Daddylonglegs
|
| posted on 14/5/09 at 06:07 AM |
|
|
Bump Steer
Mornin all.
I have mounted my steering rack (tacked the supports at the moment) as best I can. To try and minimise bump-steer, I placed the rack, then jacked up
each wheel in turn to see if they toed in or out. I think I've found the best position but would like some comfort feedback if poss 
What (if any) bump steer is acceptable?
Cheers 
JB
It looks like the Midget is winning at the moment......
|
|
|
|
|
Phil.J
|
| posted on 14/5/09 at 07:33 AM |
|
|
It should be possible to virtually eliminate all bumpsteer with careful design and testing.
Just concentrate on the normal suspension operating range, say 2" bump and 1 1/2" droop and be less concerned with effects outside of this
range.
|
|
|
Doofus
|
| posted on 14/5/09 at 07:53 AM |
|
|
A small amount of toe out on bump at the front improved my car, rather than the other way round. Toe in on bump caused lift off oversteer and a less
planted feel through corners.
Mine was way out and didn't feel confident mid corner.
Correcting the bump was achieved with a surprisingly small lift of the rack.
Paul.
|
|
|
l0rd
|
| posted on 14/5/09 at 07:55 AM |
|
|
I am not trying to overtake your post. I have been thinking the same thing for some time.
Does it say anywhere in IVA or is it common sence that the steering mount plates, the ones that are welded in the chassis need to be solid mounted?
I was thinking of making them with rose joints. so you can adjust the steering rack in every possible angle until you eliminate completely the bump
steer effect.
Has anyone else done something like that?
|
|
|
procomp
|
| posted on 14/5/09 at 08:01 AM |
|
|
Hi
As above ^^. But rather than lift the wheels separately also try doing it by leaving both wheels on the ground and moving the chassis through the dims
mentioned above. This will give a more simulated car movement than raising and lowering a single wheel. Once you have the bump reduced as low as you
can with the chassis being moved up and down squarely then try by imitating a bit of gentle roll. This can be achieved by lifting the chassis under
one of the rear corners by say 1" and again moving the front chassis up and down with the roll simulated.
On a book type chassis using an unmodified Escort rack it should be able to get down to as low as 16 tho of toe change over 3" of movement which
is what i usually use. Ie as above 2" bump but only 1" droop. Although it dose take considerable time to achieve those measurements.
Cheers Matt
|
|
|
l0rd
|
| posted on 14/5/09 at 08:12 AM |
|
|
And this is what i mean.
[img][/img]
|
|
|
maartenromijn
|
| posted on 14/5/09 at 10:10 AM |
|
|
I have used a cheap laser spirit level to check bump steer. If you do a search you will find more topics about this.
See here: picture laser setup
BLOG: http://thunderroad-super7.blogspot.com/
|
|
|
Daddylonglegs
|
| posted on 14/5/09 at 10:15 AM |
|
|
quote:
Originally posted by maartenromijn
I have used a cheap laser spirit level to check bump steer. If you do a search you will find more topics about this.
See here: picture laser setup
AHA!
Good idea
I go one of these as a pressie many moons ago and now I have found another use for it
It looks like the Midget is winning at the moment......
|
|
|
blakep82
|
| posted on 14/5/09 at 12:14 PM |
|
|
a lot of production cars have bump steer. i'd be surprised if you even noticed it really
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
|
|
|
MikeRJ
|
| posted on 14/5/09 at 12:44 PM |
|
|
If using the laser method, note that the suspension will naturally gain and lose camber in bump and droop, so even with zero bump steer the laser dots
will move a little.
|
|
|
