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Today at Atelier Kaz - Private NSX Enthusiast, ex-Honda R&D engineer with F1, Indy/CART background

BC Racing Coilover kit with Swift spring upgrade

Rating: 2 votes, 5.00 average.






Finally, the package from US has arrived.


It was already at my local depot at the end of last month but
due to miscommunication between UK Customs and Parcelforce,
I had to call them twice a day for a week to get the things sorted.


Initially, I thought about getting the BC standard coilover kit from
UK vendor and get the Swift spring from Japan because it’s a
Japanese company and I can get it with ease.


However, after some calculation,
it became clear that it would be cheaper even paying for the
delivery/tax to simply order the complete upgraded kit from US
unless the owners were happy to DIY swapping the
spring by themselves.

There is nothing wrong with the standard BC spring.

For street driving, there are several UK owners running the
standard BC kit with good feedback.
However, after talking with the owner and his objective,
we decided to go for the Swift upgrade.

There are lots of other coilover kits available on
the market and several years ago,
I was in discussion with one of the major suspension company to
develop a kit for our NSX.

For mainly street driving usage,
you need to put high priority on the future maintenance and
the ride quality.

Some of the expensive kit requires the maintenance
every one or two years especially if it is using the aluminium shell.



Big thank you goes to NSX Prime member ‘Honcho’ for
spending long time compiling the detailed review on this coilover kit.

http://www.nsxprime.com/forum/showthread.php/159029-BC-Racing-Coilovers-Comprehensive-Review

I exchanged several information with him and although I had
several contacts in US,
I placed the order to Tristan at Circuit Motorsports in
Florida based on his recommendation.

http://www.circuitmotorsports.net/


As this was the first time buying anything from
Circuit Motorsports and also being as an international customer,
took long time but Tristan was kind enough to spend the extra time
for me sorting out this order.







The build quality is very good considering the affordable price.










Each damper tested and then matched between R and L.








30 adjustable damping rate.
For some reason, reasonably priced kit always
comes with 10s of adjustable damping positions........







Pillowball top mount.










Unlike some of the aftermarket kit,
it comes with brake hose mounting bracket for the front.


It will take more time to remove the OEM coilover than
installing the aftermarket rideheight adjustable kit

Will be installing the kit from this week.


Kaz


Categories
Suspension

Comments

  1. Senninha's Avatar
    What impact on ride height do you expect?

    is this set up for a coupe or t-top?

    Will this set up require a change to other elements of the chassis set up?

    interesting new blog ...

    regards, Paul
  2. Sudesh's Avatar
    Hi Paul,

    I have the BC kit in my car for quite a while now. If you remember I had the very stiff zeal suspension fitted, which was way to hard, so bought the BC instead, cost me £528 from memory as I had the VAT zero rated.

    Andrew also just installed the same kit along with another member here from here, and I have another NSX in for work and that owner is also considering the kit.
  3. bbvnsx's Avatar
    Very interesting new blog!

    Do you know the weigt of this setup F/R?

    Do you have any expirience with D2 Racing coilovers and how do they compare?

    regards, Bruno
  4. nobby's Avatar
    Very interesting blog update ... why the Swift springs Kaz?

    Was this a decision based from you or your customer?

    As Sudesh stated I have the BC Racing Coilovers (as standard) on my car and initial impressions are very positive. I dropped the car 1 inch from standard drive height ... as I also DRIVE my car, I can say they are very capable and at a very decent competitive price too

    interested to hear about the swift springs couple with the BC's
  5. Kaz-kzukNA1's Avatar
    Quote Originally Posted by Senninha
    What impact on ride height do you expect?
    is this set up for .........
    ....................
    regards, Paul
    Doing bit of catch up as I have been busy with other projects and couldn’t respond to the comment…..


    Hi, Paul.

    The ride height is fully adjustable without loosing the travel so you can set it depending on your needs.
    For this owner, I’ll just aim for the factory ride height although I won’t be able to do so until after the coilover settles.

    The setup depends on your package and objective.
    BC coilover preload is set at 3 – 4mm by the manufacture and if you are really into the chassis setup, you can adjust the corner weight by altering several adjustments as well as physically shifting the parts around the chassis. Many factors to consider... Brake balance, anti-roll bar, driver, etc, etc, etc....

    Having said this, for RHD NSX, the ride height already showed significant difference between R & L even straight out of the Honda factory so not sure of the significance on street driving production cars.
    I guess the tyre model and tyre pressure will have more effect.


    If you want to change something on the suspension for mainly street driving NSX, I would just get the reasonably priced coilover kit like this one and spend the money on the rear pillow bushing at the toe control arm and lower A-arm (the bush is actually pressed into the rear beam and bracket).
    To me, this is more cost effective than investing into the expensive coilover kit for street usage.

    Addition to this, you could go for the upper A-arm one and also all of the front bushings but the effect won’t be as big as the rear lower section ones.
    At the front, you have compliance pivot which will move any way unless you lock them. It will also increase the vibration through your steering wheel.

