Runoffs Updates - E Production

Thanks man. Big fan of the yeoman's work you've done on the E30. You've got a mess in the rear suspension like I do to figure out! lol

If I can get a dry sump in the car and actually get some seat time I'm pretty confident the car is a 3/4th to 6th/7th car next year at VIR. That may be its limits though at this power to weight. I do think I'm maxed out or very close to it power wise, and 2675 is a lot to be hauling around (with 300 lbs ballast!).
 
I thought the same thing, too (man, you guys like your mini-clutches) but the only load on that outer ring is the starter.

I'd be interested in what the meat looks like underneath the pressure plate.
 
Look at the huge crack on the spoke aiming straight down in the photo. maybe a bend in the flywheel or unbalanced/ vibrations caused a fatigue failure?
 
Good eye! The other cracks started at the same place at 3 o'clock and 5 o'clock and they failed in the same place. 4 spoke o'clock is twisted, leading me to believe the flywheel failed at 3 and 5 and then twisted itself into oblivion at 4 (while making lots of noise in the process).

...leading me to further notice: is it an illusion or is that starter offset wicked wrong? It looks WAY too close on centerlines. If tha'ts the case, the starter itself cracked those spokes, causing the failure.

And...why is the bendix still engaged (another illusion)? Is it bound up on the gears?
 
That looks like a cut flywheel. Not a flex plate . Too thic for flex? The starter hits the teeth but would have some shove it in motion that could tweak the poorly cut./radiused edges.
 
Greg Amy":2al0r2t9 said:
Good eye! The other cracks started at the same place at 3 o'clock and 5 o'clock and they failed in the same place. 4 spoke o'clock is twisted, leading me to believe the flywheel failed at 3 and 5 and then twisted itself into oblivion at 4 (while making lots of noise in the process).

...leading me to further notice: is it an illusion or is that starter offset wicked wrong? It looks WAY too close on centerlines. If tha'ts the case, the starter itself cracked those spokes, causing the failure.

And...why is the bendix still engaged (another illusion)? Is it bound up on the gears?
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I think that's just camera angles and whatnot. the started/bendix is sitting back behind the flywheel and not engaged, but since the photo is off-center and zoomed way out there's a bit of a fisheye distortion going.
The teeth on the bendix do look to be worn- shark fin shaped- but I don't think that's the cause of it.

Is there a dust cover of any sort between the engine and trans? Since there's nothing behind it in this photo, I'm curious if it's not there and debris (rock, lugnut, etc) could have been introduced and caused damage to the flywheel, which then spiraled downhill from there.
 
Bingo, yes, dust cover of light sheet metal. It looks like an exit wound there though, not entry. I think the broken piece of the flywheel exited there.

Starter is not engaged, that is in fact an illusion.

Failure was shifting at full throttle on the front straight. 7,000 rpm.

Flywheel is from a rally outfit in Australia that uses them on their 400 hp, 7000 rpm rally cars using the Rover V8. It's chromoly steel. They've had no failures.....but that doesn't mean road racing stresses it differently.

Car is down significantly power to weight versus other cars in class so you look for every place you can gain. You all know rotating mass is about as easy hp as it comes.

I'm wondering if the dog box puts more stress on the flywheel and causes the harmonics Jesse points out likely cause failures like this.

This sucker was 6 lbs. I'll move to something more solid and go further in the hole power to weight wise...lol....
 
Jeffyoung":zfjkrv63 said:
Bingo, yes, dust cover of light sheet metal. It looks like an exit wound there though, not entry. I think the broken piece of the flywheel exited there.

Starter is not engaged, that is in fact an illusion.

Failure was shifting at full throttle on the front straight. 7,000 rpm.

Flywheel is from a rally outfit in Australia that uses them on their 400 hp, 7000 rpm rally cars using the Rover V8. It's chromoly steel. They've had no failures.....but that doesn't mean road racing stresses it differently.

Car is down significantly power to weight versus other cars in class so you look for every place you can gain. You all know rotating mass is about as easy hp as it comes.

I'm wondering if the dog box puts more stress on the flywheel and causes the harmonics Jesse points out likely cause failures like this.

This sucker was 6 lbs. I'll move to something more solid and go further in the hole power to weight wise...lol....
Click to expand...

You could actually have something custom made with a flex plate, go with a triple disc 5.5 inch clutch and gain a ton of moment of inertia which will actually help everything over that 7.25 clutch you're currently using. And btw, this won't affect anything. Make it reliable and get that car out there. Driving and setup will help more than anything.
 
One comment was "the only load on that outer ring is the starter." As a mechanical engineer, I must point out that this is not correct. When the gear is spinning, there is a large centripetal acceleration, resulting in tensile stresses. The material has to resist those to stay intact. The sections of gear between the spokes have to transfer their force to the spokes, so there is more stress on each side of a spoke. Also, each gear tooth "valley" is a known stress-concentration point. The failed and visible cracks (there might be a few more barely visible ) are at those locations.
One other thing might be a factor: the material was given as "chrome moly" which refers to a number of steel alloys. Many of these are heat-treated to develop the full strength. One text-book problem with heat-treating parts is that not all areas will heat and cool at the same rate. Here, there is a larger area of metal at the outer end of each spoke, so it will heat/cool more slowly. This can result in residual stresses. This might be part of the problem if the process was not well-controlled. The process of "normalizing" is often used to reduce the residual stresses - maybe it got skipped/missed? The maker should be able to tell you what they did. Regards, Joel
 
Hello Joel! that was actually very helpful. The seller (Triumph Rover Spares in Australia) says their suppliers says (hearsay!) they do normalize. They (the seller) are mystified by the failure and I take them at their word as these guys do actually race (well, rally, but in a much higher hp application than mine) these cars (TR8) and motors (Rover V8).

All that said, I'm going to try the Atspeed setup from the UK, custom drilled for a 140 mm (5.5") clutch. Link here:

http://www.atspeedracing.co.uk/products ... 184mm-race

If anyone sees any obvious issues with that choice, I'd be grateful to be forewarned.
 
thank you sir. I appreciate the wisdom based on real experience!

The crazy thing is this is only a few lbs heavier.
 
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