Race Car Tech Discuss anything related to road racing and auto X.

bump steer gauge

Old 03-09-16, 08:15 PM
  #1  
Rotary Enthusiast
Thread Starter
iTrader: (1)
 
Join Date: Feb 2012
Location: CA
Posts: 1,075
Likes: 0
Received 0 Likes on 0 Posts
bump steer gauge

I'm thinking about buying a bump steer gauge. Does anyone have recommendations? I see then from 200 to 300 bucks. Any of then check camber as well, or do you you just put a camber gauge on the bump steer plate?
GrossPolluter is offline  
Old 03-10-16, 09:42 AM
  #2  
Rotary Enthusiast
Thread Starter
iTrader: (1)
 
Join Date: Feb 2012
Location: CA
Posts: 1,075
Likes: 0
Received 0 Likes on 0 Posts
Which one do you guys use? Are there any improvements you think your gauge should have?
GrossPolluter is offline  
Old 03-10-16, 10:20 AM
  #3  
Fistful of steel
iTrader: (7)
 
LargeOrangeFont's Avatar
 
Join Date: Nov 2008
Location: OC, So Cal
Posts: 2,146
Received 8 Likes on 8 Posts
I have done it before with laser levels and some paper on the wall.
LargeOrangeFont is offline  
Old 03-10-16, 07:23 PM
  #4  
Armchair engineer
iTrader: (2)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: http://www.k2rd.com
Posts: 24,491
Likes: 0
Received 116 Likes on 106 Posts
we just set the toe with it as high as it goes, and check the toe as we lower it, lot of work, but it works with no fancy tools
j9fd3s is offline  
Old 03-10-16, 07:36 PM
  #5  
Rotary Enthusiast
Thread Starter
iTrader: (1)
 
Join Date: Feb 2012
Location: CA
Posts: 1,075
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by LargeOrangeFont View Post
I have done it before with laser levels and some paper on the wall.
That is a good idea. You just mark where the lazer points and determine which spacing gives you the leasetoe change?
GrossPolluter is offline  
Old 03-10-16, 09:55 PM
  #6  
1308ccs of awesome
iTrader: (9)
 
eage8's Avatar
 
Join Date: Sep 2003
Location: Woodbine, MD
Posts: 6,176
Received 10 Likes on 10 Posts
I just have a longacre one. it works fine... but wouldn't be that hard to make yourself if you're crafty/have the time.

Longacre Bump Steer Measurement Tools
eage8 is offline  
Old 03-10-16, 10:32 PM
  #7  
Rotary Enthusiast
Thread Starter
iTrader: (1)
 
Join Date: Feb 2012
Location: CA
Posts: 1,075
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by eage8 View Post
I just have a longacre one. it works fine... but wouldn't be that hard to make yourself if you're crafty/have the time.

Longacre Bump Steer Measurement Tools
I'm Chinese. I would have to see it to copy it, lol! I get the main idea of it, I just never seen it in person. I am in the process of possibly starting a small shop of my own. I am debating if I invested in this tool, if people would pay me money to check/ adjust their bump steer and give them specific numbers. If not, the lazer method LargeOrange mentioned seems to work for me. $300 bucks is not much. Now $1000 on weight scales is a little steep for someone barely starting off and looking at equipment I must have. Everything else is adding up real quick and I have to prioritize
GrossPolluter is offline  
Old 03-10-16, 11:16 PM
  #8  
1308ccs of awesome
iTrader: (9)
 
eage8's Avatar
 
Join Date: Sep 2003
Location: Woodbine, MD
Posts: 6,176
Received 10 Likes on 10 Posts
basically it's a frame that pivots on a hinge at the bottom. There is a large plate bolted to your hub (think toe plate). The pivoting frame is propped up against the two edges of this plate, on one side by a static length roller, on the other side by a dial indicator.

you zero the dial indicator at ride height. then cycle the suspension up or down. anything the dial indicator registers is a difference between the front of the frame (which is fixed) and the rear of the frame (the dial indicator)... which translates to toe change.

you can also do this with a fixed frame and two dial indicators.... just subtract the two numbers to get a delta.
eage8 is offline  
Old 03-11-16, 09:25 AM
  #9  
Rotary Enthusiast
Thread Starter
iTrader: (1)
 
Join Date: Feb 2012
Location: CA
Posts: 1,075
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by eage8 View Post
basically it's a frame that pivots on a hinge at the bottom. There is a large plate bolted to your hub (think toe plate). The pivoting frame is propped up against the two edges of this plate, on one side by a static length roller, on the other side by a dial indicator.

you zero the dial indicator at ride height. then cycle the suspension up or down. anything the dial indicator registers is a difference between the front of the frame (which is fixed) and the rear of the frame (the dial indicator)... which translates to toe change.

