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Old 03-25-2020, 08:26 PM   #1
02hybridwrx
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Default v7 STI struts w/ lowering springs

Hey, does anyone have any info on what spring rates the v7 struts work well with? I've been searching and can't find any numbers. I know the v7 has 3 different strut/spring packages, and they slightly vary with ride height. I'm trying to know what the limits are here so I know what would be too low or too high of a spring rate.

My thought is that if the v7 struts with the JDM pink springs works (257f/217r with a 20mm drop), then say tein H techs would also pair well with the struts since they sit slightly lower with a lower progressive spring rate.

Basically my situation is that I'm currently riding on H-techs on stock struts with group N top hats, and the ride honestly isn't nearly as bad as everyone makes it sound. I found a set of v7 struts with 40k miles on them for $175 which is an absolute steal. I wouldn't want to swap the struts in though if I'd be better off just going with struts that pair better with the H-Techs. Thanks!
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Old 03-25-2020, 09:36 PM   #2
02hybridwrx
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it's funny because the only similar posts, have zero responses...

Sources: https://www.clubwrx.net/threads/best...uts.134342062/

https://www.clubwrx.net/threads/new-...struts.145337/
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Old 03-26-2020, 12:46 PM   #3
02hybridwrx
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I'm also reading that the STI struts have lower damping rates, which is interesting considering they're paired with higher spring rates and lower ride height... So what is there to prove that STI struts are any better than WRX struts when being lowered? Would lower damping rates result in less pressure when reaching suspension travel limits, preventing the seals from blowing? Even if that were to be true, wouldn't the ride quality be worse than a strut with a higher damping rate? Someones gotta know more about this...
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Old 03-26-2020, 01:09 PM   #4
2pot
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STI struts are inverted and usually stiffer in compression.

Sti front struts are significantly shorter in length than wrx struts.
Later model wrx were also fitted with inverted struts.
Shorter STI springs are likely to dislodge at full droop when used on non-inverted wrx struts.
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Old 03-26-2020, 01:44 PM   #5
02hybridwrx
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Quote:
Originally Posted by 2pot View Post
STI struts are inverted and usually stiffer in compression.

Sti front struts are significantly shorter in length than wrx struts.
Later model wrx were also fitted with inverted struts.
Shorter STI springs are likely to dislodge at full droop when used on non-inverted wrx struts.
Hey thanks for the reply man. So is it the shorter strut length that misleads me to thinking they pair better with lowering springs? I certainly won't be running shorter sti springs on wrx struts. It's either 2002 wrx h-techs on oem struts, or the h-techs on v7 sti (2002) struts.

What exactly makes a strut more compatible with lowering springs, higher compression?
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Old 03-27-2020, 07:32 AM   #6
2pot
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Are your H-tecs recommended for use with inverted STI struts? If they are, they may specify you keep the stock 60mm front stops or you will encounter coil bind.

Lowering means less travel before bump stop contact. More compression damping would delay/could stop you from contacting the bump stops

Damping should consider the chosen spring rates: at low, medium and high speed damper movements.
On a road car, spring rate will need to achieve the chosen ride frequency for a particular, or average, road surface. Stiff springs on poor roads = stupidity, unless you want a particular stance?

OEM inverted struts have a rock-hard 60mm front stop. If you lower the ride height, you must consider that bump stop.
When new, stock STI front ride height 386mm
When new, stock WRX front ride height 396mm
Most bushes, top mounts and springs have collapsed/sagged over time: meaning the ride heights are already way below stock.

IMO, for a road car, no lower than 365mm front height + softer, shorter, front stops.
The 60mm front stops were a form of pitch control. OK on smoother roads, but understeer and poor ride quality, on undulating/uneven roads.

STI pinks spring rates are fine, but, their height lowers you on to that front stop. The STI pinks also excessively lower the rear height, again, for looks.
If they'd kept the rear height at stock, then you could have reduced the understeer, without the use of an excessive rear bar size.

Smaller bars retain independence in the suspension. Bigger bars transmit a suspension movement on one side of the vehicle, to the other - destabilising the tyre contact patches on both sides, reducing grip.
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Old 03-27-2020, 10:37 AM   #7
02hybridwrx
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I gotcha. The h-techs I have are not for inverted struts. I wasn't sure if the inverted v7 struts aren't compatible with those springs or if they hold the same springs just with an inverted shaft.

The springs are said to lower just under 30mm which would be right around 365mm ride height in the front. I'm cool with that, no lower.

I also understand how sway bars affect the independent suspension. Luckily mine are adjustable so I can tune that once I have the springs and struts set up. I was more less trying to understand if the v7 inverted struts are compatible with springs that are for noninverted struts. And if so, would they be worth swapping in. I think the answer would be yes, if they are compatible.
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Old 03-27-2020, 12:36 PM   #8
2pot
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Tein H-tech v7 wrx, when new:
196lb/in front -36mm
140lb/in rear -14mm

They're too soft to be that low.
Also, the ratio of front spring to rear spring means 'flat ride' won't occur until 250mph. 'Flat ride' is the point at which the chassis is self-settling, so requiring less damping. On a road car 'flat ride' at 60mph would be a guide.

OEM inverted struts are usually failing by 40k. The arc that the rear strut operates through wears the 40mm (20mm +10mm +10mm) of internal bearings - usually the top 20mm bearing is worst affected. The grease nipple mod is usually a waste of time, as the bearings are already worn; does make the strut quieter though.
Bilstein also found the internal bearing issue, on the RB320 rear dampers and installed an additional, 3rd, 20mm upper bearing - giving 60mm of bearing in total.
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Old 03-27-2020, 01:14 PM   #9
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Quote:
Originally Posted by 2pot View Post
Bilstein also found the internal bearing issue, on the RB320 rear dampers and installed an additional, 3rd, 20mm upper bearing - giving 60mm of bearing in total.
Learn something new every day! Wonder if those are still available new?
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Old 03-27-2020, 02:07 PM   #10
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Sadly, no.

But, I am trying to create an insert for the Subaru inverted housings.

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Old 03-27-2020, 02:10 PM   #11
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Oh NICE! Keep us informed!

The Ohlins rear struts also have this issue.
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