Page 2 of 2 FirstFirst 12
Results 21 to 25 of 25

Thread: droop load

  1. #21
    Join Date
    May 2007
    Posts
    259

    Default

    Why we are on this topic...When you increase the droop the bars become steeper and obviously moves the rearend forward ...which also increase roll steer and makes our car way to loose... if we limit the droop (limit the roll steer) the car seems a better ... I’d love to be able to increase the droop... here is my question... should I try to maintain the same bar angles and the wheel base or just focus on the wheel base and keep the bars in the same holes ( with much more angle) with the extra droop?

    Hope I explained that ok

  2. #22
    Join Date
    May 2007
    Location
    Kansas
    Posts
    1,935

    Default

    pa_dirt

    Your correct increasing the drop with no other changes will add rollsteer and can just loosen the car. If this happens is dependent on where you was on the steer curve vs Lift, meaning if you are already at the point the LR moves forward about as much as it lifts then lengthening the chain will likely add enough steer (loosen) overcomes the extra wedge/anti squat (tightens car) and just end up with a looser car.

    You have 2 main choices to keep the lift and reduce the dynamic steer:

    1. You move the LR back or the RR forward Statically to end up with less dynamic overall steer. This can be either adjusting bar lengths (alters dynamic path of LR also though and alters the thrust angles and likely index amount) or you can move the 4 link plate on the frame and keep the bars the same (newer cars with movable plates)

    2. You can adjust the bar angles so you have less steer. Say you lengthen chain 1/2", maybe you need to lower both bars 1 hole to end up with the same dynamic steer. Obviously this effects the static bar angles and thus thrust and could make the car lazy if the car sets all the way down or on starts when the LR isn't rolled up already from cornering.

    Like I said everything is a compromise. Moving the plates on the frame to adjust steer has the least side effects but not every car has these.

  3. #23
    Join Date
    May 2007
    Posts
    259

    Default

    I think I understand what you are saying ...So basically if it were you you’d move the plates back and leave the bars in the same holes first .... which would keep the bars the same angle at ride height and make them even steeper at race height... and then recheck the lr trail? What would be your next step? Or are you saying that the bar angle at race height isn’t nearly as important as what they are at ride height and in motion?

  4. #24
    Join Date
    May 2007
    Location
    Kansas
    Posts
    1,935

    Default

    I'm going to leave out thrust angles and indexing, thrust will effect the car as it effects how easy the bars can lift the car (thrust angle) and index effects the spring rate the LR sees and well as spring loads (static or extended loads) so it does effect the car but for simplicity I'm going to leave these out.

    So what we are basically left with is LIFT and ROLLSTEER.

    Using your car as an example, when you lengthened the chain you add say a 1/2" of lift. Lets say this tightens the car up a 4 (on a 10 scale). However at the same time this allowed the LR to pull forward more, lets say it's a 1/2" more forward thus loosening the car at the same time. We will say this loosened the car a 6 on that 10 scale, so you have a net loosening effect of 2 (6 looser - 4 tighter = net gain of 2 looser).

    Making up numbers here: So with the shorter chain length you have a lift of say 5" and LR pulls forward 3". When you lengthen the chain this goes to 5.5" of lift and 3.5" of steer. If you move the LR 4 link plate back 1/2" on the frame the static wheel base moves back 1/2" but with the longer chain the total dynamic steer is the same as the shorter chain and the plate in STD position.

    STD shorter chain = 5" lift and 3.0" steer
    Longer chain = 5.5" lift and 3.5" steer (.5 more dynamic steer but same static steer)
    Longer chain with LR plate back 1/2 also = 5.5" lift and 3.0 steer (actually 3.5" of steer from suspension movement but since the LR was moved back 1/2" the LR tire is in the same location as the shorter chain dynamically)

    Ultimately your looking at the ending amount of steer you're getting (actual location of the LR at full hike) because where it starts (static steer) isn't where the car is raced. However you have to keep in mind that when the car is down/flat like on a start the LR is back a 1/2" and can effect the car on starts or when the LR settles a lot on entry.

    Hope that is a little clearer, but like I said everything has an effect and the index and thrust can come into play and you have to think about that stuff. Many times it won't overly effect the car at full dynamic hike but can at times when the car isn't at full hike (starts and times on entry if the car settles)

    Yes the bars end up with more angle in them at full hike moving the plates and increasing the chain, but your mostly worried about the lift and steer aspects of it. You also need to keep in mind that over indexing of the cage from lengthening the chain can also cause the LR to become more rigid if you get too close to over centering. Many things are going on at the same time, but trying to list and explain all of this at one time can get confusing so I skipped those to just concentrate on the lift and steer aspect.

    Side note: Lengthening the chain will change your extended length on the shock, so it will change your extended load on the LR spring and you will likely want to compensate for this.

  5. #25
    Join Date
    May 2007
    Posts
    259

    Default

    Thanks for the information billet

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

All times are GMT -5. The time now is 03:19 PM.


Powered by vBulletin® Version 4.2.0
Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.