 offset versus scrub radius |
|
|
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
|
| r_towle |
 May 23 2013, 12:41 PM
Post
#1
|
|
Custom Member  Group: Members Posts: 24,646 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States 
 |
Does it make a difference what the offset is on a wheel with regards to scrub radius?
It does not seem that it would, given the stock suspension, no custom struts etc. Aside from that, what is the reason (aside from cost and availability) for using large spacers versus getting wheels that mount up with no spacer, yet are wide for flared cars? rich |
   |
 
|
  |
Replies
| J P Stein |
May 24 2013, 07:32 AM
Post
#2
|
|
Irrelevant old fart Group: Members Posts: 8,797 Joined: 30-December 02 From: Vancouver, WA Member No.: 45 Region Association: None |
The following sketch does not represent all of the aspects of SR vs its effects....but the best I got.
It does show the method of measuring SR and one fella's attempt to fix it thru camber changes An increase in SR does indeed effect the car & handling, basically one increases the leverarm of the axle against rotation....leading to increased steering effort....that's the easy part to figure out. The increase also puts the CL of the tire/wheel farther fom the center of rotation.This gets this center "out ahead"of the rotation when turning....not a problem for minor (say 5-10 deg) steering inputs. Major inputs , such as found at AX, are another story. These will cause the tire to "shuffle" sideways rather than roll. ....been down this road with 10 inch wide front wheels...giving me about 2.5+ inches of SR.....resulting in an increable PUSH. Fixed it with 8 inch wide wheels but with only a .5 inch loss in tire width. Attached image(s) 
|
|
|
|
| Matt Romanowski |
May 25 2013, 09:55 AM
Post
#3
|
|
Senior Member Group: Members Posts: 878 Joined: 4-January 04 From: Manchester, NH Member No.: 1,507 |
QUOTE(J P Stein @ May 24 2013, 05:32 AM)  The following sketch does not represent all of the aspects of SR vs its effects....but the best I got. It does show the method of measuring SR and one fella's attempt to fix it thru camber changes An increase in SR does indeed effect the car & handling, basically one increases the leverarm of the axle against rotation....leading to increased steering effort....that's the easy part to figure out. The increase also puts the CL of the tire/wheel farther fom the center of rotation.This gets this center "out ahead"of the rotation when turning....not a problem for minor (say 5-10 deg) steering inputs. Major inputs , such as found at AX, are another story. These will cause the tire to "shuffle" sideways rather than roll. ....been down this road with 10 inch wide front wheels...giving me about 2.5+ inches of SR.....resulting in an increable PUSH. Fixed it with 8 inch wide wheels but with only a .5 inch loss in tire width. That diagram has nothing to do with camber. The guy is changing the strut to spindle angle, which changes the scrub radius. Changing just the camber of the wheel has no affect on scrub radius. |
|
|
|
Posts in this topic
r_towle offset versus scrub radius May 23 2013, 12:41 PM
Matt Romanowski
Does it make a difference what the offset is on a... May 23 2013, 03:01 PM r_towle Still confused, sorry.
Just wondering if a wheel b... May 23 2013, 08:26 PM
Randal
The following sketch does not represent all of th... May 24 2013, 04:53 PM
J P Stein
That diagram has nothing to do with camber. The g... May 26 2013, 07:09 AM Matt Romanowski
[quote name='Matt Romanowski' post='1869513' date... May 26 2013, 07:40 AM r_towle Seems to me, given my original quest, that anythin... May 24 2013, 08:27 AM J P Stein One is limited by the 914s front suspension. The m... May 24 2013, 09:14 AM andys And increased scrub radius creates a cross jacking... May 24 2013, 09:25 AM zig-n-zag In an effort to eliminate front spacers, I found s... May 24 2013, 02:03 PM SirAndy In an effort to eliminate front spacers, I found s... May 24 2013, 02:52 PM tomeric914
Whatever you use, make sure your front wheels are... Jun 22 2013, 08:04 PM r_towle Lots of great knowledge.
Seems that my initial que... May 24 2013, 03:55 PM J P Stein For anyone that has the chance........
Take a look... May 25 2013, 05:47 AM Randal
For anyone that has the chance........
Take a loo... May 25 2013, 12:04 PM J P Stein
Going to dial in a bit more front bar for the Cas... May 26 2013, 07:20 AM Randal
Going to dial in a bit more front bar for the Ca... May 27 2013, 03:47 PM andys Slight hijack, but since we're talking scrub r... May 27 2013, 02:10 PM byndbad914 ...will taking out that scrub radius and going to ... May 31 2013, 04:55 PM stownsen914 I believe all car suspensions have some scrub radi... Jun 15 2013, 04:09 AM andys You know, I have to appologize for throwing out so... May 27 2013, 04:06 PM J P Stein Let's keep it simple.
A certain amount of Scru... Jun 23 2013, 07:19 AM |
24 User(s) are reading this topic (24 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 2nd December 2024 - 05:04 AM |
Invision Power Board
v9.1.4 © 2024 IPS, Inc.