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Old 08-15-2019, 06:13 PM   #1
tzbang
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Coil over options for BC-Gold swap

Sorry if this has been covered before I'm sure it has.. I am looking for a bit of advice regarding my coil overs. My car came with BC-Gold Racing coil overs, adj camber plates, cusco camber arms, whiteline sway bars etc. It also has 235/45/18s and it's set quite low. (not stupid low)

This is my first car with coil overs and it's just a street car / daily driver. Doesn't see track use.

Handles pretty good but rides is HARSH on the road. Not bad on the highway but around the streets I can feel every single bump and crack in the road. Pretty horrid really but I've put up with it for years.

I know BC-Golds are not great and I thought about swapping them out. But I quickly became over-whelmed with the options and worried that I'd change to something only to find it's not difference, maybe a harsh go-kart feel is just what it's like with coil-overs.

However recently I went for a ride in someones Rx7 Batman which also had BC-Golds and his wasn't horrible like mine. Different car of course.. but it does make me wonder why they're so terrible on mine. I have the dampening set at the softest setting too but it makes no difference.

Then just yesterday I read about someone in the 86 club in my country changing his BC-Golds to KW V3's and was MIND-BLOWN at the improvement. Raving about them. Now I'm tempted to get those except maybe they're an overkill of adjustability for a streetcar.

So I'm just reaching out to see what people would advise would be the best option to change my BC-Gold. I want a comfortable street setup that can be set at least 50mm lower than stock.

Thoughts and opinions appreciated as always.
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Old 08-15-2019, 06:57 PM   #2
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Well, in my book 50mm lowering is "stupid low" for twins, with reasonable drop AFAIK being within inch. So from already relatively short bumpstop free shock travel even stock (IIRC just ~2.5" bump travel including bumpstop) you want to deduct most, when in most cases it is accompanied the lower one goes, the stiffer spring rates used to not ride on bumpstops, and still want no comfort compromised while dropping that low? Good luck on your quest.
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Old 08-15-2019, 07:07 PM   #3
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Raise it up and get some more suspension travel. This is the first car I have owned out of 10 or so that I wasn't in a hurry to lower because there isn't a whole lot to work with.
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Old 08-15-2019, 07:20 PM   #4
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You can also go throwing money at it route, if so set on "at least 50mm" (sounds like want even more then that) comfortable way. Add to basket topmounts that relocate top coilover mounts higher to retain a bit more travel, add whiteline roll center kit to fix fscked up geometry, LCAs to dial camber gained from lowering back, add diff risers to reduce back extra angle in axle joints to reduce wear on them, do homework on finding coilovers of more travel (KW/ST and based on those fare well on that front AFAIK), or something that will make bottoming a bit less harsh (eg. hydraulic bumpstops of Tein Flex-A-s), replace some of that dropping with visual mods that may reach somewhat similar effect, eg. larger diameter tires, misc. body kits like front/side/rear lips, lowering car body/reducing ground clearance w/o touching suspension, you can also go air suspension route, if static high drop is your thing .. but something hints to me, that if you had initially chosen BCs, your overall budget won't cover all of that.
So how about not dropping that low to begin with to keep handling/comfort/spending sane? There are twins that are dropped very low. But owners of such usually are willing to sacrifice things for that goal, because they care about specific arguable looks or specific handling change more so then eg. comfort. Or also have very high budget to do very low drop properly. From your post your goals at your guesstimated budget seem contradictory.
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Old 08-15-2019, 07:50 PM   #5
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Alright so I can probably answer to some of your questions since I am in the "low boi" crowd...

My car is lowered ~2 inches (I can scrape my front lip on speed bumps) on HKS Hipermax IV GT Coilovers ($1500) and it rides very well overall. It's actually less harsh/bouncy than when it was on the stock Performance Pack Sachs suspension for the most part. I'm also on 18x9.5 Rays wheels with 245/35/18 tires. The ride is more supple overall EXCEPT when I hit a large pothole or bump in the road-- then you really feel how little travel the suspension has. But I'm talking a big bump here, like a spill-your-drink kind of bump. So to reiterate here, the ride is really good about 95% of the time and easily daily-driveable.

