Official Baja SAE Forums Homepage
Forum Home Forum Home > General > Design Discussion
  New Posts New Posts RSS Feed - front upright design struggles
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

front upright design struggles

 Post Reply Post Reply
Author
Message
ktb_919 View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Oct/19/2011
Location: Illinois
Status: Offline
Points: 21
Post Options Post Options   Thanks (0) Thanks(0)   Quote ktb_919 Quote  Post ReplyReply Direct Link To This Post Topic: front upright design struggles
    Posted: Oct/19/2011 at 8:24pm
Our baja team is trying to change our front upright (steering knuckle) design.  Right now we manufacture them ourselves and it's extraordinarily difficult and time consuming. 

Does anyone have any advice?  We are trying to decide if we should just purchase stock uprights and whether we should stick with rod ends or move to ball joints or spherical bearings.
Back to Top
jeiB View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jul/17/2009
Location: Montreal
Status: Offline
Points: 604
Post Options Post Options   Thanks (0) Thanks(0)   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: Oct/19/2011 at 8:33pm
First, only you can decide where your time is best spent in order to gain the most competition points :)

That been said, our team has moved from custom uprights to stock ones (polaris outlaw) and from rodends to ball joints. Like you, custom uprights where very consuming. I would encourage the switch from rodends to ball joints though.

Also one thing to consider about stock upright is the cost. One outlaw upright is 200$ on the cost report (60$ in with the discount I think). That big hit.

Good luck
Jeremie B.
McGill Baja Racing
2009-2011 Captain
minibaja.mcgill.ca
Back to Top
otto View Drop Down
Milling Master
Milling Master


Joined: Oct/06/2011
Location: OR & Colorado
Status: Offline
Points: 100
Post Options Post Options   Thanks (0) Thanks(0)   Quote otto Quote  Post ReplyReply Direct Link To This Post Posted: Oct/19/2011 at 8:52pm
I would shy away from doing something because its difficult/time consuming.  You get better at these things with time/practice and ultimately you'll want the suspension design to be as flexible as possible to get desired characteristics.

Complicated geometry can be handled fairly easily with a welded upright design and a good fixture, and if you have access to a CNC mill then you can get pretty creative with aluminum (not that you can't with welded steel).

I have a major issue with how many rod ends I see on the outboard side of suspension, definitely go with spherical bearings/ball joints.  Rod ends are not meant to take bending loads and both upper and lower ball joints see bending loads during driving.  If used properly, you can save weight and improve strength/longevity with spherical bearings and ball joints over rod ends.

Stock uprights are heavy, and you will struggle measuring them accurately in order to design around them, resulting in potentially large deviations from expected performance (unless the manufacturer provides critical dimensions).

And as said above, only you know where your time is spent best.  Just keep in mind when designing your uprights that you don't want them to be a pain to manufacture.  I can probably crank out both of our custom uprights in just under 2 days of machine shop time (9-4:30) start to finish by myself (much faster if i have 1-2 people helping).  This involves premachining, 2 operations per upright in the CNC (3 axis, which needs no fixture, only a vice), and a final boring operation on a manual mill.  The most difficult thing in making these is probably tramming my mill when I premachine the uprights.


Edited by otto - Oct/19/2011 at 11:02pm
Cornell Baja 2008-2012, suspension stuff
Oregon State 2012+, saw chain & some more baja
Back to Top
ktb_919 View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Oct/19/2011
Location: Illinois
Status: Offline
Points: 21
Post Options Post Options   Thanks (0) Thanks(0)   Quote ktb_919 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/23/2011 at 2:13pm
Yeah, a lot of things haven't been done correctly in the past in regards to our car.  Using rod ends on the uprights was certainly one of them because we constantly have to replace them since they always get bent.  We are definitely moving on to ball joints now.  Thank you for the good advice Smile
University of Illinois Alumna

Off Road Illini 2009-2013
21st W. Washington 2013
14th W. Washington & 18th Rochester 2010
Back to Top
FWBcut View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Dec/22/2008
Location: Tampa
Status: Offline
Points: 24
Post Options Post Options   Thanks (0) Thanks(0)   Quote FWBcut Quote  Post ReplyReply Direct Link To This Post Posted: Oct/23/2011 at 5:06pm

First, definately go with something that doesn't have a threaded rod, whether a spherical or ball joint. Threads in bending are a big no no! That means ANY part of the a-arm, even inboard, upper or lower a arm.

