CorteX JRi Double Adjustable Front & Rear Damper Adjustment Settings

Discussion in 'CorteX Racing' started by twistedneck, Dec 12, 2014.

  1. Grant 302

    Grant 302 OPM Spent: $205,706 Moderator

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    Re: Help me understand my new DA coilover adjustments (JRi - CorteX)

    Instructions are here now:
    http://cortexracing.com/tech-tips/instructions/

    DA Struts:
    http://cortexracing.com//wp-content/uploads/Installation-instructions/jri-da-struts.pdf

    DA Shocks:
    http://cortexracing.com//wp-content/uploads/Installation-instructions/jri-da-shocks.pdf
     
  2. 2013dibgt

    2013dibgt TMO Advanced

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    Re: Help me understand my new DA coilover adjustments (JRi - CorteX)

    Thank you very much Sir!

    I tried the hyperlinks earlier in the thread and they were dead at the time.

    So it looks like the adjustment is different for the DA struts then it is for the SA struts because for the SA diagram listed earlier in this thread they say that full stiff is all the way UP on the clicker knob. The DA seems to say the opposite.

    In any case I appreciate you posting this info and I will take your advise and purchase the tool.
     
  3. VoodooBoss

    VoodooBoss Rick Moderator

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    Re: Help me understand my new DA coilover adjustments (JRi - CorteX)

    Grant thanks for the new links. My reading is the low speed adjuster on the DA strut and adjuster on the SA strut operate the same way.

    I was told the SA had 40 clicks so I need to update my spreadsheet for matching front and rear adjustments. What I mean by that is to loosen from full stiff a 10% reduction would be 3 clicks on the front and 6 clicks on the rear. If anyone wants my spreadsheet send me a PM.

    BTW I changed the thread subject to better reflect the DA damper info.
     
  4. 2013dibgt

    2013dibgt TMO Advanced

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    Re: Help me understand my new DA coilover adjustments (JRi - CorteX)

    Actually hold the phone.... The directions talk about adjusting the "Hex" nut for compression on the DA struts. I was under the impression that the round wheel with the holes in it directly below the clicker was the thing I should be turning. Am I mistaken on this?

    Also, is it normal for the round thng with holes (assuming that's the right thing I should be turning) to have a fair bit of resistence when turning it?

    Lastly, do the "+" & "-" symbols seen on the Rebound adjuster also apply to the Compression adjuster? By this I mean, If I turn the Compression knob in the same direction seen on the Rebound knob is that what I'm getting?

    Sorry for the elementary questions on this but I wasn't expecting these adjustments to be so vague.

    Thanks again
     
  5. twistedneck

    twistedneck TMO Race

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    Re: Help me understand my new DA coilover adjustments (JRi - CorteX)

    The adjustments were noticeable for me. I was at middle on the big knob (low speed compression and rebound damping).. I backed that off about 7 clicks to the minus - and the big bumps were much more tolerable. I left the high speed rebound damping alone (flats below the main knob) because I didn't mind it packing up a little during a series of bumps.

    The rear SA is what I have and its so simple.. I backed off 15 clicks to the minus so I could loosen the compression / rebound low speed. I don't have the high speed rebound on my rear JRi cortex coilovers.
     
  6. Grant 302

    Grant 302 OPM Spent: $205,706 Moderator

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    Re: Help me understand my new DA coilover adjustments (JRi - CorteX)

    The high speed adjuster is the part with the holes in it. It must have been updated since the PDF was created. The +/- are consistent with both, but I think you are always best going back to the 0 reference points (full soft for High Speed and full stiff for Low Speed)

    I also suggest writing ALL your adjustments down. I didn't make much useable progress understanding *how* to adjust until I did...and make notes about what settings were better or worse.

    That resistance in the HS adjuster is why I suggest getting the JRi tool. The allen wrench (that I lost) was terrible at staying in the hole and feeling like I was going to break something.

    I suggest wrapping the tool with tape on the knurled section if you don't want it to mar the paint around the strut tower hole. I also put mine on a separate key chain so it's harder to lose if I drop it.
     
  7. 2013dibgt

    2013dibgt TMO Advanced

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    Re: Help me understand my new DA coilover adjustments (JRi - CorteX)


    Thanks again for the info.

    I believe I got it sorted out now. Ended up starting at 5 on the top high speed knob and maybe a 2 on the lower knob. Took it for a long ride today and it felt suprisingly smooth considering the crapy roads around here. Once I started to push the car a bit harder I think a 7 top and 4 bottom combo may work a bit better and maybe even a touch more then that. I've got quite a few roads around here that have many abrupt elevtaion chages which cause the suspension to go thru its full range of motion in both directions. During that time when using the 5 Top and 2 Bottom configuration it was easy to tell a bit more stiffness was needed to help prevent kissing the bump stop on the strut shaft in both directions.

