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Sierra rear coil springs - a mystery
bumpy - 13/10/12 at 03:06 PM

I am a little confused. The Sierra saloon car had parallel coil rear springs of about the following dimensions:

Thickness 14mm
Length 306mm / 12"
Outer diameter 134mm / 5.27"


I have been offerred a pair of 'Sierra' springs at a breakers yard which are about the right length and outer diameter. (310mm and 140mm)

BUT, the spring thickness is different. The coils seem to be about 14.5mm thick for 80% of the spring then change to about 10mm for the last 20%.

These look to be progressive springs, but what car did they come off?

[Edited on 13/10/12 by bumpy]

[Edited on 13/10/12 by bumpy]

snapper - 13/10/12 at 03:47 PM

Estate?
Later Ford spec?

marcjagman - 13/10/12 at 04:04 PM

Progressive rate springs, could be better for you if they fit. As previously said, probably of an estate or XR4/similar

bumpy - 13/10/12 at 05:13 PM

quote:
Originally posted by marcjagman
Progressive rate springs, could be better for you if they fit. As previously said, probably of an estate or XR4/similar


Yes the only reference I've seen so far to progressive springs is on the XR4i. Would love a picture to compare with.

The normal way to create progressive springs is to change the number of coils per inch at one end. I have never seen a spring where the coil rate stays the same but the coil wire diameter changes.

I called them progressive but it may have some other use.

[Edited on 13/10/12 by bumpy]

[Edited on 13/10/12 by bumpy]

bumpy - 14/10/12 at 10:41 PM

quote:
Originally posted by bumpy

The normal way to create progressive springs is to change the number of coils per inch at one end. I have never seen a spring where the coil rate stays the same but the coil wire diameter changes.

I called them progressive but it may have some other use.


I've just waded through about 2000 pictures of used coil springs on Ebay and not a single one has the construction I described. So, I'm beginning to think the springs have been welded up by a previous owner and are to be avoided.

britishtrident - 15/10/12 at 05:59 AM

Nothing to do with welding up, using wire with ground tapers at one or both ends is a normal way of making a rising rate spring, it is however more expensive than varying the coil pitch to achieve the same result.

bumpy - 15/10/12 at 07:59 AM

quote:
Originally posted by britishtrident
Nothing to do with welding up, using wire with ground tapers at one or both ends is a normal way of making a rising rate spring, it is however more expensive than varying the coil pitch to achieve the same result.


Thats exactly what I needed to hear. Given the absence of replies on here and the lack of evidence from goolge I was fearful it was a bodge.

loggyboy - 15/10/12 at 08:11 AM

Could just be that they are aftermarket springs. Just because no standard sierra doesnt have them from the factory. Provided they are in good nick I cant imagine their being any issues using them.

aeromanboeing - 16/10/12 at 07:55 PM

My Advice Sunshine. if you are building a car that you are going to trust your life with, go to a reputable supplier and buy springs and shocks that are suitable for your particular car. Dont trust some dodgy breaker. After all it will have to pass an IVA or SVA. (Thank god for the inspectors.)

daviep - 16/10/12 at 08:23 PM

quote:
Originally posted by aeromanboeing
My Advice Sunshine. if you are building a car that you are going to trust your life with, go to a reputable supplier and buy springs and shocks that are suitable for your particular car. Dont trust some dodgy breaker. After all it will have to pass an IVA or SVA. (Thank god for the inspectors.)


You've got patronising down to a tee, some people should just stick to saying nothing.

Cheers
Davie

bumpy - 17/10/12 at 07:59 AM

quote:
Originally posted by daviep
quote:
Originally posted by aeromanboeing
My Advice Sunshine. if you are building a car that you are going to trust your life with, go to a reputable supplier and buy springs and shocks that are suitable for your particular car. Dont trust some dodgy breaker. After all it will have to pass an IVA or SVA. (Thank god for the inspectors.)


You've got patronising down to a tee, some people should just stick to saying nothing.

Cheers
Davie


A valuable point, well presented.

bumpy - 17/10/12 at 08:21 AM

OK, I bought the springs, and after cleaning off some of the muck and a rubber sleeve, it turns out the spring is not welded, but the coil wire narrows from one end to the other.

A standard Sierra spring has a consistent coil wire diameter of about 14.5mm.

This spring has a coil wire diameter at the base of about 16mm, at the mid point of about 15mm and at the top of about 11mm.

Does this help to identify it?


bumpy - 31/10/12 at 02:14 PM

quote:
Originally posted by bumpy
OK, I bought the springs, and after cleaning off some of the muck and a rubber sleeve, it turns out the spring is not welded, but the coil wire narrows from one end to the other.

A standard Sierra spring has a consistent coil wire diameter of about 14.5mm.

This spring has a coil wire diameter at the base of about 16mm, at the mid point of about 15mm and at the top of about 11mm.

Does this help to identify it?




Got you all beaten eh!