Go Back OFN Forums > Fabrication > Offroad Fabrication

Offroad Fabrication Offroad Fabrication


Offroad Fabrication Offroad Fabrication

Reply
 
Thread Tools
  #61  
Old 11-07-2012, 06:43 PM
entropy's Avatar
entropy entropy is offline
Master Fabricator
 
Join Date: Sep 2007
Location: 95-miles from the center of Oregon.
Posts: 8,329
Check your bump-steer with that VW box before you get to far....
__________________
When did empirical knowledge get replaced by a theoretical education?

Reply With Quote
  #62  
Old 11-07-2012, 06:58 PM
vectorsolid's Avatar
vectorsolid vectorsolid is offline
Fabricator
 
Join Date: Apr 2008
Location: Montana
Posts: 66
exciting and fun as always. :)
Reply With Quote
  #63  
Old 11-07-2012, 07:30 PM
Redliner's Avatar
Redliner Redliner is offline
Master Fabricator
 
Join Date: Dec 2011
Posts: 315
.

Last edited by Redliner; 01-12-2013 at 08:32 PM.
Reply With Quote
  #64  
Old 11-07-2012, 09:46 PM
entropy's Avatar
entropy entropy is offline
Master Fabricator
 
Join Date: Sep 2007
Location: 95-miles from the center of Oregon.
Posts: 8,329
the reason that there is an idler and or the rack is a specific width is to locate the pivots between the A-arm frame pivots. The VW beam suspension the tires move up and down on a For-aft arc for little toe change.
The A-arm moves up-and-down in addition to in-and-out thus there are two displacements, for-aft and side-2-side, Toe changes are likely and that is Bump steer.

E
__________________
When did empirical knowledge get replaced by a theoretical education?

Reply With Quote
  #65  
Old 11-07-2012, 11:03 PM
Redliner's Avatar
Redliner Redliner is offline
Master Fabricator
 
Join Date: Dec 2011
Posts: 315
.

Last edited by Redliner; 01-12-2013 at 08:33 PM.
Reply With Quote
  #66  
Old 11-08-2012, 12:46 AM
entropy's Avatar
entropy entropy is offline
Master Fabricator
 
Join Date: Sep 2007
Location: 95-miles from the center of Oregon.
Posts: 8,329
Quote:
Originally Posted by Redliner View Post
You have my interest! Pardon a dumb chum question, but how can you have in & out movement on equal length top & bottom A arms?
Only dum question is the one not asked

In the attached picture the black lines are an imaginary parallel equal length design viewed front on. with the steering link also parallel.
The Green lines are the same length only bumped some amount.
Notice that there is a distance between the black vertical line and the green one. That is the side to side displacement or scrub.
The red line is if I located the tie rod (Steering link) at a random point inboard of the A-arm pivots and the red arc in comparison to the green one is bump steer or Toe change.

Yes/no?

E
Attached Thumbnails
Click image for larger version

Name:	Paralell bump.jpg
Views:	234
Size:	21.5 KB
ID:	7549  
__________________
When did empirical knowledge get replaced by a theoretical education?

Reply With Quote
  #67  
Old 11-08-2012, 01:38 AM
alwaysFlOoReD's Avatar
alwaysFlOoReD alwaysFlOoReD is offline
Master Fabricator
 
Join Date: Jan 2010
Location: Red Deer,AB Canada
Posts: 704
I don't know if this will help, or if I can explain it well but, another way to look at this is;
from the front of the vehicle at rest the distance between the hubs is 100". At bump or droop it is 98". Bump steer is introduced if the steering input is not at the same parallel as the upper/lower arms in all travel positions. And with s/l arms aimed at a point the pivot point would need to be the same as the steering pivot.
Richard
Reply With Quote
  #68  
Old 11-08-2012, 01:58 AM
Redliner's Avatar
Redliner Redliner is offline
Master Fabricator
 