I will say though, the HKS Coils rode alright when I got them straight out of the box and put them on (about a 1.1"-1.2" drop)-- fairly comparable to stock. However, when I got my car lowered even further to ~2" & got an alignment with -3 deg of camber, etc. the car was wayyyyyy too stiff afterward. Like it was unbearably stiff and I thought I might have majorly screwed up in my suspension selection. The car was basically like a skateboard on that setup.

To fix the ride quality, I had to dial back the dampening setting nearly all the way. The HKS coils have 30 clicks of adjustability for dampening, and I'm now 1 click from full soft all around. The way the car sits now, it's perfect honestly. It's low to my liking and handles like a dream-- all while not being bad to daily at all. It doesn't even bother my 60 year old dad and he drives a stock Porsche...

Summary (lol) - It's possible to be low and comfortable. Get fully adjustable coilovers and figure out the config that will work best for you. If you're a daily driver / some canyon use kind of person I recommend my HKS Hipermax IV GT coilovers because I know they're comfortable firsthand (rides as well as stock did and I'm picky). I also rode in an FRS with Fortune Auto 500s and it was pretty smooth too. KW V3s are good, but I think a little overkill unless you're going to the track a lot, and at that point, I prefer some other options.
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Old 08-15-2019, 08:22 PM   #6
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Decent coilovers should ride pretty smooth unless they're slammed...

hell for a street car you might consider the KW V1s. No adjustability but i hear good things. Other than that the Tein Flex Zs are really popular.
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Old 08-15-2019, 08:25 PM   #7
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Apart from the suspension geometry changes from being too low and so long as you aren't banging your tire against the fender walls, your ride quality shouldn't change much from just lowering the car.

Ride height doesn't affect the shock travel length on the BC coil overs you have: ride height adjustability is independent from preload. It also happens that, due to these design choices, the shock body on theme is also shorter than factory damper body (leading to reduced travel length before bottoming out). This tends to lead to these types of systems requiring stiffer springs.

This is different from how budget (like the Tein Street Basis) and euro-style coilovers (like K&W V3) provide height adjustment. In these instances, when you adjust ride height, you also change the preload and available travel distance. However, many high end systems have very long damper bodies since they don't have to incorporate a separate ride height adjustment collar. Therefore, you can accommodate a softer spring and still avoid bottoming out.

----

With that being said, make sure the preload is set-up correctly on your coilovers. Also ensure none of the shocks are blown. Other than that, all you can really do is change the dampening.

If those changes didn't help, then you know that the harsh ride is due to they way your coilover system was specified/designed. Some just ride harsher than others due to spring rate, dampening rates, allowable travel, etc.

----

If you're looking to stay on a budget, Tein Flex A or Flex Z are really affordable and streetable entry level coil overs
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Old 08-15-2019, 08:26 PM   #8
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Quote:
Originally Posted by Shizuka View Post
Summary (lol) - It's possible to be low and comfortable. Get fully adjustable coilovers and figure out the config that will work best for you. If you're a daily driver / some canyon use kind of person I recommend my HKS Hipermax IV GT coilovers because I know they're comfortable firsthand (rides as well as stock did and I'm picky). I also rode in an FRS with Fortune Auto 500s and it was pretty smooth too. KW V3s are good, but I think a little overkill unless you're going to the track a lot, and at that point, I prefer some other options.
HKS Hipermax IV GT coilovers. Thanks I'll look into those. Do you know what spring rates they have?

The BC-golds are 8k/8k
I read this review:
https://www.drifted.com/gt86-coilove...NTixTjG8Zsk1T4

Noticing that the spring rates on the preferred Ohlins (4/3) and KW (6/7) are quite a bit lower.

I hear the people saying raise it up. I have actually raised it up and it made no difference. I don't really understand if coil-overs are wound lower.. the spring still has the same amount of travel why would it make a difference raising it? I'm not bottoming out, it just rides harsh.. even going really slowly over cracks in the road I can feel them.

