rocket
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| posted on 13/7/05 at 08:10 AM |
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steering rack
just into this part of my build and low and behold I have a alloy sierra rack!!
From what I've read here on the forum this isn't any good to me!
but inlooking on the net for picture of modified racks I came across a picture of this one which looks like the one MK uses.
It is from a skoda estelle ( used for a porche kit car.)
 
Rescued attachment s_rack_ref.jpg
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James
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| posted on 13/7/05 at 08:27 AM |
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MK uses the alloy Sierra rack.
They chop out the middle and fit extensions on the end to compensate.
You've just got to make sure that the balljoints of the track rod arms are inline with a line drawn between the bushes of the top and bottom
front wishbone.
This minimises bump steer.
Hope that helps,
James
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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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Mark18
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| posted on 13/7/05 at 09:33 AM |
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Having said that, that rack does look like it'd be better suited - so long as it steers the front of the hub rather than the rear - any chance
you could put up the dimensions and turns lock to lock?
Mark
"I don't know what I may seem to the world. But as to myself I seem to have been only like a boy playing on the seashore and diverting myself
now and then finding a smoother pebble or a prettier shell than the ordinary, whilst the great ocean of truth lay all undiscovered before me." -
Isaac Newton
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NS Dev
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| posted on 13/7/05 at 09:59 AM |
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the rack in that pic looks uncannily like a short escort mk2 rack!!!
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MikeR
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| posted on 13/7/05 at 12:12 PM |
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hmmm, i'm not sure, the turny bit for the steering column to attach to appears to be at an angle to the body of the rack. I thought the escort
was at 90 degrees.
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NS Dev
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| posted on 13/7/05 at 12:45 PM |
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I thought it was angled? The splined shaft looks a touch longer than the escort one but the casting around that end of the rack looks very similar!
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rocket
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| posted on 13/7/05 at 08:08 PM |
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no probs
Got my grinder out and attacked rack!!
took 5" out of it and is now perfect fit!
Not as big a job as I thought, just got to weld the extensions on ( after I make wish bones and I know where everything lands!!)
My cars a bit "odd" as I'm making it fit a westfield body that I got cheap. So the top rails are wider but the bottom is as per
book.
Rgds
Roger
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NS Dev
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| posted on 14/7/05 at 08:01 AM |
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bear in mind that the whole handling characteristics of the car are set by the difference in width of the chassis between top rails and bottom rails!
(without going into further detail, but camber change etc is affected dramatically!)
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britishtrident
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| posted on 14/7/05 at 08:15 AM |
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Look at the picture carefully --- who can spot why it won't work :-)
Also it looks to me like a Hillman Avenger rack.
[Edited on 14/7/05 by britishtrident]
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Mix
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| posted on 14/7/05 at 08:26 AM |
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It's from a vehicle with the track rod ends attached behind the hubs.
Could always try crossing your hands
Mick
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rocket
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| posted on 14/7/05 at 08:51 AM |
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camber
quote:
Originally posted by NS Dev
bear in mind that the whole handling characteristics of the car are set by the difference in width of the chassis between top rails and bottom rails!
(without going into further detail, but camber change etc is affected dramatically!)
But surely this is set by the length of the wish bones?
If I shorten the top one to compensate for the extra with this should work yes?
rgds
Roger
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NS Dev
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| posted on 14/7/05 at 10:07 AM |
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That's exactly the point, you will have to horten the upper wishbone to get the wheel upright! The shorter upper wishbone then gives greatly
increased camber change in bump and droop, affecting the handling. Exactly what effects I'll leave to the experts but it has a major effect. A
basic rule is to have wishbones as long as possible, as this removes unwanted effects. The design of the generic "7" type chassis is based
around the ratio of the upper and lower wishbone lengths, and the chassis then fitted to these lengths.
At the very basic level, if your wishbones are equal length, the wheel stays upright in bump and droop. If the upper wishbone is shorter, it takes on
negative camber in bump and droop, and this is exploited in the "7" to roll on negative camber on the outside wheel when cornering. The
shorter the top wishbone, the more negative camber is rolled on. Taken to the extreme, where the upper wishbone is reduced to 0 length, you end up
with a swing axle where the wheel angle simply rotates about the bottom wishbone pivot (a la Imp)
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