Welcome to the North American Subaru Impreza Owners Club Sunday November 23, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC General > Motorsports

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 01-12-2006, 06:32 PM   #1
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default Swaybars hollow- solid

I would like opinions on swaybar size recommendations. I have 7K springs front and rear and I like the balance I have now. Therefore, I would like to increase the sizes proportionately. My front is a 21MM solid and the rear is a 17MM hollow. I'm looking at a 27MM solid in front and I'm not sure what to go to in the rear.

Oh and I realize this is the motorsports forum but I don't track the car much.
Thanks.
* Registered users of the site do not see these ads.
04furesterXT is offline   Reply With Quote
Old 01-12-2006, 07:07 PM   #2
ratt_finkel
Scooby Specialist
 
Member#: 46218
Join Date: Oct 2003
Chapter/Region: TXIC
Location: Dallas, Tejas
Vehicle:
06 EVO 9
Silver

Default

Why do they have to be the same size? Just get the bigger front, if you don't like it, add a bigger rear. Or just take it off.
ratt_finkel is offline   Reply With Quote
Old 01-12-2006, 08:41 PM   #3
wrrrx
Scooby Specialist
 
Member#: 23993
Join Date: Sep 2002
Location: Portland, OR
Vehicle:
2004 STi, PDXTuned
WR Blue

Default

He didn't say they had to be "the same size"- just both increasing proportionally.
Hard to say... I think Whiteline pairs up a 24mm rear when using the 27mm front- that would be a 6mm increase front and 7 mm increase in the rear, which is quite a bit. I'd go for an adjustable one (22-24mm), that way you can fiddle w/ it until you're happy.

The fact that one is hollow and one solid shouldn't really affect performance- one's just lighter than the other.

Good luck,
Russ R
wrrrx is offline   Reply With Quote
Old 01-12-2006, 09:31 PM   #4
Scooby921
Merci Buckets
Moderator
 
Member#: 88606
Join Date: Jun 2005
Chapter/Region: MWSOC
Location: Clarkston
Vehicle:
2011 GMC Sierra
'13 JCW

Default

A solid bar is going to be stiffer than a hollow bar of the same diameter. There is more material and its able to handle more load.

From what I've read most people think you should get the biggest bar you can up front and adjust the rear until you like the way it drives. I personally have a stock front and 22mm solid rear. It performs pretty well. In an attempt to get better turn-in, but also maintain the reduction in understeer I currently have, I just ordered a 22mm front and 24mm adjustable rear. We'll see how it works out, but I have good feelings about it.
Scooby921 is offline   Reply With Quote
Old 01-12-2006, 11:38 PM   #5
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default

Quote:
Originally Posted by wrrrx
He didn't say they had to be "the same size"- just both increasing proportionally.
Hard to say... I think Whiteline pairs up a 24mm rear when using the 27mm front- that would be a 6mm increase front and 7 mm increase in the rear, which is quite a bit. I'd go for an adjustable one (22-24mm), that way you can fiddle w/ it until you're happy.

The fact that one is hollow and one solid shouldn't really affect performance- one's just lighter than the other.

Good luck,
Russ R
Thanks.Correct on the proportional increase in size. The rear bar is 17MM HOLLOW so I guess I was also looking for a calculation for the solid equivalent. Otherwise I could just increase them a like amount and be close to the balance I have only at a higher grip level.

I was also kind of questioning what would work right with the spring rates I have.
04furesterXT is offline   Reply With Quote
Old 01-12-2006, 11:41 PM   #6
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default

Quote:
Originally Posted by Scooby921
A solid bar is going to be stiffer than a hollow bar of the same diameter. There is more material and its able to handle more load.

From what I've read most people think you should get the biggest bar you can up front and adjust the rear until you like the way it drives. I personally have a stock front and 22mm solid rear. It performs pretty well. In an attempt to get better turn-in, but also maintain the reduction in understeer I currently have, I just ordered a 22mm front and 24mm adjustable rear. We'll see how it works out, but I have good feelings about it.
Do you know what the SOLID equivalent would be to the 17MM hollow?
Your theory on picking the front bar first makes sense. My car is pretty neutral as it is, probably part from the even spring rates and also it sits with a bit of rake (13.75" from axle to fender lip F&R).

