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Emeritus Forum Staff
2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #1
As the title says, I'm looking at getting some suspension springs custom made for me (comes in at < £200 inc VAT and delivery :woohoo:)

The company I spoke to said that the fronts should be no problem. However, the rears could be an issue because I will be swapping from SLS rear struts to non-SLS rear struts and thus the new spring would need to compensate for the reduced support from the non-SLS strut.

As I only have an SLS spring I can send them as a template, I need to know one of the following:

  • How much lower SLS rear springs would be on non-SLS rear struts so the manufacturer can add this back on when designing the new spring?
  • What is the spring rate of a non-SLS rear spring?

The other option is to send them a non-SLS rear spring - anyone have one I can borrow as I don't fancy buying one just to use as a template? ;o)

On a slight aside, the company has said that once they have the springs designed, they can make them again at whatever spring rate and ride height is required. Oh, and they can powder coat them in a colour of your choice!
 

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2008 GRB 20th anniversary 6 MT
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Which company are you using Gigsy and are you going to use these with the WRX struts?
I am thinking of ordering a set of Sti pinks from japan but looking at other options as well.
Do you think they can replicate the Sti pink springs given their height and rates?
 

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2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #3
They said to me that as long as they can have one of your current front and rear springs for an hour as a template then they can make them with pretty much any drop and spring rate that you require.... my struts are off the car already so that's easy for me but a bit more difficult if you happen to need them to keep the car up!
 

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They said to me that as long as they can have one of your current front and rear springs for an hour as a template then they can make them with pretty much any drop and spring rate that you require.... my struts are off the car already so that's easy for me but a bit more difficult if you happen to need them to keep the car up!
The question is to have a uniform drop of e.g. 2.5cm and keep the car level you might need to reduce the spring length by a different amount front and back since the spring will compress when the car sits on it.
How will you be able to make sure the car is level with the new springs?
I like to over-complicate things :biggrin:
 

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2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #5
I left that bit to them... they seemed to think it was no problem and certainly seemed to know their stuff - at least to a layman
 

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2002 SG XT Auto
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£200 for a full set of springs. Sounds good. Now to find info on King Springs 1" lifters and send it 'em.
 

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2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #7
There's a sticky in the suspension section with spring rates etc
 

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2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #8
The question is to have a uniform drop of e.g. 2.5cm and keep the car level you might need to reduce the spring length by a different amount front and back since the spring will compress when the car sits on it.
How will you be able to make sure the car is level with the new springs?
I like to over-complicate things :biggrin:
You said you like to over-complicate things so here's the theory...

To work out what the length of a spring needs to be to give a specified ride height for a given spring rate, we need to have a reference point - a spring rate and free length for a spring that gives us a known ride height.

Thanks to Peaty on Scoobymods, we can use Pink STi springs for a Forester XT as our referrence. I'll use the rears in this example but the fronts are the same principle.

These have a free length of 13.75in and a spring rate of 167lb/in (fronts are 11.75in and 195lb/in).

Now that we know this, we'll work out the compressed length of the spring.

The equation for this is:

Deformed Length = Free Length - (Load / Spring Rate)

Since the Earth's gravity exerts a constant force on it's surface, we don't need to know the weight of the car in order to work out our ride height. All we need as a referrence is the force required to compress the spring a set distance, i.e. the spring rate.

In the case of Peaty's STi Pink springs, this is is 167lb/in. Thus, our refernce points are 167lb and 12.75" (13.75" - 1").

Now that we have our load and compressed length reference points, we can re-arrange the equation above to calculate the free length of the spring required to maintain the same ride height for our new spring rate. Thus equation is now:

Free Length = Deformed Length + (Load / Spring Rate)

If we wanted to increase our spring rate to say 180lb/in (as per King Springs) then to maintain the same ride height as the STi springs, the free length of the new spring would be:

(167 / 180) + 12.75 = 13.68" or 0.07" shorter than the STi one.

Now that we know the free length of our new spring, we just need to add or subtract the amount of lift/drop that we want.

Q.E.D.

(I might be wrong of course, but this is what came out when I scratched my head a bit ;o)
 

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2004 Forester Sti 6 MT
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You said you like to over-complicate things so here's the theory...

To work out what the length of a spring needs to be to give a specified ride height for a given spring rate, we need to have a reference point - a spring rate and free length for a spring that gives us a known ride height.

Thanks to Peaty on Scoobymods, we can use Pink STi springs for a Forester XT as our referrence. I'll use the rears in this example but the fronts are the same principle.

These have a free length of 13.75in and a spring rate of 167lb/in (fronts are 11.75in and 195lb/in).

Now that we know this, we'll work out the compressed length of the spring.

The equation for this is:

Deformed Length = Free Length - (Load / Spring Rate)

Since the Earth's gravity exerts a constant force on it's surface, we don't need to know the weight of the car in order to work out our ride height. All we need as a referrence is the force required to compress the spring a set distance, i.e. the spring rate.

In the case of Peaty's STi Pink springs, this is is 167lb/in. Thus, our refernce points are 167lb and 12.75" (13.75" - 1").

Now that we have our load and compressed length reference points, we can re-arrange the equation above to calculate the free length of the spring required to maintain the same ride height for our new spring rate. Thus equation is now:

Free Length = Deformed Length + (Load / Spring Rate)

If we wanted to increase our spring rate to say 180lb/in (as per King Springs) then to maintain the same ride height as the STi springs, the free length of the new spring would be:

(167 / 180) + 12.75 = 13.68" or 0.07" shorter than the STi one.

Now that we know the free length of our new spring, we just need to add or subtract the amount of lift/drop that we want.

Q.E.D.

(I might be wrong of course, but this is what came out when I scratched my head a bit ;o)

Wow gigsy, may I ask what you do for a living? Does it involve rockets?
 

