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Old 04-04-2020, 06:16 PM   #26
2pot
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I have made some further progress on the Bilstein inserts.



Yet to re-assess front bump stops, rear damping and fill pressures, in a wagon.

Don't seem quite so important with the current state of the World.
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Old 04-05-2020, 11:02 AM   #27
Norm Peterson
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Quote:
Originally Posted by 2pot View Post
The natural frequency of the springs? Or the ride frequencies?

Ride frequencies: front 1.56Hz, rear 1.81Hz @63mph. I was aiming for 'flat ride' around that speed.
Ride frequencies, and thanks.

I don't think many people think in terms of 'flat ride' when they're choosing springs, so it's refreshing when somebody mentions it. FWIW, the motion ratio of a strut suspension (either MacPherson or Chapman) is slightly less than 1.00:1, but 1:1 is probably close enough for most practical purposes (0.95-ish?).

The amount of damping also affects ride frequencies (more damping reduces the frequencies slightly) and seems to make flat ride considerations somewhat less important. I've played around with this a bit in Excel, and you can get some pretty wild plots when both the ride frequencies and the %critical dampings are poorly matched, front vs rear. Pitch jerk would go to the difficulty you'd experience trying to keep your head from being tossed (head toss accelerations not constant).







Quote:
They're dual-rate springs - linear from 15mm above ride height to coil bind.
So for more than half of suspension travel they're operating at the firm rate. Clearly favors performance, so my kind of spring over anything other than linear over the full range of actual suspension travel.


Norm

Last edited by Norm Peterson; 04-05-2020 at 11:13 AM.
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Old 04-05-2020, 12:13 PM   #28
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The 'flat ride' calculation also leads to a self-settling chassis, requiring less damping.
I'm definitely in favour of increased compression damping, to control the un-sprung weight.
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Old 04-06-2020, 08:08 AM   #29
Norm Peterson
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For those dual-rate springs, are you selecting damping to suit the firm rate and not worrying too much about being a bit overdamped once the suspension rebounds up into the soft rate region (and wheel loads are less)?


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Old 04-06-2020, 10:59 AM   #30
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As opposed to the open coils of a lower rate tender spring, in a dual-rate/progressive system, the lower rate coils are closed at ride height and operating as if a helper spring, to stop the springs dislodging at full droop.

Last edited by 2pot; 04-06-2020 at 11:05 AM.
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Old 04-06-2020, 11:20 AM   #31
Norm Peterson
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Understood.

I was mostly wondering if occasional excursion on the inboard side in a hard corner sufficient to involve the soft rate was worth any consideration. Sounds like it wasn't.

I can see where this might be a bigger issue with dual-rate spring designs that put the car close to or in the soft rate at static ride height. At least one dual-rate design over in the Mustang world specifically puts normal ride height in the soft rate region, mainly for ride quality reasons being my guess.


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Old 04-06-2020, 04:31 PM   #32
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Quote:
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At least one dual-rate design over in the Mustang world specifically puts normal ride height in the soft rate region, mainly for ride quality reasons being my guess.


Norm
Creating a damping curve, for that scenario, would be a nightmare.
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Old 04-06-2020, 05:54 PM   #33
Norm Peterson
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That's for sure.

I think you'd have to get into position-sensitive damping and/or magnetorheological technology to solve it. A business opportunity without much of a business case, methinks.


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Old 04-12-2020, 11:59 AM   #34
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I've had a few further questions; just to reiterate:
WA/A2 have a 363mm front ride height.
23mm lower at the front than sti, when new.
33mm lower at the front than wrx, when new.

The rear ride height of the WA/A2 springs is not lowered.
Intentionally increasing the forward rake is to increase the roll axis inclination.

The WA/A2 springs are designed to give only a 5mm difference, in rear ride height, when fitted on a sedan or a wagon.
If you're running old, sagging, springs, old collapsing bushes and/or old gas filled struts your ride heights are already way below stock.

The WA/A2 front springs are longer than a jdm sti pink and rb320. This allows their use with sti struts, as well as with wrx length struts (koni insert, agx etc) - as long as the wrx strut has the ability to damp the higher spring rates.

JDM sti pinks are not the same rate at their ride height and just before coil bind.

The WA/A2 front springs have the same coil bind (stack height) as an RB320 front spring.


Last edited by 2pot; 04-13-2020 at 11:55 AM.
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Old 05-01-2020, 12:26 AM   #35
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Quote:
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Feal FPS + WA/A2
What tire size is on this?
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Old 05-01-2020, 05:59 AM   #36
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I think he's got 235/45 x 17
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Old 06-23-2020, 11:19 AM   #37
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Something a bit different! I think the GD front ride height, at something like the Cyprus rally, would be 15" - this looks close to that.
Feal FPS +1"

Last edited by 2pot; 06-23-2020 at 11:37 AM.
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Old 03-08-2021, 09:51 AM   #38
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After 1,000 miles - six speed, full tank, new struts, new strut mounts and new bushes settling - well made springs don't settle.
Sedan would be 9mm higher at the front, as the sedan front arch is cut higher. Sedan rear would be 5mm higher, due to less rear weight.