Thanks
04furesterXT is offline   Reply With Quote
Old 01-13-2006, 04:11 AM   #7
wm07
Scooby Newbie
 
Member#: 26529
Join Date: Oct 2002
Location: STU
Vehicle:
04 STi
White

Default

Not very sure, but I guess 17mm hollow is equivalent to 14mm or 15mm solid? I don't know, but isn't stocks around 19mm or so? and you actually have a smaller than stock rear swaybar? interesting...
wm07 is offline   Reply With Quote
Old 01-13-2006, 03:06 PM   #8
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default

[
That is what initially makes sense as an equivilant solid bar. I just want to be sure. Stock is a 17MM hollow. It's a Forester XT.
04furesterXT is offline   Reply With Quote
Old 01-13-2006, 03:42 PM   #9
AUTOwrXER
Scooby Specialist
 
Member#: 5817
Join Date: Apr 2001
Location: Atlanta, GA, USA
Vehicle:
2005 STi
Silver

Default

Quote:
Originally Posted by wm07
Not very sure, but I guess 17mm hollow is equivalent to 14mm or 15mm solid? I don't know, but isn't stocks around 19mm or so? and you actually have a smaller than stock rear swaybar? interesting...
You would be surprised by how much less additional force you get from a solid bar vs. a hollow of the same size. Without knowing the inner diameter of the hollow bar, you cannot answer the original question. My guess is that the equivalent solid bar would be 16.25 - 16.5 mm.
AUTOwrXER is offline   Reply With Quote
Old 01-13-2006, 05:37 PM   #10
draggin wagon04
Scooby Specialist
 
Member#: 39474
Join Date: Jul 2003
Chapter/Region: MWSOC
Location: MPLS, MN
Vehicle:
form er WRXwag owner
Integra GSR 4-door

Default

If performance is the issue, hollow bars can have some weight saving advantages. Knowing the gauge of the tube is very important to figure on it's force. Try to find some Numbers from tests.
Pro-Hollow-
http://www.hotchkistuning.com/bin/Mi...SwayTech-D.pdf

If tubes get a kink or knicked, they -could- create a crease in the wall and can fail pretty quickly vs. a solid rod. If I was daily driving and not really concerned about track performance, and the price is close, I'd take piece of mind that if I hit road debris, rocks, etc., that the solid bar could take more everyday road condition abuse.

Last edited by draggin wagon04; 01-13-2006 at 05:43 PM.
draggin wagon04 is offline   Reply With Quote
Old 01-13-2006, 06:14 PM   #11
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default

Appreciate all the replys! I don't want to stray too far from my original question. I don't really care hollow or not, but mentioned hollow only in reference to my stock rear bar and finding an equivalent solid size but thanks for the info nonetheless.

If anything it seems as though I would have less fitment issues with the smaller O.D. of a solid bar. I know I can get the Strano to fit but it seems like in my case it would be like trying to stuff a large sausage into a small hole- fun but tricky.
04furesterXT is offline   Reply With Quote
Old 01-13-2006, 06:14 PM   #12
Porter
NASIOC Supporter
 
Member#: 486
Join Date: Nov 1999
Chapter/Region: MAIC
Location: Roanoke, VA
Vehicle:
2004 Forester XT
bug spattered

Default

Solid bars FTW.

Read up here for some good info on hollow vs. solid:

http://www.whiteline.com.au/docs/bul...%20Swaybar.pdf
Porter is offline   Reply With Quote
Old 01-13-2006, 06:19 PM   #13
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default

Thanks for the PDF. Any suggestions on what sizes would work well with the 7K springs? Just canyons and a lot of daily driving. I love the balance as is, it just feels a little mushy with full throttle transitions.

At this point the 27MM Whiteline seems to be the chit and I guess an STi 21 MM stocker?
04furesterXT is offline   Reply With Quote
Old 01-13-2006, 06:45 PM   #14
subieworx
Scooby Guru
 
Member#: 47769
Join Date: Nov 2003
Chapter/Region: MWSOC
Default

I have never heard of the Foresters have a hollow rear bar.

In what way does it feel mushy?
subieworx is offline   Reply With Quote
Old 01-13-2006, 10:24 PM   #15
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default

Well to be honest, I haven't cut it open but it sure feels light. I'm pretty sure it's hollow.

Maybe mushy wasn't the right word. Turn-in feels great- immediate and tight. It's when i'm really on it exiting a turn and when I change directions it almost feels like it has memory steer where it takes a second for it to react. I know it could be my steering rack or bushings.

