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Thread: The Suspension Setup Thread

  1. #51
    Senior Member sr_rolla's Avatar
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    (quote old thread slydar)

    rebuild your coil overs with a spacer under the insert.

  2. #52
    Senior Member sr_rolla's Avatar
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    Pretty much what slydar said, you need to rebuild the front coilovers with a spacer under the strut insert to in effect raise the insert in the strut and allow more droop. As previously mentioned, i'd aim for about 2-3 inches of droop from static hieght to allow for this countries fine roads (not). For the rear, u need longer shocks, plain and simple. measure what you need and head to a parts place (not supercheap) and find a monroe or gabriel parts book, look thru it till you find something with the apropriate length (comodore, celica, seirra shocks are a good start)

    I can put up a few basic pics to explain all this for people if the demand is there, i'll have to draw it up though.

    GILLY: what you said about aiming for the middle of the stroke is not a bad idea, if you have shocks with a very short stroke.
    The koni dampers I'm going to be ordering soon have a stroke of 153mm front and 143mm rear, so in this case your theory would be pretty good.
    However they make dampers that due to there design have anywhere up to 300mm of stroke, now in that case (depending on application) i would be running whatever droop is apropriate and leaving the rest as compression.

    HATZO: agreed on the drive car comment but i have no idea what you are talking about with the whole rest of your post, roll steer is bad, plain and simple, as the car rolls into a turn roll steer causes the car to get toe changes (in effect) that cause the car to under/oversteer. The only way that this may be used is if a chassis is over powered for a particular circuit or to solve another problem. For example, say an light sedan (corolla, escort etc) has like, 400kw's, because of the shitty aero traits that this vehicle has it will be a handfull at high speeds, you may want to dial in a little roll understeer to make the car more stable at speed. I can't think of any other reason to have rear roll steer on purpose in a racing sense. Genrally, the problems that roll steer fixes are caused by something completly different that can't be changed (due to class rules for example, ie aero inefficiences).

    Unless you are talking about something to do with adjustable rear rollcenters?

  3. #53
    Senior Member sr_rolla's Avatar
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    (simon ae86)

    SR_Rolla: whats your views/opinion on shortening the LCA, and redrilling the mounting point for the LCA on the crossmember further out? Hypothetically if u redrilled the hole further out by 40mm, then shortened the LCA by the corrosponding amount what kind of effects, both negitive and positive would it have.

    not looking for a flame war or "why the fuk would u do that" but just curious.

  4. #54
    Senior Member sr_rolla's Avatar
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    In theory, it could work, if i was to be trying this mod though i would be concerned about bump steer problems to do with shortening the LCA. I'd move the inner mount outboard, get a spare set of LCA's with new bushes and ball joints that are stock length and then get some shortened ones, also with new bushes and balljoints. Then i would get hold of some adjustable strut tops and a spirit level. 1st i'd get a wheel alignment, then do a few runs of either a road that you know really well or a race track, with stock LCA's at the standard inner mounting point. Bring a mate and take some notes about corner speed, rpm, how the car feels etc. After that do your mods to the inner mounting point but put the stock LCA's in, then get it wheel aligned to all the previous neg/caster/toe settings and go for another run, take notes etc, then put the shortened LCA's in, wheel alignment to previous settings/test again.

    This is really the only way to properly see if it has a reasonable effect or not. My guess is it wont have a real positive effect but thats just my personal opinion. Go nuts and try it if u feel it may work.

  5. #55
    Senior Member sr_rolla's Avatar
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    In theory, it could work, if i was to be trying this mod though i would be concerned about bump steer problems to do with shortening the LCA. I'd move the inner mount outboard, get a spare set of LCA's with new bushes and ball joints that are stock length and then get some shortened ones, also with new bushes and balljoints. Then i would get hold of some adjustable strut tops and a spirit level. 1st i'd get a wheel alignment, then do a few runs of either a road that you know really well or a race track, with stock LCA's at the standard inner mounting point. Bring a mate and take some notes about corner speed, rpm, how the car feels etc. After that do your mods to the inner mounting point but put the stock LCA's in, then get it wheel aligned to all the previous neg/caster/toe settings and go for another run, take notes etc, then put the shortened LCA's in, wheel alignment to previous settings/test again.

    This is really the only way to properly see if it has a reasonable effect or not. My guess is it wont have a real positive effect but thats just my personal opinion. Go nuts and try it if u feel it may work.

  6. #56
    Senior Member sr_rolla's Avatar
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    (quote old thread simon ae86)

    Thanks for that, ok no more hypoteticals here, I'm running the S13/14 crossmember in my KE, and have stock KE LCA's on there, obviously the LCA mounts on the LCA is much much further out compared to stock (and i have the camber to show for it) Now i am trying to make it all work and work well.. just to get the car going i rigged up the stock KE susp, stock struts and springs and all... whilist it works, its a little on the bump steery and vauge side.

    So I'm in the process of running the nissan stuff in terms of brakes, hub, strut etc, makes sence since the rack and crossmember is all nissan, so should work reasonably well...

    my biggest prob is, i can't run the standard length S13 LCA, since it is miles too long and combined with the LCA mounts on the Xmember which are further out already in relation to the K Xmember, the track os going to be huge.

