This thread is just a ray of sunshine for this Luddite.

 

Sun and sound, great package.

My only beef was when we were looking at a CX-7, which we loved (pre CX-5 existence). In order to get the sunroof, you had to get the sun & sound package, which was only available on the turbo, which suddenly brought our $20k car to $30k.

 

Why would you want the one without the turbo?!?!

--Ian

 

Consider that a blessing, because the CX-7 was a flaming pile of dogshit whether turbo or non-turbo.

 

So I swapped the track brakes and tires onto the car this evening, getting it ready for Laguna on Friday. While doing that I did a little investigation into the non-directional rotors, trying to figure out why the track pads wear onto the "ears", but the street pads don't. My theory was that this was related to radial slop in the bolts holding the bracket to the upright and caliper to the bracket, but there's actually not very much there at all. You can wiggle it, barely, but it's not even close to enough to cover the difference.

So next I checked the radial thickness of the pads -- the track rotors always used DTC-60s, and the street ones used Wilwood BP-20 pads, so maybe the Hawk pads are oversize. Well, they are, but only by a very tiny amount, maybe 0.5mm. Again, not enough.

Finally I checked the thickness on the rotors and discovered that the street rotors that were on the car have a friction surface that's about 2mm wider than the one on the single broken track rotor that I kept for investigation purposes. Buh?

So my new theory is that the Wilwood non-directional rotor changed in there somewhere. I've had four sets of the non-directional rotors, the first (and therefore oldest) are the ones that became my street rotors, the second (which I got a couple weeks after the first) were my first set of track rotors, the ones that did 4-5 track days before getting normal radial cracks. Those are the ones that didn't wear onto the ears. The two sets I've had since then wore onto the ears and got tangential cracks, and at least one of those 4 rotors is radially narrower than the old ones.

--Ian

 

@Savington pls advise kthx.

 

Ian is going to send me some measurements from his, and I'm sure he'll share those here. I'm going to check all of my straight-vanes against those measurements, and also call someone at Wilwood and yell at them a bunch.

 

Walk into Wilwood all like

 

So my 2mm guess was a bit high.

The thickness of this part of the rotor is not totally consistent around the whole thing, presumably because it's a cast part and that bit hasn't been machined. I took multiple measurements and aimed for the center values:

Newer rotor (the one that got destroyed) is 41.5mm:



Older rotor (one of my street rotors) is 42.5mm:



Wear on the ear is about 1.5mm:



So I think 1mm of that is the rotor, the other .5 mm may be the pad difference. The Hawks are definitely beefier than the Wilwood pads by a small amount. I didn't measure them before I installed them, but lining htem up against each other there was a small difference and .5mm sounds about right.

This is on the outside friction surface, the one with the mounting ears on it. The innner friction surface is the same on both, 43.5mm. I also checked overall diameter and they were both 298mm.

--Ian

 

Random photo of my Miata when it was new. This is 1998:



--Ian

 

I see that was before you added the socks under the sandals.

 

I don't have photographic evidence, but I'm pretty sure TK was wearing socks+Tevas at that point.

It was, however, back when there was less of me and more of my hair.

--Ian

 

 

You were like a taller version of Jeffbuc

 

19 years ago there was less of me and more of my hair. The car was cleaner, primarily because it only had a hundred miles on it.

Took the car to Laguna today for an event with Hooked on Driving. The first two sessions were rained out (well, they happened, but it was wet enough that I didn't go out), but then it dried out and the last three sessions were good. The directional rotors seem to have survived just fine. The fuel starvation is the same as it was (I haven't done anything about it, so that's not surprising), had to cut the middle session short by a lap or two because of fuel starvation. HoD runs slightly longer sessions than Miatas@MRLS, apparently that's enough to prevent me from running two full ones there.

The last session got cut short as well because the tires are rubbing on something in turn 11. I pulled off, couldn't diagnose it quickly, and since it was the last session of the day I just put the car in the trailer and came home.



--Ian

 

Some video from the Laguna day with Hooked on Driving/MPCA. Due to a miscommunication I wound up in the wrong group (was aiming for 'D', ended up in 'C' -- they run the group order backwards from most track day organizations, so 'A' is the beginners with HoD), so there was lots of traffic, much of which didn't want to point a Miata by. Ah well, still fun.

I swapped it back to the street brakes and got a close look at everything, the brakes survived just fine. There's a shiny spot on the right front brake duct mounting bracket where I think it was rubbing, that's probably want I was feeling in turn 11.

Some video w/ overlay. This is the session that I cut short due to fuel -- I felt it stumble coming out of 5, so I immediately went into cool-down mode, didn't bother to post the video after that. Due to traffic the best lap in here is a 1:48. Apparently my car will outrun a Cayman GT4 down the straight, but not whatever kind of Lambo that is (Aventador?).

I'm still braking too much though.


There are a few issues with the data stream. The ECU data is going from the MS3 to a CAN-to-serial converter that RaceTechnology sells, and from there into the DL1. Somewhere in that translation it's getting converted into an unsigned 16-bit int in 10ths of RPM, which means it truncates at 6554 RPM. That's why the tach stops and pauses there in the video before shifting. There are a couple other interesting values that are getting corrupted somewhere (oil temp, MAT, VSS). Gear is computed using RPM and GPS speed, and it's got a few glitches in it. Brake is the output of the brake pressure sensor, and is also giving a bogus absolute number, although the range appears to be right.

--Ian

 

jeez. that thing hauls ***.

And yes, that was an Aventador SV. How did that thing pass sound?

 

It didn't. The previous session, he didn't want to point a Miata by, so he was romping on it up the hill. 2 turns later he got a meatball, which he ignored until he got it again at start/finish, and only THEN did he let me by.

This was a 90db day, no problems at all for the Miata. The wonderful thing about turbos, they take all that sound-limit-busting noise and turn it into extra horsepower.

--Ian

 

Hopefully I can get my exhaust situation squared away soon. My car needs one badly.

 

(goes and looks it up on wikipedia). I guess I can live with not being able to out-drag a 750hp Lamborghini.

--Ian