×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Leaf Spring and Axle position.

Leaf Spring and Axle position.

Leaf Spring and Axle position.

(OP)
On a leaf spring/live axle suspension why is the distance shorter at the front of the spring - from axle to eye, than the rear? I understand it has something to do with axle wrap but what exactly does the shorter distance at the front do? Also what problems would/might occur if I reversed the spring?

Thanks for your help.

RE: Leaf Spring and Axle position.

The short front distance also helps to give some antiroll stiffness.

I'm not sure what you mean by reversing the spring - if you put the shackles at the front that could be quite interesting. If you effectively mean moving the axle rearwards along the spring then you'll just lose some antiroll and gain some pitch/castor change under traction and braking.

I suspect I have not really answered your question.

Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Leaf Spring and Axle position.

All of what Greg said, plus any solid rear axle located on longitudinally mounted leaf springs, even low hp cars, is subject to violent "wind up" of the axle on acceleration and/or braking.  Making the front part stiffer (shorter) has a remedial effect on the problem.  

I'm not sure I have seen a front mounted axle mounted the same way, at least I cannot visualize one at the moment.  I'm also sure that I'm probably mistaken and someone here will correct me.

Rod  

RE: Leaf Spring and Axle position.

I see it as Rod does, but I'm not a suspension guy.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
 

RE: Leaf Spring and Axle position.

I have communed with the spirit of the Last Leaf Spring Designer, and his apprentice.

Basically, you do it for traction control. You get less windup, less danger of buckling, less lateral compliance steer, better ride, and a bit of antiroll action.

There is no rule for the front rear split - 40/60 up to 50/50 is used  quite often.



 

Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Leaf Spring and Axle position.

(OP)
Thank you for all your replies.

Greg, your second reply was the answer I was looking for. (Sorry my question was not well asked). Before yesterday I thought all springs had a forward bias and I wondered if there was an ideal ratio, but after looking at some more closely I did find some that were equal spacing. I was also wondering how the spring rate would change, I know that car companies would never waste material and in making one side shorter I thought the spring rate would be reduced to the rate of the short side but the longer rear side probably increases the rate somewhat. Another thought I had was maybe the shorter side changed the arc that the wheel made.

I was toying with the idea of reversing a spring (not the shackles) and using it on a different car but I have given up on that as it had quite a large difference in spacing (32" - 27") and would probably suffer too much from axle wrap.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources