Steering racks

[Cropper]

Just a quick question, has anyone used anything apart from the Mk2 escort steering rack?

[Enoch]

In theory you could use any rack but it needs to have the right distance between the knuckles - ie the swivel where the track arms joint to the rack. If you were to draw a straight line from the pivot point of your top wishbone to the pivot point of your bottom wishbone the pivot points of your rack need to lie along that line. As the distance between the top wishbone pivots is wider than the bottom ones the distance obviously changes with the mounting height of the rack. If the three pivot points are aligned correctly bump steer is eliminated. The other thing is to try to keep the lower wishbone arm and the track rods at a similar angle - this also helps eliminate bump steer. In Chris's book he shows a diagram of this and gives in ideal rack length of 533mm - this is the length from the centre of 1 pivot point to the centre of the pivot point on the other side.
Other considerations are the number of turns from lock to lock, the mounting methodology and the size of the spline on the input shaft.
Hope that helps,
Dave.

[loony]

I will use RHD Fiat Punto Mk2 steering rack - but mounted upside down and in my LHD project should work OK. The length is suitable for roadster, and is quite "quick" - 2,7 turns lock-to-lock (originally used with electric power steering at column)
Important for me - it's cheap (even in Poland, where it's hard to find RHD steering rack).

[Cropper]

That sounds interesting, do you have the joint to joint measurement mentioned by Enoch?

[twinturbo]

the big consideration is the mounting location, if the donor rack sits behind the centre line of the hubs then it must stay behinf ( unless flipped for a LHD<>RHD ) swappage as mentioned.

likewise if the donor is in front then it needs to stay in front.


I am not sure if the IVA actualy specifies the direction of turn for a given steering input, and as such you may get a car passed with back to front steering on a technicality.. but driving it could turn you brain to mush.


TT

[loony]

Originally Posted by Cropper

That sounds interesting, do you have the joint to joint measurement mentioned by Enoch?

As I mentioned in my thread - it is about 530-540mm (hard to measure because of rubber boot)

If I am right - it should fit to chassis - I even draw some mounting plates in SolidWorks, but it's still only drawing.

First of all - I need to go back to my build...