Graham Hill as he and Chris
Loader are working on sourcing springs and it would be good to
feed your findings into that effort.
#Post#: 8088--------------------------------------------------
Re: Indespension Spring
By: Ian F Date: January 21, 2023, 12:20 pm
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You can buy spring steel cheap on eBay, etc. so was thinking
annealing it, then shaping a d drilling, then getting it
tempered. Rather than forming the eye ends was going to weld
some tubes to tangs and then bolt onto the end. Just an idea at
the moment, but expect to do some proper investigation in Spring
(no pun intended) 🤣
#Post#: 8093--------------------------------------------------
Re: Indespension Spring
By: RhysN Date: January 23, 2023, 1:38 am
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If it's any help, the calculated rate on the front of Dave
(Bentaxle on the US site) Maserati 250F is 160 lbs/inch (per
side), he says that works well.
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