IS F (2008-2014) Discussion topics related to the IS F model

BC Coilovers..best spring rates for comfort?

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Old 01-14-17, 04:54 PM
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Jz39
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Are you all having to do camber arms, toe bolts, etc at these drops?
Old 01-14-17, 10:28 PM
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bnizzle87
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I have not tinkered with any of the arms or additional suspension components, and mine feels quite smooth and planted. Gaining feedback from my passengers and their positive impressions of how the car behaves on both smooth and jagged roads here in LA is more of the norm now. I am at 16k/12k with upgraded Swift springs with both front and rear settings to hardest/stiffest. It is also note mentioning that I am not dumped by any means, as my shop and I determined a subtle 2/3 in. drop all around would suffice and allow the car to have my wheels and tires fitted without issue.
Old 07-30-18, 12:13 PM
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LexusfanVA
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Originally Posted by LexusfanVA
Here is my 08 on BC racing with swift 14/10. I have it set at 20/25 from full stiff and it rides pretty well! Harsh bumps are no where near as bad, but it is a bit soft in that it's a little floaty. Just fine for me as it's a 3k a month daily. Can always tighten up for any sporty driving days, takes all of 1 minute for both sides. I am pretty content, as the 08 suspension was really making me reevaluate my purchase. Owned plenty of sports cars before that were nowhere near as harsh.
Just a update. I have put about 40k on these coilovers since January 2017, with zero quality issues. No clunking or leaks, though in the winter I did have an odd squeak from somewhere under the car over big bumps. But that lasted 2 weeks :/ . The only problems I've had is if I go too soft and too low, there seems to be more travel and thus more chance of bottoming out or rubbing, my aggressive wheels/tires have not helped much in that aspect though I did go to a less aggressive 18" setup since last year. Overall the ride is smooth and very livable at 10 to 20 from full stiff, though does get floatier and looser at softer than 15 rates. For sporty days such as autox or mountain cruises I usually change it to 3-5 from full stiff, but a nice in between is 10-15 for me. I've even had 3 people in the car at 7 from full stiff and drove 1k miles last week even offering to soften it if needed but had zero complaints.

Now then, nearly two years is the longest I've owned the car and between loving it and about to be married, my preferred choice is to simply upgrade/update the car and keep it another 1-2 years. I am looking to upgrade to either 16/12 or 16/10 new BC racing+swift coils, or better yet the HKS Hipermax around the $2k range, or perhaps the greddy/kw for $1300-1400 range. RR Racing and Fortune auto are also in the running, though people seem to have less experience with them. Greddy/kw seem soft at 15/10, but a nice price for a better name/quality. HKS seem like it's where it's at for the price range, but I've gone nearly two years on BC, and can't say I've been unhappy, just maybe went too soft with the 14/10 rates..Yes, the handling lost some of it's track focused setup, but I've only autoxed and dragged once and taken many many more 5+hour trips. So kind of lost on if the better coils are worth the price if I've been "happy" thus far. Have considered just swapping front springs and have been told that coils should last me another 50k easy..but who wants that risk? end of rant. Any thoughts on what I should do?

Pic for attention of current setup:
Old 07-31-18, 06:47 AM
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I went with BC 16/10 set up and have no complaints, The summer time ride is great, maybe it just me but it seems to take a little bit longer in the winter for them to warm up, you can feel the stiffness in the cold weather. Yes I daily drive this in all year round in Canadian weather and I love it!
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Old 08-06-18, 03:35 AM
  #95  
samsonn25
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BR 21 series.

Daily driver, 42k on them so far, only the front right strut mount bushing has worn out.

