TRD Sportivo Suspension Kit

Discussion in 'Gen 2 Prius Accessories & Modifications' started by ZPrius, Oct 19, 2005.

  1. ZPrius

    ZPrius New Member

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    I am considering installing a TRD Sportivo Suspension Kit for the following reasons;

    1. On numerous Rally Cars that I have driven the most common initial mod was to upgrade the Shocks/Struts and Springs. The Shock/Strut of choice was a Koni adjustable. This overall improved the Contact Patch of the Tires and reduced loss of contact.

    2. The Springs where of a progressive nature and also where able to maintain a better contact patch to the road surface.

    From what I have read the Sportivo Kit lowers the car but I have not found out any information as to spring rates and shock/strut rates.

    After installing this or other suspension upgrade I am planning on installing the Stiffening plate. Since, at this time, I am not planning on doing any TSD Rallies with my Prius I will wait to add the stiffening plate and then address the strut towers and steering linkages.

    Thanks for your help,
    Bob W
     
  2. ZPrius

    ZPrius New Member

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    I just spoke with Koni and they do not make an adjustable shock for the Prius.

    They have a Shock for the Echo but are unsure what the Rear setup is like.

    Does anyone have any Dyno Data on the Prius's suspension system.

    Also they recommend upgrading the Sway bars. Has anyone upgrade their front sway bar?

    Thanks,
    Bob W
     
  3. NuShrike

    NuShrike Active Member

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    Which Rear setup? The Echo's or the Prius'?

    If anybody gets the Sportivo installed, please give us some feedback on it.

    The last guy that picked up the lowering Modellista springs seems to have never put them on, nor given any feedback on them.
     
  4. efusco

    efusco Moderator Emeritus
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    Z,
    I strongly encourage you to get the frame stiffener now. You needn't be doing rallies to appreciate the improved drive/handling. Esp. if you expect to get it later anyway.
     
  5. FredWB

    FredWB New Member

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    Bob, I'm looking into getting a stiffer rear anti-sway bar. For front wheel drive cars that's the one that will give us the most bang for the buck according to some suspension experts I've talked with. I have a source but I have to remove mine and send it to him so he can construct a jig (that we all can benefit from). One of these days I'll get around to that and look for others here that want one for themselves to go in with me. The bar will be about 21mm or so (stock is 19.5 mm) and unpainted. That should be about 60+% stiffer.

    But we'll get a better deal if we order more than one. I can't promise anything because I don't know what the results will be other than less sway. But I'm willing to take a chance even if I only order one of them because I think that's part of the Prius handling problem.

    Oh Brian from BT Technologies is going to try those stiffer lowering springs very soon so we'll have some feedback on that I hope. He also has some ideas about the suspension geometry that may prove to be very beneficial once he proves them out on his car.
     
  6. ZPrius

    ZPrius New Member

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    I made some calles to TRD and the Tom's rep in the US as well as to ProgressAuto (a suspension company) as well as to Koni USA. The bottom line was that they all suggest either upgrading the front and rear sway bars (at the same time to keep proper suspension geometry) or using the Tom's front suspension brace and soon to be release Rear suspension brace.

    Thanks Fredwb for removing your front sway bar for a template for a HD sway bar replacement. Does anyone have a souce for a the rear sway bar and are there differances between the model years? I definately want to make this change.

    As far as changing the Springs and Struts/shocks I am not sure that I want to lower my Prius and would prefer an adjustable shock/strut and stay at stock height.

    Thanks,
    Bob W
     
  7. ZPrius

    ZPrius New Member

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    From what i gather from talking with TRD or Koni the Prius's front suspension Shock/Strut & Spring are interchangable with an Echo however the rear is specific to the Prius.

    Thanks,
    Bob W
     
  8. NuShrike

    NuShrike Active Member

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    So if Brian eventually comes out with a complete stability overhaul kit for the Prius (including the stiffening plate and the rear mini-spoiler) that would be quite dandy!

    Meantime, seems best bet is the Sportivo kit although it seems to be missing updated braces as the other kits do have. Spring/shock rates would be nice too, but I guess we're supposed to "trust" it works as advertised since they're TRD. However, isn't the rear trailing-arms torsion bar suspension in the Prius basically a HUGE brace, and so we don't really a bigger one back there? Or am I confusing brace with anti-sway?