Join Date: Dec 2011
Posts: 315
OK. So what would you do if you were me? I have a rack the right length but the pinion is angled the wrong way & a VW box (freebie by the way). Should I 1) put in Pitman arms for the VW box 2) Narrow a Pittman arm setup out of something else to fit 3) Try to get uni-joints to make my short rack work 4) Something else?
Reply With Quote
  #69  
Old 11-08-2012, 02:31 AM
alwaysFlOoReD's Avatar
alwaysFlOoReD alwaysFlOoReD is offline
Master Fabricator
 
Join Date: Jan 2010
Location: Red Deer,AB Canada
Posts: 704
It's always better to do it right the first time. But then the factory doesn't always seem to care too much. IMO You're racing on dirt and can adjust your driving style to suit the vw box. But this is a newby talking, all I've done is research for my own project and don't have any experience worth counting. Maybe tack the steering you have into place and then move the suspension to see what you get for bump steer, it may be acceptable. I haven't done the measurements, but I was told that the steering knuckles for 1983 thru ~ 1997 rangers and bronco II's [ and full size fords too?] are all the same no matter the frame length....seems the factory isn't hell bent on accurate steering, at least with ackerman anyway.
Good luck,

Richard

Last edited by alwaysFlOoReD; 11-08-2012 at 02:33 AM.
Reply With Quote
  #70  
Old 11-08-2012, 05:04 AM
350 Vortec's Avatar
350 Vortec 350 Vortec is offline
Master Fabricator
 
Join Date: Jun 2011
Location: Ireland
Posts: 487
Why dont you just put a second joint on that steering axle???hope the 30kg of weld wire was a typo
Reply With Quote
  #71  
Old 11-08-2012, 08:48 AM
Redliner's Avatar
Redliner Redliner is offline
Master Fabricator
 
Join Date: Dec 2011
Posts: 315
That short Peugot rack already has 2 joints on it and I still can't get safe turning of it because the shaft is not only up one end, but sharply angled the wrong way. A few buggies here have got round this problem by fitting gears and chains... one used timing chain - the other bycycle!! Neither have a tensioner, and I think this is suicidally stupid and should not be passed by the scrutineers. One guy has had his chain slip off in the pits driving to the start line. Unbelievable.

My next job is to design, fabricate & build the front top & bottom wishbones, so I think I'll attack the steering after that, when I can try a few ideas and check the effects of wishbone movement.
Reply With Quote
  #72  
Old 11-08-2012, 11:53 AM
entropy's Avatar
entropy entropy is offline
Master Fabricator
 
Join Date: Sep 2007
Location: 95-miles from the center of Oregon.
Posts: 8,329
Quote:
Originally Posted by Redliner View Post
That short Peugot rack already has 2 joints on it and I still can't get safe turning of it because the shaft is not only up one end, but sharply angled the wrong way. A few buggies here have got round this problem by fitting gears and chains... one used timing chain - the other bycycle!! Neither have a tensioner, and I think this is suicidally stupid and should not be passed by the scrutineers. One guy has had his chain slip off in the pits driving to the start line. Unbelievable.

My next job is to design, fabricate & build the front top & bottom wishbones, so I think I'll attack the steering after that, when I can try a few ideas and check the effects of wishbone movement.
If you use the VW (or similar) the way VW did, well, you now know what to expect. It is possible that the effect could be something you could live with.
My choice wold be to get a rack that fits the application correctly or if I am not mistaken there is an Idler arm on your Ute. I would check that and see if it will fit one on each side thus the linkage can be located in the sweet spot and then fab an idler link to that VW box or something similar.
In the states custom racks can be had for a couple bones.
http://www.appletonrackandpinion.com/
http://www.dansperformanceparts.com/...ack&pinion.htm
I see lotz of buggys build down there you must have similar resources?

E
__________________
When did empirical knowledge get replaced by a theoretical education?