you can also do this with a fixed frame and two dial indicators.... just subtract the two numbers to get a delta.
Your right, it doesn't look very complicated
Toe plate with bolt pattern drilled in the middle with a centerline to determine inches going up and down suspension movement.
And then a fixture that holds 2 dial indicators. Hmmmmm, maybe I will make my own
GrossPolluter is offline  
Old 03-19-16, 02:17 PM
  #10  
Fistful of steel
iTrader: (7)
 
LargeOrangeFont's Avatar
 
Join Date: Nov 2008
Location: OC, So Cal
Posts: 2,146
Received 8 Likes on 8 Posts
I just measure the hub to fender distance for ride height (so I know when I cycle the suspension later) then jack up the car, undo the swaybar and strut from the top hat (to preserve alignment) drop the lower arm, pull off the springs then bolt the strut back to the top hat. I made a little fixture to bolt the laser level on the wheel studs. Then cycle the suspension with a jack and draw the projected arc from the level on the wall or some paper.

The only real setup you need to do is make sure your projection surface where you are going to trace the line is very close to equal distance from each front hub.
LargeOrangeFont is offline  
Old 03-19-16, 10:13 PM
  #11  
Rotary Enthusiast
Thread Starter
iTrader: (1)
 
Join Date: Feb 2012
Location: CA
Posts: 1,075
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by GrossPolluter View Post
Your right, it doesn't look very complicated
Toe plate with bolt pattern drilled in the middle with a centerline to determine inches going up and down suspension movement.
And then a fixture that holds 2 dial indicators. Hmmmmm, maybe I will make my own
I just ordered a precision level. I also bought the laser that bolts up to it. I'll use that for now. I didn't buy it for this exact purpose, but I'm sure I can figure something out to minimize toe change. Thanks for that info. Bump street gauge would be cool to get exact numbers, especially for customers at the car shop.
I'm sure some people are willing to pay for those numbers. Do a package deal with corner balance, bump steer adjustment, then alignment
GrossPolluter is offline  
Old 03-20-16, 08:43 AM
  #12  
Racing Rotary Since 1983
iTrader: (6)
 
Join Date: Oct 2001
Location: Wisconsin
Posts: 5,341
Received 39 Likes on 27 Posts
as you know, bump steer/toe steer is determined by the relationship between the steering arm and lower control arm on the FD and any double A arm suspension.

it is what it is and on an FD it is zero. and not adj unless you move the rack or lower control arm neither of which is advisable.

the only reason the bump steer plate exists is for real racecars that have adj steering and/or lower control arms. generally bump steer can help in situations where you are only turning in one direction.

i don't see too many FDs on short tracks.

it is impossible to over-emphasize the role of suspension settings. most chassis are designed to deliver understeer when pressed so generally non OE settings are like putting lipstick on a pig.

not the FD.... you have true racecar dynamics.

think non optimal suspension settings (including tire pressure) aren't a big deal and you can drive around them?

the new Boss Mustang has altered ball joint angle to set the scrub radius at a dynamic rather than static point since under cornering the tire moves laterally!

and you bolted on a new set of rims that re-center the tire an inch outboard?
Howard Coleman CPR is offline  
Old 03-22-16, 07:59 PM
  #13  
Automotive Designer
 
RGHTBrainDesign's Avatar
 
Join Date: Aug 2012
Location: San Jose, CA
Posts: 1,450
Received 40 Likes on 37 Posts
Originally Posted by Howard Coleman CPR View Post
as you know, bump steer/toe steer is determined by the relationship between the steering arm and lower control arm on the FD and any double A arm suspension.

it is what it is and on an FD it is zero. and not adj unless you move the rack or lower control arm neither of which is advisable.

the only reason the bump steer plate exists is for real racecars that have adj steering and/or lower control arms. generally bump steer can help in situations where you are only turning in one direction.

i don't see too many FDs on short tracks.

it is impossible to over-emphasize the role of suspension settings. most chassis are designed to deliver understeer when pressed so generally non OE settings are like putting lipstick on a pig.

not the FD.... you have true racecar dynamics.

think non optimal suspension settings (including tire pressure) aren't a big deal and you can drive around them?

the new Boss Mustang has altered ball joint angle to set the scrub radius at a dynamic rather than static point since under cornering the tire moves laterally!

and you bolted on a new set of rims that re-center the tire an inch outboard?


Howard, have you heard of anyone designing front suspension setup with a positive ackermann split at low speeds that transitions to negative ackermann split at high speeds?

It's not for lack of technology...
RGHTBrainDesign is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
unek87
2nd Generation Specific (1986-1992)
11
04-02-16 10:29 AM
Dorito Powered
General Rotary Tech Support
2
03-09-16 10:57 AM


Thread Tools
Search this Thread
Quick Reply: bump steer gauge


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: