BC Racing BR Coilovers Impressions

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Mazda 2
I know this thread is dead, but figured I'll leave some input for future information.

Installed BC Racing BR coilovers this past weekend. I ordered the custom coilovers with 12 kg/mm front and rear springs rates with Swift Springs.
There was some mix up and BR sent me the coilovers with their own springs. The Swift springs are on the way.
The build quality seems good. I really like that shock adjustment is easy on both the front and rear.
Rear shock:

Front top mount for camber adjustment:

Note for front camber adjustment: Since the shock tower hole is small on the 2, not much adjustment can be made. After you install coilover, turn your steering wheel left and right to make sure the nut below the adjustment knob is not hitting the sheet metal. The hole can be made bigger to get access to the allen bolts, but I'm not sure if that's allowed per SCCA street touring rules.

With the BR racing springs, the ride is unbearable for daily driving (coming from stock). 12 kg/mm front and rear has me jumping all around in my car. I still need to play around with the shocks, but doubt it'll make much of a difference.
Taking corners are a joy though. Car stays nice and flat.
I am hoping the Swift springs will improve the ride a little. If not, I may have to look into lowering the spring rates in the rear.
Autocross is in two weeks so I'll update after the event. I'll also update if I can tell a difference between the BR and Swift springs.
 
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flatlander937

Drives a clown car
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'11 Mazda2 Sport
Shocks make a massive difference. With super high rates on anything but 200TW Extreme Performance Summer tires(RE71R, Rivals, Dunlop ZII Star Specs, Kumho V720, etc), it will feel bouncy no matter what.

When the shocks are adjusted too soft, the springs will be under damped and of course bounce.

When they're adjusted too hard, the shocks will effectively act as close to solid with up/downtravel changes in shock direction... so all the give will happen in the tire sidewall. The tire is a spring as well, and full-retard coilover springs will rival the rate of the tires, and anything but tires with ridiculously stiff sidewalls(200TW or less or R-compound tires) will bounce no matter what.


When I was commuting on 700/450lb springs and all season tires I couldn't get it to ride well no matter what. I put my auto-x tires on and it improved a lot over undulations and whatnot... small jolts will be more apparent but the whole car won't oscillate up and down repeatedly in smaller cycles... I felt this primarily in my neck tensing up.


You have pretty close to my 700/700 setup... in no way would I ever recommend that. Get some softer rear springs... 7 or 8k and it'll be more tolerable. Not great. But tolerable.


I never drove on the BC coilover setup that Jeff ran, but he said my Koni race insert setup with KYB AGX Focus rear shocks was very similar but with better compression damping up front. I can't quantify how much better, but messaged him a link to this thread so he can hopefully give you some insight.


Disconnect the front sway bar, remove the end links and ziptip the bar out of the way. With super stiff springs, the sway bars really beat you up over bumps when you hit one with only one wheel.
 
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2013 Mazda2 Sport
Please don't take this with anything but face value. It's not meant to demean you, just provide answers.

The BC springs are not your problem. It's the rate you've chosen. 12k BC springs were tested 150,000 oscillations at 2" compressions and spring rate deviated by less than 2% over published rate. You'll never see that kind of abuse on a street car, nor will you ever be able to discern a 2-3% difference in linear spring weight. Swift springs will not ride better, they "may" fatigue less over time but their real advantage is they are lighter and reduce unsprung weight.

As Tony said, run a lighter spring in the rear and run your shock adjustment up 3-4 clicks more stiff in the front. You'll get a much improved ride.

Anything more than a 350lb rear Spring in this car is going to ride rough. As you approach 700#, you have more spring in the rear of the car than the rear beam can handle. This causes all sorts of oscillation and twisting in the rear beam. To fix this, You can get 2.25" or 2.5" springs (60mm or 62mm will also work) 350# 7" long linear springs fit the rear. You don't need the BC adjusters. Just zip tie them into the stock upper mounts. They'll sit the car at the perfect rear height and just swap in your 700# at the track. You can also try one if the 3 rear bars available to stiffen the beam however, these actually make the car much worse on course as the rear never really feels planted in slaloms.


Sent from my iPhone using Tapatalk
 
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Mazda 2
Tony and Jeff,

Thanks for the info. I'll consider the tires and play around with the shocks more.
I did put in softer springs in the rear as you guys recommended and it improved the ride quality quite a bit.

From my old civic, I had 5" long 425 lb and 6" long 375 lb Eibach springs laying around. Luckily, they are the same ID as the BC springs, which are 2.5".
I ended up using the 5" long 425 lb because they are the same length as the BC springs and I can use the BC spring perches without messing around with the adjustment. I forgot to measure the car height before and after the swap, but it doesn't look that much lower. I'll drive on these for a bit and test out the 375 lb later.
The swift springs came in, but I didn't have time to test them out yet.


