Thursday, 3 December 2009

The Dreaded Bump Steer

Now I’m not sure why but I wasn’t really looking forward to this bit. I had read with interest Simons detailed account of setting bump steer using magic and mirrors and also looked at the GD method as described in the video and in the build manual. In the end I decided on a slight adaptation of this one by one of the Cobra Club members.
I started by taking a piece of angle and drilling a hole in it centrally. I then placed this on the stub axle with a packer washer behind and tightened it up.
Next I placed the laser level on the angle and checked the chassis was level in all directions as well as the laser level.
You then need to place a piece of paper 3m away at a height where the laser will hit it, making sure it is vertical or as I did just draw a vertical line on it using a spirit level. The suspension is then set at ride height determined by the top wishbone being horizontal. I then plotted this point where the laser hit.
.Using a trolley jack under the axle you can then jack it through full droop to full bump and back again noting the movement of toe in / toe out as the laser dot moves with reference to your marked vertical line and plotting it.
It is then just a case of moving the steering rack up or down to bring the dot as close to the vertical line as possible as shown in the video below:

Now I am not sure how accurate this is and if my method is correct but I would welcome any comments or suggestions. And yes I do realise that I’ve spelt height wrong on the piece of paper. No excuse really it was late and I didn’t have my spellchecker working at the time.

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