Impreza struts vs. Forester struts: The Difference - Subaru Forester Owners Forum
User Tag List

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 161 (permalink) Old 08-22-2006, 02:00 PM Thread Starter
Asphalt Surfers Unlimited
Contributing Member
 
Porter's Avatar
 
Join Date: Feb 2006
Location: Roanoke, Virginia
Posts: 756
Car Year: 2004
Car Model: Forester XT
Feedback Score: 0 reviews
Arrow Impreza struts vs. Forester struts: The Difference

There is a lot of speculation that floats around about Impreza struts and Forester struts and mixing and matching and what works and what doesn't.

I got the hard data from KYB directly, they manufacture the OEM struts themselves in all the variations, and they produce the most common OE replacement and OE fitment sport shocks currently available for the Subaru platform.

All measurements are in Millimeters.

The Differences:
Code:
FRONT
  Lower Hole To Spring Seat
     Impreza   252
     Forester  253
  Total Strut Body Length
      Impreza   356
      Forester  377
  Extended Length (Body + Shaft)
       Impreza   525
       Forester  560 [514]
  Compressed Length (Body + Shaft)
       Forester  391

REAR
  Lower Hole To Spring Seat
     Impreza   315
     Forester  330
  Total Strut Body Length
      Impreza   367
      Forester  407
  Extended Length (Body + Shaft)
       Impreza   605
       Forester  643 [632]
  Compressed Length (Body + Shaft)
       Forester  455
Hopefully this will help some of you with the differences in strut geometry.

The second figure on the Forester extended length measurements is due to the internal droop limiting spring that is in the Forester struts. The figure in brackets is the free extension before the spring becomes involved. The total extension is the length when the limiting spring is fully compressed (shaft fully extended under load).

I have not touched on the differences in spring length or preload, those are equally important figures... but this chart should illustrate why there are different spring designs between the Impreza and Forester.


Enjoy,

Porter


-Porter-
'04 F-XT Silver

I love the smell of brake pads in the morning. Smells like... victory.
Porter is offline  
Sponsored Links
Advertisement
 
post #2 of 161 (permalink) Old 08-22-2006, 02:03 PM
The Seventh Sister
Administrator
 
pleiad7's Avatar
 
Join Date: Jan 2006
Location: Sonoma County, CA
Posts: 29,817
Car Year: 2004
Car Model: Forester XT Premium
Transmission: 4EAT
Garage
Feedback Score: 53 reviews
This deserves a sticky.


~ Silke ~
'04 FXT 4EAT PSM - "Subed Up"
'98 S 4EAT DBP - "Slynki"
pleiad7 is offline  
post #3 of 161 (permalink) Old 08-22-2006, 02:07 PM Thread Starter
Asphalt Surfers Unlimited
Contributing Member
 
Porter's Avatar
 
Join Date: Feb 2006
Location: Roanoke, Virginia
Posts: 756
Car Year: 2004
Car Model: Forester XT
Feedback Score: 0 reviews
Thanks!

-Porter-
'04 F-XT Silver

I love the smell of brake pads in the morning. Smells like... victory.
Porter is offline  
 
post #4 of 161 (permalink) Old 08-27-2006, 06:17 PM
Developer
Contributing Member
 
Join Date: Jan 2006
Location: Houston, TX
Posts: 139
Feedback Score: 4 reviews
Did you by chance get the difference in total stroke w/o the spring (fully compressed to fully extended)? That would be tremendously helpful. I am working on trying to make some sort of adapter to fit the AGX shocks/struts onto Foresters.

Got Boost?
mo_boost is offline  
post #5 of 161 (permalink) Old 08-27-2006, 07:53 PM Thread Starter
Asphalt Surfers Unlimited
Contributing Member
 
Porter's Avatar
 
Join Date: Feb 2006
Location: Roanoke, Virginia
Posts: 756
Car Year: 2004
Car Model: Forester XT
Feedback Score: 0 reviews
I believe both struts retract almost fully into the housing, with about an inch of shaft exposed. The "fully extended" measurement is to the top of the chrome shaft surface, not including the threaded area.

Subtracting the strut body length from the total extended measurement should give you a rough idea of the length of total travel.

I will call KYB back tomorrow and get a real answer on the total stroke.

BTW... I don't think it's going to be easy to "adapt" AGXs to the Forester and keep Forester geometry... the spring perch height and total travel are quite different.

My personal solution would be to use a set of Koni inserts sized for the Forester, or a Forester-specific coilover.

-Porter-
'04 F-XT Silver

I love the smell of brake pads in the morning. Smells like... victory.
Porter is offline  
post #6 of 161 (permalink) Old 08-28-2006, 06:55 PM
The Modfather
 
Peaty's Avatar
 
Join Date: Jan 2006
Location: Lawrence, KS - Rock Chalk
Posts: 8,112
Car Year: 2016
Car Model: BRZ Limited - Manual
Transmission: 6 Speed Manual
Feedback Score: 10 reviews
Just a little pic to add since I happen to have one, notice the top of the Foresters strut, it appears the top can be screwed off but I have not tired myself. I'm not sure if it's threaded or not.
Attached Thumbnails
Click image for larger version

Name:	f-xt vs gc8.jpg
Views:	16397
Size:	59.4 KB
ID:	2510  

Peaty

2016 BRZ, 2010 Leg 3.6 R, 2013 OB, 2001 Forester S and 1999 Miata
Peaty is offline  
post #7 of 161 (permalink) Old 08-29-2006, 02:18 PM Thread Starter
Asphalt Surfers Unlimited
Contributing Member
 
Porter's Avatar
 
Join Date: Feb 2006
Location: Roanoke, Virginia
Posts: 756
Car Year: 2004
Car Model: Forester XT
Feedback Score: 0 reviews
Peaty,

It's not threaded. That is a standard KYB/Showa strut top cap. It is press-fit into place and holds the inner strut cartridge assembly in place. There is a seal system underneath the cap.