    By now, all of the NSX will be suffering from tired/hairline cracked rubber bushing if they were still using the original one.
    In Japan, I drove the one with aftermarket pillow bushing installed at the rear and the difference was night and day.
    So much smoother and predictable than my NSX.
    With all other NSX that I drove on the same day, it just confirmed that the original bushings were so tired on many NSX.

    Kaz
  6. Kaz-kzukNA1's Avatar
    Quote Originally Posted by Sudesh
    Hi Paul,

    I have the BC kit in my car for quite a while now. If you remember I had ..............
    ............................
    Hi, Sudesh.

    Thank you for the feedback.
    As we all know, if you are happy with the parts, then it must be good based on your detailed work described in your refresh thread as well as the parts you have developed.

    I’ll be installing another BC coilover kit with standard BC spring for NSX (10kg/10kg, at the time of writing) later so I’ll have the chance for the direct comparison with Swift.

    One mistake I made on my NSX is the Type-S suspension.
    While it's really great on smooth road, not great for the B road with lots of holes and rough surface in UK.
    At some point, I'll replace it with coilover kit with Swift.

    Kaz

  7. Kaz-kzukNA1's Avatar
    Quote Originally Posted by bbvnsx
    Very interesting new blog!

    Do you know the weigt of ...............
    .............................
    regards, Bruno
    Hi, Bruno.

    I don’t have accurate enough scale to measure the weight but each corner kit weighs about 3.5Kg (using Swift spring).

    I have never used D2 Racing parts but they seemed to be around for a while.

    From what I heard from two different sources, before BC Racing went on the market, they used to build coilover kits for several different brands.
    They changed the factory location several times and when they were ready to go on the market under the BC brand, they put high priority on the quality control for several reasons including the feedback they got for the parts manufactured under different brand names.

    Since then, I think they are only making BC brand coilover and wheel but can’t confirm this part.

    So, it is possible that old days D2 Racing parts were manufactured at the same old BC factories but not sure of the recent ones.

    Kaz
  8. Kaz-kzukNA1's Avatar
    Quote Originally Posted by nobby
    Very interesting blog update ... why the Swift .............
    ........................
    I don’t know whether this is something to do with the Swift marketing strategy or not but it seems that Swift is not well known in the Europe.
    When I contacted many UK vendors, almost all of them didn’t know the brand, Swift.

    On the other hand, Swift or I should say Tokyo Hatsujo Manufacturing Co., Ltd. has been the leader of spring industry for many years and well known in Japan.
    It’s not just the suspension spring but anything to do with the spring in many different industries.
    Swift is the brand name being used for their motorsports spring.

    It’s widely used in many racing categories, teams including Super GT, Le Mans, etc and several NSX specialists in Japan are using it for their own coilover kits.

    With the technology advancing every day, there are different spring manufactures with different concepts of course (and possibly better than Swift these days), but I prefer something already proven and tested by many NSX owners driving on all sorts of different road conditions in Japan as well as in the racing environment.
    I personally drove one of the aftermarket coilover kit developed by NSX specialist using Swift spring and really happy with it.
    For the clarification, it’s the package and not just the spring but part of the ride quality is affected by the spring technology.
    Lightweight and linear throughout the range are the characteristic of their material and technology.
    When the load changes while the car is moving, the coilover doesn’t just move up or down. The coilover body itself moves in all axis around the top mount so depending on the factor, the ride quality will be affected.
    As mentioned, there is nothing wrong with the BC standard spring.

    Kaz
  9. nobby's Avatar
    thanks for clarification on the swift springs ... interesting feedback as always
  10. greenberet's Avatar
    “For mainly street driving usage,
    you need to put high priority on the future maintenance and
    the ride quality.”

    Do the pillowball top mounts transmit more noise, vibration, and harshness into the vehicle than the OEM top mounts? Do you expect the pillowball top mounts (that don’t look like they are sealed) to last as long as the OEM top mounts in daily driving, including on salted roads?

    The OEM spring rates for early NSXs are around 3 kg/mm in the front and 4 kg/mm in the rear. Do you know what spring rates you installed and how is the ride quality on rough UK B roads compared to an OEM 3kg / 4kg suspension?


    “One mistake I made on my NSX is the Type-S suspension.
    While it's really great on smooth road, not great for the B road with lots of holes and rough surface in UK.
    At some point, I'll replace it with coilover kit with Swift.”

    If you want to install Swift / BC springs and dampers in your own NSX in order to improve the ride quality, that’s quite an endorsement!
  11. madras's Avatar
    I'm going to order a set of these from the UK, BC says the spring rates are 8kg Front and 10kg at the rear (or 7kg front and 8kg rear) which is different to what has been posted on nsxprime and here.

    I understand the type-R had front 10kg and rear 8kg.