My main reason for upgrading is at my height (13.75") the lower control arms are above parallel and even though it doesn't seem to have any quirks because of it(besides the aformentioned one) I'm thinking I should try and keep the alignment where it should be. It's a bit contradictory i'll admit.

Thanks.
04furesterXT is offline   Reply With Quote
Old 01-13-2006, 10:29 PM   #16
kfoote
Scooby Specialist
 
Member#: 39180
Join Date: Jul 2003
Chapter/Region: NESIC
Location: Trying to get :unamused: on TV
Vehicle:
2004 WRB STi
Slash Ten - FBHIC

Default

The rate of a hollow sway bar is also dependant on the wall thickness. For a 17mm hollow bar with a 1 mm wall thickness, it's equivalent to a 13.4 mm solid bar, for a 2mm wall thickness, a 15.3mm bar, and for a 3mm wall thickness, a 16.2mm bar.

The formula to determine the equivalent solid bar is ((outer bar diameter)^4-(inner bar diameter^4))^(1/4)
kfoote is offline   Reply With Quote
Old 01-13-2006, 10:34 PM   #17
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default

Thanks. Now all I need to do is cut it open!
04furesterXT is offline   Reply With Quote
Old 01-14-2006, 09:02 AM   #18
subieworx
Scooby Guru
 
Member#: 47769
Join Date: Nov 2003
Chapter/Region: MWSOC
Default

I really think the bar is solid. I have never heard of Subaru making a hollow bar before. I know my rear on my 04 is a 17 mm solid and is very light. Especially in comparison to my 22mm aftermarket bar on there now.
subieworx is offline   Reply With Quote
Old 01-14-2006, 11:35 AM   #19
dave bruener
Scooby Newbie
 
Member#: 11726
Join Date: Oct 2001
Chapter/Region: MWSOC
Location: Port Edwards WI
Vehicle:
2004 STi!
white

Default

You can tell if a bar is hollow by looking at the ends of the bar. If you look at the ends of a hollow bar you can see a seam on the collapsed portion of the bar--you know where the end links bolt on. On a solid bar you can tell that the ends are flattned and the seam is not evident in the end.

As a side note, I have Honda Prelude and the stock bars on that are hollow. This is the only car I know of off hand that has hollow bars from the factory. I believe hollow bars are more difficult and expensive to produce compared to solid ones.
dave bruener is offline   Reply With Quote
Old 01-14-2006, 11:49 AM   #20
Porter
NASIOC Supporter
 
Member#: 486
Join Date: Nov 1999
Chapter/Region: MAIC
Location: Roanoke, VA
Vehicle:
2004 Forester XT
bug spattered

Default

Quote:
Originally Posted by dave bruener
As a side note, I have Honda Prelude and the stock bars on that are hollow. This is the only car I know of off hand that has hollow bars from the factory. I believe hollow bars are more difficult and expensive to produce compared to solid ones.
The stock bar on the rear of the Forester XT is hollow. Also, hollow bars are not necessarily more expensive to produce... it depends on many factors including the cost of raw materials, whether the extrusions are made in-house or sourced, the type of bender used, etc.
Porter is offline   Reply With Quote
Old 01-14-2006, 11:59 AM   #21
AUTOwrXER
Scooby Specialist
 
Member#: 5817
Join Date: Apr 2001
Location: Atlanta, GA, USA
Vehicle:
2005 STi
Silver

Default

Quote:
Originally Posted by Porter
Solid bars FTW.

Read up here for some good info on hollow vs. solid:

http://www.whiteline.com.au/docs/bul...%20Swaybar.pdf
I disagree. The downsides of hollow bars cited in that article are related to manufacturing issues, which many manufacturers have been able to solve (Hotchkiss, Addco, etc.). Perhaps Whiteline does not have the equipment to manufacturer hollow bars correctly, so these are real issues to them. I'll take the weight savings of the hollow bar vs. a slightly smaller diameter solid bar any day. The one exception that I see is if space constraints do not allow a larger diameter bar.

To the original poster - If you can find the inner diameter of the stock hollow bar then I can tell you the equivalent solid bar diameter.

-Joel
AUTOwrXER is offline   Reply With Quote
Old 01-14-2006, 01:42 PM   #22
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default

Thanks for all the replys! All valid points. I will try and at least find the inner diameter or wall thickness to calculate the exact solid equivalent.

