Forums » Grassroots Motorsports » Learn me Bars 1 2

• 

  June 10, 2010 7:24 a.m. 3Door4G Reader

  So I don't need an introduction to the world of alcoholism, thanks anyway. I'm talking about suspension bars here.

  I understand the basics of sway bars- they tighten the lower end of the chassis. Too thick in the front can increase understeer, and too much in the rear can increase oversteer... etc etc

  But what about strut bars? Is there a time when a sway bar would not be appropriate for an application but a strut tower bar would? And if so, why? Is it just that the effect is milder? And if so, wouldn't a thinner sway bar do the trick?

  SO MANY QUESTIONS!

• 

  June 10, 2010 7:34 a.m. HappyAndy HalfDork

  A strut bar and sway bar are for completly different jobs, a strut bar is for reducing chassis flex common in mac-strut equiped cars. not all mac-strut cars flex enough to need one, and there was an article in a recent grm about chassis set up that went into detail about that.

  As for sway bars, what you mentioned about front/under steer and rear/oversteer is generaly true for FWD cars and it is often the other way around on RWD cars, but every car is different so it would help to know what type of car you have in mind.

• 

  June 10, 2010 7:37 a.m. 914Driver SuperDork

  My understanding of strut bars is they reenforce the unibody. Look at a car from the front, lower horizontal cross member and a vertical upright at each end. Looks like the letter "U". The strut bar across the shock towers connects the top of the "U" making a box; more rigid than a U.

  My old 914 was so loose that a bump at the right angle would pop the engine compartment cover open.
  

  Strut bars in the trunk do the same thing. The rear floor pan on my BMW 2002 under the rear seat was called a "torsion box". I have no idea why or what it did, but I'm guessing taking a Saw-Zall to it would be bad.

  Dan

  BMW -- You don't need a hibachi to cook rice.

• 

  June 10, 2010 7:40 a.m. DaveEstey Reader

  Sway bars do not tighten the chassis... They connect the suspension right and left, transferring torque from the compressed outside tire in a turn to the inside, thus reducing roll.

• 

  June 10, 2010 10:22 a.m. iceracer Dork

  The stiff front, soft rear = understeer holds true regardless of the drive wheels. The effect of the drive wheels is the problem .

• 

  June 10, 2010 10:29 a.m. carguy123 SuperDork

  iceracer wrote: The stiff front, soft rear = understeer holds true regardless of the drive wheels.

  Thank you, I thought I was going crazy and everything I knew was false.

  "mobilito ergo sum" I drive therefore I am!

• 

  June 10, 2010 10:39 a.m. amg_rx7 HalfDork

  Here is a link to GRM articles on sway bars, shocks etc:

  http://grassrootsmotorsports.com/articles/category/tech/suspension/

• 

  June 10, 2010 10:42 a.m. 96DXCivic Dork

  Strut bars are used to stiffen the chassis. However they promise a lot but they don't always provide. Cheap eBay strut bars probably won't do too much. The strut bar is most useful if they are triangulated like the one seen below.

  

  Swaybars are basically torsion springs which connect the sides of the car. When the car rolls in a turn, the bar twists and restricts the roll of the vehicle. I have all the equations to calculate how much it will restrict the roll. Let me know if you want to post these.

• 

  June 10, 2010 10:58 a.m. tuna55 HalfDork

  Go over to corner carvers and tell them how much stiffer your car will be with your new strut bar off of ebay.

  Then run.

• 

  June 10, 2010 11:03 a.m. njansenv Reader

  carguy123 wrote:

  iceracer wrote: The stiff front, soft rear = understeer holds true regardless of the drive wheels.

  Thank you, I thought I was going crazy and everything I knew was false.

  Depending on suspension geometry, a stiffer front bar can DECREASE understeer. Common with Macstrut front suspension.
  Reason: less body roll = better outside front contact patch.

• 

  June 10, 2010 11:09 a.m. Carson Dork

  96DXCivic wrote: I have all the equations to calculate how much it will restrict the roll. Let me know if you want to post these.

  Yes please. I has thirst for knowledge!

• 

  June 10, 2010 11:22 a.m. 96DXCivic Dork

  Carson wrote:

  96DXCivic wrote: I have all the equations to calculate how much it will restrict the roll. Let me know if you want to post these.

  Yes please. I has thirst for knowledge!

  Ok but how do you post a pdf?

• 

  June 10, 2010 2:48 p.m. Capt Slow HalfDork

  you need to upload it to the web, most people do this through a hosting service.

  If you use gmail for your email, that means you have access to google docs which may afford you some options in this regard (I think).

  1995 subaru impresa -- to be sold | 1996 Miata -- woot!

• 

  June 10, 2010 2:53 p.m. 96DXCivic Dork

  http://docs.google.com/fileview?id=0BxJNiOGL1WdeN2M5MGVmNWYtMjEwMy00NjYzLThlNzQtM2...

  I hope this works.

  Edit: Yup it works.

• 

  June 10, 2010 2:57 p.m. Tom Heath Webmaster

  amg_rx7 wrote: Here is a link to GRM articles on sway bars, shocks etc: http://grassrootsmotorsports.com/articles/category/tech/suspension/

  amg_rx7 wins 1 sticker. PM me your address, please.

  I tried drag racing, but kept blowing the apex for turn 2... Xbox Live gamertag— GRM Tom

• 

  June 10, 2010 3:02 p.m. Tom Heath Webmaster

  njansenv wrote:

  carguy123 wrote:

  iceracer wrote: The stiff front, soft rear = understeer holds true regardless of the drive wheels.

  Thank you, I thought I was going crazy and everything I knew was false.

  Depending on suspension geometry, a stiffer front bar can DECREASE understeer. Common with Macstrut front suspension.
  Reason: less body roll = better outside front contact patch.

  The relative relationship in bar size front to rear is still affecting the balance of said car.

  In dungeons and dragons terms, consider it +1 roll stiffness, -1 weight transfer. Still worthwhile in some cases, stock class autocrossing comes to mind.

  I tried drag racing, but kept blowing the apex for turn 2... Xbox Live gamertag— GRM Tom

• 

  June 10, 2010 3:05 p.m. Tom Heath Webmaster

  96DXCivic wrote:

  Carson wrote:

  96DXCivic wrote: I have all the equations to calculate how much it will restrict the roll. Let me know if you want to post these.

  Yes please. I has thirst for knowledge!

  Ok but how do you post a pdf?

  Just like you would a photo. You may want to convert it to an image first.

  I tried drag racing, but kept blowing the apex for turn 2... Xbox Live gamertag— GRM Tom

• 

  June 10, 2010 3:05 p.m. Tom Heath Webmaster

  TRIPLE POST COMBO!

  I tried drag racing, but kept blowing the apex for turn 2... Xbox Live gamertag— GRM Tom

• 

  June 10, 2010 7:30 p.m. Gearheadotaku Dork

  The relative relationship in bar size front to rear is still affecting the balance of said car.

  In dungeons and dragons terms, consider it +1 roll stiffness, -1 weight transfer. Still worthwhile in some cases, stock class autocrossing comes to mind.

  D&D referece! WIN!!!! (I still can't make quotes work right)

  Old enough to know better, too young too care!

• 

  June 14, 2010 9:53 p.m. 3Door4G Reader

  I think I'm finally getting it.

  I bookmarked that link. And this thread.

  I'm trying to figure out suspension because my Civic will be getting new pieces soon. It's a daily driver and I'm very poor, so I want to get it right the first time.

  Clean cars can be found at http://rabidclean.blogspot.com

• 

  June 14, 2010 10:03 p.m. DaveEstey Reader

  custom spring rates, front 400lbs rear 500lbs. Stock front sway and 22mm ST rear bar. Add some good shocks and you're done!

• 

  June 14, 2010 10:59 p.m. AngryCorvair SuperDork

  3Door4G wrote: I think I'm finally getting it. I bookmarked that link. And this thread. I'm trying to figure out suspension because my Civic will be getting new pieces soon. It's a daily driver and I'm very poor, so I want to get it right the first time.

  how to get it right the first time, poor person daily driver edition:

  LEAVE IT THE berkeley ALONE! HONDA ENGINEERS ARE SMARTER THAN YOU!

  if you're gonna be a bear.... be a grizzly bear!

• 

  June 14, 2010 11:18 p.m. 3Door4G Reader

  I can't come up with any rational argument against the above statement. I don't believe there is one. So I'm not going to try.

  I'm still going to go ahead and drop the car though. This is still a project car, just a very slowly progressing one. It's taken me almost a year to get the exhaust right.

  Clean cars can be found at http://rabidclean.blogspot.com

• 

  June 14, 2010 11:20 p.m. neon4891 SuperDork

  AngryCorvair wrote:

  3Door4G wrote: I think I'm finally getting it. I bookmarked that link. And this thread. I'm trying to figure out suspension because my Civic will be getting new pieces soon. It's a daily driver and I'm very poor, so I want to get it right the first time.

  how to get it right the first time, poor person daily driver edition:

  LEAVE IT THE berkeley ALONE! HONDA ENGINEERS ARE SMARTER THAN YOU!

  FTMFW!!!

• 

  June 15, 2010 6:20 a.m. ZOO Dork

  Gearheadotaku wrote: The relative relationship in bar size front to rear is still affecting the balance of said car. In dungeons and dragons terms, consider it +1 roll stiffness, -1 weight transfer. Still worthwhile in some cases, stock class autocrossing comes to mind. D&D referece! WIN!!!! (I still can't make quotes work right)

  Leave it to a guy with an X-11 in his avatar to quote D and D!

  No offense meant -- I loved both in the 1980's, too. Especially since the X-11 was kind of obscure, and quite elegant looking in its simplicity.

  1990 Miata, 1998 M3, Locost in progress

1 2  

You'll need to log in to post.