Cat, etc.

  Ciro Design supplied the 100 cell race catalytic converter and Yawsport welded it directly behind the race header which gives plenty of clearance everywhere.  This mounting position loses the OE catback flange location so when SMOG time comes I will need to swap the entire exhaust to legally pass inspection.

During the shop visit we noticed the rear swaybar is making contact with both lower control arms.  Moving the swaybar mounting brackets up is an easy adjustment but it may not be enough.  Longer endlinks may help too so I will keep an eye on this problem.

Edit: Some quick searching and I think that I have the rear swaybar mounted upsidedown - Oops.

Okay, the first two pictures below show the new correct installation of the Hotchkis Competition swaybar.  Gained about a half inch more clearance to the LCA, but now the right side swaybar arm hits the exhaust when the swaybar mounting brackets are placed in their maximum 'up' position.  New poly bushings and new brackets are also installed at this time and there is enough wiggle room to make it work without interference, but the ultimate test will come at the next autox.

Thinking more about the catback exhaust and potential future swaybar changes and upgrades, it would be easy to save weight and avoid swaybar clearance issues altogether by using a custom muffler located where the resonator sits with a dump at the rear wheel. It would be a very tight fit, but a custom 6"x8"x24" muffler should keep the sound levels reasonable, especially if a Burns stage 2 muffler is used.  I think two Vibrant Ultra Quiet resonators would fit back-to-back but may not have enough total volume. Magnaflow sells a 6" round chambered muffler that is cheap enough to try.  Underbody exit and exhaust gasses entering the passenger compartment is a major concern.  Would also want to keep the sound quality good with minimal drone or raspyness. Stuff to think about.

EM2

  The front swaybar interference with the OBX race header does not seem to cause a problem or make any noise during normal street operation, but just looking at the bar mount bushings you can see that the bar is jammed to the right at least an inch due to full constant contact at the right top corner of the header.  The base Honda Civic EM2 front swaybar is a direct fit into the RSX chassis and is reported to clear most all race headers due to the lager main hoop section.  This civic swaybar measures 15.9mm and the 02-04 RSX-S bar measures 23mm; both swaybars are hollow and the weight difference is less than two pounds.

Front swaybar elimination or a minimal front bar will help put the power down better, but will also allow more roll and lean thus reducing active camber - transitions should be slower too.  From what I have seen all of the aftermarket RSX front bars are nearly the same size or larger than stock and will most likely have race header clearance issues as well, so the EM2 swaybar should meet my needs - low cost, decent fit, moderate stiffness.  Eventually I can see removing the front bar altogether and spring rate can be increased to help combat chassis roll.  Other possible options include modifying or replacing the header or making a custom under-the-header swaybar.

One step forward, two steps back.  Due to the design, the long tube race header needs to be dropped to remove or install the swaybar.  Careful not to damage the [new] primary O2 sensor, the header removal is simple and the new swaybar slips in with just 2mm clearance at the header.  I was expecting more room, but it is a much better fit than the OEM bar.  The EM2 bar has enough room on the arms to accept another endlink hole so I drilled it before the install and I mounted the Hotchkis adjustable endlinks to the newer stiffer holes.

Power is Everything - Part 1

I purchased a used OBX header and AEM intake about three months ago.  I have been waiting to install them until I got the car in a better state with fresh mounts, preventative maintenance, etc., and I also wanted to abuse the car a little in stock trim to feel it out and find any potential weak spots.  No problems found so I bought a new Yonaka catback exhaust and got to work.

The AEM Dual Chamber intake is basically just a filter on a tube, but AEM says it gains 18hp over stock.  http://www.aemintakes.com/  Not allowed per ST* rules to trim the fender liner or radiator shrouding to fit a true cold air or ram air intake so this was an easy off the shelf choice. Got is used at half price and the install was easy so I actually stuck it on the day before the last autox.  Stock intake weighs 10.2 lbs.  AEM weighs 3.8 lbs. This thing makes a loud intense growl on vtec so the perceived power increase is there.

The OBX V2 header is a Comptech long tube replica and I snagged it locally used for under $200. With so many header options for this vehicle, I just chose the one that is reported to make decent power, fit well, and is reasonably priced.  No braided flex hose or slip joints on this header, however the collector flange includes an oem style donut gasket with spring bolts which should help reduce any stress or cracking.   Aside from a known front swaybar interference issue and a damaged O2 sensor, the install was a simple nut and bolt procedure.  There is no provision for a catalytic converter.