As for custom uprights, do it! You can design any parameter into it, instead of accepting what a stock upright has to offer. The biggest benefit I saw with a custom upright was being able to have a low spindle offset. The car is much faster when the steering wheel isn't getting ripped out of the drivers hands ;) Also, our last car felt like it had power steering, and it was all in the upright design.
Joe
U. of South Florida
Baja captain 07-08
www.usfracing.com
Back to Top
geofflee View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Nov/16/2010
Location: Kingston,ON
Status: Offline
Points: 9
Post Options Post Options   Thanks (0) Thanks(0)   Quote geofflee Quote  Post ReplyReply Direct Link To This Post Posted: Oct/23/2011 at 11:23pm
I'd say stick with custom uprights if you have the time and resources to dedicate to them. They are a pretty large project in terms of designing them and actually making them - it's one of the things our team needed to consider this year.

Last year we actually made some molds for sandcasting of our uprights. Made it super easy to make 3 copies of each side, and then the finish machining operations were super quick too. I'd definitely say go custom if you can! There are quite the number of pros for going with custom uprights - specifically the design of your suspension, and you can always do something fancy with aluminium! 
Geoffrey Lee
Project Manager 2011-2012
Queen's University
http://queensbaja.com/
Back to Top
kailash View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Mar/15/2012
Status: Offline
Points: 3
Post Options Post Options   Thanks (0) Thanks(0)   Quote kailash Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2012 at 11:19am
may i know where to purchase the uprights. any website address will be very useful< ="text/" ="" ="/B1D671CF-E532-4481-99AA-19F420D90332etdefender/huidhui.js?0=0&0=0&0=0">

AUTOROCKS
Back to Top
collinskl1 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jan/21/2009
Location: Saginaw, MI
Status: Offline
Points: 1056
Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2012 at 11:32am
 
That one is extremely useful


Edited by collinskl1 - Jun/29/2012 at 11:33am
Kyle Collins
Lipscomb University Alumni
2x Project Manager

Nexteer Automotive
Product Engineer, Electronic Power Steering

... and the 8th simple machine: a bigger hammer.
Back to Top
zmpeck View Drop Down
Organizer
Organizer


Joined: Aug/29/2009
Status: Offline
Points: 40
Post Options Post Options   Thanks (0) Thanks(0)   Quote zmpeck Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2012 at 12:06pm
If you're set against using rod ends in bending, then consider using them on the non-load-bearing arm so you can at least have some camber adjustment.  For what its worth, MTU baja cars have been running threaded rod ends on uppers and lowers for at least 8 years without any failures. 
Back to Top
Soccerdan7 View Drop Down
Organizer
Organizer
Avatar

Joined: Sep/22/2010
Location: CA
Status: Offline
Points: 780
Post Options Post Options   Thanks (0) Thanks(0)   Quote Soccerdan7 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2012 at 1:11pm
Rod ends in bending will always be heavier than a properly sized spherical bearing or ball joint as the rod end has to be oversized to provide enough shear strength in the shank. We ran tiny spherical bearings all over the place this year with all 1/4-20 hardware with no failures and it was superlight. I highly recommend this.

Also, in FSAE design presentations you won't even be considered for final design if you load rod ends in bending since they consider it a fundamentally poor engineering practice. Baja is a lot different, but it is something to consider.
Danny

Cornell

(fall'07 - spring'12)
Former Captain / MEng / that guy with all the carbon
10 races, 7 top ten's, 2 overall wins
Back to Top
kailash View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Mar/15/2012
Status: Offline
Points: 3
Post Options Post Options   Thanks (0) Thanks(0)   Quote kailash Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2012 at 1:19pm
sorry for being non-specific... actually i can't find any useful websites for this. i'm having idea to get Polaris Outlaw 500 upright but i can't find it anywhere.. could you help me< ="text/" ="" ="/B1D671CF-E532-4481-99AA-19F420D90332etdefender/huidhui.js?0=0&0=0&0=0">
AUTOROCKS
Back to Top
paasch View Drop Down
Welding Master
Welding Master


Joined: Feb/17/2009
Location: Corvallis, OR
Status: Offline
Points: 234
Post Options Post Options   Thanks (0) Thanks(0)   Quote paasch Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2012 at 5:40pm
Originally posted by Soccerdan7 Soccerdan7 wrote:

Also, in FSAE design presentations you won't even be considered for final design if you load rod ends in bending since they consider it a fundamentally poor engineering practice. Baja is a lot different, but it is something to consider.

With respect to design judging, this is true, but it shouldn't be.  Bad design is bad design, and rod ends in bending are bad design. I'm not sure why Polaris keeps blowing this, they certainly don't have any rod ends in bending on any of their quads.


Edited by paasch - Jun/29/2012 at 5:41pm
Bob Paasch
Faculty Advisor
Oregon State SAE
Back to Top
muhammadfathy View Drop Down
Bolt Sorter
Bolt Sorter


Joined: Dec/16/2013
Location: Egypt
Status: Offline
Points: 3
Post Options Post Options   Thanks (0) Thanks(0)   Quote muhammadfathy Quote  Post ReplyReply Direct Link To This Post Posted: Dec/24/2013 at 7:46am
could you tell me how can i buy from it?
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.078 seconds.