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rear axle motion ratio

Discussion in 'Gen 2 Prius Accessories & Modifications' started by Solar Element, Dec 8, 2013.

  1. Solar Element

    Solar Element Junior Member

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    Hi Agent, nice to hear you went for BC coilover too !! Did you ask for 6/5 Kg instead of default 5/4 Kg ? Did you receive 6/5 Kg as a replacement or first supply ? I'm going to open my Excel spreadsheet and calculate your front and rear NF with 6/5 Kg springs... very, very aggressive !!!
     
  2. Solar Element

    Solar Element Junior Member

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    I'm back with NF. With last update of my Excel spreadsheet the unsprung masses are not assumed as 9% of total car mass, but have been replaced with real values. I've been weighting front and rear unsprung masses directly ON the car. I'm not 100% sure about my values but that's what I obtained at each corner: 42,2 Kg front and 30,1 Kg rear.

    With this input values we have:

    with mine 5/4 Kg Front/Rear spring rates:

    NF Front: 1,75 Hz (versus OEM 1,20 Hz)
    NF Rear: 1,56 Hz (versus OEM 1,28 Hz)

    and with yours 6/5 Kg Front/Rear spring rates:

    NF Front: 1,92 Hz (versus OEM 1,20 Hz)
    NF Rear: 1,74 Hz (versus OEM 1,28 Hz)

    How can you stand this spring rates ??! You are ready to race !!
     
  3. Agent J

    Agent J Hypoliterian

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    yup! came in as first supply already when i requested it as a custom order from one of the distributors here.

    great effort on coming up with the unsprung weights and the estimates are very reasonable. did u take into account half the weight of the connecting arms from the chassis?

    thanks for calculating my NFs! its good to have this comparison and il continue to give feedback on this setup. coming from a slightly aggressive H&R setup, my tuner said 6/5 can still be liveable which confirmed my thinking. i still cringe whenever i run over some unfamiliar potholes and bumps though. but in my daily route, i already know how to approach them. some are avoidable, some are not. just have to live with that. but i know the car can take it. my H&R and stock struts have survived 35,000 miles and still looks strong even if i have no need to replace it. : )

    i have a 2 minor issues to resolve first. first is to get shorter sway bar links because the steering arm started to rub on the sway bar at close to full lock. the 2nd is the -2.0 camber. the previous vales were -1.20 which i think is just right for even tire wear at 42 psi. i dont want to sacrifice uneven tire wear for better cornering speed on a daily driver. no need for extreme angles here. i also didnt notice any decrease in glides. in fact it might have increased it because of the slight decrease in conatct patch on a straight line at -2.0 camber.
     
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  4. Solar Element

    Solar Element Junior Member

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    Hello Agent, nice to have someone to talk with about these BC coilovers !! First please let me know what measures your coil springs are. Mine 5/4 Kg default first supply are: 62.220.005 (cilindrical shape) front and 62.190.004 rear (barrel shape). What specifics are yours 6/5 Kg ??
     
  5. Agent J

    Agent J Hypoliterian

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    Mine are 62.220.006 and 62.180.005. The fronts are cylindrical and the rear barrel. So the rears look progressive a bit.

    _MG_9834_DxO copy.jpg _MG_9840_DxO copy.jpg
     
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  6. Solar Element

    Solar Element Junior Member

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    Hello Agent, thanks for your photos. Nice to have someone to talk with... you have a different spring setup and this is even more exciting !! I've got an issue with rear shocks, left and right there is no difference: a knocking, mechanical noise is heard on little-medium road irregularities. When you drive on flat roads no noise is heard, but as the rear suspension moves knocking noise comes up. (Front shocks are right and no mechanical noise comes from there, tought road noise is more present than OEM struts). Something as if there was something unlocked, but I'm sure every bolt and nut is installed at reccomended torque values. I have personally installed the coilovers. Do you experience some knocking noise like me ? What torque did you lock lower rear struts nut ?
     
  7. Daves09prius

    Daves09prius Active Member

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  8. Agent J

    Agent J Hypoliterian

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    Dave, I've also considered Megan when i was canvassing, but settled for the BC as it looks to have more of a following over here than Megan.

    Solar Element, I know what you're talking about. I started hearing the faint knocking on both rears about a month ago. I think it's just the rubber sleeves on the upper coil thinning out. I'm going to have it checked by my installer hopefully within the week and have them adjust the rear dampers 2-5 clicks stiffer. If it is, then i'm sure it can easily be remedied. Currently, i just turn the radio a tad higher to drown out the noise. lol!
     
  9. Daves09prius

    Daves09prius Active Member

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    Do you guys know if there is a way to cut a small 'flap' in the interior panels to allow access to the rear struts? It would be so nice not spending 1/2 a day disassembling the trunk aka "boot" interior to access the rear struts.
     
  10. Agent J

    Agent J Hypoliterian

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    Cutting a hole through the panels is easy. However, the metal panels are still in the way unless you completely take them out. Besides, the strut adjustment knobs are still a fair way inside. You'd still need really long damper adjustment extension cables.
     
  11. Daves09prius

    Daves09prius Active Member

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    It really sucks that there's no easy way to get to the rear struts...
     
  12. Agent J

    Agent J Hypoliterian

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    Oh, i forgot to mention, the right rear has the battery cooling duct getting in the way. I had a go at it again today, taking out the interior panels. Adjustments can be done on the left without taking the metal plate out if you have long slender hands (i have small hands). I had to look for the right position using my right hand to get a grip on the knob in order for it to turn. The right rear is easier and quite exposed for adjustment if you take out battery cooling duct which is very easy.

    With regards to the knocking sound, all bolts are tight including the top hat nut. My mechanic thinks it might be the swing arm rubber bushing where he saw a slight tear (both left and right) and feeling a bit of play in it. That's one possible area to check, Solar Element.

    If that's the cause then I can probably live with it for a while till it gets really worse and annoying. It will be a big job for sure to replace the big bushing with polyurethane ones. Can't complain much because it still does its job quite well.
     
    #32 Agent J, Jul 4, 2014
    Last edited: Jul 4, 2014
  13. Erickunkel09

    Erickunkel09 Junior Member

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    Awesome post with lots of impressive information! Im trying to figure out the motion ratio of the front and rear suspension on my prius and was hoping you might still have those measurements?