-Porter-
'04 F-XT Silver

I love the smell of brake pads in the morning. Smells like... victory.
Porter is offline  
post #8 of 161 (permalink) Old 08-29-2006, 03:05 PM
The Modfather
 
Peaty's Avatar
 
Join Date: Jan 2006
Location: Lawrence, KS - Rock Chalk
Posts: 8,112
Car Year: 2016
Car Model: BRZ Limited - Manual
Transmission: 6 Speed Manual
Feedback Score: 10 reviews
Is there a way to remove the cap, change the insert and put a new cap on?

Peaty

2016 BRZ, 2010 Leg 3.6 R, 2013 OB, 2001 Forester S and 1999 Miata
Peaty is offline  
post #9 of 161 (permalink) Old 08-29-2006, 07:00 PM Thread Starter
Asphalt Surfers Unlimited
Contributing Member
 
Porter's Avatar
 
Join Date: Feb 2006
Location: Roanoke, Virginia
Posts: 756
Car Year: 2004
Car Model: Forester XT
Feedback Score: 0 reviews
Quote:
Originally Posted by Peaty
Is there a way to remove the cap, change the insert and put a new cap on?
If you remove the cap the strut is essentially "ruined" for KYB-valving purposes.

It is however quite ideal for Koni-insert use... though the housing will need to be trimmed down somewhat (slightly) depending on the exact length of the Koni insert.

Hmm... lots of Koni interest here. I'll be on the phone with Koni tomorrow.

-Porter-
'04 F-XT Silver

I love the smell of brake pads in the morning. Smells like... victory.
Porter is offline  
post #10 of 161 (permalink) Old 08-31-2006, 04:40 AM Thread Starter
Asphalt Surfers Unlimited
Contributing Member
 
Porter's Avatar
 
Join Date: Feb 2006
Location: Roanoke, Virginia
Posts: 756
Car Year: 2004
Car Model: Forester XT
Feedback Score: 0 reviews
EDIT

Added compressed length to the figures. Note that this is total body and strut shaft to the end of the chrome rod area, not including the threaded end.


-Porter-
'04 F-XT Silver

I love the smell of brake pads in the morning. Smells like... victory.
Porter is offline  
post #11 of 161 (permalink) Old 09-12-2006, 04:57 PM
Forum Member
 
Join Date: Apr 2006
Location: Seattle, WA
Posts: 852
Car Year: 27
Car Model: car
Transmission: gear
Feedback Score: 3 reviews
Whats the word from Koni?

I'm about to work with Tom@kartboy and seeing if it's possible to make our own spacer (ala whiteline's kit) for the stockers.

This information is provided "as-is".
teiva-boy is offline  
post #12 of 161 (permalink) Old 09-13-2006, 05:28 AM Thread Starter
Asphalt Surfers Unlimited
Contributing Member
 
Porter's Avatar
 
Join Date: Feb 2006
Location: Roanoke, Virginia
Posts: 756
Car Year: 2004
Car Model: Forester XT
Feedback Score: 0 reviews
I have not gotten a chance to speak with the folks at Koni, work has been crazy. I know the right individual there though, we worked together somewhat on the SVX fitment inserts a few years ago.

-Porter-
'04 F-XT Silver

I love the smell of brake pads in the morning. Smells like... victory.
Porter is offline  
post #13 of 161 (permalink) Old 10-05-2006, 11:37 AM
Forum Member
 
Join Date: Apr 2006
Location: Seattle, WA
Posts: 852
Car Year: 27
Car Model: car
Transmission: gear
Feedback Score: 3 reviews
Any word on speaking to your contacts at Koni?

This information is provided "as-is".
teiva-boy is offline  
post #14 of 161 (permalink) Old 11-28-2006, 09:11 AM
Forum Member
 
Evil XT's Avatar
 
Join Date: Jan 2006
Location: NJ
Posts: 619
Car Year: 13
Car Model: Work Boot
Transmission: Do it yourself
Feedback Score: 4 reviews
Anywork from koni?
Can we usethe Koni incerts?

Positive Pressure Research and Development &
Peculiar Mollusks
Evil XT is offline  
post #15 of 161 (permalink) Old 12-21-2006, 02:22 PM
Forum Member
 
Join Date: Dec 2006
Location: Vancouver
Posts: 5
Car Year: 2000
Car Model: Impreza
Feedback Score: 0 reviews
Koni inserts

Quote:
Originally Posted by Evil XT View Post
Anywork from koni?
Can we usethe Koni incerts?
..........Don't know if this will help,but you can try contacting Dave or Barrett at www.allwheelsdriven.com, he might be able to help you out or at least answer your questions.They have been been fabbing up Subaru strut bodies to take Bilstein HD strut inserts(same as Koni I believe) for Impreza rally cars,they have the screw top which you need anyway,H&R springs,Group N top hats
marooned RS is offline  
Sponsored Links
Advertisement
 
Reply

  Subaru Forester Owners Forum > Technical Forums and Vehicle Assistance > Suspension and Handling

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome
 


Content Relevant URLs by vBSEO 3.6.1