Project Trackday

Another fun test’n'tune event at Gingerman Raceway yesterday.  I got the opportunity to try out the new front brake pads and also experiment a bit with my line at the 2.21mi 2010 layout course.  Firstly I have to say that I am very happy with the performance of the Carbotech XP10.  With the Yellowstuffs I was finding that I had to press harder on the brake pedal as the pads got up to temperature, but on the Carbotechs the bite feels a lot more consistent between cold and hot.  Overall the braking power between both compounds is hard to judge because it feels like there is now too much front bias as the XP10s have more bite than the EBCs.  That’s not to say they have more stopping power, but just that the brake balance is a bit off.  I will either need to change the rear pads/rotors to Carbotech XP8/XP10 or consider getting a brake proportioning valve installed.

No open-wheel cars showed up, therefore the 3hr test’n'tune was split amongst two run groups, with 1.5hrs of track time per group.  As for the event, there were a few drivers in the novice group that had never been to Gingerman before so the first session was run under full-course yellow (no passing).  I went out on track first but by lap 3-4 was catching up to the back of the group so I decided to pull in and request some open track space.  Back out again and a further 2-3 laps into the session I’m back stuck behind again.  With no point-bys and basically getting 1 lap of running between warm-up and cool-down laps I decided to scrap the session.

After the run the course director suggested that I try running with the intermediate group to see if that would get me some more open track.  Obviously I was slower but at least I could point-by the faster guys and focus on my own driving.  I tried different lines and shifting during the session, setting several 2:04.7s laps (about 4 laps timed at 2:04.7 during the session).  That’s a slight bit slower than the times I estimated from reviewing video footage from the last time at Gingerman (2:02 +/- 1s) but the track and ambient temperature was also about 15F cooler, and the Azenis are probably closing in on the end of their usefulness.  All in all I feel like I was driving pretty hard on the tires so I’m not sure where the discrepancy is in the timing, though I will review the on-board footage in more detail later.

(note:  after reviewing the previous footage it looks like I was running a low 2:07 last time around, so a 3 second lap improvement this time around is a pretty productive day!)

At least I wasn't being easy on the tires...

On-board footage from session 2 of 3 with the intermediate group:

$60 entry fee for the test’n'tune (not bad for 1.5hrs of track time!) puts the season entry fee total to $815.

A few minor things going on the last week.  I decided to lower the car a little bit to reduce the amount of wheel gap and lower the ride height by switching the perch settings on the koni sports.  Both front and rear shocks were set on the middle perches, resulting in a ride height of 13.5″ front, 14.0″ rear.

Top: Middle perch setting, Bottom: Lower perch setting

For the front I was able to get the spring compressor on without removing the shock from the car, however due to space constraints in the rear (namely the upper A-arm and drive axle) I had to remove the rear shocks to get the rear adjusted.  Current ride height is 12.875″ front, 13.75″ rear, though I do expect the rear height to still settle a bit more.  I’d like for the rears to sit at about 13.5″ but I’m not confident it will get there..

Also took the opportunity to change out the front brakes as they were just about at the end of their usefulness.

One shot front pad...

Going with vented blank rotors from a national chain auto parts store ($40 for two) and replaced the front pads with a set of new Carbotech XP10 pads I purchased from NASAforums ($75).  The A/C parts were also sold off (-$50) so the running total for the season is now at $750.

Was a little concerned initially about the brake bias difference between running the Carbotech XP10 in the front and keeping the EBC Yellowstuffs in the rear, but after doing some brake testing it seems to be very well balanced under braking.  Will get a better idea of how good these Carbotechs stand up when I head back to Gingerman next week.

The brake pedal was feeling slightly mushy after the trackday so I finally got around to bleeding the brakes and checking the pad wear today.

Rear rotors and pads still in great condition

There is some minor scoring on the front rotors, but no cause for concern.  Originally thought I was running low on pad material in the front but after removing the caliper it looks like there is still a good amount of front pad too.  I need to lube up the upper and lower caliper slider pins as the pad wear is uneven.

Outside had is wearing a bit more than the inside pad

Bled all four corners and the brake feel is back to normal again.  While I was at it I also checked on the spark plugs to see how they were holding up.  They all look to be in pretty good condition.  I still need to do a writeup of the last trackday, so I’ll get to it later this week.

Spark plugs still looking good.

As expected, the EBC Yellowstuffs pads are quite a bit more agressive than your run-of-the-mill brake pads.  As a consequence they tend to dust up quite a bit more as well.  After 350mi (most of which was highway driving) you can see that there is quite a bit of brake dust on the rims already.  It’ll be interesting to see how much brake dust buildup I get after a trackday…

Lots of brake dust already...

On an unrelated note, I decided to remove the factory strap down “baby teeth” hooks over the weekend.  Doesn’t seem like much, but the mass of the 6 bolts and the 2 hooks alone are probably around 1.5kg (won’t really know exactly how much until I put them on a scale).  They are all 14mm bolts, and can be removed without too much fuss with a wrench (not socket wrench, it won’t fit up in there!), though if you have one of those ratcheting wrenches that would be a big plus!

Small pieces, but they add unnecessary mass

Not only is this for weight savings, but also opens up the front air dam for if I decide to install a mesh grille at some point in the future.  Hard to tell from the picture, but the radiator has had some minor damage from rocks in the past, so it may be a worthwhile investment.