12k/10k bc springs, front struts set 4-6 off hardest, rear set 6 off hardest because we have alot of potholes here in Philly, but when hitting big road bumps at speed it hits Hard!
Old 06-23-19, 12:50 AM
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OneFastF
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Originally Posted by FIGS
Guys the springs are your gross travel limit and our suggestions are based on how you will use the car.
14/10 is a setup for stock power, wheels, tires looking for the ability to adjust for more spirited driving and better balance but not the added energy of modifications, lowering beyond that 1" front and .6" rear and with comfort in mind. The 16/12 is just a step up of 120lbs/in on each corner of travel limit. That means for people looking for a lower ride, or aggressive fitment, or added power/braking, they will resist this added energy. The damping is the "how fast will the suspension travel" portion of the equation and where most of the perceived comfort comes in. We derived these rates from street and track testing on different tires and ride heights. Currently with the advancements to our car we are running 18k/14k on the Penske shocks that utilize a more sophisticated vavle design (dual flow) that can handle the complex energy exchange in the fluid. The 18k/14k rates will be too narrow a dynamic range with the BC damper design as it will push you into the more restrictive rebound settings which will cause the ride to go unbounded (bouncy).

The 16/12 setup is intended to add more dynamic range to the damping adjustment for spirited drivers and get more settings our of the shock that are usable. The balance has been chosen due to the braking power and the F's tendency to shift a lot of weight fwd. The rear-link design bumpsteers and with our suspension we actually like to have the rear settle the remainder of the front's shockwave by both steering into the corner appropriately and damping in a difference mode that the front. For this reason we also always have you tune the front damping first, then let the rear come in after to get the remaining settling done.

Its a pretty simple equation for a very simple shock design in the BC. To get more complicated, you need a more sophisticated means of tuning the damping. This is one reason we worked on the Ohlins setup as a stepping stone to the full Penske setup. It has a more sophisticated valve design that will handle higher rates batter if chosen. So far I think most people would feel pretty uncomfortable pulling the G's we are doing now with relative ease, but its a different level of product.

So look at your preferences, look at your long term goals for the car and give us a call, test or email and we will do our best to set you up for how you would prefer a car to handle.
Thanks
Mike

Very old thread. but how would this coilover setup (18k/14k) withstand with the newer DS shocks by BC racing? Would any major bouncing occur?
Old 06-24-19, 04:48 AM
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samsonn25
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I find that the BC struts last about 70-75k (But deterioration starts at 25-30k)

and the strut mounts (if rubber) last about 20-30k (Front) and 40-50k (Rear) depending on road conditions.

Last edited by samsonn25; 06-24-19 at 04:52 AM.
Old 06-24-19, 07:32 AM
  #98  
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Originally Posted by OneFastF
Very old thread. but how would this coilover setup (18k/14k) withstand with the newer DS shocks by BC racing? Would any major bouncing occur?
Bouncing is really a function of damping adjustment. The spring rate will deliver appropriate travel for the load you put into it. Usually bouncing is more severe on under sprung cars that are over damped because the shocks have been cranked to full rebound stiffness, in most cases in an effort to prevent shock bottoming from being under sprung.

Unless you are on full r-compound tires I think that 18/14 spring rate would be unnecessary unless you were excessively low. The DS is going to have a stiffer damping curve in the low-speed range, meaning it will sway less on the initial steer in. Bouncing tends to fall into the high-speed range and the DS will be roughly the same in that range. So it all depends on how you intend to use the car ultimately and your ride height.

Mike
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Old 06-24-19, 07:39 AM
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Originally Posted by samsonn25
I find that the BC struts last about 70-75k (But deterioration starts at 25-30k)

and the strut mounts (if rubber) last about 20-30k (Front) and 40-50k (Rear) depending on road conditions.
If used in the settings you outline above you will stress the shocks more and the bushings as well. It sounds like they are under sprung for your preferences or ride height.
Assuming be the application that you have these on a GS450?
Mike
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Old 06-24-19, 08:01 AM
  #100  
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Originally Posted by samsonn25
I find that the BC struts last about 70-75k (But deterioration starts at 25-30k)

and the strut mounts (if rubber) last about 20-30k (Front) and 40-50k (Rear) depending on road conditions.
So I ran a set of 14/10 Swift’s BC Racing on my 08 for about 21 months and 50k or so. A lot of highway driving and also a lot of bad roads especially in Baltimore/DC. By about 45k my front driver’s side started making noises and shop said at 50k that one front was done and the other front had to take the brunt of it and was on its way out. I sold them for $400 to someone who had them fixed. Overall they were decent but I wanted to go lower than an inch so I ultimately constantly had rubbing issues.

