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

1st dibs on the two types of catches please.
Will u2u tomoz.
Cheers

Thanks no problem

hi,

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

hi maurof74 not sure how I would do that but any suggestions welcome

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

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!

number of turns is 8
od of coil is 70.10
diameter of coil is 10.75
is that all you need

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

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]