Open mouth, no teeth

Another break from the rain today allowed me to finish off preparations on the brake system for trackday/auto-x.  I went with new rotors and pads all around because the old rear rotors were shot, and the fronts weren’t worth resurfacing (only $10 more per rotor to get brand new ones!)

First I started off with the rear rotors.  See below on the condition of the old rear left rotor, not looking too great.

Rear left rotor is not in the best condition...

First thing to do is to retract the caliper piston by turning the manual adjustment screw.  Find the 14mm bolt below the brake hose and remove the bolt completely as it is just a cover for the 4mm hex manual adjustment screw inside.  Turn the hex screw counterclockwise to retract the caliper piston.  I removed the master brake cylinder reservoir cap just in case, and kept going back and forth to make sure the brake fluid did not overflow (note:  not even close…)

The 14mm bolt below the brake line is a cover for a 4mm hex nut that retracts the rear caliper piston

Brake Master Cylinder reservoir cap off just in case...

Once the caliper piston has been retracted the caliper can be removed by unscrewing the bottom caliper pin bolt.  It is covered by a plastic cap in the picture below.  Remove the cap and then use a 14mm socket to remove the caliper pin bolt.  Now the entire caliper should swing up, giving you access to the pads and rotor.

Cap for the caliper pin bolt needs to be removed to access the 14mm bolt

I tied the caliper up and out of the way so I could take pictures of the process, however this is not necessary.  The old pads come off pretty easily here, however the old rusty rotor had rusted on and seized to the backing plate.  Couldn’t get the damn thing off with several whacks of the rubber mallet.  Instead I put a bolt into the screw thread hole on the rotor and turned it until the bolt pushed the rotor off the backing plate.  Worked like a charm!

Caliper retracted and tied to suspension with some twine

Finally the rotor comes off!

Be careful when removing the old pads, making sure to make note of how the various springs are placed on the pads.  I cleaned up everything with a bit of brake cleaner and then proceed to install the new rotor on there, temporarily holding on the rotor in place with 2 wheel lugnuts.

Shiny new rotor...

Then the new pads with the guides go on the caliper frame.  I went with EBC Yellowstuffs as per tefnut’s recommendation as he has tracked his Miata before and says lots of nice things about them.  Unfortunately here I forgot to take a picture of it all assembled back together.  A dab of anti-squeal on both surfaces that will touch the caliper, and then I removed the string and lowered the caliper back in place.  Putting the caliper pin bolt back in I applied a generous amount of high temp brake caliper grease on the bolt first:

Green stuff is high temperature brake caliper grease.

Now everything reassembles back together.  Remember to replace the plastic cap over this 14mm bolt.  Now we need to adjust the brake caliper back with that 4mm hex screw again.  Turn the hex screw until the pads are in contact with the rotor, and then back off by about 1/3 of a turn.  Replace the 14mm cover bolt on over the hex screw, replace the wheel and then the first corner is done!  Repeat the same procedure for the rear right.

One brake rotor/pad done!

Rear right, before the change

Rear right, after the change...

Now for a cold beverage break and a back stretch!

Onwards with the front brakes!  First the front right.  I removed the wheel, and then removed the lower caliper pin bolt (14mm) first thinking I could pretty much folow a similar process to the rears.  Wrong!  I had to remove the entire caliper frame in order to remove the old rotor

Couldn't find a way to remove the old rotor without removing the caliper frame first

There are two 14mm bolts holding the caliper frame to the suspension.  Remove these and the entire caliper frame (with caliper attached) will come off, along with the rotor.

Removing the caliper frame bolts...

With the caliper+frame out of the way a new front vented rotor finds its home, temporarily held in by two lugnuts.  You can see the caliper + frame sitting on top of the old rotor to the left.

Shiny new vented front rotor

Once again, out with the old pads, keeping all of the springs and the other metal clip.  In with the new EBC Yellowstuffs front brake pads.  I reassembled the caliper frame to the car, using some loctite blue on the caliper frame bolts.  The only thing holding your brake caliper to the car is these two bolts, so better make damn good sure that they aren’t coming out!

Loctite blue theadlocker on the caliper frame bolts

With the caliper frame + caliper that can rotate (remember the 14mm bottom caliper pin bolt is already removed!) back on, compressed the caliper piston with one of the old brake pads + a clamp to get it to fit around the new pads.  Once again, keep an eye on that master cylinder reservoir to make sure nothing is about to overflow, brake fluid will eat right through the paint in the engine bay!

Clamp pushes the caliper piston back

With the piston depressed the caliper can rotate back into place over the new pads, and the caliper pin bolt can be replaced (after getting a nice dose of high temp brake caliper grease of course!).

Three down, one to go!

Three down, one to go.  Now repeat the procedure for the last corner and you’re all done!

Front left rotor is probably the only one not in terrible shape. Doesn't matter, it's still getting the same treatment as all the other corners

All done!

Now make sure to bed in your pads as per the specifications stated in the instructions.  I drove out of town to some open roads to conduct the bed-in procedure.  The brakes definitely feel much better than before and it seems like I don’t need to step so hard on the brake pedal to get the same braking input now.  The car is much more poised and confident under hard braking, though we’ll see how it performs at the track…