    All and all my first impressions of the dampers are very postive so far though.
     
  8. Grant 302

    Grant 302 OPM Spent: $205,706 Moderator

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    Re: Help me understand my new DA coilover adjustments (JRi - CorteX)

    Glad to help...this was probably the steepest learning curve stuff I've ever done with *any* car. The top (clicker) is Low Speed.

    If I'm reading your settings correctly, you were running -25/+2 and -23/+4?

    If I'm understanding your settings, I think you definitely could go stiffer. I also suggest trying closer to the baseline setting -15/+5.
     
  9. 2013dibgt

    2013dibgt TMO Advanced

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    Heh...I guess that explains why the thing felt so smooth. Coupe DeVille GT ;D

    Yup looks like its sitting at -25/+2 right now using the correct terminology. I cranked the Top Knob all the way down then cranked it backwards 25 clicks. Using a little fuzzy math I came up with a setting of 5 :p Looks like I'll need to make some corrections and take another ride.

    I was perfectly happy with the simple Rebound and Compression terminology used on the "Cheap" dampers, now these fancy high dollar ones need to go changing things. I'm just a dumb systems engineer, why make it harder then it needs to be ;D
     
  10. VoodooBoss

    VoodooBoss Rick Moderator

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    LOL Filip first told me about the SA struts at the 50th celebration in Vegas last year and I waited until February of this year until they were available. I've dealt with multi adjustable dampers on dirt bikes but with four wheels it adds complexity I didn't need for 6-8 track days a year.
     
  11. 2013dibgt

    2013dibgt TMO Advanced

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    Hello,

    I wanted to resurrect this thread back from the dead to talk a bit more about the settings on the JRi D/A Front dampers I am using. I've recently found the need to go in and start twisting knobs again after I installed some new rubber all around on the car. Prior to the new tires I started to notice some undesirable behavior with the cars handling that seemed mostly damper related but I'm sure the worn tires weren't helping matters either.

    Anyway, For the better part of a year I was running with the following settings on the Front JRi Dampers:

    High Speed Adjuster = +7 Flats
    Low Speed Adjuster = -20 Clicks

    With those settings the car was pretty decent overall but def on the stiff side. Then recently, for whatever reason, those settings started to result in loosing contact patch with the road surface over sharp, highway speed type expansion joints..etc. The best way to describe what the car was doing when encountering those types of bumps would be a slight skipping that resulted in the car bouncing up on initial impact then slightly shifting to the left of right upon the wheels returning to the ground. This was with the steering wheel pointed straight resulting in a need to make slight corrections with the wheel to counter the skip that occurred.

    My latest settings of the Front Dampers are now as follows:

    High Speed Adjuster = +5 Flats
    Low Speed Adjuster = -22 Clicks

    With these settings the car feels much better over most bumps encountered and in general the car feels much less "nervous/high strung" at highway speeds. It also feels more predictably tossable on back roads without sliding around as much. Previously it would feel as if the car was trying too hard to fight any sort of chassis rotation or movement that naturally occurs when driving on tight, twisty roads.

    With that said though, there is still one condition I am trying to correct with the new settings but am not sure which way to go to correct it while at the same time trying to maintain as much of the new, more preferred feel.

    The condition I am speaking of is what I can best describe as a compacting, bunching up or slight washing out of the damper when the car encounters a series of sharp, consecutive bumps at any speed found under normal or more aggressive driving conditions. The slight washing out more occurs during a turn that happens to also have those types of bumps described when the weight of the vehicle is headed towards or resting on one corner. At that corner of the vehicle is where I encounter the situation described. Its not corner specific and occurs on both sides of the car.

    This is all happening when the shock in the compression phase of the bump. To add to that description, I would say that I don't believe the shock is anywhere near its limits of travel under those conditions but yet it does seem to behave as if it were touching the internal bump stops. Again, not likely and I say this because I have witnessed just how much travel these dampers have in both directions while setting up the Bump Steer a while back.

    So I am on the fence as to which way to go to correct for this condition.

    1. Reduce Compression
    2. Increase Compression
    3. Something else I'm not thinking of

    Part of me thinks that going with Option 1 would allow the damper to move with less resistance under those previously described bumps which in turn may allow for more movement to soak up/absorb the sharper impacts. This of course assumes that its not a travel/Bump Stop impacting issue to begin with

    The other part of me thinks that Option 2 may allow for the damper to better resist any potential bottoming out even though it certainly doesn't seem as if the shock is anywhere near the top of its range for that to be taking place.

    I'm leaning towards Option 1 as a possible cure which would mean a reduction in the number of "Clicks" (starting with 1 less) found on the Low Speed knob since this is the only one that adjusts Compression according to the post quoted above by Cortex.