So assuming i'm able to calculate a solid equivalent, am I wrong in thinking I can increase both the front and rear an equal amount to maintain my F. to R. balance? Or is there more to it than that? I realize that there are only a finite amount of options out there but was curious if this approach is correct or not.

Also i'm not sure if trying to pick swaybar sizes corresponding to spring rates has any validity or not.

Thanks again.
04furesterXT is offline   Reply With Quote
Old 01-14-2006, 02:53 PM   #23
kfoote
Scooby Specialist
 
Member#: 39180
Join Date: Jul 2003
Chapter/Region: NESIC
Location: Trying to get :unamused: on TV
Vehicle:
2004 WRB STi
Slash Ten - FBHIC

Default

Quote:
Originally Posted by 04furesterXT
Thanks for all the replys! All valid points. I will try and at least find the inner diameter or wall thickness to calculate the exact solid equivalent.

So assuming i'm able to calculate a solid equivalent, am I wrong in thinking I can increase both the front and rear an equal amount to maintain my F. to R. balance? Or is there more to it than that? I realize that there are only a finite amount of options out there but was curious if this approach is correct or not.

Also i'm not sure if trying to pick swaybar sizes corresponding to spring rates has any validity or not.

Thanks again.
You are incorrect. Assuming the geometry is the same, the bar rate is proportional to the diameter of the bar to the 4th power. If they are both solid, a 23mm sway bar is 44% stiffer than a 21mm bar, while a 19mm bar is 56% stiffer than a 17mm bar
kfoote is offline   Reply With Quote
Old 01-15-2006, 03:11 PM   #24
Porter
NASIOC Supporter
 
Member#: 486
Join Date: Nov 1999
Chapter/Region: MAIC
Location: Roanoke, VA
Vehicle:
2004 Forester XT
bug spattered

Default

Quote:
Originally Posted by AUTOwrXER
I disagree. The downsides of hollow bars cited in that article are related to manufacturing issues, which many manufacturers have been able to solve (Hotchkiss, Addco, etc.). Perhaps Whiteline does not have the equipment to manufacturer hollow bars correctly, so these are real issues to them. I'll take the weight savings of the hollow bar vs. a slightly smaller diameter solid bar any day. The one exception that I see is if space constraints do not allow a larger diameter bar.

To the original poster - If you can find the inner diameter of the stock hollow bar then I can tell you the equivalent solid bar diameter.

-Joel
Well, functionally there is a significant space constraint. By going to the huge hollow bar that you were using you were forced (IIRC, correct me if I'm wrong) to go away from the stock-style endlink design entirely.

I honestly believe that the Whiteline 27mm bar is the highest effective springrate product on the market that fits in the stock location and uses the stock-design endlinks.

Has something changed in the last few months that makes this no longer true?
Porter is offline   Reply With Quote
Old 01-15-2006, 07:45 PM   #25
04furesterXT
Scooby Specialist
 
Member#: 73223
Join Date: Oct 2004
Chapter/Region: SCIC
Location: Los Angeles
Vehicle:
2009 STI

Default

Quote:
Originally Posted by kfoote
You are incorrect. Assuming the geometry is the same, the bar rate is proportional to the diameter of the bar to the 4th power. If they are both solid, a 23mm sway bar is 44% stiffer than a 21mm bar, while a 19mm bar is 56% stiffer than a 17mm bar
Thanks Kevin. Figured it wasn't linear and wouldn't be a no-brainer. So as you can tell i'm dragging my ass as far as finding inner diameters and wall thicknesses. What would be a proportional increase in stiffness be if I went from a 21MM to a 27MM in front, and say my 17MM hollow is equal to a 14 or 15MM solid? 20-21MM? I'm just guessing.
04furesterXT is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Need Opinion on Mixing Hollow/Solid Sway Bars? AutoXRex Brakes, Steering & Suspension 10 09-21-2007 07:04 PM
07 FXT rear swaybar HOLLOW!!???? Davenow Forester Forum 7 06-01-2007 09:28 PM
Solid Vs. hollow swaybars seattleswimboy Brakes, Steering & Suspension 16 06-11-2006 01:45 AM
Are the stock WRX swaybars hollow? Heather Brakes, Steering & Suspension 4 05-15-2003 01:22 PM
22mm Rear Swaybar and Solid Aluminum Links Maniac Brakes, Steering & Suspension 22 10-23-2002 11:36 AM


All times are GMT -4. The time now is 12:15 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.