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Lengthening a steering rack
carcentric - 16/10/03 at 04:33 PM

I'm planning to add 5" to my GT6/Spitfire steering rack (because I'm widening the frame that much) and would like some input on how to go about it. These are my assumptions (subject to correction):

1) It doesn't matter whether I add material to both ends of the rack or just one end (with the rack mounted off-center).

2) The rack is made of material that can be welded to a mild steel extension.

3) The rack and pinion will work as usual when inverted. (I'm thinking about flipping my LHD rack over so I can have RHD for that "full British" effect.)

If you see any other issues, please bring them up as well.


Mk-Ninja - 16/10/03 at 04:59 PM

Hi

One thing you must concider is to have the joints on the rack in line with the pivots on the suspension or you will get bump stear.

Gordon


Stu16v - 16/10/03 at 05:26 PM

1. Both the inner rack and outer casing would need to be extended, (and probably equally on both sides) or else you will issues with the rack pinion running out of travel. Or are you on about merely extending the arms?

2. Possibly, but some outer casings are made of alloy (unless you are on about the arms....). Also, welding of the inner rack near inner balljoints, or rack teeth *may* affect the material properties.

3. No. Inverting the steering rack will move the wheels right when the steering whell is moved left.

I personally reckon you might be better off search for a rack to suit off something else....

HTH Stu.

[Edited on 16/10/03 by Stu16v]


carcentric - 16/10/03 at 10:26 PM

Gordon - By extending the rack joints out the same amount that I widen the frame, the suspension arcs should remain as they were originally. The other option (less desirable to me) is to not widen the frame or steering rack, but to lengthen all four a-arms plus both tierods - again, the suspension arcs should remain as they were.

Stu - I'll check the construction of the rack; I wasn't planning to extend the rack housing, too. If I invert the rack, though, I'd also swap uprights left to right which would move the steering arms from in front of the axle to behind the axle (turning the steering wheel left would still turn the road wheels left and vice versa).


Stu16v - 18/10/03 at 12:34 AM

quote:

. If I invert the rack, though, I'd also swap uprights left to right which would move the steering arms from in front of the axle to behind the axle (turning the steering wheel left would still turn the road wheels left and vice versa).



.....and unfortunately knacker up the old Ackerman (sp?) angles.

Not the best solution IMHO.....


carcentric - 19/10/03 at 04:47 AM

I'm not sure if it would or not, but it's something I completely forgot to even check . . . .


JoelP - 19/10/03 at 10:17 AM

as you turned the wheels, the outside wheel would turn in faster than the inside wheel, and would get worse as you approached lock!