    I asked Speedracer of his opinion of Sportivo at the last Prius meet about this, and he doesn't know much about it. He says the US Prius has seats that ride higher, and the suspension is mushier. It seems the ride and suspension in Japan is good enough that the Sportivo is unnecessary except for the more hardcore.

    I too do not need my car lowered, but if that's an attached part of getting less roll and swaying, then I'll bite the bullet and deal with the occasional road scraping. :p
     
  9. FredWB

    FredWB New Member

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    Bob, I'm going to do the rear first not the front. I've read up a bit on this in autospeed.com and the rear is going to have the most influence. Besides I'm thinking the front is a bear to remove and ship while the back is small and simple to remove. I could do the front as well. My source will do both but first needs to make a jig for bar. Depending on the complexity, he would want to keep my stock bar for reference because there might be some things you just can't put in the jig fixture. But I think the rear is pretty simple and I told him I want the stock one back. We would get a better price the more we order but I'm reluctant to involve a lot of people because I just don't know how this will work out. For that reason I'm probably going to go from the stock 19.5 mm to 22.2 mm which is the equivalent to 0.875". That's about 69% stiffer in torsion neglecting the ID, which probably has a very small effect. I'll post the company and all the particulars soon once I get around to deciding on what to do. The bars will be unfinished and it will be up to us to paint or powder coat them. This guy is in Oregon and makes anti-sway bars for lots of other cars too. I'm going to pay about $30 extra to get mine done in about 3 days rather than wait 10 days for it.
     
  10. FredWB

    FredWB New Member

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    Brian just advised me that since I didn't see much difference with the sway bar removed that I might not see much with a stiffer one either. But then why would Toyota even bother installing one. This suspension is much like a Corolla's and they upgrade the bar all the time...those crazy enough to hot rod a Corolla that is, lol.

    The Sportivo is going to be pretty costly to install and there's the language barrier and the lack of other that have tried it here in the States. TRD in the US doesn't offer a thing for the Prius right? If only Toyota would step up and offer those of us that want it, some suspension improvements like they do for other cars.
     
  11. ZPrius

    ZPrius New Member

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    As in anything we do to modify and improve our cars it always comes down to T&E Engineering (that's trial and error).

    I would definately want to try a new front and rear sway bar of equal diameter or wait till Tom's comes out with their rear suspension brace and try that with their front suspension brace.

    Thanks,
    Bob W
     
  12. rutafox

    rutafox New Member

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    The Prius does not come with sway bars..
     
  13. BT Tech

    BT Tech New Member

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    It's not that adding a larger rear anti-sway bar won't make a difference, its just the difference it migh make may not be woth all the effort. The 2004-2006 Prius incorporates a rear torsion bar that is quite rigid. Since the rear is not a IRS (Independent Rear Suspension) the addition of a slightly larger anti-sway bar in the rear in ADDITION to the torsion bar would probably not make a tremendous difference.

    I am going to install different springs this week and what I am looking for is a bit more tension for both the front and the rear along with a decrease in ride height of aprox 25mm/15mm F/R.

    This rake will help the aerodynamics of the car and lower the CG which should provide better tracking. This is of course is all speculation until I actually do it though!! :)

    One of my concerns though is that the springs I have will be a little too aggressive for the average Prius owner and if this is the case, I might have to make my own so that they have more compliance yet still provide the decreased ride height and rake that I am looking for.


    More to come....

    Brian
    BT Tech
    305-652-3115




     
  14. NuShrike

    NuShrike Active Member

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    Okay, so this confirms what I said earlier about the rear. But, because it is IRS in the front, bigger sway bars there may have more effect.

    It's gonna look like one of those funny-car drag-racers! ;) But increasing the tension should be about the same as when FredWB was sticking wedges into his rear-springs, which should improve something.

    Body rolling seems to be the rear lifting while the front dives, and if increased suspension/shocks prevent that, then it's all good. This stuff should be all well-known, researched enough, that somebody should know definitively what changes to make.

    Afterall, we have the Prius GT, and also the other guy who's modified his Prius for AutoX.
     
  15. BT Tech

    BT Tech New Member

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    A larger swaybar in the front would be a step in the right direction. I custom made a set of endlinks for the Prius but I did not like the effect it had on the ride.


