Author Topic: My TII...  (Read 193 times)

0 Members and 1 Guest are viewing this topic.

Online toplessFC3Sman

  • Sr. Member
  • ****
  • Posts: 296
  • Karma: 6
Re: My TII...
« Reply #30 on: April 06, 2011, 10:24:22 PM »
Replacing the DTSS bushings just stops the bushing deflection's component in the DTSS's action.  Racing Beat's explanation isn't untrue, they just don't tell the whole story, and how that bushing contributes to the rear suspension's motion (at least when the car is stock).

The DTSS was designed to provide some toe-out at lower lateral accelerations (up to .5ish G's), and then provide toe-in for more stable (aka more understeering) cornering on the limit.  It did this by having the bushing reacting roughly linearly to the side force, and since it is  positioned ahead of the mounts that the floating hub pivots around, as it reacts to a side force (assuming its the outside wheel in a corner), the bushing deflection provides some toe-in.  The suspension geometry of a semi-trailing arm naturally provides some toe-out as the suspension deflects, which is not linear with side force & is determined by the effective spring rate, the amount the car rolls (and thus anti-roll bars, cg height & suspension's roll center => ride height) at that wheel. 

The interaction of these two effects, DTSS bushing making toe-in and suspension geometry making toe-out, combine to form the initial toe-out followed by terminal toe-in reaction of the DTSS system.  If you replace the bushing with one that doesn't deform, you'll never get the toe-in, instead getting a car that increases its toe-out and oversteer-iness the harder you corner as the rear suspension deflects (even if the static toe on an alignment machine is set to 0).  To combat this, you need to set the static toe slightly inwards.  To mitigate the amount that the toe changes when cornering, you need to keep the wheel from deflecting as much, so anything that you'd do to combat body roll (roll bars, stiffer springs etc) will help.  Generally lowering the car will increase the roll since you move the suspension's roll center further away from the CG, although I haven't gotten around to analyzing the FC's rear suspension far enough to really say the effect for certain.

Offline awfc3s

  • Rotary God!!
  • ******
  • Posts: I am a geek!!
  • Karma: 3
  • Gender: Male
  • ~Keep It Sideways~
Re: My TII...
« Reply #31 on: April 06, 2011, 10:34:12 PM »
I don't know the whole story behind the DTSS elims yet without driving the car. Im pretty sure with the elims, my Tein 10 kg/mm coilovers + roll cage are going to seriously help for what I need the car to do. The car is so stiff right now even with my solid mounted diff the rear is going to slide very easily.
'88 SE LS1 (Dead)
'87 LS1 drift car
'90 vert

Offline awfc3s

  • Rotary God!!
  • ******
  • Posts: I am a geek!!
  • Karma: 3
  • Gender: Male
  • ~Keep It Sideways~
Re: My TII...
« Reply #32 on: April 06, 2011, 10:40:07 PM »
I do understand what you are saying though by the DTSS eliminating the toe-out i need to run static toe-in to counteract the lateral forces of the car. If I were trying to keep the rear end from coming out then yes I would do this but I am not trying to achieve that (well not right now). The car is pretty uch set up for drift right now but with a few adjustments (alignment) I can turn the car into a track car very easily.
'88 SE LS1 (Dead)
'87 LS1 drift car
'90 vert