Last edited by entropy; 11-08-2012 at 08:04 PM. Reason: missing letterz
Reply With Quote
  #73  
Old 11-08-2012, 07:56 PM
350 Vortec's Avatar
350 Vortec 350 Vortec is offline
Master Fabricator
 
Join Date: Jun 2011
Location: Ireland
Posts: 487
As i see it a lot will depend on the length of your wishbones and where they pivot from but with the width of your chassis i think your already heading for trouble with steering box,the original VW front end would not have had much suspension movement either
Can you move wishbone pivot's closer together in an effort to equalize W bone/track rod length??
Reply With Quote
  #74  
Old 11-10-2012, 07:37 AM
Redliner's Avatar
Redliner Redliner is offline
Master Fabricator
 
Join Date: Dec 2011
Posts: 315
Can you explain that last sentence?
Reply With Quote
  #75  
Old 11-10-2012, 11:32 AM
entropy's Avatar
entropy entropy is offline
Master Fabricator
 
Join Date: Sep 2007
Location: 95-miles from the center of Oregon.
Posts: 8,329
Quote:
Originally Posted by Redliner View Post
Can you explain that last sentence?
The length of Steering link (Tie Rod) is determined by the lower A-Arm (wishbone).
As viewed from the front (or back) there are 4 points that you are dealing with. They are the 2 front pivot points at the frame for the upper and lower A-Arms and the upper and lower Ball Joint on the steering knuckle.
The steering link being connected to the Knuckle (Upright, spindle, etc) and the Steering Gearbox or Rack & Pinion must swing with the Knuckle in such a way that it's arc is the same as the Lower A-Arm.
In the drawing I did back a bit I made everything equal length and parallel not the best suspension design but everything moves the same; change the frame end of the steering link and instantly the arc changed and Bump steer. In the case of a working suspension design everything will not be parallel. Thus to get the Steering link to move along an arc that will generate the minimum amount of divergence, the Steering link is aligned parallel to the lower A-Arm in the Front view, and the pivot points are located at the imaginary lines that connect vertically, one vertical between the frame pivots, and the other between the ball joints. If this is done there will be the minimum amount of bump steer.
That is what 'I think' was said.

E

Note this is real general description and when the actual parts are used things may not work exactly the way we think it should.
__________________
When did empirical knowledge get replaced by a theoretical education?


Last edited by entropy; 11-10-2012 at 12:13 PM.
Reply With Quote
  #76  
Old 11-11-2012, 09:57 AM
350 Vortec's Avatar
350 Vortec 350 Vortec is offline
Master Fabricator
 
Join Date: Jun 2011
Location: Ireland
Posts: 487
Yes ta E,tie rod is called track rod here as it keeps your wheels in track
To simplify redliner,take your steering box track rod mounting points as a starting point of your track rod radius and try to match that radius with your longest wishbone(or position preferably IMO of your hub steering arm)
As i see your setup you'll be mounting the VW box in center of frame so you'll need to put wishbone mounts as close to center as poss
Reply With Quote
  #77  
Old 12-16-2012, 05:16 PM
Redliner's Avatar
Redliner Redliner is offline
Master Fabricator
 
Join Date: Dec 2011
Posts: 315
Part 4 video: Front suspension mounts and making a fibreglass fuel tank

http://www.youtube.com/watch?v=BR8Wr...ature=youtu.be
Reply With Quote
  #78  
Old 12-31-2012, 06:14 PM
Redliner's Avatar
Redliner Redliner is offline
Master Fabricator
 
Join Date: Dec 2011
Posts: 315
Part 5 video - Front suspension mounts & rear brakes

http://www.youtube.com/watch?v=aH6EEjzmOYM
Reply With Quote
  #79  
Old 12-31-2012, 06:56 PM
vectorsolid's Avatar
vectorsolid vectorsolid is offline
Fabricator
 
Join Date: Apr 2008
Location: Montana
Posts: 66
Love the videos, you're getting things done! :)
Reply With Quote
  #80  
Old 12-31-2012, 07:28 PM
entropy's Avatar
entropy entropy is offline
Master Fabricator
 
Join Date: Sep 2007
Location: 95-miles from the center of Oregon.
Posts: 8,329
When you flipped the rear calipers did the bleeder stay on the top of the Caliper?
__________________
When did empirical knowledge get replaced by a theoretical education?

Reply With Quote
Reply

Bookmarks


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

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


All times are GMT -4. The time now is 04:22 PM.

Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Template-Modifications by TMS
Copyright 2012, Offroad Fabrication Network