    What are your thoughts on all this and would you approach it a different way? Am I missing something? Obviously I can just go out and start turning knobs and find out eventually but I am hoping to arm myself with a bit more "Method" before I tackle the madness.

    Thanks for any thoughts you can provide
     
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  12. Grant 302

    Grant 302 OPM Spent: $205,706 Moderator

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    I'd suggest increasing your low speed. Fewer negative clicks. Try again using either/both baseline or the quoted softer setting above. Make small changes from there. Make notes after every change.

    Or...

    Leave the high speed on +5 and start using more low speed. add one click at a time. -21, -20 etc. and go all the way up to -10 and record your notes along the way.

    Hope that helps!
     
  13. 2013dibgt

    2013dibgt TMO Advanced

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    Hello,

    Thanks for your reply Grant302. Much appreciated.

    Once the weather starts to take on some form of decency I will give these suggestions a try and report back.
     
  14. ArizonaBOSS

    ArizonaBOSS Because racecar. Moderator

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    If the shock is "packing down" over multiple consecutive bumps like you noted, it is being compressed "too easily" and also not allowing the spring to extend the tire back to the ground fast enough.

    If that is the case, increasing your level of compression damping (preventing the shock from compressing as much over the bumps) combined with decreasing your rebound damping (letting the spring extend the wheel back to the road surface faster) should help.
     
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  15. Grant 302

    Grant 302 OPM Spent: $205,706 Moderator

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    Great explanation Drew. That's exactly what I'd expect to happen with +7/-20 settings.

    Having the high speed rebound that high moves up the 'knee' of the rebound curve too much. In that condition, most of the total damping comes from the rebound side...hence the packing down over bumps. Could work on really smooth surfaces like at Chuckwalla, but not most other tracks and roads I've driven.
     
  16. 2013dibgt

    2013dibgt TMO Advanced

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    Thanks for your reply.

    The one rub I have with these JRi's is that they have combined both Compression & some form of secondary Rebound adjustment together within the same Low Speed Adjuster according to the post by Cortex. When I increase Compression I assume I will also be increasing Rebound in some way which is not what I want.

    There is already a dedicated Rebound adjustment via the High Speed setting so I'm a bit baffled why this adjustment has been included again within the Low Speed adjustment. Its presence seems to be a contamination of my Compression settings :D

    So in the case we are discussing here, Compression needs to be increased and Rebound decreased but since some form of Rebound has been piggybacked/combined with the Compression setting I am going to see an increase in Rebound whether I want it or not as I attempt to add Compression. :eek:
     
  17. ArizonaBOSS

    ArizonaBOSS Because racecar. Moderator

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    Time to upgrade to 4-ways lol
     
  18. Grant 302

    Grant 302 OPM Spent: $205,706 Moderator

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    Might help if you look at them more as a Single Adjustable, with the ability to adjust your High Speed Rebound for comfort/grip. Use the Low Speed Adjustment to control body roll.

    Or it might help to think of your 'total' rebound damping where if you increase the low speed, you have to reduce the high speed a bit to compensate, when you are trying to target a compression side increase.

    I certainly understand that there's a pretty steep learning curve with this arrangement. But I've seen people really screw things up when you give them more things to adjust. Might help to call Filip. I talked to him a bit before I pulled the trigger on these to help understand the adjustments and how they affect the damping curves.
     
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  19. 2013dibgt

    2013dibgt TMO Advanced

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    OK,

    Well I've made some adjustments based on the helpful input recieved here and things are looking very good now.

    I ended up with a slightly less than +6 & a -21 setup now and the car finally feels the way I had hoped it would all along. All previous gripes seemed to have gone away and Im very pleased with the results.

    Its amazing how you can be off by 1 Click and a small sweep away from misery or greatness with shock tuning. As I look back at all my previously logged settings I can see that this particular combo was never tried to date so indeed keeping logs here is very important.

    I like the explanation on thinking of the damper more as a 1 1/2 way unit with the main clicker knob taking care of almost all of the damping needs and then only using the sweeper as more of a secondary/fine tuning option. I dont think I would have considered that nor the idea of needing to reduce the sweeper knob by a touch when increasing the clicker adjustment to offset the Rebound by a hair.

    I do wonder though if anyone else noticed that the definition of a sweep on the lower bolt seems to be much less then what I would have thought would be considered a sweep? In other words, it seems my previous definition of a sweep would be much more then expected. If I used my thought of a sweep I would only get 8 before reaching the max setting in either direction. Once I realized this my sweeps became much smaller in order to achieve the advertised +13 or +14 that its supposed to provide.

    Anyway, great advise here guys, thanks very much
     
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