BC Racing Coilovers - Comprehensive Review

[Honcho]

I have not driven the BC springs so I cant really comment, though my research indicates they will be fine on the street. As Ryu pointed out earlier, the Swift option is more of a track issue, but due to the superior material aand manufacturing quality the swifts will ride better.

I'm sure Honcho will chime in again, but so you guys know the Swift springs will make a big difference whether you are just cruising on the street or on the track

 

[Honcho]

Quick update. I just had the car aligned and the ride height set to NSX-R spec. I have to say it is AMAZING. :biggrin:

 

[NetViper]

Mine are squeaking a little in the fronts.

 

[tbnsxt]

Bust out the acura silicone spray! works wonders for squeaks.

 

[Honcho]

Mine are squeaking a little in the fronts.

How many miles on them?

 

[NetViper]

How many miles on them?

No more than 2,000.

 

[CircuitMotorsports]

They can get dirty and the springs will squeak a little bit, or something may need to be tightened.

The proper way to set preload on a coilover-

-Loosen both lock rings under the spring (spring seat ring(top) and spring lock ring(bottom)) so that the spring is loose and can move up and down slightly.

-Tighten up the spring seat ring so that the spring is snug, but do not tighten it down past simply holding the spring snug, this will be "0" preload.

-Now bring the bottom lock ring up so that it is just touching the spring seat ring, but do not tighten to lock, you will be moving the spring seat ring next.

-Now tighten up the spring seat ring so that you are now preloading (compressing) the spring.

-Measure the distance between the bottom ring and the top ring as you are tightening, once there is a 3mm gap between the two rings, you have 3mm of preload on the spring.

-Tighten up the lock ring to lock your preload in place

-Repeat for all 4 corners.



You also want to check and make sure the top 17mm center nut is tight, it's best to check it with an impact gun if you have access to one, a wuick hit is all it should need. A few other areas to check are the lower mounting bolts, the 4 allen bolts that adjust camber, and the 4 lock bolts underneath the pillowball bearing, make sure all of these are tight.



Sometimes noise can come from somehwere else, endlinks, swaybars, and chassis contact can all be problems. Make sure now that the car is lowered and stiffer that you don't have exhaust contact anywhere. These are all common noise issues.

 

[Dhalsim]

OK I put mine in last night. Was wondering if anyone had a pic of how they hooked up the brake lines in the front.

And I didn't have time to adjust them but the fronts were too low and I need to raise them up. What is the proper way to do this?


EDIT: Nevermind I found the below video on Youtube. Thank God because I was gonna try raising the car by raising the upper spring perch which apparently would have been foolish. Yes this is my first coilover suspension.

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[anesthesia]

Thanks for posting the video, so when lowering the front, how do you know if the driver side and passenger side are drop equal? Is there markings?

 

[Dhalsim]

Thanks for posting the video, so when lowering the front, how do you know if the driver side and passenger side are drop equal? Is there markings?

I measured the distance from top hat to the top of the very bottom ring. This distance should increase if raising the car or decrease when lowering. Then I just made sure that the distance from the top hat to the top of the bottom ring was the same on both sides.

I used a tape measure just like in the video.

Of course after I did all this I thought I was done with adjusting and went on a long drive during which I thought it "just didn't feel right" and then 30 minutes into the drive remembered that I had not adjusted the damper settings. So I got out and started by turning them all the way down to full soft and then went up 15 clicks from there. I also then realized each damper was set differently. No wonder it didn't feel right.

Anyway I drove home with all dampers at 15 clicks from soft and I thought it felt great. :smile:

 

[Honcho]

I measured the distance from top hat to the top of the very bottom ring. This distance should increase if raising the car or decrease when lowering. Then I just made sure that the distance from the top hat to the top of the bottom ring was the same on both sides.

I used a tape measure just like in the video.

Of course after I did all this I thought I was done with adjusting and went on a long drive during which I thought it "just didn't feel right" and then 30 minutes into the drive remembered that I had not adjusted the damper settings. So I got out and started by turning them all the way down to full soft and then went up 15 clicks from there. I also then realized each damper was set differently. No wonder it didn't feel right.