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Emeritus Forum Staff
2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #10
Sadly, no such glamour... I'm a software developer turned user interaction designer - aka geek! ;o)
 

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2017 VW Golf SportWagen 5MT
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I think the Forester pink springs are progressive, that may have an influence on your calculations above.

Stan
 

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2008 GRB 20th anniversary 6 MT
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I think I will go for a set of Sti pinks to be safe.
Gigsy, it seems that you have done your homework, but where does the 1" appear from in (13.75" - 1")?
 

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Emeritus Forum Staff
2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #13 (Edited)
I think I will go for a set of Sti pinks to be safe.
Gigsy, it seems that you have done your homework, but where does the 1" appear from in (13.75" - 1")?
1 inch is the deflection a 167lb/in spring is deformed by when you place a 167lb load on it. The spring rate is just the amount it deflects by for a given load... in this case, it takes 167lb to compress the spring by one inch.

As for STI springs being progressive, yes that would complicate things but these were the only springs I could find a rate and uncompressed length for. The above is just an example of the mathematics.... the actual specifics, I'll leave to the manufacturer to work out! ;o)

EDIT

STi pinks will be a good bet... best price I can find for them is £400ish including delivery and a 4 - 8 week lead time ;o(
 

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STi pinks will be a good bet... best price I can find for them is £400ish including delivery and a 4 - 8 week lead time ;o(
From where?

Another option would be Eibach as Smiles had on his car, the question is what the part numbers are as Eibach don't do springs for the SG9 AFAIK.
I have emailed him and the previous owner but no reply yet.
Revolution list Eibach lowering springs but only for the front.
FSTI with Eibach springs:
** JDM MY06 FORESTER STI - 345 BHP - FSH Immaculate** PX - ScoobyNet
 

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Don, King of the parts diagram
MY11 WRX STi Sedan 6MT
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From where?

Another option would be Eibach as Smiles had on his car, the question is what the part numbers are as Eibach don't do springs for the SG9 AFAIK.
I have emailed him and the previous owner but no reply yet.
Revolution list Eibach lowering springs but only for the front.
FSTI with Eibach springs:
** JDM MY06 FORESTER STI - 345 BHP - FSH Immaculate** PX - ScoobyNet
Fivos,

Smiles hasn't posted on here since Aug'09, on scabbynet since Jan and on Surreyscoobies since '08.

AFAIK he's still based in Paris.

You could have at least used the "For Sale" thread from here ......:biggrin::biggrin:

http://www.subaruforester.org/vbulletin/f110/jdm-my06-forester-sti-345-bhp-36414/

Eibach's list front springs only for the SG (self leveling rears).
Eibach Springs and Anti-Roll Bars for Subaru

This may be of interest to you.......... but note the year

ScoobyNet - View Single Post - Lowering a Forester
 

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Fivos,

Smiles hasn't posted on here since Aug'09, on scabbynet since Jan and on Surreyscoobies since '08.

AFAIK he's still based in Paris.

You could have at least used the "For Sale" thread from here ......:biggrin::biggrin:

http://www.subaruforester.org/vbulletin/f110/jdm-my06-forester-sti-345-bhp-36414/

Eibach's list front springs only for the SG (self leveling rears).
Eibach Springs and Anti-Roll Bars for Subaru

This may be of interest to you.......... but note the year

ScoobyNet - View Single Post - Lowering a Forester
Don, I am aware and I have sent him and Fullham71 (original owner who still logins in SN) an email at their addresses indicated in SN and hope they reply. I got a reply from revolution that Eibach have stopped making springs for the Forester :(
Looking at smiles car, it does look quite low so I wonder if the springs were Impreza specific. Is it possible to fit Impreza springs on Forester struts?
I will take a look at the above links.

Lol about the For Sale from here, a google search didn't reveal this.

EDIT: I have already contacted Revolution who told me that Eibach have stopped making springs for the Forester and the list is for front ones anyway :(
I wonder if we can get hold of the part numbers they might have some old stock somewhere.
 

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2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #17
From where?

Another option would be Eibach as Smiles had on his car, the question is what the part numbers are as Eibach don't do springs for the SG9 AFAIK.
I have emailed him and the previous owner but no reply yet.
Revolution list Eibach lowering springs but only for the front.
FSTI with Eibach springs:
** JDM MY06 FORESTER STI - 345 BHP - FSH Immaculate** PX - ScoobyNet
Japanparts.com - Mail order from Japan directly|JDM Parts,Performance Auto Parts,for Subaru, Mazda,Mitsubishi,Honda,Nissan,Toyota car
 

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Emeritus Forum Staff
2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #18
I have already contacted Revolution who told me that Eibach have stopped making springs for the Forester and the list is for front ones anyway :(
As have TEIN... seems the only options are to have some custom made or buy King Springs, Swift or Pink STi - all of which require importing.
 

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2008 GRB 20th anniversary 6 MT
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As have TEIN... seems the only options are to have some custom made or buy King Springs, Swift or Pink STi - all of which require importing.
Swift might be able to make some as Eibach according to the post from Don above. The Sti pinks are the safest bet although I would be looking for some slightly stiffer and lower.

OK, was aware of Japanparts, thought you had another source ;)
They say delivery within 10-15 days, have you enquired and they mentioned up to 8 weeks?!

Edit: I wonder who the new owner of smiles car is. I guess he is not here...
Anyone happens to know?
 

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2015 Triumph Tiger XCx 1 Down. 5 Up.
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Discussion Starter #20
They say delivery within 10-15 days, have you enquired and they mentioned up to 8 weeks?!
Not sure where 8 weeks came from... been speaking to a lot of people trying to tack some springs down.
 
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