Last edited by 2pot; 03-08-2021 at 09:57 AM.
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Old 03-17-2021, 01:53 PM   #39
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Great thread with lots of detail. Also there aren’t as many threads dedicated to our cars these days, I drive a Hawkeye wagon as well. This is also pertinent to me as I am thinking of making a suspension change. My current suspension is 8 years old, Komi inserts with US STi pinks. I have replaced two of the inserts due to leaks/being blown. I was considering the Feal struts but not sure about springs. These WA/A2 sound like they would be perfect for me, daily driver with some track use. Can you let me know how I can get the springs. I am in Canada.
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Old 03-18-2021, 03:52 PM   #40
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Quote:
Originally Posted by hghonbst View Post
Great thread with lots of detail. Also there aren’t as many threads dedicated to our cars these days, I drive a Hawkeye wagon as well. This is also pertinent to me as I am thinking of making a suspension change. My current suspension is 8 years old, Komi inserts with US STi pinks. I have replaced two of the inserts due to leaks/being blown. I was considering the Feal struts but not sure about springs. These WA/A2 sound like they would be perfect for me, daily driver with some track use. Can you let me know how I can get the springs. I am in Canada.
You have a PM and an email (check your junk folder it sometimes goes in there).
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Old 11-26-2021, 04:37 AM   #41
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Looks like KYB have finally released US after-market struts for the 05-07 114.3 pcd widetrack

5510035
5510036
5510029
5510030


OEM blob/hawk sti rear spring - 171lb/in at ride height, 195lb/in before coil bind.

WA/A3 rear springs:

224lb/in - linear from 15mm above ride height to coil bind.
20mm lower than WA/A2 rear springs
10mm lower than Prodrive S05/D5/001 rear springs

Last edited by 2pot; 11-26-2021 at 11:44 AM.
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Old 12-01-2021, 07:06 PM   #42
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Hey,

Just wanted to let you know I love these springs. Had then installed in the spring and really enjoyed driving on them through the summer. The raked look really grew on me. I decide not to go back to 16 inch rims for the winter because of the higher stance at the back. Put the 17 inch 5 stars on with 215/50/17 winter tires. Summer runs are BBS LM with 225/45/17.

Here are some pics that I meant to post up

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Old 12-02-2021, 06:31 AM   #43
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Thank you for taking the time post those pics
I'm using the taller WA/A2 rear spring too - loads/passengers.

The 3/4" lower ride height, WA/A3 rear, is helpful when using a higher pressure strut, as per the recently US released inverted KYB struts - higher fill pressure gas struts raise ride heights.
Or, some may prefer the look of more even ride heights.

Last edited by 2pot; 12-29-2021 at 12:03 PM.
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Old 12-29-2021, 12:01 PM   #44
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If anyone is OK with colour mismatched front and rear STI springs, let me know

Due to an Eibach miscommunication, I now have some Diamond red WA/A2 fronts and Prodrive red WA/A3 rears!

Eibach have agreed to discount any colour mismatched sets, that can be sold. As it reduces the quantity returned to Germany, in the new year, for re-coating.

£260 for a colour mismatched set, as opposed to £325.


Last edited by 2pot; 12-29-2021 at 12:24 PM.
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Old 01-02-2022, 12:02 PM   #45
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Quote:
Originally Posted by 2pot View Post
Looks like KYB have finally released US after-market struts for the 05-07 114.3 pcd widetrack

5510035
5510036
5510029
5510030
Just wanted to say thank you so much for posting this info; I've been looking for replacement struts for my 2006 STi driveline swapped WRX and the Feal adjustable FPS units were the only option to my knowledge. I run JDM STi pink springs and I want to give these KYB struts a try now that they are available instead of spending $texas on the Feal units.
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Old 01-02-2022, 01:13 PM   #46
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Originally Posted by 03SubyWRX View Post
Just wanted to say thank you so much for posting this info; I've been looking for replacement struts for my 2006 STi driveline swapped WRX and the Feal adjustable FPS units were the only option to my knowledge. I run JDM STi pink springs and I want to give these KYB struts a try now that they are available instead of spending $texas on the Feal units.
The jdm pink springs are so low, you'll have to find some alternative internal stops.
For the front:
You could cut the 60mm, 4 node, front stop in half and use the stiffest two nodes.
I wouldn't usually suggest utilising the stiffest end of a cut-down bump stop, but the jdm pinks are so low, you have no choice - as you've so little bump travel to play with.
If your running wide wheels/tyres don't cut the oem front stops. The ride will be rough, but otherwise you'll contact the arches. Unless you've pulled/rolled the fenders?