Anyway I drove home with all dampers at 15 clicks from soft and I thought it felt great. :smile:

Make sure you measure your suspension height the way it is shown in the service manual, i.e., at the (F) lower arm bolt and (R) toe arm bolt from level ground. Ride height affects toe and camber, so even being off a little bit can cause dangerous instability. That is why I don't like "eyeballing" the ride height. Also, you should always align after changing ride height, because it does affect the toe and camber. The NSX is particularly sensitive to these variations, especially on a wet road.

I spent the $$ to have Acura set the height on their level rack and then align. But, I am tracking my car so I cannot afford any misalignment issues.

I am running at 10 clicks from soft and am going to try 12 this weekend- I'm still getting a little pogo stick effect. Also, when you adjust rebound, Ryu gave good advice- always start from full stiff and work your way back. So, to get my settings, I did 20 clicks from stiff.

 

[Dhalsim]

Make sure you measure your suspension height the way it is shown in the service manual, i.e., at the (F) lower arm bolt and (R) toe arm bolt from level ground. Ride height affects toe and camber, so even being off a little bit can cause dangerous instability. That is why I don't like "eyeballing" the ride height. Also, you should always align after changing ride height, because it does affect the toe and camber. The NSX is particularly sensitive to these variations, especially on a wet road.

I spent the $$ to have Acura set the height on their level rack and then align. But, I am tracking my car so I cannot afford any misalignment issues.

I am running at 10 clicks from soft and am going to try 12 this weekend- I'm still getting a little pogo stick effect. Also, when you adjust rebound, Ryu gave good advice- always start from full stiff and work your way back. So, to get my settings, I did 20 clicks from stiff.

Thank you Honcho.

I do intend to have the car aligned but I am waiting for my new wheels to arrive first.

I have a question regarding ride height. Are you saying you had your ride height adjusted to OEM level? What if you wanted the height lower? Most people run lower than OEM.

Can't you just set the ride height to what you like and then get the car aligned to make sure the toe, camber are all correct?

Also, I adjusted from full soft and went up 15 clicks. Shouldn't be any different than adjusting from full hard and going down 15 clicks right?

 

[Honcho]

Thank you Honcho.

I do intend to have the car aligned but I am waiting for my new wheels to arrive first.

I have a question regarding ride height. Are you saying you had your ride height adjusted to OEM level? What if you wanted the height lower? Most people run lower than OEM.

Can't you just set the ride height to what you like and then get the car aligned to make sure the toe, camber are all correct?

Also, I adjusted from full soft and went up 15 clicks. Shouldn't be any different than adjusting from full hard and going down 15 clicks right?

I have my NSX set to NSX-R height. I started with the 2002+ ride OEM height (because I have 2002+ wheels- it matters.) and had Acura lower to NSX-R spec on their rack. My rear suspension is sitting at 202mm, as measured per the service manual from the ground up to the center of the toe control arm bolt. Front I can't recall siting here in the airport lol. But yes, you should set your height to whatever you want and then align. The idea however (unless you are corner balancing) is to get all of your suspension heights even. I would suggest you try to maintain the factory rake (difference between front and rear heights) no matter what height you go with. The OEM ride heights give a range. The top end of the range is for a new car on new suspension with new, full tire tread at oem pressures.

FWIW, I "eyeball" set the suspension heights with a tape measure on my not-so level garage floor and drove the car for a week before I got it aligned. It was nervous and twitchy to say the least, and when we got it on the rack it was massively off, though I managed to hit NSX-R height dead-on on the front suspension. The rears were jacked way too high though.

As for rebound adjustment, I suppose it doesn't matter which way you go. The valve adjustment is really just a flat washer with a graduated slit or holes cut into the surface, which controls flow rate of the shock oil. Conceptualy, as long as you start from one end of the adjustment, I can't see why it would make a difference. Maybe someone who understands more about shock valving can chime in.

 

[Dhalsim]

More good info. Thanks. I didn't think about making sure the rake is set the same as OEM.

BTW - Where can I get the NSX-R height? I assume OEM is in my handbook?

 

[Honcho]

TRACK REPORT UPDATE

Well I spent 4 hours today at High Plains Raceway with NSXCA's own Bruce McPherson and I can report the BC Racing suspension is a great track system. Bruce liked it at 15 F 20 R (0= soft), but it was too loose for me and I preferred 20 F 20 R. The suspension was predictable, smooth and transitioned sharply. I did not experience any reduction in performance due to heat and never did it feel like the car was wandering or unstable (other than the compliance bushing stuff, which is normal for these cars). Strangely, my right front suspension now appears to be sitting about 1/2" lower than the other side. Not sure what that is, but I will have the guys at Acura take a look.

