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  1. GregLocock

    LandRover Death wobble

    "I'm not aware of decent independent suspension designs getting into positive-feedback steering situations" BMW X5 gen 1 could get into a self excited steering oscillation when going round a corner. So the path of the vehicle resembled a superposed circle and sine wave. It had another error...
  2. GregLocock

    LandRover Death wobble

    @cibachrome thanks. When new the live front axle LandRovers were safe to drive at any feasible speed, so we know it is a wear thing, perhaps excited by poor geometry
  3. GregLocock

    LandRover Death wobble

    I am told that live front axle LRs of a certain vintage may suffer from the death wobble popularised by Jeep. Rumor has it that on the Landys this is due to to worn bearings/shafts in the steering box and that reshimming may fix it. Has anyone worked on this?
  4. GregLocock

    Follow Up

    That's why they have a preload in the springs. Adding a check strap to the rear axle will increase the tendency to spin if the inside wheel lifts, as it suddenly overloads the outer wheel which can then break away. So the proper solution is to design a 2 stage coil spring with a soft initial...
  5. GregLocock

    Follow Up

    In theory it seems a good idea, sometimes in practice it is the other way round. It can be useful to force a sudden change in weight transfer across the axle in limit handling events.
  6. GregLocock

    Follow Up

    Professionals design springs for road use such that they have a minimum preload of X with the wheels at full droop, ie on a 2 post hoist. Amateurs don't, they worry about powder coating.
  7. GregLocock

    Follow Up

    Although this topic is not technically oriented Oh, I thought that the detail of what color you selected was pretty technical. Compared with the rest.
  8. GregLocock

    Tire deflection impacts on determining roll center?

    roll gain is how much the car body rolls in degrees per g of latacc. It is not directly important in a circuit car unless you have aero, but it also affects how much roll steer you get which changes your understeer. In a road car a car that rolls a lot may feel uncomfortable when cornering...
  9. GregLocock

    Global Coordinate System in Adams Car

    It is usually MA/0100, at 0,0,0, and fixed to the ground, from memory. It is probably defined in your template. Moving it might break things, you'd be better off defining a new marker and write new requests referring to that.
  10. GregLocock

    Tire deflection impacts on determining roll center?

    Yes you could do that. It should make your hand calculations more accurate. Tire deflection will directly effect your roll gain as well. That is total roll gain=suspension roll gain+direct contribution from tires. Both effects will increase roll gain in the example given.
  11. GregLocock

    Lower Ball Joint in Tension

    If this it , yes
  12. GregLocock

    Lower Ball Joint in Tension

    Up until a couple of decades ago there was no recommendation either way. Then a whole bunch of manufacturers ran into durability failures in service that hadn't shown up in testing. In at least one case it turns out the boot manufacturer had surreptitiously changed the material used for the boot...
  13. GregLocock

    Tire Vertical force FZ

    It is definitely there in Car. Which Test Rig are you using? I don't have ADAMS any more so i can't tell you directly, but if you post the .adm file i'll find it.
  14. GregLocock

    Thoughts on decoupled suspension.

    They might have used the subframe mounts to give some compliance steer, so you may have reduced the linear understeer margin. That being said I prefer to do most of the understeer heavy lifting at the front end, but sometimes you just have to grab what you can. For Bronco we had some pretty...
  15. GregLocock

    Thoughts on decoupled suspension.

    Yes, hydraulics can hiit several hundred Hz, I used to have a hydraulic shaker for doing modal analysis on big things. However Lotus went the pure hydraulic route and not surprisingly found the tiny theoretical improvements were vastly out weighed by practicalities.
  16. GregLocock

    Thoughts on decoupled suspension.

    Yes, Prosig's right. So primary is up to about 4-6 Hz, secondary is about 4 Hz up to 30 Hz.
  17. GregLocock

    Thoughts on decoupled suspension.

    Situation normal with research projects. https://www.vehicledynamicsinternational.com/john-miles-archive/remembering-sid-a-significant-active-dynamics-programme.html Richard occasionally posts on motorsports/dynamics related forums, John died a few years back. The other two are after my time...
  18. GregLocock

    Thoughts on decoupled suspension.

    Yes I was part of the rather small team that designed Lotus' SID which had any sort of suspension interlinks you want. Sadly it fell into a black hole when it was nearing completion but eventually got finished and used. First of all define whet you mean by decoupled - zero warp and fully...
  19. GregLocock

    Suspension Factors Behind Mustang S550 Crashes in Parking Lot Exit Scenarios

    And Lambos.
  20. GregLocock

    Strut tower bar preload: tension or compression?

    An entertaining experiment is to measure the distance between the strut tops, and then repeat with the front wheels free. I've seen 6mm. Mazda used to tie bits of string around the car and see which bits went slack when cornering. Cheers Greg Locock New here? Try reading these, they might...

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