I can't post up a thirlling race report of victory and glory like Al, so figured I'd put this up instead.
Certainly not the worst failure I've had, but one of the ones that stunned me the most. (Matched only by the starter that had the flange crack, and starter fell off. Bolt and flange still attached to car.)

Early in the first race of our last race weekend, we see this (engine is fine, turns out to be transmission fluid on hot exhaust):





Fluid seems to be leaking from everywhere, which baffles us. So we just dropped the transmission. I was shocked. Tail-shaft is cracked 3/4s of the way around. Can't say I've seen that before. It may be terrible luck, but I prefer to think that now the ignition issues are fixed, Joe just built me a heck of a motor.

 

Is your rear tranny mount a lot stiffer than the motor mounts?

The only time I have ever seen something like this is when an old style Duster with a 440 used stock motor mounts and a machined aluminum tranny mount. One clutch drop and BANG!

The only other possibility is that the tranny was dropped and a stress crack started inside and the billiard table smoothness of your home track worked on the crack and it finally failed. Once the crach starts it will move very quickly.

Now on to the more important question. Is that a race SAAB Sonnet or a 260Z ahead of you at the start?

Eric

 

Mazdaspeed competion mounts for tranny and motor. Bought them together. My thinking is you are right, and it took a hit at some point in it's 20+ years of life, and that's the result. Such is my luck. I'll just choose to believe it's the motor that Joe built making it happen.

But, as you said, on to more interesting stuff. No SAABs I'm afraid. (Although there is a really cool TR7 with a huge widebody kit that shows up once in a while.)

Blue and white car immediately ahead and to the right is a Nissan Pulsar Turbo. Silver car to the left is a 240Z with ridiculous fender flairs. We have the normal collection of Civic's, Golf's, CRXs etc. and on the left side going over the crest of the hill are a former Motorola Cup Elantra and an Accent. The Datsun 510s are over the crest.

 

I was driving during the first race, and I was like "Do I smell something burning??" Then I did another lap. Definitely smelled something burning. Another lap, "hey there's smoke behind me...." Another lap "*cough cough* Now there's smoke in front of me. I'm going into the pits."

Haha

 

Oh Snap! haha i couldn't resist.
It always sucks retiring in the middle of a race however it does give stories to tell.
get then next one in there and have some fun!

 

Holy David.....dont be beating on it so hard!! haha.

 

Second question if I may. Are you running on 23.5x9.0x15 Goodyear slicks?

What size wheel are you using? Are you feeling any vibrations?

My thoughts are leading me in a different direction.........hmmm?????? I may have seen something like this before.

Eric

 

Sweet carnage.

Neve a dull moment with mechanical things.

 

RPM: Half the reason I'm at the back is I'm afraid to break it. I'm starting to think I share parts with Al's car. But, at least if we break it, we do it with style.

Eric: Ask away. This is why we share this stuff. 23 * 9 * 15 Goodyear slicks it is (not 23.5). R430 compound on the car. (You have a heck of an eye if you spotted that.) wheels are 7" wide, which is Goodyear's recommended width. No vibrations (other than bumps in the track etc.) but I'd love to hear the theory.

Classic: We aim to please. Love to see what other carnage people have managed. Jump on in.
I'll have to dig out that starter with the broken flange. Got dragged around the track on the starter wire for a half a lap, bouncing between the track and the floor.

 

Tales of victory? How about tales of me driving like an idiot lol! My video's arent up yet but there will be a great moment where I try and drive into the turn 5 wall! I too always start at the back because I only run the one day here. Saves me about $125.00 in entry fee and parts/fuel etc etc. lol I cant get a stock tranny to live beyond 40 minutes but we always break something internal. I am truly starting to think all RX7's are possessed maybe its time to sell and buy a stock car with a crate motor....................... Btw we run solid aluminum engine mounts but keep the rubber ones on the gear box, I was told by a Guyanese guru solid tranny mounts break the case....

 

I should throw up those pics of my front torrington bearing (or should I say the metal shards that were left or it). You did an amazing job on that transmission. The only other time I saw anything like that was when a guy had two different size tires on his cummins diesel ram and decided to drive in 4wd on pavement. That tranfer case turned into a grenade.

 

Just an idea.

Check the country of manufacture. There was a bunch of those tires that were made in Chile that had a belt issue where the internal belts overlapped. I will check today with my buddies in Vancouver for more information on batch codes or date codes. It balanced fine, but under load the tires would wrinkle like Top Fuel slicks. It was happening all the time in NASPORT Races out on the west coast.

Now the theory. The transmission had some stress on the tailshaft. This could be from the main case to tailshaft case not being a perfect fit, different bolt torqueing, the perpendicularity being off between the transmission and the rear differential, the transmission being dropped at some point in its life, whatever..... The car is now developing about 2X the power of the previous motor. Things are okay for a while. You add in the extra stress from the slicks, more confident driving, then a tire vibration from the bad belt wrap. This vibration gets transferred back through the diff to the driveshaft. This manifests itself into a slight front shaft whip that causes the tailshaft to start oscillating side to side and up and down. A period of time goes by and then CRAACK!!!!

I used to see this stack up of issues all the time during dyno durability testing of brackets on the front of motors. A motor would see a vibration from an unbalanced dyno flywheel and it would keep throwing the alternator off at a certain sustained rpm. When you looked at it using stop motion cameras you would see it moving about 2 inches.

I bet that half the unexplained failures in modified cars is due to issues like this.

Eric

 

Eric that was pretty insightful. Food for thought for sure.

I like to use my timing light at high RPM sometimes to just look at stuff. It's amazing how much belts flop around sometimes.

 

Eric: Wow. Great post. I hadn't even thought of a chain of events like that, but, something like that wouldn't surprise me at all. I guess that's why I'm more bemused than annoyed at the carnage. If you had any info on those tire batches, I'd love to give it a look.

Buggy: Go ahead and post it up. I'd love to see other examples of what we've managed to destroy.

Al: 40 minutes on a transmission? Wow... I thought I was hard on the gear. Mind you, last season I only completed we had a couple of test days, one race weekend, and one day of Solo2 (Canadian nationals were here) and I went through 4 transmissions...

 

Stock RX7 n/a gear box=JUNK! Vids are posted on Vimeo of last race if you want to dumb driving (referring to me!) about the 9 minute mark
http://www.vimeo.com/5332670 1st race Sunday
http://www.vimeo.com/4633223 2nd race Sunday

 

How did that go? If i didn't have bad luck i'd have no luck at all!

 

Sorry to hear about the setback, keep smiling if you can.