 

[Honcho]

More good info. Thanks. I didn't think about making sure the rake is set the same as OEM.

BTW - Where can I get the NSX-R height? I assume OEM is in my handbook?

If your service manual is the 1991 version, then possibly no. Those ride heights are for the OEM "phat fives" wheels at the factory pressures. If you have OEM 1991 wheels, then yes those heights are correct. Otherwise, they will be off a little bit. Given my recent post-track alignment woes, I remembered the NSX-R numbers, since we had to re-align the car.

Measuring height per the service manual method (to middle of control arm bolts), NSX-R ride height using 2002+ wheels is:

Front = 156 mm
Rear = 202 mm

 

[Dhalsim]

If your service manual is the 1991 version, then possibly no. Those ride heights are for the OEM "phat fives" wheels at the factory pressures. If you have OEM 1991 wheels, then yes those heights are correct. Otherwise, they will be off a little bit. Given my recent post-track alignment woes, I remembered the NSX-R numbers, since we had to re-align the car.

Measuring height per the service manual method (to middle of control arm bolts), NSX-R ride height using 2002+ wheels is:

Front = 156 mm
Rear = 202 mm

I was actually measuring using the method in the 91 manual just last night. I decided that I'm not really interested in having my car at NSX-R height but just having the correct rake and having the car at the height I think looks good with my wheels (17/18).

According to the 91 manual the front height should be 6.7" ~ 7.1" (170 ~180mm) and the rear should be 8.4" ~ 8.9" (213 ~223mm) making the rake 1.7" ~ 1.3" or 1.3" ~ 1.8" (43mm~ 53mm or 33mm ~ 43mm). I used 1.5" for the standard rake.

BTW - How did you measure the front with the car on the ground?

 

[BATMANs]

i'd like to get a ride in ur car when ur done.

 

[Dhalsim]

i'd like to get a ride in ur car when ur done.

"Who wanna ride it won't cost you a dollar whether soft or harder of course you still gonna holla". - Big Pun

ha ha...I couldn't help myself :biggrin:

 

[BATMANs]

its u not you

 

[Honcho]

I decided that I'm not really interested in having my car at NSX-R height but just having the correct rake and having the car at the height I think looks good with my wheels (17/18).

Nothing wrong with that. Just make sure you lower front and rear by the same amount and you will preserve the factory rake.

According to the 91 manual the front height should be 6.7" ~ 7.1" (170 ~180mm) and the rear should be 8.4" ~ 8.9" (213 ~223mm) making the rake 1.7" ~ 1.3" or 1.3" ~ 1.8" (43mm~ 53mm or 33mm ~ 43mm). I used 1.5" for the standard rake.

BTW - How did you measure the front with the car on the ground?

Not quite correct because the front and rear bolts sit at different heights relative to each other. You would have to find a bolt or piece on the rear that is in the same plane as the front bolt to get an accurate rake.

Using the jack points to measure is a really bad idea btw and I now have data to prove it. My car, with the OEM NSX-R heights measures 4.5" at the front jack points and 4.25" inches at the rear. Just goes to show the jack points are not a reliable indicator of suspension settings, i.e. the frame of the car may sit differently than the suspension. You should not rely on them or fender gaps to set height. This just goes to show pbassjo and MacAttack were right. All of these measurements were taken on Acura's level rack.

 

[Dhalsim]

Not quite correct because the front and rear bolts sit at different heights relative to each other. You would have to find a bolt or piece on the rear that is in the same plane as the front bolt to get an accurate rake.

I don't think you are saying that Honda made a mistake in advising how to measure the suspension correct?

Maybe I need to clarify (I thought you already understood) that the front measurement is taken from the center of the lower control arm bolt to the ground and the rear measurement is taken from the center of the toe control arm bolt to the ground.

This is how I did it.

