Sways: PT v. RB v. FM

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Sways: PT v. RB v. FM

Postby ManishS409 » Sun Apr 20, 2014 5:35 am

I want to install sways on my car and I am considering these 3 choices mostly because all 3 of these are adjustable and have good reviews from people that have tried them.

I currently have Koni + Progress springs. I initially wanted to go with Progress because everyone raves about their quality but they seem like too much bar for the street for me. Especially if I decide to upgrade to ohlins one day, they will definitely be too much bar. That and all the rough roads/potholes.

Next I was leaning towards RB sways because they are like Progress but less stiff. After reading about them, they seem to have a "rear bias". On their website it seems that the front is something like 2.67x stiffer than stock and rear is something like 6.2x stiffer than stock. I know they are adjustable but with even the softest setting in the back, I feel like it'll still be tail happy. I want understeer at one end of the settings and oversteer at the other end of the settings.

Finally I am now looking at FM sways. Again very similar in adjustability with Progess and RB but even a little less stiff. I read somewhere that they are 25% less stiff than RB because of thinner tubular wall thickness but same diameter as RB. Here is a quote from their website:

"These sizes are typically not harsh enough to cause damage to the stock swaybar mounting points. Some other bars on the market are 2.5 times stiffer than ours, which is far too stiff in our opinion."

Now I am throughly confused. Can someone tell me if:

1. RB has more rear bias than the other two. Assume all are set to full soft rear and middle in the front.

2. Which one would you go with knowing what I am looking for? Let me know if I have missed an option with sways…I want them front/rear adjustable.

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Re: Sways: PT v. RB v. FM

Postby Brian » Sun Apr 20, 2014 6:21 am

Check around miata.net and likely you will notice the Progress Springs/Koni shocks/RB sways is one of the most popular combinations...and yet I can't ever recall complaint about oversteer on that setup. Thus, I don't think there is a basis to be concerned about too much oversteer on that combo.
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Re: Sways: PT v. RB v. FM

Postby RyanJ074 » Sun Apr 20, 2014 4:37 pm

FWIW I found the RB bars to pair really well with Progress Springs and the NC2 Bilsteins with the settings discussed. I would not described them as more prone to oversteer...but rather more neutral than the factory understeer...which depending on one's range of experience may seem like oversteer :?:

Just bought my second set of RB sways for a new car...just saying :wink:
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Re: Sways: PT v. RB v. FM

Postby morrisg » Sun Apr 20, 2014 10:39 pm

I have used RB front and rear bars with a set of Ohlins 7k/4k coil overs. Front bar set to middle, the rear bar on either setting was not tail happy on an autox course, which is probably driven harder than you will ever drive on the street. The Racing Beat bars are well engineered and quality pieces. I have not used the PT or FM bars, so no opinion on them.
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Re: Sways: PT v. RB v. FM

Postby Curves » Sun Apr 20, 2014 11:10 pm

morrisg, what ride height / amount of rake and tire sizes are you using with the RB Sway and Ohlin 7k/4K setup?
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Re: Sways: PT v. RB v. FM

Postby Va MX5 » Mon Apr 21, 2014 4:41 am


I have the Ohlins 7/4 setup, with PT sways (both ends set on soft), 6 track days on it so far (4 days dry/2days rain). On the street, very pleasant with dampeners 10 clicks out, on track (F3/R4 clicks out), very neutral / balanced handling in the corners. When the car is at the limits, both ends very manageable by steering or throttle inputs, I have only found a few times on certain tracks where the car is too softly sprung for what I was asking it to do. So my vote is for the PT sways, they will be great when you upgrade to the Ohlins.

Regards, Pat
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Re: Sways: PT v. RB v. FM

Postby Altair » Wed Apr 23, 2014 8:23 am

As we're comparing the 3 main brands of sways, I would be very interested in knowing the relative stiffness of the stock RX-8 sways, compared to those 3. I assume that they must be quite close.
Does anyone know ?
Thanks in advance.
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Re: Sways: PT v. RB v. FM

Postby ManishS409 » Thu Apr 24, 2014 12:41 pm

The PT are the stiffest, followed by RB, and the FM is the softest of the bunch. I believe FM might be the closest to the RX-8 sways. PT is apparently quite a bit stiffer than RX-8 sways.

Here is a link to someone who is trying to collect this data. Some of this data may be incorrect. You can see how much stiffer PT is than the rest:

http://forum.miata.net/vb/showpost.php? ... ostcount=7
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Re: Sways: PT v. RB v. FM

Postby morrisg » Sat Apr 26, 2014 9:32 pm

Sorry for the late reply, have been a bit busy with things lately. I have the car about as low as it can go, in the 12.5" range, front and rear no rake. Running BFG Rivals in 245/40x17 on 17x9 RPF1s with a full fender lip roll I did myself. The car is a well balanced autox machine, and quite competitive nationally when a faster younger driver is at the wheel. :D
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