You could use this at the front instead - Honda part 51722-SE0-003
This is a non-gen copy:
https://www.amazon.com/MTC-9049-5172...t-items&sr=1-1

The rear stop in the inverted struts is 83mm - it's too soft, if running a 20mm or 22mm rear bar. If you're running bigger than a 22mm rear bar, on the road, you're a muppet
83mm stop was used with a 365mm rear ride height, wheel centre to fender, with a full tank (or put 100lb in the trunk instead).
Lower than 365mm at the rear and you need a shorter, stiffer, rear stop.

What are your front and rear ride heights?

Last edited by 2pot; 01-02-2022 at 06:37 PM.
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Old 01-02-2022, 07:51 PM   #47
03SubyWRX
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Quote:
Originally Posted by 2pot View Post
The jdm pink springs are so low, you'll have to find some alternative internal stops.
For the front:
You could cut the 60mm, 4 node, front stop in half and use the stiffest two nodes.
I wouldn't usually suggest utilising the stiffest end of a cut-down bump stop, but the jdm pinks are so low, you have no choice - as you've so little bump travel to play with.
If your running wide wheels/tyres don't cut the oem front stops. The ride will be rough, but otherwise you'll contact the arches. Unless you've pulled/rolled the fenders?

You could use this at the front instead - Honda part 51722-SE0-003
This is a non-gen copy:
https://www.amazon.com/MTC-9049-5172...t-items&sr=1-1

The rear stop in the inverted struts is 83mm - it's too soft, if running a 20mm or 22mm rear bar. If you're running bigger than a 22mm rear bar, on the road, you're a muppet
83mm stop was used with a 365mm rear ride height, wheel centre to fender, with a full tank (or put 100lb in the trunk instead).
Lower than 365mm at the rear and you need a shorter, stiffer, rear stop.

What are your front and rear ride heights?
I appreciate the detailed response! I bought the JDM pinks already mounted on Spec C (I think?) 4 way adjustable struts (fully assembled from an importer in Canada), but they will need to be replaced eventually. They even came with Group N top hats. I'll be running the OEM 17x8 05-07 USDM STi wheels with 235/45/17 tires. Would it still be worth trimming the existing internal bump stops in the new KYB units, or would I be better off with replacing them with the Honda stops you linked?

For the rear, I'm running whatever came on a Version 8 JDM STi...I think it's a 20mm rear bar? I plan to stick with the OEM equipment that came with my V8 swap I purchased and installed. Are different stops available for the rear struts?

I'll take measurements of my front and rear ride heights w/ full tank and get back to you with numbers.
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Old 01-05-2022, 04:36 AM   #48
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I'd use the Honda stops for the front.
The rear stop length/durometer will depend on your ride heights.
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Old 01-18-2022, 05:35 AM   #49
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Might help:
KYB widetrack 114.3 pcd sti front strut install (some late blobeyes were also widetrack).
5510035
5510036

Additional info:
The following links are UK, but the pics/part numbers should help.

If you want new front inverted STI strut dust boots:
2 x 20322AC000 https://www.importcarparts.co.uk/par...y=&searchPart=
The above image is wrong - it's showing rear inverted dust boots.
Don't order 20322AA000 by mistake! - those are the standard non-inverted front dust boots.

If new cone washers required 20326AA000
2 x https://www.importcarparts.co.uk/par...&var=0&dc=&gen
Make sure you fit cone-side up INBETWEEN the top mount and the spring perch.

Check the front top spring seat central locating holes for circularity, before re-assembly, as they may have been incorrectly tightened/damaged/made oval in the past.
If damaged:
Front perch 20323FA000 https://www.importcarparts.co.uk/par...y=&searchPart=

Front upper rubber isolator - 2 x 20325FA000 https://www.importcarparts.co.uk/par...y=&searchPart=

Using 33N/m lower nut torque removes the, very real, possibility of rounding off the flats on the base of the strut housing, or stripping the M10 x 1.25 pitch threads on the damper insert. Removing ALL grease transfer onto the M10 threads, before torquing, is important.
Torque incrementally: 10, 20, 30 then 33N/m

You can lightly grease the strut housing rubber seal, before re-inserting the damper insert - reduces the chance of inverting the seal.

The stiff front stops are tricky to remove (the rears are much softer/easier).
Best to put the M10 end of the damper insert on hard ground and slide/press the bump stop towards the ground. That helps clear the first/tightest node of the bump stop.

The OEM/KYB front stop is 60mm, the Prodrive front stop was 50mm, the replacement front stops in the video, are 40mm.

Last edited by 2pot; 01-18-2022 at 05:58 AM.
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Old 01-18-2022, 05:35 AM   #50
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