Spring info from left to right: Swift 6"L 12kg/mm; Eibach 6"L 375lb; Swift 5"L 12kg/mm; Eibach 5"L 425lb


Spring info from left to right: Eibach 6"L 375lb; Eibach 5"L 425lb; BC Racing 5"L 12kg/mm

Since Jeff mentioned weight, I weighed the springs so I could feel better about my Swift springs purchase (wiggle)
BC racing 5"L 12kg/mm - 1168g
Swift 5"L 12kg/mm - 787g

Thanks guys
 
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Mazda 2
Went autocross this weekend at the Sonoma Raceway parking lot. It was a half wet half dry day with a lot of runs so it was a very good day to get used to the coilovers. I love that the 2 can keep up with faster cars like the S2000 in the wet.
I had the 650lb front and 425lb rear springs on the whole day and worked really well. I tried putting in the 650lb rear springs, but forgot these don't compress as much and I couldn't get the bottom shock bolt back on so I went back to the 425lb springs. It's really a joy to chuck the car around now. It's also great to finally not have to worry about tipping the car over, no matter how unlikely it is. More fine tuning and playing around with the springs in the future.
Now to invest in some racing seat. The stock one really sucks...
 
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2013 Mazda2 Sport
If you want to take it one step further than either I or Tony went, I have a set of BC front inserts valved for 800# springs( 700# to 900# range sweep). I was going to test them with a soft rear spring setup for daily driving and then 700-900# springs for the rear on course to see just how flat I could keep the car in slaloms. When I say flat, I mean front roll rate and gas matted to the floor. I, like you, was looking to see if I could get the 2 to do the things my old Civic hatch could do. I would be able to get into a corner, set the nose and power out with little or no wheelspin. The 2 was close, but always seemed like it would pull the inside front wheel. Was playing around on the setup sim that Tony had, and we were going to try a HUGE front spring with no front bar to see if we could make it work. Sadly, I compressed a nerve in my left hip and had to abandon the high rate daily driving setup and ultimately the car. If you'd like to try it, let me know. I'm willing to sacrifice the inserts for half of what they retail for. I'll even toss in the shipping. Look me up on FB or email me jyatsko5@hotmail.com as I really don't lurk here much anymore Tony tags me on something.
 
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Mazda 2
Some updates since my last post.
I got an alignment and corner balance last month. Front: -2.5 deg camber and 0 toe Rear: -1.4 deg camber and 5/16 toe in (can't adjust).
Also went to three autocross events. The car handles great and is a lot of fun for such low powered car.
With the RE-71rs, I run around 37 PSI front and 39 PSI rear pressures. Front shock is 10 clicks from hard and rear is full hard. With the torsion bar, the car rotates nicely and I can get the rear to come out if I try.
Overall, I think I'm about 1.2 seconds faster with the coilovers versus stock suspension on a 60 second course. I'm still about 85 out of 120 in PAX times so my driving needs much improvement.
For Autocross, I'm very happy with the BC racing with the 12mm/kg springs. I hope to go out to track days soon.
 

flatlander937

Drives a clown car
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'11 Mazda2 Sport
Glad you're enjoying it!

FWIW me and Jeff both ended up running 33 psi in the front, I favored 35-36psi in the rear usually, and I think Jeff liked a bit less(33-34) in the rear with the same tires. I would occasionally run up to 38psi but only on our higher grip concrete site where I could get away with that.

This is assuming 205/50R15 RE71Rs on a 15x7.5in wheel... if you're on a 7in wide wheel then that might be part of the reason you're running higher pressures to keep from rolling over.


The single best thing you can do it improve(aside from seat time itself!) is to get a faster codriver to drive your car, and ride with you, and you with them to learn how to push the car to it's limits as much as possible, and doing so smoothly. Last season I started doing this as much as possible and was able to get #5 in season overall PAX for our region, and while it's not a big region, there are a few guys who are nationally competitive. My car was also not anywhere near built to the limit of the rules... it was basically suspension, tune, intake, and muffler. And with a freaking 30lb battery. Haha.
 
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Mazda 2
Yup, you're right. I'm running 195/50R15 on a 15x7. I started off at around 33 psi and was rolling over a lot, especially when I didn't have any camber.
I did entertain the idea of a co-driver to improve my driving. We have many good drivers out here so I'll probably do it when I get more serious.
But my tires are pretty much done now so I'm trying to decide if I should get back to fixing my Datsun 280Z or get new autocross tires and tune for the 2. Decisions decisions