Currently I run HKS hipermax 4 with their 16/10 rates. Absorb bumps better and handle nicely in the corners but still a bit too soft if you want to go lower than an inch. Keep in mind my wheel specs are also more aggressive than stock and fairly flush. I only rub every so often really, just on the worst dips or bumps.
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Old 06-24-19, 03:22 PM
  #101  
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Originally Posted by FIGS
Bouncing is really a function of damping adjustment. The spring rate will deliver appropriate travel for the load you put into it. Usually bouncing is more severe on under sprung cars that are over damped because the shocks have been cranked to full rebound stiffness, in most cases in an effort to prevent shock bottoming from being under sprung.

Unless you are on full r-compound tires I think that 18/14 spring rate would be unnecessary unless you were excessively low. The DS is going to have a stiffer damping curve in the low-speed range, meaning it will sway less on the initial steer in. Bouncing tends to fall into the high-speed range and the DS will be roughly the same in that range. So it all depends on how you intend to use the car ultimately and your ride height.

Mike
The car will be fitting fairly low with about half a finger gap all around. There will R comps on the car, I do not mind a stiff car but I do mine the bounciness. As long as I can achieve a stable ride. I'll be happy.
Old 06-24-19, 04:04 PM
  #102  
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Originally Posted by OneFastF
Very old thread. but how would this coilover setup (18k/14k) withstand with the newer DS shocks by BC racing? Would any major bouncing occur?
BC coilovers to me never satisfied my needs. I had 18k/16k and it just never felt stable or made me confident in the corners. After switching over to Penske 18k/16k I’m blown away and will never get anything less. BC coilovers to me just never felt right and never inspired great handling. Over bumps and dips it bounced bad and I had the adjust like 5 clicks below max. Maxing it out made no difference either and lowering the adjustment made it worse. I’m also on fire hawk Indy 500 tires and it feels absolutely amazing with the Penske coilovers. People forget how heavy this car is. We’re not talking about a 3000 pound car here with a heavy driver your looking at almost 4000 pounds for a sedan.
Old 07-02-19, 02:16 PM
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samsonn25
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Originally Posted by FIGS
If used in the settings you outline above you will stress the shocks more and the bushings as well. It sounds like they are under sprung for your preferences or ride height.
Assuming be the application that you have these on a GS450?
Mike
They dont have a kit soecifically for the 450h but they have the gs350 kit. The difference is there is no passenger fromt battery on the 450h, they moved it to the rear left and also the traction battery in the trunk.

12/10k here, daily driver on some of the worst roads in the country, Philadelphia PA. HUGE potholes, dps,waves and road imperfections

Been driving it 2 years and put 85k,on the kit I find the top rubber strut mounts only last half as long as the struts.
Old 07-05-19, 09:25 PM
  #104  
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For an R-comp setup, you would want to be in the higher spring rate range to handle the load. I would also suggest the DS series as it will add more initial anti-roll while still maintaining the higher speed damping in am more relaxed range. For a bigger step, the ER series is a great performer, this is what we have been testing the last 8 months or so. It will allow more fine tuning on the low/high speed compression.
Mike
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Old 07-16-19, 06:17 PM
  #105  
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Originally Posted by FIGS
For an R-comp setup, you would want to be in the higher spring rate range to handle the load. I would also suggest the DS series as it will add more initial anti-roll while still maintaining the higher speed damping in am more relaxed range. For a bigger step, the ER series is a great performer, this is what we have been testing the last 8 months or so. It will allow more fine tuning on the low/high speed compression.
Mike

Hey Figs I know you are very knowledgeable, I just installed 18k/14k spring rate coilovers and R compound tires for the track and I am FBO. I have a track day next Monday but do not know where I should start my dampning settings?


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