Custom Springs...... attn Scott!

[SpecB]

The front of the Spec B is sitting about 1’ higher than I’d like on the new shocks and springs, the springs are new OE Spec B and the shocks are Bilstein B8s (not quite OE but £300 a shock cheaper than buying from Subaru!). Shock length is slightly shorter than OE.

Does anybody (Scott?) know of a company that can refurbish and shorten my old springs or even make a custom slightly shorter set - maintaining OE spring rates.

[Scott.T]

We ended up using 2 different companies to produce different spring rates/heights. Both were a bit hit and miss. We dropped the 1st company after the 1st set because the windings on a pair was visually diffetent.
Even with us providing them with about 4 different sets of classic Subaru springs (STi lowered, prodive 1998 and 2 different prodrive 1999 and P1) for them to test and record the resulting springs produced were still very hit and miss.
The final sets were ok but I never did achieve the ride height target.
Imho it's a very difficult process if you do not know the weight applied to the spring when fitted to the car with the car settled on the spring.
Even after alot of work my car ended up 10mm higher than target.

[SpecB]

Any experience of having OE springs adjusted - I have found a company in Sheffield who claim to be able to modify the stock springs by altering the spring (not cutting so I assume some kind of heating and rewinding), shot blasting and re-powdercoting to give an as new spring with the same spring rate but a 1' reduction in overall length.

There is a slo a company in Chichester that can manufacture new springs (but obviously more expensive especially for a one of set)

[Scott.T]

Probably the same company we used in Sheffield.
They may be able you heat and compress the spring but they would have to compress the part of the spring with the widest gap when loaded. The majority of the lower windings compress to touching point at rest. You don't want the open windings compressing to binding point when in motion as the severely effects the spring rating under load.

There is also the risk they will be loose in the struts at full droop if the overall spring length is reduced..

The less windings/coils over an equal spring length with the same gauge steel gives a harder spring rate. So if they rewind rewind them the rates will change. And a harder spring rate will actually give a higher ride height at rest if the maths are incorrect.
It's quite a science.....

[Scott.T]

If you look at your spring at rest you probably have 1 or 2 very close coils and 2 wide spaced coils.
The close coils give you your compliance and softer ride. Once you lean on them a bit the close coils close and you end up with the stiffer rate of the wider spaced coils.
The wider the spacing the harder the ride.

Think of spring in its raw form as a steel rod. A straight steel rod is solid if you try to compress it over it's length. Put a bend in it and then try to compress it and it will flex. Put some coils in it and it will flex some more.

Linear setups have equal spacing but a standard Subaru strut would not be linear if they were spaced as such. Due to the spring also being tappered. Wider at the bottom than top.
This is also used to create a progressive rating.

[SpecB]

I'm guessing the springs on the Spec B are progressive as seen here:

I may well send my old set off to be fettled and see what comes back - I'll still have the new ones to replace them if all else fails. The only issue I have is that the standard spring compressors will not compress the springs enough!

[asperformance]

basically most OEM springs are progressive to some degree

[SpecB]

Alyn - any chance you have a supplier for lowering springs for a UK 3.0 Spec B? They seem pretty hard to find!

[asperformance]

there may be a listing for a very early BP5 chassis (not sure what changed on the later facelift off hand) but few and far between

seems odd you have only encountered this issue after fitting new parts which might suggest the front shock is possibly specced slightly wrong??
would be good to have factory ride heights and compare them to what you have??

[SpecB]

Shocks aren’t quite OE Spec as they are direct from Bilstein not the Subaru versions.


Front
Before 375mm centre to arch
After 380mm centre to arch
Difference +5mm

Rear
Before 335mm centre to arch
After 350mm centre to arch
Difference +15mm (mostly due to collapsed rubber washer on original shocks)

[asperformance]

a little confused now as you have gained positive rake and yet you seem to think the front should go down??