    A 10mm difference in ride height is not a huge amount so it is doubtful that anyone casually looking at the car would even notice. Looks are deceiving though and that difference makes a HUGE difference in aerodynamic performance of the car.


    Thanks!!

    Brian
    BT Tech
    305-652-3115
    .

     
  16. vibeowner

    vibeowner New Member

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    I am interested in this thread for different reasons -- my wife bought a 2005 knowing that with any load it tends to drag the belly on the sidewalk getting into our short/steep driveway. Not much we can do short of trading in the house or modifying the car. Would the suspension still track right if I raise the rear a bit, and how might I do that?
     
  17. Strong Bad

    Strong Bad New Member

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    Here were the pics I posted a while back, completely one-off but it has been done. FYI, Prius suspension is not based off the Echo platform
    [Broken External Image]:http://img431.imageshack.us/img431/8659/picture115a2yq.jpg
    [Broken External Image]:http://img431.imageshack.us/img431/315/picture114a4ox.jpg
    a good idea of race trim ride hieght
    [Broken External Image]:http://img504.imageshack.us/img504/2024/priusphotoshoot1010050535ps.jpg
     
  18. DocVijay

    DocVijay Active Member

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    I'm going to start looking into some sort of aftermarket suspension. The first thing I noticed about the Prius' handling is the large amountof body roll in the curves. That is something I want to eliminate. I realize this may mean stiffer shocks and hence a stiffer ride, but if that's what it takes. Also, I'd like to see some sort of height adjustability.
     
  19. DaveLadely

    DaveLadely Junior Member

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    Any stiffer springs should be progressive, which address several issues.
    The ride with progressive springs is relatively soft, a little firmer than stock, then, when pushed, becomes firmer. So, first, the springs are much more resistant to loads reducing car height, in fact, the loaded car will likely be higher than the stock car with a load. Second, progressive springs progressively reduce body lean significantly. Third, progressive springs pretty much eliminate bottoming out by resisting more and more.
    The higher spring rate requires a shock that reacts faster than a stock shock, to prevent "bouncing". The result is all positive with the cars on which I have used such a suspension mod. A lot more control in every way, with no harshness, just a little firmer ride and a lot more resistance to "sloppiness".:)
    I haven't changed anti-sway bars because the spring/shock enhancement improves both ride (more controled) and handling (a lot less sway/roll), whereas larger anti-sway bars affects suspension geometry and may negatively affect handling as well as cause a harsher ride (which progressive springs minimize by their design).
    I wonder which Eibach springs are on that AutoX Prius? I know they are progressive as that is the brand I purchased for other cars and found them to greatly improve handling with a comfortable highway ride, not harsh at all.
     
  20. DaveLadely

    DaveLadely Junior Member

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    I noticed that the SCCA solo2 used Eibach prograssive springs and TRD shocks. I have used the Eibach springs with great results, cost about $200.00 for a set of four. Since the spring rate is faster than stock, fast acting shocks are necessary. In the past, I bought Tokico performance shocks for about $150. each and they worked great with the Eibachs. I would change anti-sway bars last, since when I changed them, they caused oversteer, which I did not want. It proved tricky, whereas the spring/shocks made a great difference while being very streetable since the springs were progressive: better control, way less sway/roll, way better resistance to bottoming even with a load in the car, just slightly more firm when not being pushed. I felt much more secure when I pushed the car. Great when I was heading through the Shasta hiway in California, with sweeping curves! I haven't done anything with my Prius yet but have no reason it would not respond similarly.

    Another possibility: In one car, which I used for car pools, I added those small, inexpensive Air Lift air bags in the coils as I was often carrying a couple passengers. I had only 24 pounds of air in each, and they really prevented the car from wallowing and made it impossible to bottom out, without any effect on the ride or ride height. When I did add more air, when I loaded the car for a trip, I did notice the height increase about an inch at most, then settle back down when I loaded the car. The car felt even more stable with the air bags. This car also had the Eibach springs and Tokico shocks. I will not use "air shocks" as the air bags in those are very small and at too high a pressure, and tended to blow out. Not nearly as good as the Air Lifts. And the Air Lifts have a lifetime guarantee.
     
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