   

The Yonaka catback exhaust was purchased mainly because of the canister size and volume and my need and desire to keep the car relatively quiet.  It is an Apexi WSII clone 2.5" OD and reported to be barely louder than stock and at just over $200 I could not resist. Quality is very good and includes all hardware and gaskets.  Fit is excellent.  Sound is mellow at low revs and mildly aggressive without being obnoxious at vtec. No drone.  Plans are to install a race cat in the mid-pipe; probably at the S-bend or immediately following the header collector.  The main muffler is shorter than the stock muffler which should allow some clearance for a future upgraded speedway style ASR swaybar.

Combined, the complete OEM exhaust weighs 57.4 lbs.  The OBX and Yonaka together weigh 41.5 lbs.  Midrange horsepower feels stronger between 3500-5000 rpm.

Hondata just released version 4 of their popular and powerful Kpro ecu.   This is next on my shopping list after some of the other suspension items are dealt with.

Event 1

First STF autox with a decent setup and the car works well and the initial results are promising.  Still have the B-Street MX5 16x7 wheels and 225 ZII tires on the car, but I did adjust the rear swaybar to full stiff.  Balance is still pushy, but the increased caster/camber and spring rate make the car come alive.

More pictures from LateApexPhoto.com

  After this first autox event I realize the front strut travel and caster may be less than I anticipated, even with the newest set of camber plates and a moderate ride height.  Some of this may be spring rate and swaybar choice, but either way I see the immediate need for another variation of top strut mounts / camber plates to increase bump and caster before other major setup changes should be made. Swaybars, ride height, rake, and alignment will all need tweaking after the basic spring balance is achieved, but for now I consider this first event a success.

November San Diego Autox Results

      


With the holiday season upon us the next autox event is not until mid-January or later.  This gives me plenty of time to make some changes and add more power.

Roadworthy

Two weeks ago the car's front suspension was a mess with massive toe and a 4x4 stance.  I am happy to report the car is home now with a sporty ride height and good alignment thanks to shorter Swift springs and hard work from Yawsport.

We bailed on the original plan to use Todd's camber plates because of suspension travel and tie rod issues.  Utilizing Todd's trick design gives alot of caster and camber, but the strut mounted tie rods run out of adjustment well before the camber plates limits are met.  Custom length tie rods would solve all the alignment issues but are not allowed per the ST* rules.  Top mount camber plates are on the design board, but in the meantime a semi-custom bottom mount setup adds over an inch of strut travel while still maintaining similar alignment parameters available with Todd's plates.

The current front ride height is conservative until I can run a few autox laps and determine range of travel and bump stop clearance.  If and when the front suspension ride height is lowered it should change the tie rod angle in a good way that could allow more camber/caster at the current toe.  Right now the front camber is about -3* with 1/4"+ total toe out. Rear camber is -1.5* with 1/8" total toe in.

Feels like a new car with the firm suspension and all new front bushings and motor mounts. Thrashed the car on some twisty roads for the drive home and it is much more confident, precise, and agile.  Drove it hard enough to stink up the brakes or clutch.  Ride is very firm, but not nearly as jarring as I expected, well at least not on the current spring rates and damper valving.  Initial impression is that the rear shocks may be under damped.  Got some funky rear dynamic toe / bump steer too.

Below, the left picture shows the SPC upper rear camber arm and Bilstein ASN shock with Swift springs. Also visible is the 27mm Hotchkis swaybar.  The right picture is the 'before' variation of the front strut.

          

At The Shop

Shock and strut assembly and install has begun.

Rear shocks are Bilstein ASN with 70mm 6" Swift main springs and Swift helper springs.  Swift thrust sheets are utilized at all the spring contact points.  A simple adapter keeps the upper spring seated and centered within the oem top mounts and heim spacers for the lower eye mount complete the basic install.  With a race ready ride height, rear suspension travel and range of adjustability appear to be very good.

Front struts are Bilstein B8 with 2.5" ID Swift springs and Swift thrust sheets with planned use of tender or helper springs. The struts are oem length and Todd's camber plates mount to the underside of the strut towers which creates a problem with ride height and suspension travel.  Just over an inch was removed from the internal strut bump stops, but the assembly is still too long for the ride height I am trying to achieve.

There are a few ways to solve this problem.  One is to shorten the internal strut and strut housing, which is an expensive and complicated procedure.  Two is to machine the strut stem to eliminate the 'step' and allow the strut to rise higher into the top mount.  Third is to use alternate camber plates that mount to the top of the strut tower instead of below it.  The least expensive and most simple current solution is to use option number three which could gain up to 2" of travel over the current configuration.  Will that be enough?  Maybe a combination of option 2 & 3?

Of course there is another option; buy 8611 DA Koni inserts and start over.  If the internet chat rooms are to be believed, the 'race' koni strut inserts are short enough to use Todd's camber plates and maintain a low ride height.  Major drawback is the strut tower prevents top strut adjustment when set at max caster.

