Midget Rack
I have just spent a bit of time correcting bump steer on my Tiger. When I purchased the car it had the Midget rack and MGB steering arms fitted. After having driven it on the open road for about 1600 miles constant movement of the steering wheel, quite violent when encountering bumps, forced me to look closely at what was happening. I set up a rough jig (broomhandle strapped to the wheel) and jacked the car up until the wheel almost left the ground, and then measured the movement at the end of the broom stick. It had almost 50 mm toe in per wheel which worked out to be in excess of 4 degrees on rebound, and probably an equal amount of toe out on bump. Moving the rack would have been a last resort, so I played around with the arms to see what could be acheived. In the end I turned the arms upside down and swapped them from side to side. I made up 2 tapered sleeves with 7/16" bores, which take 7/16 HT bolts, to fit inside the end of the arms, and made up new adaptor ends with F/M 5/8" RH threads and 7/16 LH threads and fitted spherical 7/16 male l/h rod ends. By shimming these down .200" below the steering arm, I virtually eliminated all the bump steer. If I played with the shims a bit more it would be possible to eliminate it completely, but at the moment i have about 3 mm change at the end of a 900 mm broom handle over full rebound, so thats close enough for me. I think the ackerman angle could also be improved by shimming out the back of the steering arms a little. From what I remember from my apprenticeship days, lines drawn rearward through the centreline of the steering arms should intersect around the centreline of the diff.The car is now totally different and much less darty to drive, particulary under hard acceleration, and the best thing of all it cost very little to fix.