Its official: Cusco line of handling parts is out (link to PR inside)

Discussion in 'Gen 4 Prius Accessories and Modifications' started by galownia, Mar 29, 2016.

  1. galownia

    galownia Previous master neon mechanic

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  2. E46Prius

    E46Prius Active Member

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    These chassis reinforcements look gimmicky. You already have solid boxed sections and subframe that run parallel to most, if not all, of that bracing. That front one would concern me in a front crash. Instead of aborbing crash energy as designed, it seems it may transfer that load into the front of the passenger cell. No bueno. The strut brace and sway bar would be cool though.
     
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  3. PaulG4

    PaulG4 Junior Member

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    I tried to measure the stock anti-roll bars the other day, but really it needs a micrometer rather than a tape measure. It looks as though the Cusco parts aren't that much bigger than the stock ones, but would need to measure properly to be sure.

    I'm struggling a bit with the suspension tuning for this car. Tein, HKS, TRD and Blitz are doing springs/coilovers, but I'm worried about messing up the tail-happy handling Toyota has already dialled in to the stock car.

    It almost feels like there is a bit of passive steering on the rear axle, in which case stiffening might not be the way to go. Tein is offering 4.7kg/mm springs on the back, but HKS and Blitz are only running 4kg/mm there. All offer 4kg/mm on the front.

    Is it possible that Cusco are supplying a softer front arb, in which case it might be worth getting that one too.

    Paul.
     
  4. ZVW51

    ZVW51 New Member

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    I have just installed the tower strut brace (caution: bring the right tools or have small hands to tighten the bolts to the frame) call me crazy but I notice a minimal improvement. I also have the front brace, but it will take me an entire day to remove the under plastics to install.
     
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  5. RightOnTime

    RightOnTime Senior Member

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    If anyone is interested on a 2016 Cusco Strut Tower please DM please (y)(y)
     
  6. Kenny94945

    Kenny94945 Active Member

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    In for answers.

    For post 3, tail happy, to me implies the rear slides with acceleration.
    Under braking, I could imagine the rear getting loose and wiggling...maybe that's tail happy.

    Reads to me more like a brake balance/bias ratio.

    Plus good point in post 2 about compression from crashing...track vs street desires.

    Again in for answers.
     
  7. Lucifer

    Lucifer Senior Member

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    I am, left a note on your profile page.
     
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  8. bhtooefr

    bhtooefr Senior Member

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    Oversteer in FWD cars isn't always caused by locking up the rear wheels, and I'd expect that the ABS system would actually prevent that.

    Weight shift under braking, or even just lifting off the accelerator, is enough to provoke oversteer in some cars.

    If it's being described as tail-happy, I wouldn't be surprised if lift-off oversteer is easy to provoke in the Prius. (When I test drove a Three Touring, I didn't push it hard enough to provoke any lift-off oversteer, though, but I didn't feel any reluctance to turn in, so I wouldn't be surprised if it's not hard to provoke it.)
     
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  9. galownia

    galownia Previous master neon mechanic

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    I have been racing cars for over 20 years.

    This car stays very well planted, even under breaking/ lift off. I have got it to get slightly into a powerslide, but this was an extreme condition, planned, and easily controlled. I would NOT call this car tail happy in the least. In general, OEMs make cars tend to understeer as this is much safer and easier to control than oversteer. This is definitely the case here.

    I will report back my findings with the rear sway. I suspect it will still be well balanced. I doubt much improvement from the front strut tower brace. It is a flat sheet, not boxed, so it will flex under compression rather than provide any real support. I have to say I'm very disappointed in the design from Cusco on that one.

    Jonathan
     
  10. galownia

    galownia Previous master neon mechanic

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    Even a 2mm increase in OD is roughly 25% - 30% increase in torsional stiffness. Small changes = big difference in handling. On my race cars, I had multiple bars I would run: 19mm, 21mm, 22mm, 24mm, and 25mm. I also had different attachment points I could use to increase stiffness.
     
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  11. eric1234

    eric1234 Active Member

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    From the pic, I'd agree...

    I'd love to hear if any crash tests were done with the front power brace...
     
  12. PaulG4

    PaulG4 Junior Member

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    Good to know, thanks.

    My feeling with the Prius is that there is not much front end grip (195 economy tyres, 1370kg car) but it turns in quite nicely because there is even less grip at the back.

    Not sure where the centre of gravity is, but there is a bit of bulk at the rear with the high sides and we know that the rear springs are quite a bit stiffer than the ones on the front. Stiffness at the back of course helps oversteer in a front-wheel-drive car.

    Will hopefully get some more information this weekend. I have been racing a hybrid Yaris up to a couple of months ago and that had Tein Street Flex coilovers and AD08R tyres. I'm racing against the same people in the stock Prius on the same track, so should get a feel for how fast the Prius is compared to the Yaris.

    My hybrid Yaris was similar speed as a tuned (coilovers + R888s) Yaris T Sport from 2004 or so, which is maybe not what you might at first think given the power-to-weight advantage of the T Sport.

    Will post some results next week.

