I don't know if you've mentioned this elsewhere before, but I'm curious how you've gone about mounting the steering components.
Note the pictures included are a mock-up from scrap to test the theory and not indicative of my typical standard of finish! (Some people don't understand mocking-up!).
The Bex Steerlink, bit of a mix of Hoekens and Pantograf linkage priciples.
Advantages; bump steer completly eliminated, light and simple, steering ratio easily designed for quicker steering using a standard production rack, variable steering ratio (ideal slower at center and faster as more lock applied).
2,3,4 and 5 are floating pivots while pivot 1 is the fixed pivot.
Links A,B,C and D must aproximately meet the formula; A/A+B = C/D
For example A 100mm, B 50mm, C 400mm and D 600mm therefore 100/150 = 400/600 (3/4 = 3/4) - there is virtually no limit to these combinations.
Lengths of A and B will determine final steering ratio (over the rack's final ratio), for example, longer A and/or shorter B will decrease advantage (slower steering) and of course shorter A and/or longer B will make steering faster (and heavier).
Examples 1 and 2 are sample lengths and example 3 has the drag link moved away (we hit a bump!) demonstrating the theory of no lateral movement of the all important pivot 5. Example 1 dimensions are the actual pictures below.
Examples show all joints at 90 degrees but there is no problem at quite large angles, I have tested AB link up to aprox 45 degrees (to the drag link) and pivot 5 still travels perpendicular to the drag link in bump/extension. This is certainly an advantage for mounting.
Links C and D must be generally parallel to each other although not required to be parallel to the drag link and all 3 should be aprox. on the same plane.
Fixed pivot 1 may (or may) not require a single plane pivot to stop lateral fall ('T' bush or twin hiem joints etc).
Pivot 5 will only travel in a strait and perpendicular line for so long before eventually link arcs determine direction change, this is totally dependent on link lengths and I have no formula yet to determine that but pivot 5 stays straight for a suprisingly long time and there should be no need for stupid link lengths to achieve your goals.
Example 5 is alternate design but is weaker if you want steer ratio increases.
There is no example 4 as nudity was involved.
Oh, and for what it's worth, the mock-up works very well, as you can see it's almost directly steering the the drag link and if you are happy with the amount of travel your rack offers then you can almost apply all of the rack's travel to drag link (although it can never be 1:1). This setup gives me 2 turns lock to lock using a steering rack that otherwise would be 3 turns.
No reason why you couldn't use a steering box as the medium also and it doesn't matter if it's mounted vertical or horizontal, you can see mine tilts back about 60 degrees.
Anyway, maybe none of you need it but I see many discussions about steering systems for beams so I thought I would throw this in - and remember, Bex is better!
Bex Steerlink 1.jpg [ 50.91 KiB | Viewed 437 times ]
Bex Steerlink 2.jpg [ 60.17 KiB | Viewed 437 times ]
Bex Steerlink 3.jpg [ 83.81 KiB | Viewed 437 times ]
Bex Steerlink 5.jpg [ 54.12 KiB | Viewed 437 times ]
Bex steerlink test.jpg [ 86.65 KiB | Viewed 437 times ]
Bex steerlink under.jpg [ 45.37 KiB | Viewed 437 times ]