    So.. was thinking of still running all the Nissan stuff, with S13 control arms, but shortened, I feel that bump steer should be eliminated compared to the K series susp due to the steering arm linkage point being matched to the rack location.

    Cheers!

  7. #57
    Senior Member sr_rolla's Avatar
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    bump steer may be eliminated but unfortunately everthing else ends up stuffed. basically, the only way to run nissan stuff properly is to A) run stupid wide track and + offset wheels, or shorten the LCA's like u said and move the strut tops in a similar amount.

    Sorry to break it to u but it just doesnt work well, the ackerman angles are stuffed, the front 2 rear track is stuffed, and even if u do alter the rear track to suit the front the car ends up over-square and it wont handle anyway.

    Theres a reason beau yates and co. don't tend 2 do this mod, and if it was an awesome mod they would use it in N2.

    Sorry dude if that destroys your ideas but thats what i have found from what ive researched

    What may fix your problems is to used ae86/ke70 style struts and LCA's and redrill the crossmember 2 bring it back 2 stock position, then adjust the bump steer out of it. It is posible and way easier than making the nissan stuff work

  8. #58
    Senior Member sr_rolla's Avatar
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    (quote old thread simon ae86)

    yeah but redrilling the LCA's further IN (back to where stock KE/AE mounts would be) is an ideal solution, however then you regain the bumpsteer due to the rack end (tie rod) and LCA pivot points being totally different.

    I used to run s13 susp in my drift ae86 back when i was drifting with beau before anyone knew who he was.. and while it was slapped together, it worked reasonably well., however i was using a AE86 crossmember with cut and shut s13 LCA's and overly stiff coilovers.

    this time round, i'm looking at doing things a little differently.... I'm with you tho, on paper it seems it may not work, but i'll give it a go and see what happens, if worse comes to worse i'll redo it all

  9. #59
    Senior Member sr_rolla's Avatar
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    (quote old thread ke70dave)

    this is interesting to read....

    i have S13 front end in my car (s13 stocko LCA's),8kg springs, and am running 15x6.5 + 23? wheels, with 195/50/R15 tyres and with completely untouched ke70 guards, -2 degrees camber (set with camber tops), and castor set to zero. The tyres foul on the guards but only when you hit really really big bumps (so essentially clear guards, just need to give them a bit of a roll). and car is around 130-140mm off ground at chassis rails.

    anyway....

    i do not experience any bump steer at all with this setup (my definition of bump steer as explained in the following)

    the way i have tested this is as so, i drive down the bumpiest road i can find (not hard in backstreets of wynnum), and get the car going straight, and let the wheel go between my hands, so let it do what it wants. i do not find that the steering wheel moves at all in relation to when the wheels meet the bumps.

    i have looked at my LCA and steering arm, and they appear to be very close to parallel at the static position as shown in the pic i just took (not the best, but its too cold to stay for too long out there..)

    Click image for larger version. 

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    now unfortunately i have not had a chance to experience "bump steer" in the sense of lowering my car with stocko stuff withouth adding RCA's....as i went straight from stocko height to this setup.

    i also have not had the opportunity to drive "proper" ae86 coilover/lowered spring with RCA setup to compare with, so i guess I'm kinda in the dark a bit when it comes to that...

    so basically I'm wondering if any of you goo-roo's of suspension can either point me in the direction on how to find this apparnetly bump steer that is present with s13 gear, or address me in any of my possible wrong thinking?



    ps: one thing i would like to try, is to take the springs out of my coilovers and put it all back, jack up the car, and move the front suspension through its complete suspension travel, and see if i can see any of this bump steer...but taking springs off is to much hard work...

  10. #60
    Senior Member sr_rolla's Avatar
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    I am so glad you put that picture up in here biggrin.gif

    Basically, bump steer, is not steering caused by bumps, that is a scrub radius problem (refer to 1st post).

    Bump steer (refer to 1st post) is when the toe angles change under suspension compression/extension. This is commonly caused by different lengths of the tierod end to rack end vs ball joint to inner bush, or the LCA and tie rod being in different points of there arc of movement

    Now on to said pic, and I'm gonna be brutally honest here.

    Firstly, the tie rod end is all cocked over at a bad angle, that has the posibility of pulling out the ball of the tierod.

    secondly, the steering can, under the right circumstances, invert, as in the tie rod could pass across the LCA and end up in front of it.

    Third, the arms arent parallel, well, the arms are but there pivot points arent. u need 2 draw a line between the rack end and the tierod end and thru the center of the ball joint (where it pivots) and the center of the LCA inner bush. If you do that you see that the arms arent level at all.

    fourth, u need 2 measure the length from the rack end to the tie rod end and the measurement from the balljoint pivot point and inner bush pivot, if these are way different then you will get bump steer.

    My basic point is that while i think this setup could be made to work, it is much easier to make the standard design work. All u really need to do for a basic setup that will do what 90% of people here want, drift or grip drivers included, is get some nice bushes, some corona front arms, some RCA's and a rosejointed castor arm arangement. The major issue in the front of ae/ke's is that the castor rod bush is a shitty design and moves around alot, giving a vague feeling, if you rosejoint it or change the design to something similar to a silvia castor arangement then it will handle very predictably and wont have any issues with geometry.

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