    Paul.
     
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  13. RightOnTime

    RightOnTime Senior Member

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    If you are still interested, I got 4 New Cusco Strut Tower Bars for the 2016 Toyota Prius in stock! email me at: [email protected]
     
  14. PaulG4

    PaulG4 Junior Member

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    I had a fun time on the track yesterday. You can find the racing results here:

    http://www.toyotasprint.com/tss16/image/Documents/2016/tss16r2_ov.pdf

    You have to bear in mind that I am driving a factory stock Prius on 15in wheels in a competition where everybody else has at the very least modified suspension if not tyres, chassis and engine.

    I found that when the tyres were cold, front end grip was quite good and oversteer on trail-braking into corners was the way to go, but it was too easy to melt the fronts early in each lap and end up with understeer the rest of the way round. Still I think we are about as fast as the Yaris with coilovers and decent tyres. The Prius has a much better straight line but we are losing a lot in the corners.

    Was wondering whether to go with 18in wheels and road tyres or 16in and something like AD08Rs. I think really we will need to go with the stickier AD08Rs, as it isn't really possible or desirable to use a wide wheel and street tyre.

    Let you know when I get some parts fitted.

    Paul.
     
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  15. galownia

    galownia Previous master neon mechanic

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    Looks like fun!!

    Stock tires are terrible. I expect you will have dramatically different results with some sidewall stiffness and grip. I fully expect the true suspension characteristics of the car are masked by the terribly flexible and poorly sticking tires, especially on the front.

    I just put the Cusco rear bar in the car. Compared to the stocker, it is much heavier, so, while similar in diameter, it is solid while I suspect the stocker is hollow (go Toyota!). I haven't driven the car too much yet, but I do notice the front sway much more than previously, and it seems like I am less on the side bolsters on the seats during corners. Stay tuned for a deeper analysis when I can get some quality time in the corners.

    Jonathan
     
  16. PaulG4

    PaulG4 Junior Member

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    I found at the weekend that even the stock ARB causes the inside rear wheel to lift when trail braking, so very interested to hear how it feels with an uprated one. Looks like the TNGA platform may be actually quite good when it comes to suspension tuning.


    Paul.
     
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  17. galownia

    galownia Previous master neon mechanic

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    Paul,

    3 wheeling in front wheel drive cars is very common. The multiple neons I autocrossed over 20 years all did this, even the nationally tuned one to some extent. It had 800lb/ in springs and custom valved inverted aluminum dampers, no front bar and a big fat rear bar. Doesn't mean it is slow. My FSP neon was usually top 5-10 in raw times (fields of ~150), despite stock internal engine and natural aspiration. It was a handling machine. My other neons were also fast, ~top 30 usually with much less aggressive suspension (~300 lb/in, konis)

    That being said - holy front end lean. It almost looks like you are about to get on two wheels. Evening out the weight distribution would certainly help for ultimate grip. Dampers would do a lot to help you out. High compression in front or high rebound in the back if front isn't adjustable in whatever you end up with, would be a good thing.

    Jonathan
     
  18. Kenny94945

    Kenny94945 Active Member

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    Post 16 perfect picture.
    Yes I agree w/ post 17.
     
  19. PaulG4

    PaulG4 Junior Member

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    Jonathan,

    In general, yes, but this is the first Toyota I have owned that lifts a wheel in factory tune. Normally in the UK we get softer suspension that doesn't do the handling much good. It's very interesting for European Toyota owners that the TNGA platform is this stiff from the factory, usually Toyota is seen as a very conservative marque over here so handling isn't really a priority, especially on previous Priuses.

    I'm not sure much can be done about the weight distribution, as this is going to stay as my daily drive so don't plan to remove any parts. But definitely looking at spring and damper options. The only problem with adjustable dampers is that it is not easy to get access to the top of the struts either front or rear, so changing the damping settings could be tricky without taking them off each time.

    However, there are several aftermarket damper options available, Tein, Blitz and HKS for a start and we might have a BC Racing option soon. Haven't managed to get a set yet, but hopefully soon.

    That picture I posted above is on the first corner of the circuit, when the tyres are cold and fresh and have plenty of grip. Unfortunately the fronts heat up quickly and you don't get much grip for the rest of the lap. I'm wondering if the stiffer rear arb would take a little bit of pressure off the front tyres, as you would get the inside wheel off the track earlier in the corner and that might help to bring the back round.

    Paul.
     
  20. bhtooefr

    bhtooefr Senior Member

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    Now I'm wondering what suspension you're actually getting in Europe, versus what's available in the US, on the Gen 4. Someone correct me if I'm wrong, but on previous generations (Gen 2 and 3, anyway), I believe your normal suspension was our Touring (read: "sportier") suspension, typically, and what came on a "normal" Prius was even softer than what you got. (Granted, the US likes its cars softer than Europeans in general, and this tends to apply to all marques.)

    Here, we allegedly get a stiffer, more damped suspension on the Tourings than the regular models, but I wonder if it's just the European parts, or whether you're getting the same difference between stock 15" and 17" setups.
     
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