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Author: Subject: bits and bobs
rash12
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Building: built sr2 ,hillman imp 1.8 under development

posted on 28/10/17 at 11:11 AM Reply With Quote
bits and bobs

1 pair rubber iva bonnet catches from car builder solutions Part Number: BNLCH 10 .00 inc postage
3 southco catches as per rs catalogue RS Stock No.245-5547 10.00 for the three inc postage
1 pr front coil springs of a seven 1.9 id not sure of poundage 200mm long good condition black powder coat 16.00 inc postage
can provide pics if required all catches new in bags

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cfc999

posted on 28/10/17 at 10:31 PM Reply With Quote
1st dibs on the two types of catches please.
Will u2u tomoz.
Cheers

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rash12
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posted on 29/10/17 at 07:02 AM Reply With Quote
Thanks no problem
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maurof74

posted on 19/11/17 at 09:26 PM Reply With Quote
hi,

could be interested in the springs if you are able to check poundage

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rash12
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posted on 20/11/17 at 02:43 PM Reply With Quote
hi maurof74 not sure how I would do that but any suggestions welcome
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maurof74

posted on 20/11/17 at 07:48 PM Reply With Quote
If it is not possible to read the rate (typically written in the flat end of the coil), two methods are possible but it is not so simple to get accurate results:

1)
In principle I can perform the calculation but to be accurate eough I need the following measures with the required accuracy:

1. Coil ID or OD with 0.5 mm accuracy
2. Wire diameter within 0,1mm accuracy
3. Number of turns (considering the portion of wire that is free from contacts, i.e. not the upper and lower flat part)

Even with these accuracy the approximation is roughtly +/- 20 lb/inch for typical coils. Most part of the error comes from wire diameter as the stiffness is proportional to d^4.

2)
Alternatively you can make a test with known test load.


Cheers,
Mauro

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cliftyhanger

posted on 20/11/17 at 08:05 PM Reply With Quote
Indeed, just worked out some springs in my garage.
I grabbed an assistant (wife!)
Measured spring unloaded.
Weighed myself on bathroom scales (yikes, need to lose a few lbs)
Put a bit of wood on top of spring (easier to measure to) and stood on spring. Wife measured the loaded length.

In my case I am 170lb, and the spring compressed by 30mm
So, 25x170/30=141 lb/inch

Simple!

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rash12
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posted on 20/11/17 at 08:35 PM Reply With Quote
number of turns is 8
od of coil is 70.10
diameter of coil is 10.75
is that all you need

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maurof74

posted on 21/11/17 at 11:55 AM Reply With Quote
81000 x pi/32 10,75^4 / (2 pi x 8 x ((70,10-10,75)/2)^3) = 80,8 N/mm = 461 lb/inch

Probably they are 450 or near.
7/100 mm less in wire diameter (e.g due to pai t tickness) are enough to justify the difference between 461 and 450.

For me are too stiff. I'm looking for 275 or near, but at least you have this estimation. I would be curious to see if the suggested experiment will give the same...

Cheers

Mauro

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fregis

posted on 27/11/17 at 06:44 PM Reply With Quote
i think i take springs, looking 400-450
compare: i have 350, wire 10.4, so 10.75 will be near what i need

[Edited on 27/11/17 by fregis]





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