mistergrumpy
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 posted on 25/3/07 at 03:11 PM |
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Bump steer - I Know!
Despite having read all previous threads, and I have read them all  I've been at this for about half a day now and can't get it.
There's obviously some black art to it and I can't figure what it is. These are my conclusions, however, please be patient here with me.
Steering arms to be parallel to the wishbones, the pivot between the arms and the actual rack to be in the line of the upper and lower front wishbone
pivot points.But, the rack and therefore distance between the two pivot points is 600mm and the only place their is 600mm between the two imaginary
lines ( between the wishbone pivots) is just below the actual top bracket which therefore means the steering arms can't be parallel to the
wishbones. I'm missing summat here aren't I? I can't go too low and far back either as my lower steering column fouls on the
chassis, which I found out to my cost when trying to fit it Pished off with it now, gonna go and sulk in the corner 
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russbost
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| posted on 25/3/07 at 03:49 PM |
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Suspension is always a compromise, unless you're planning a lot more travel than the average seven type vehicle you're unlikely to
encounter much problem with bump steer (unless you're going to put the rack somewhere really peculiar)- I think it is something which tends to
be somewhat exagerrated. If you're building a "seven style something" is there not a set design place for the rack or are you
building your own one off design from scratch?
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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David Jenkins
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| posted on 25/3/07 at 04:16 PM |
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Agreed - I put no special effort into getting rid of bump steer, apart from getting the rack the right height.
There may be some bump steer, but it doesn't bother me at all.
David
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ecosse
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| posted on 25/3/07 at 05:13 PM |
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i have my rack fitted just below the top bone brackets and have mounted the steering arms above the hub arms rather than below using rosejoints
instead of TRE's - result = practically no bumpsteer at all and thats through a range of movement greater than my shocks will allow, sorted
Cheers
Alex
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JB
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| posted on 25/3/07 at 05:22 PM |
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Bumpsteer
I disagree and feel it is worth the effort to get zero bumpsteer. Its one of the things that add up to a car feeling just right instead of OK. If you
are positioning the components you may as well as position them in the place that will minimise bumpsteer.
I did the calculations as per the books etc but did not trust these to actually cut metal. So I made a model of my suspension, upright and proposed
steering arms out of stiff card with pins on a board. Then I could move the suspension up and down and check that I had minimal bump steer.
Then once on the car I checked it and fine tuned by altering the height of the track rod end on the upright. It was worth the effort because a friend
drove the car down a particular bad bit of road where they test Jags and Landrovers and proclaimed my car better.
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mistergrumpy
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| posted on 25/3/07 at 05:23 PM |
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Wahey, I've got it. I'm out for my tea now but I've found a computer just to show off. More luck than anything. Its only a few mm
now, thats good enough for me. Cheers fellas
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