- Edit just read the above posts. I have wondered if something is wrong with my setup from previous owner. Perhaps the preload or the shocks ruined. Perhaps I should get someone to check it out first. I do hear most people with BC-Gold coils say that they are harsh.
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Old 08-15-2019, 09:14 PM   #9
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Quote:
Originally Posted by tzbang View Post
HKS Hipermax IV GT coilovers. Thanks I'll look into those. Do you know what spring rates they have?

The BC-golds are 8k/8k
I read this review:
https://www.drifted.com/gt86-coilove...NTixTjG8Zsk1T4

Noticing that the spring rates on the preferred Ohlins (4/3) and KW (6/7) are quite a bit lower.

I hear the people saying raise it up. I have actually raised it up and it made no difference. I don't really understand if coil-overs are wound lower.. the spring still has the same amount of travel why would it make a difference raising it? I'm not bottoming out, it just rides harsh.. even going really slowly over cracks in the road I can feel them.

- Edit just read the above posts. I have wondered if something is wrong with my setup from previous owner. Perhaps the preload or the shocks ruined. Perhaps I should get someone to check it out first. I do hear most people with BC-Gold coils say that they are harsh.
8k springs are very high for these cars. That's into the territory of 86s with decent downforce.
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Old 08-15-2019, 10:55 PM   #10
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Originally Posted by tzbang View Post
HKS Hipermax IV GT coilovers. Thanks I'll look into those. Do you know what spring rates they have?

The BC-golds are 8k/8k
I read this review:
https://www.drifted.com/gt86-coilove...NTixTjG8Zsk1T4

Noticing that the spring rates on the preferred Ohlins (4/3) and KW (6/7) are quite a bit lower.

I hear the people saying raise it up. I have actually raised it up and it made no difference. I don't really understand if coil-overs are wound lower.. the spring still has the same amount of travel why would it make a difference raising it? I'm not bottoming out, it just rides harsh.. even going really slowly over cracks in the road I can feel them.

- Edit just read the above posts. I have wondered if something is wrong with my setup from previous owner. Perhaps the preload or the shocks ruined. Perhaps I should get someone to check it out first. I do hear most people with BC-Gold coils say that they are harsh.
HKS are 4k I believe
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Old 08-16-2019, 09:34 AM   #11
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Raising it up didn't make much difference because these coilovers have separate ride height and preload, and there just isn't that much travel as @EndlessAzure mentioned.

It's still worth having a look at your coilovers to see if they were set up correctly. There just might not be much for you to gain.

KWs do ride substantially better even at the same spring rates. However, 8 kg/mm springs are high for a street car.

- Andrew
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Old 08-20-2019, 06:30 PM   #12
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Yeah I don't know why the previous owner went for 8k/8k springs.. but it seems like they were the standard option for the BC-BR Coilovers at one stage. And now they seem to be listed at t 6k/4k?

What about upgrading to a Swift Spring?
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Old 08-20-2019, 06:51 PM   #13
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A swift spring in the same rate won't feel any different, despite the marketing hype.
A softer spring may improve things greatly if the damper has the range to support it without overdamping it, something in the 4k-6k range is the go to for sporty but road livable. 2k-3k is stock if you want to try something radical it could work out quite well.

But if the current springs don't feel under damped with the adjusters clicked all the way soft I'd be worried about being overdamped on a significantly softer spring.
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Old 08-20-2019, 08:30 PM   #14
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Yeah I have the dampners wound all the way soft.. I can't turn the dial anymore.

I don't bottom out.. the BC-R's have plenty of travel. It's just way too stiff.

I was hoping to find someone else here who had either ditched the 8k/8k springs on their BC coils for a different rate. Otherwise it's ditch the whole setup for something else. But I feel like for a street car the BC coils should at least be able to be made half reasonable.

I certainly don't mind a stiff suspension in a low car, but what I have is a bit much (despite me actually putting up with it for years I've decided I want to do something about it)
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