Todd's camber plates are preferred because they give alot of caster which relates to great dynamic camber, but because they need to mount underneath you lose valuable travel unless the struts are very short or a stock ride height is preferred.

The Hotchkis camber plates are a top mount design no longer in production and difficult to find. The range of adjustment is not as good as Todd's, but suspension travel will be gained.  Custom camber plates on the menu if used parts are not found.

Toe is also a major concern.  Due to the steering arm location on the strut housing, maximum camber and caster settings at the strut tower can result in toe changes that cannot be corrected by using the standard tie rod ends. A delicate combination of ride height and top strut alignment settings can get toe back to zero.  One or two pairs or camber bolts at the strut mounts can help the alignment issues without affecting toe.

On the lift, Yawsport installs new Mugen compliance bushings and Hardrace front control arm bushings.  New NAPA lower ball joints are replaced too. Mugen also supplied upgraded motor mounts for the left, right, and front locations.

Debut Autox

Our local region hosts a championship autox event the weekend after SCCA Solo Nationals and my MX5 is not home yet so I throw the Hotchkis rear sway bar and some tools into the car and head to Qualcomm Stadium.  Tires are very old 225/45-17 BFG Rivals on 17x7 Kosei wheels taken from my Mazda.  Two tires were already blistered so I put those on the back.  50 psi front, 35 psi rear.

The swaybar bracket holes are slotted bigger than I think they should be and I did not have new bolts or any washers .  After my runs I discovered that the bolts were barely loose with one being backed out about 1/4".  This may be one reason why the car slightly tightened up during my runs.  I re-torqued all the bolts and two days later everything seems fine - no stripped nuts or damaged threads.  A future trip to the hardware store will get me some new bolts and large washers. Also gonna keep my eye on the bushings and brackets as I think the left one is looser than it should be - replacements are $20 / pair.  I positioned the endlinks on the soft outer setting for today's adventure.  Stock swaybar weight is 6.75 lbs.

The stereo subwoofer is unique for the Type-S and is secured in the spare tire with one long bolt. I removed it all to save weight.  The subwoofer can be installed without the wheel/tire but is much more solid when assembled as designed.  With the factory supplied hardware, the spare tire cannot be properly secured without the subwoofer.  The spare is reported to weigh 28.5 lbs. and the subwoofer is reported to weigh 6.5 lbs.

The driving experience was better than I thought.  The course had a few long straights and fast kinks with a couple slow sweepers and a small slalom.  I was able to stretch the legs of the K20 engine and it pulled hard and smooth all the way to rev limit. The brakes worked fine for what I assume is OE equivalent pads and old brake fluid.  ABS is too intrusive and something that I will have to adapt to.  With positive front camber and practically zero caster, the handling is what I expected - pushy - and as mentioned above an 'active' rear swaybar probably did not help.  The old tires certainly did not help as the fronts blistered, peeled, and corded about half way through our session.  

Hood open between autox runs to help cool the engine I notice oily fluid sprayed beneath the power steering reservoir.  Might be a leak at the lower non-pressurized hose but I cannot find a problem.  Fluid is full and PS works fine. Engine oil is full also; no leaks.  After my third run I notice the engine note has changed and minor vibrations can be felt through the gas pedal.  I press on with uncertainty fearing the worst and complete my runs and park it in the pits to cool down.  Post event bench racing with the hood up we notice the engine side (passenger) motor mount is damaged - the oily mess is from the fluid filled mount and the vibrations are from the busted mount being metal-to-metal.  Such a relief to know it was nothing worse.

Suspension Pieces

 
   I am teaming up with YawSport to help with the suspension fabrication and setup.  Front Bilstein struts, originally designed for a Civic SI will have the steering arm reworked to accommodate the RSX tie-rod taper and stock oem spring perches will be cut off and replaced with threaded coilover sleeves.  The strut inserts will be sent to Bilstein for revalving.  11.20 lbs each as pictured.

Here is what Todd's camber / caster plates look like.  These are daVinci Designs Version 1. Allows maximum 7* caster without slotting or cutting the strut tower.  Each plate weighs 3.25 lbs.

Version 2 is a much more simple design with fixed maximum caster, but I got these V1 plates used for a good price.  The upper spring perches are for 2.5" springs.  The shoulder nuts pictured are sized for the 14mm PSS9 shaft instead of the 12x1.25mm shaft on my B8 Bilstein struts and new replacement parts are not available at this time.  We may need to custom machine new parts.  Also need to sleeve the upper  perches to precisely fit the strut shaft.


Keeping an eye on the classified section at ClubRSX and I scored a used Hotchkis rear swaybar.  No longer in production and originally priced at a whopping $400, this one is 27mm diameter hollow with two adjustment holes on each arm and room to drill another stiffer hole if required. Weight 7 lbs with brackets and urethane bushings.