    What would you recommend ordering?

    thanks
  12. Kaz-kzukNA1's Avatar
    Quite surprised so many forums focuses on spring rate.

    I’m afraid it’s like asking the question 'in what colour should I paint my room' to someone who you have never met.

    Discussion on spring rate alone means almost nothing.
    For example, applying 100kg input to a 10kg rate spring on damper A doesn’t mean it will be the same response on damper B.

    Without knowing the lever ratio, rest of the chassis setup such as weight distribution, rideheight, etc, damping/compression spec, brake setup, antiroll bar spec, etc, not much to say.


    100kg input at the contact on 10kg/mm spring doesn’t mean 10mm movement especially at the front on our NSX.


    Not sure what kind of chassis package you have and also how many days you are likely to track your NSX each month but there are several options for you.

    I went for F: 10Kg, R: 8Kg with Swift spring because that’s what I drove using the same Swift spring at the same spring rate on similar damper spec, coupe package, removed Type-R front/lower bars, standard front antiroll bar, Type-S rear antiroll bar, later spec calipers with upgraded ABS.
    For me, I didn’t like Type-R thick front antiroll bar or the Type-R front/lower bars.
    Just couldn’t shift enough weight towards the front with my skill.


    If going for BC kit with 15inch wheel at the front, you need to review your required ride height because even with the max adjustment, you are still lower than the OEM setup.

    NSX Prime member Honcho has great write up on Prime so worth reading.
    I posted the link in my blog above.


    If you track your NSX regularly, you may want to invest a lot more as the response speed on this damper may not be sufficient for your demand.
    KW seemed to be the most cost effective one for NSX but unless you have the skill to make enough suspension movement or have the ability to setup the car, bit of overkill.
    You are better off spending the extra money on tyres and also pillow bushing at the rear and practice more.


    If your NSX is track only car and lap time means everything, then you can ask Penske or likes to valve their adjustable damper to your needs.
    Mega-expensive but worth it.


    If you want to keep OEM spring but better dampening, then using Bilstein damper is good option.
    I installed it on LHD NSX and ex-F3 driver test driven it with very good feedback.
    It’s valved for the OEM spring and has two ride height setup.
    It uses the OEM upper mount and not pillow one so quieter than the BC one.
    Having said this, by the time you obtain all the short parts and new damper, you better compare the price with complete BC kit as it will allow you extra adjustment such as ride height, damping.


    If you want OEM, Type-S kit is good option but not sure whether it is still available or not.
    The Type-S kit spec is [ figure in ( ) is of the standard model ];
    Spring rate: F: 6.5kg (3.5kg), R: 5.0kg (4.0kg)
    Damper spec at 0.3m/sec: F: damp195kg/comp150kg (115kg/109kg), R: damp230kg/comp170kg (183kg/125kg)
    Antiroll bar spec F: 18.3mm (same), R: 19.1mm (17.5mm)
    Damper mount bush F: 370kg/mm (83kg/mm), R: 370kg/mm (83kg/mm)
    If using this kit on standard Coupe model, you must raise the rear a bit by adding spacer at the damper mount otherwise your weight distribution would be completely wrong.
    The rear would be too low compared to the front.
    I mentioned this on here in the past and I always ask this kind of question to the vendors by pretending to be an amateur to see whether the person I’m talking to knows NSX setup well enough or not.
    Another good example of not much point in talking about only the spring rate.
    On my NSX, I have Type-S kit.
    As you can see from above, the spring rate is F: 6.5kg, R: 5.0kg.
    The BC kit with Swift spring, I requested the spec as F: 10kg, R: 8kg.
    If you have ever driven Type-S kit on UK road, you would think that the spring rate that I requested with BC kit would be a disaster because on bumpy surface B-road, my NSX looses traction because the dampening is not suitable and the weight input to the tyre is lost.
    Basically, the car is jumpping.
    With BC kit, the result is completely the opposite.
    Better ride quality with good traction.
    The damper is doing its job and suitable for the B-road.


    From what I heard, as long as the spring rate is within +/-2kg, you can ask BC Racing to swap the spring rate to your spec without re-valving or any extra charge.
    Also, if you order directly through BC Racing UK, they won’t be able to offer you the discount but if you search through their official distributor, there is always someone offering some discount so worth checking.

    BC Racing UK used to send out the kit with F: 10kg, R: 10kg.
    When I measured the kit, they were using the same spring diameter and length between the front and rear.
    So, if you get 10kg and 8kg spring, you can swap them between the front and rear after you have played a bit.
    One simple concept is that if you are getting close to the adjuster limit (30 clicks) then it’s time to move on to the next spring rate.

    Kaz

  13. jamieburke's Avatar
    Hi kaz
    ypud mentioned before about suspension bushings.

    - how would you tell if they need replacing?

    - where do you get them?

    - what do they cost?

    id rather replace those - my car is a 91 with 70k- than change spring and damper. I run twin springs which helps reduce nose pitch under hard braking.

    many thanks