About 1/2 way through Saturday's race I was sitting firmly in 3rd place (in class) and still within reasonable striking distance of 2nd place. 1st had sort of checked out.

I was having trouble dealing with the backmarker spec miata traffic (go figure), but 2nd place had the same stuff to deal with. Only problem was that he was slowly but surely dealing with it better than I was and gradually gaining ground on me. I still had a shot though, 4th place wasn't even in my mirrors, so I could concentrate solely on what was in front of me.

Thats when it happened. Coming down the front straight at WOT I hear a "pop." No, not really a "pop," more like a "thump." No... Maybe a "thud."
Hmmm... Lets go with "Dull Pop" and you get the idea.
The "dull pop" was followed by alot of smoke inside the car. I glanced in my mirrors and could see nothing trailing out behind me (smoke or fluid). A quick glance at the oil pressure and temp gauges showed all was well there. By this time I'm already in turn 1 and trying to be at least a little off line in case I'm dropping fluids.
As I climb the hill out of 1 I recheck all the gauges and all is still well. Motor sounds normal, car feels fine. I enter turns 2 and 3 slightly off line still playing it safe and checking the tranny on the downshift... No problems.

So now I'm in a position of "Something definately happened, but everything seems fine." If I pull in I give up a sure 3rd place finish. If I stay out I might damage the car further.
During this time I've lost even more ground to 2nd place. The smoke is gone, and I'm not being shown any flags saying I'm dropping stuff off the car. So I decide to back out of it a bit and bring it home in 3rd place. By this time I've pretty much decided that I've blown an inner CV boot and the smoke was grease hitting the exhaust pipe. Well, I'm HOPING thats what it is.

Car continues to run fine and finishes the race in a solid 3rd. It only took a quick lift of the hood and a hand full of grease from its underside to verify the boot issue.
The specific diagnosis... Earlier in the day we were working on the car and idling it for a long period of time trying to heat it up (it was a cool day). Apparently during this time the exhaust pipe weakened the unmoving inner CV boot above it and it ruptured later in the race. I had heat wrapped the header collector under the oil pan, but hadn't carried it back the extra 7" that would have prevented this problem. I will remedy that oversight tomorrow.

So, CRX and Civic guys... Have you sheilded your inner CV boots from your exhaust? You need to.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Catch 22 &raquo;</TD></TR><TR><TD CLASS="quote">
So, CRX and Civic guys... Have you sheilded your inner CV boots from your exhaust? You need to.</TD></TR></TABLE>

Um, no. I guess I'll add that to my list this week.

-travis, who has experienced the "dull pop" with not so benign results.

 

Although it might be tied in to letting the car idle, I had one let go last year and I couldn't attribute it to anything except luck/age/whatever. I'd think they just let go - probably not a bad idea to replace them every dozen races or so. Do you know the age of the boots?

 

The shafts were only 6 months old. You can actually see the signs of the heat stress on the boot. Its not really "melted," but its been adversely affected.

The CV joint itself seems fine. There was still a fair amount of grease in the joint and it appears that all I need to do is refill it with grease, reboot and go.

 

We used to "band" boots by putting tie wraps around the small (inside) diameters of the bellows, ostensibly to keep them from ballooning out at high centripetal accelerations. I have no idea if it made a difference but a guy who I trusted about engineering stuff gave me the idea and I've seen it on factory-team World Championship rally cars.

K

 

This post makes me glad I got the Autozone lifetime guarantee on my CV's
But seriously I have NEVER heard of anyone doing anything to keep the boots protected. Are you sure its just not a bad exhaust routing/ something like that ?

 

Scott, sounds like you are letting the car idle for way to long before you go out. You are the first person I have heard of having this problem. On your out lap you put more heat in the engine oil than 45 min of idle time, without heat soaking other parts that you might want to stay cool.

 

I normally don't let it idle that long, but Brandon and I were troubleshooting a problem and trying to get the thermostat to open and the car just wouldn't heat up. It sat idling for at least 15 minutes.

Apparently this also happened to Chuck's new CRX its first time out. It had brand new shafts on it.
Its something that I'll be keeping in mind from now on. And I'll be wrapping that section of the exhaust immediately.

 

As I sat on the backstretch watching you go by I thought I saw
smoke but wasn't sure why...Now I know....I had that happen
to me once & I pulled over right away....Kinda like this week
when it was just a coil wire!