vwong

No, this is not from my TSX, but it is from my Prelude. Ouch...

CGTSX2004

iTrader: (1)

Dayam...what caused that? It's a pretty jagged break too.

car_lost

:0uch: what happened?

dom

Prelude engines blow alot don't they? Same thing happened to a buddy.

Dan Martin

Bananaairsoft

What...happen?

CCColtsicehockey

vwong

We're still trying to figure out what the root cause is. This crank had 130k miles before I spun a bearing at the exact same place. My friend sent it out for a regrind. 10k miles, 3 track days, 2 National Tours, 1 ProSolo, and 6 weekends of local auto-x'es later, it broke. We're thinking maybe when I spun a bearing, excessive heat was introduced to that portion of the crank, and it got weaker. And those high-revving events may have helped it to develop some cracks. Fortunately, this happened during normal daily driving. So far, we haven't seen any other damages due to this broken crankshaft.

Dan Martin

Actually that's a pretty good theory. What happened when you spun the bearing is you essentially heat treated the crankshaft. Heat treated metal is harder but more brittle which could explain the jagged edges in the fracture.

CJams

ouch!

Black_6spd

Any torsional failure (as opposed to shear or tensile failure) will produce jagged edges like the ones seen in the pictures. Grab a piece of chalk and twist it until it breaks. You'll see the same thing, usually with a 45 degree angle.

My gut feel is that the high stresses caused it to fatigue.

aodaniel

Engineer speak! I thought about pictures of shafts with torsional failure from my machine design textbook when I saw this picture.

Black_6spd

LOL. I should have hung on to my Machine Design text. I kept my strengths, statics, dynamics, thermo, and some others. I've been trying to find the equation for rolling resistance that would translate the diameter and mass of a wheel into a force. Unfortunately, all of my equations from my dynamics book shows some tangental and normal forces involved in a rotating body, but I can't seem to recall how to apply it to one of our rims.

Let me know if you find the equation. I believe it should be in the section dealing with gears.

rmpage

Nice. You a ME? In any case, please post more.

05_TSX_GP

Wow! How much would repairing something like that cost? I suppose it would require at least replacing the crankshaft and some bearings? Essentially a rebuild since all internals are exposed.

I should send this thread to my ME buddy.

goddsmack

He's look at least at a new short block and if the pistons of the broken section of the connecting rods hit the valves, then he's looking at the very least a valve job if not an entire long block.

I personally would buy an entire long block at that point.

[EDIT] The first picture finally showed up. It looks as if he might be able to salvage the block.

vwong

My friend has already pulled the motor out. While I'm waiting for a new crank to come in, he's going to disassemble the motor for further inspection. From looking at the motor, it seems like the block and the rod are fine.