Rear Suspension Bind - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Suspension - Brakes - Steering
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 04-27-2002, 04:49 PM
Registered User
 
Join Date: Mar 2002
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Question Rear Suspension Bind

This is a general question based on what I think I'm seeing in some solid axle rear suspension photos in various magazines. Setups using the four bar configuration usually include some means of lateral stabilization like a panard bar. Presumably, with each of the four bars being parallel to each other and a long panard parallel to the axle, vertical suspension travel is not sufficient to produce appreciable side-to-side motion as the panard swings through its arc. However, I've seen a few layouts depicted where lateral stabilization is accomplished by bars that run from the frame a couple of feet ahead of the rear axle to the differential housing. While the front pivots on the inside of the frame are proximate to the front four bar pivots, the rear pivots on the differential are well away from the rear four bar pivots. This achieves the triangulation needed to keep the axle centered, but creates separate and conflicting arcs for the lateral stabilizers and the four bars. Unless the pivots are rubber mounted, it seems like binding would occur as the suspension moves. Granted the binding would be slight and ball ends would further reduce the problem, but why design in this kind of an inherent geometric conflict into a labor of love? What am I missing?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-27-2002, 06:52 PM
4 Jaw Chuck's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Mar 2002
Location: Manitoba, Canada
Age: 46
Posts: 4,973
Wiki Edits: 0

Thanks: 2
Thanked 89 Times in 72 Posts
Post

This design is used to put the rear axle thrust vector ahead or at the the vehicles roll center, in essence it prevents the squat you see when a car launches. You can even design in rear axle rise under power if you desired. This of course is very popular with off road racers for these reasons. The Heim joints allow free movement and eliminate binding. There's a photo at the bottom of this page that shows the best setup and it eliminates the panhard rod while keeping the axle centered.
<a href="http://www.truckworld.com/4x4-OffRoad/00-herbstf-2504x4/herbstf-250-p2.html" target="_blank">http://www.truckworld.com/4x4-OffRoad/00-herbstf-2504x4/herbstf-250-p2.html</a>
__________________
Outlawed tunes from outlawed pipes
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-07-2002, 10:28 PM
Registered User
 
Join Date: Mar 2002
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

Thanks for the feedback. Your vector comments shed light on the why, but I'm still perplexed by the how. The picture you provided is what I was talking about. Heim joints would eliminate twisting of the stabilizers, but wouldn't seem to allow the length variation you need to avoid binding due to the different arcs swung by the stabilizers and other links parallel to the frame. Do you know if some sort of rubber mounting was used on either end of any of the stabilizers/suspension rods?
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-08-2002, 09:08 AM
Member
 
Join Date: Dec 2001
Location: East Palestine, Ohio
Posts: 150
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Cool

suspension components that use a heim joint typically have one on each end to limit axle wrap. The trade off is the suspension will be a little rougher than a rubber or urithane bushed suspension. Most rodders are willing to make the tradeoff of cumfort for performance. I have seen many streat driven drag cars with heim joint bushed rear ends and they work well. It will produce a solid rear end that will hook up well at the track.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-08-2002, 10:29 AM
4 Jaw Chuck's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Mar 2002
Location: Manitoba, Canada
Age: 46
Posts: 4,973
Wiki Edits: 0

Thanks: 2
Thanked 89 Times in 72 Posts
Post

In essence DR the different lengths will rotate the axle housing which can be used to keep the universal joint aligned through the very long travel these types of suspension designs are subject to. You could compare it to a front suspension that has unequal length control arms that in effect gives more positive camber through it's travel. Of course this can be excessive and detrimental depending on the design, length of arm, position of pivots etc. You can take some paper cutouts and use pins as pivots to see the changes that occur during stroking of the suspension. In most cases universal joints will have a 30 degree range of acceptable motion beyond which the joint can lock and fail, best practice dictates a 15 degree range of motion to minimize wear and stress depending on load.
__________________
Outlawed tunes from outlawed pipes
Reply With Quote Quick reply to this message

Recent Suspension - Brakes - Steering posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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



All times are GMT -6. The time now is 12:07 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.