The above is an advertisment. If it asks you to download software or create an account, please ignore it.
Site News - 7/11: No New News Today | 5/10: Members: Log In to See Fewer Ads!
[General | Members | C900 | 9000 | NG900 & OG93 | 93 | 95 | NG95 | 99 | Sonett | Vintage Models | Clubs | Other Cars | FAQs | Gifts | Member Photo Galleries | Member Directory | Classifieds | Manuals | *Buddy Registry | *Mileage Registry | Polls | What's New | Raffle | Photo of the Month | Sponsors]

Performance Bulletin Board
[Subscribe to Daily Digest]
(Search Author's Posts: e.g. Keyword:username)*Members Only

[Main Performance Bulletin Board | BBFAQ | Prev by Date | Next by Date | Post Followup ] Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: Very interesting post. Thank you.
Like This Post: - Subscribe to Daily Digest for this Bulletin Board
Posted by 2Slow (more from 2Slow) on Tue, 13 Nov 2001 16:28:55 Share Post by Email
In Reply to: Re: Very interesting post. Thank you., lms, Tue, 13 Nov 2001 15:40:19
Alert me when someone posts in this thread:
Members do not see ads below this line. - Help Keep This Site Online - Signup

I prefer the term "stiffer" to harder. It is a bit more accurate.

I noticed the comment that the toe caster and camber almost did not change under hard cornering. I might have mis-understood the comment, but you want the camber at the very least to change while cornering.

This was especially true of bias ply tires though wide radials are fairly sensative to camber angle.

When the car rounds a corner it will roll to some degree. With a solid axle one degree of body roll will result in one degree of wheel camber change and the wheels will remain perpendicular to the road. Also with a solid axle ride events (where both wheels move up and down together) will result in no camber change and the wheels will remain perpendicular to the ground. This is all great stuff.

The problems with the solid axle are that single wheel ride events cause camber change at both wheels. Solid axles also tend to have higher unsprung mass, (although they can be lighter overall) The last bad thing about solid axles in the rear is that in order to get roll understeer the wheel that moves into jounce in roll must move forward while the one that goes into rebound must move rearward. This is fine in roll events, but the axle kinematics can't tell the difference between roll and ride events so that the entire axle will move forward when you encounter a bump. (since both wheels move in jounce they both move forward) This causes kinematic wheel procession rather than regression which is horrible for ride. As the suspension moves upward to absorb the bump energy, it is forced forward intot he bump. You can get around some of this with by trying to give some lateral force understeer and less kinematic wheel progression, or maybe just allowing kinematic progression and compliant regression. (the latter is the common solution)

With an independent suspension the camber change is usually less than one degree negative camber gain per degree of body roll. As the wheel moves into jounce it will gain negative camber, but not as fast as the body is rolling, so the tire will end up at some angle relitive to the ground.

The reason this happens is that the kinematics don't know the difference between ride and roll. Kinematically speaing any time the wheel moves into jounce it will move along a prescribed camber curve. (regardless if it was a ride or roll event that caused the motion) The camber change now happens in ride events at both wheels. (As you hit the bump, both wheel tops point towards each other) This is not good for tire wear, or on a vehicle like a truck where payload and therefore trim height change often. For this reason, the camber gain is less than one degree per degree of roll so that it can be tolerable in ride. But like I said we are still only speaking kinematically.

Kinematics basically prescribe a certain wheel orientation for a given suspension travel regardless of what caused the suspension travel. The beauty of compliant effects is that they know the difference between ride and roll. Roll events will have large lateral forces that can be used to compliantly move the suspension bits into better toe/camber settings.

You would be surprised at how much effort goes into picking the suspension geometry and compliant behavior. It is quite fun stuff...

-Joe

posted by 198.208.6....
Posts in this Thread:
Alert me when someone posts in this thread:
Members do not see ads below this line. - Help Keep This Site Online - Signup
Post a Followup

No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.

Name: Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
E-Mail: (Optional)
Re-Enter E-Mail: (Confidential & Secure - Not revealed to other users!)
Note: Please check your spam folder for BB responses.

Subject:

Posting rules are simple - No for sale/wanted ads may be posted here - use the site classifieds.
You may not cross-post your message to multiple BBs.
Not permitted: political/religious topics and being disrespectful (personal attacks, insults, etc...).
 Site Members do not see any red text, inline ad links, bottom of page anchor ads, box ads, or anti-spam check.

Message: (please no for sale/wanted classifieds - post those in the Saabnet.com Classifieds)
Links are now automatically made active, no need for any special code (or use the Option Link field below) - don't put links in () or end with a '.'
To add inline images to your post, use [img]http://www.domain.com/img.jpg[endimg] (or use the Optional Image Link field below).

Links are now automatically made active, no need for any special code (or use the Option Link field below) - don't put links in () or end with a '.'
To add inline images to your post above, use [img]http://www.domain.com/img.jpg[endimg] (or use the Optional Image Link field below).
Optional Link: (e.g. http://www.saabnet.com/)
Link Title: (Optional)
Optional Photo/Image Link: (e.g. http://www.saabnet.com/img.jpg)
Photo/Image to Upload: (Please be patient while file uploads)



StateOfNine.com
SaabClub.com
Jak Stoll Performance
M Car Covers
Ad Available

The content on this site may not be republished without permission. Copyright © 1988-2025 - The Saab Network - saabnet.com.
For usage guidelines, see the Mission & Privacy Notice.
[Contact | Site Map | Saabnet.com on Facebook | Saabnet.com on Twitter | Shop Amazon via TSN | Site Donations]

Random Saabnet.com Member Gallery Photos (Click Image)
This is a moderated bulletin board - Posting is a privilege, not a right. Unsolicited commercial postings are not allowed (no spam). Please, no For Sale or Wanted postings, SERIOUSLY. Classifieds are to be listed in The Saab Network Classifieds pages. This is a problem solving forum for over 250,000 Saab owners, so expect to see problems discussed here even though our cars are generally very reliable. This is not an anything goes type of forum. Saabnet.com has been a moderated forum since 1988. For usage guidelines, see the Saabnet.com Mission and Purpose Page. Please remember that you are not anonymous. Site Contact | Site Donations | Other Sites by SP - Poverty2Prosperity.org | Run Club Menlo Park | ScreenBot


Site Members do not see red text instructions, bottom of the page anchor ads, or box ads.
Click here to see all the Site Membership Benefits!