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steering rack position
muttley8 - 8/6/11 at 12:55 PM

Hi everyone
Please can you help
I have a problem with the clearance of the engine front pulley to the steering rack and would like to move rack forward 50mm.

I don't think this will affect bumpsteer, but will it create other problems (change of angle of trackrods as seen from above??)

any advice ,opinions ?
Thanks Phil

nick205 - 8/6/11 at 01:52 PM

In short - yes!

The rack needs to be positioned as close as possible to dead straight between the track rod ball joints as possible in each plane - i.e. viewed from above and from the front. The car should be at it's intended ride height and level etc.

Can you no move the enginefurther back - that would be the better solution for steering and overall weight distribution.

mookaloid - 8/6/11 at 02:46 PM

I think it will cause bump steer.

maybe not much but there will be an effect.

As I understand it (and I could be wrong) there is only one position for the rack to be in where it has no bump steer effect and the further away from that point you go then the worse it will get.

britishtrident - 8/6/11 at 03:08 PM

No with Cortina or Sierra uprights the steering rack centre line needs to be about 50mm behind the imaginary line joining the track rod end ball joint centres in the straight ahead position. This gives some toe-out in turns (ackerman).

Neville Jones - 8/6/11 at 05:51 PM

quote:
Originally posted by britishtrident
No with Cortina or Sierra uprights the steering rack centre line needs to be about 50mm behind the imaginary line joining the track rod end ball joint centres in the straight ahead position. This gives some toe-out in turns (ackerman).


C'Mon, you cannot be serious! (Said with John Macenroe style. )

You've told us far too many times that it is impossible to get any 'Ackerman' geometry with a rack and pinion setup!

Cheers,
Nev.

muttley8 - 8/6/11 at 06:06 PM

Okay thanks
I agree nick 205 moving the engine would be best solution but not possible the car isn't a locost, seven type, its a Gilbern and so engine cannot move back

In all the information I can find for working out rack position (to avoid bump steer) none mention for and aft movement so was hoping this didnt affect it

next I am off to search for threads about ackerman

Neville Jones - 9/6/11 at 11:04 AM

Longitudinal position affects ackerman, tie rod/rack length and height of rack affects bump steer. They all affect each other in a small way as well.

Cheers,
Nev.