Using the jack points to measure is a really bad idea btw and I now have data to prove it. My car, with the OEM NSX-R heights measures 4.5" at the front jack points and 4.25" inches at the rear. Just goes to show the jack points are not a reliable indicator of suspension settings, i.e. the frame of the car may sit differently than the suspension. You should not rely on them or fender gaps to set height. This just goes to show pbassjo and MacAttack were right. All of these measurements were taken on Acura's level rack.

I DID NOT measure from the jack points or the fender gaps.

Now knowing how I did the measurement maybe you can better understand the difficulty in getting these measurements while the car is on the ground. Not friggin easy. Sure its easy if its on a rack but I don't have a rack in my garage. :frown:

Anyway I'm getting the car aligned today and maybe when its on the rack I can make the measurements again.

After lowering my rear suspension last night I believe I have maintained a 1.5" rake rear to front. Hopefully can confirm later today (when on the rack :smile

BTW - what alignment settings are you using?

 

[Honcho]

You measured exactly right. What I was trying to say is that the measuring points will tell you how high the front or rear suspension is, but not how far off the ground they are relative to each other. The manual shows this, as the rear toe arm bolt clearly is not the low point in the rear suspension, and is higher up in the car's frame than the front lower bolt. I think Honda just wanted an easy reference point. I agree measuring to these points on the ground is a pain, especially if you are lowered like me! It is much easier on a raised alignment rack, so that is a good idea to do it then.

I mentioned the fender gap/jack point method just for general reference. Not implying you did it that way. Sorry if you took it personally.


Edit- I am using the factory 1991 alignment settings, with 6 mm rear toe instead of the post-lawsuit 4 mm. I could feel the rear toe going away on hard braking at the track, so I wanted a little more cushion. It is clear to me now why Honda wanted it at 6.

I don't think you are saying that Honda made a mistake in advising how to measure the suspension correct?

Maybe I need to clarify (I thought you already understood) that the front measurement is taken from the center of the lower control arm bolt to the ground and the rear measurement is taken from the center of the toe control arm bolt to the ground.

This is how I did it.



I DID NOT measure from the jack points or the fender gaps.

Now knowing how I did the measurement maybe you can better understand the difficulty in getting these measurements while the car is on the ground. Not friggin easy. Sure its easy if its on a rack but I don't have a rack in my garage. :frown:

Anyway I'm getting the car aligned today and maybe when its on the rack I can make the measurements again.

After lowering my rear suspension last night I believe I have maintained a 1.5" rake rear to front. Hopefully can confirm later today (when on the rack :smile

BTW - what alignment settings are you using?

 

[Dhalsim]

You measured exactly right. What I was trying to say is that the measuring points will tell you how high the front or rear suspension is, but not how far off the ground they are relative to each other. The manual shows this, as the rear toe arm bolt clearly is not the low point in the rear suspension, and is higher up in the car's frame than the front lower bolt. I think Honda just wanted an easy reference point. I agree measuring to these points on the ground is a pain, especially if you are lowered like me! It is much easier on a raised alignment rack, so that is a good idea to do it then.

I mentioned the fender gap/jack point method just for general reference. Not implying you did it that way. Sorry if you took it personally.


Edit- I am using the factory 1991 alignment settings, with 6 mm rear toe instead of the post-lawsuit 4 mm. I could feel the rear toe going away on hard braking at the track, so I wanted a little more cushion. It is clear to me now why Honda wanted it at 6.

OK....I misunderstood your original post and now understand what you are saying. But I think its good I clarified for others that might be following along.

Thanks for the info on alignment settings. I just checked the previous settings and toe is measured in degrees not mm. but I will advise the shop today.

 

[Honcho]

Just another track update from two days at the NSXPO HPDE. This setup is amazing, especially for the money. I have an incredibly stable, neutral car that sticks like glue in all types of corners. My first instructor thought I had Motons. Just for future members searches, I was running 20 clicks (from full soft) front and rear. The car is sharp and responsive with this setting. Going stiffer did not seem to have any effect. And, funny enough, I ran the first session on my "street" rebound settings (11 F / 10 R) and still was within about 2 seconds of my best time. The car definitely transitioned slower though. 20/20 is a good track setup for a NA1 NSX on the BC's with the NSX-R rates. I set the car back to "street" for the ride home and it was like a cadillac.

Anyway, the BC/Swift setup is a great track option and performed flawlessly over two days of hard road course driving.