Gary Lewis Posted December 21, 2020 Author Share Posted December 21, 2020 Gary, I am with Bill and Bob on this issue, with the suspension going up and down, the axle will be pushed somewhere due to the stiff linkage you have added. Might be worth to install something similar to and shock absorber in the same place, this just to verify if it would change something. Further more I find your angle from the pitman arm to the main steering shaft steep, sure you dont need to install a pitman arm that come down much more, to reduce the angle of the steering shaft? Adjusting toe in is an option, zero is the worst, on my Bronco I decided to use some toe out, mainly for being a 4X4, and when that is selected the wheels will be pulled in to much. Why have you not installed a steering dampener, this could reduce the bump part as well? Andre - Thanks. But when the shop checked the alignment they found it was actually toed out, so they dialed in the factory .06 degrees and it steers much better now. No perfectly, but like it is a big, lumbering truck - which it is. But I think it is what it is at this point - good but not perfect. However, I don't have a steering damper, so will consider that. Thanks! Link to comment Share on other sites More sharing options...
Nothing Special Posted December 21, 2020 Share Posted December 21, 2020 Gary, I am with Bill and Bob on this issue, with the suspension going up and down, the axle will be pushed somewhere due to the stiff linkage you have added. Might be worth to install something similar to and shock absorber in the same place, this just to verify if it would change something. Further more I find your angle from the pitman arm to the main steering shaft steep, sure you dont need to install a pitman arm that come down much more, to reduce the angle of the steering shaft? Adjusting toe in is an option, zero is the worst, on my Bronco I decided to use some toe out, mainly for being a 4X4, and when that is selected the wheels will be pulled in to much. Why have you not installed a steering dampener, this could reduce the bump part as well? My first thought was that a steering dampener wouldn't affect bump steer. That's just a function of the geometry. If the axle moving up and down affects the distance between the two points where the drag link attaches you'll have bump steer, if not, you won't. But on second thought, all the geometry means is that if that distance changes, then SOMETHING has to move. If the easiest thing to move is the stuff on the axle, then you'll have bump steer. But if a steering dampener makes it hard to move the stuff on the axle, then the stuff on the other end of the drag link will move. That means the steering wheel will saw back and forth when you go over bumps. That may or may not be objectionable, but it won't make the truck veer side-to-side (at least as much). And that's actually the situation my Bronco had when I got it. A big bump would make the steering wheel swing back and forth at least 45 degrees, but at least it stayed in the lane. A dropped track bar bracket straightened things out for me, but the F-350 geometry doesn't seem as easy to tweak for that as the early Bronco steering is. Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 21, 2020 Author Share Posted December 21, 2020 My first thought was that a steering dampener wouldn't affect bump steer. That's just a function of the geometry. If the axle moving up and down affects the distance between the two points where the drag link attaches you'll have bump steer, if not, you won't. But on second thought, all the geometry means is that if that distance changes, then SOMETHING has to move. If the easiest thing to move is the stuff on the axle, then you'll have bump steer. But if a steering dampener makes it hard to move the stuff on the axle, then the stuff on the other end of the drag link will move. That means the steering wheel will saw back and forth when you go over bumps. That may or may not be objectionable, but it won't make the truck veer side-to-side (at least as much). And that's actually the situation my Bronco had when I got it. A big bump would make the steering wheel swing back and forth at least 45 degrees, but at least it stayed in the lane. A dropped track bar bracket straightened things out for me, but the F-350 geometry doesn't seem as easy to tweak for that as the early Bronco steering is. Interesting. Hadn't thought of a steering damper causing the movement to go elsewhere. But that makes sense. I guess I'll drive it this way a bit more and see what I think. Thanks. Link to comment Share on other sites More sharing options...
Les Kerf Posted March 1, 2021 Share Posted March 1, 2021 Interesting. Hadn't thought of a steering damper causing the movement to go elsewhere. But that makes sense. I guess I'll drive it this way a bit more and see what I think. Thanks. I had an 81 F-150 2wd that bump-steered; I went completely through the front end, replaced everything and had it properly lined up. Still no joy. I finally replaced the wheel bearings in the REAR END (9 inch) and that cured the problem. Not all steering issues are in the front end. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 1, 2021 Author Share Posted March 1, 2021 I had an 81 F-150 2wd that bump-steered; I went completely through the front end, replaced everything and had it properly lined up. Still no joy. I finally replaced the wheel bearings in the REAR END (9 inch) and that cured the problem. Not all steering issues are in the front end. Les - You are right! Since my last post in this thread I’ve removed two leaves from the rear spring pack and it really helped with the bump steer. Turned out someone had installed a spring pack with far more capacity than needed and there was NO flex. So on bumps the rear end was apparently stepping sideways. So now the bump steer is pretty much gone, and I forgot to say that here. Thanks! Link to comment Share on other sites More sharing options...
FuzzFace2 Posted March 1, 2021 Share Posted March 1, 2021 I had an 81 F-150 2wd that bump-steered; I went completely through the front end, replaced everything and had it properly lined up. Still no joy. I finally replaced the wheel bearings in the REAR END (9 inch) and that cured the problem. Not all steering issues are in the front end. Les, What made you change out the rear wheel bearings on that 9"? Were they making noise and / or had a lot of play in them? My 02 Durango when new you could feel the rear end "jump out" on you over bumps because the springs were new and stiff but now with 240K+ I don't feel it or I got use to it but would say it does not do it. My 81 F100 really does not have bump steer but more of a wondering issue. All the front end parts are tight and the kingpins maybe too tight as the steering wheel will not return center. When I have some time I want to run the kingpin reamer through the bushings and see if that helps. Dave ---- Link to comment Share on other sites More sharing options...
Les Kerf Posted March 2, 2021 Share Posted March 2, 2021 ... What made you change out the rear wheel bearings on that 9"? Were they making noise and / or had a lot of play in them? My 02 Durango when new you could feel the rear end "jump out" on you over bumps... We have a long bridge (cleverly named 'The Long Bridge') near Sandpoint, Idaho; this bridge has concrete joints every ten feet or so that jostle even the best of vehicles. When rebuilding the entire front end didn't help much, I got to noticing that the pickup seemed to twitch in the back end every time I hit one of those bumps. I jacked up the rear end and found a fair bit of play in the bearings ( not terrible, just not nice and tight). I never bothered measuring with a dial indicator, just went ahead and replaced both sides. The Long Bridge is still a rough ride but at least I didn't have to worry about the pickup darting off in a different direction at every bump. Link to comment Share on other sites More sharing options...
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