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Posted by: wndsrfr Nov 11 2012, 07:59 AM

Got in about 20 minutes at Roebling then heard serious knocking from the engine...limped into paddock & shut it down. Towed it home (950 miles round trip for 20 minutes on track ) and dopped the engine. Couldn't turn the crank by hand on the fan. So, split the cases. Here's what greeted me as I opened it up--one ear of the windage tray had failed and slid over and was caught under the cam. Check the pics--you can see where the cam was striking the sheet metal piece....nice and shiny there.

It's a "CB" bus case.....anyone seen this before? Anyone with a replacement tray??

Now the plot thickens...see the pics of the crank....think it'll buff out?

No wonder it lost power....


Attached image(s)

Posted by: 914Sixer Nov 11 2012, 08:20 AM

Was the bolt that holds the tray loose or missing? Second was the tray possibly not slotted correctly in the case? If one side was out it would be bent up in to the cam. Did the tray have the seals on it or did they stay in the case.

Posted by: wndsrfr Nov 11 2012, 08:28 AM

The cross bolt was in place and tight....it was slotted correctly with the seals glued to it with a dab of weatherstrip adhesive at the ends--you can see a bit of it in the photo. Seals still in place in the case slots--looks like fatigue failure right at the ends of the louvers stamped into the tray ear.

Posted by: Matt Romanowski Nov 11 2012, 10:09 AM

I've had them break, but never dislodge from their place.

Posted by: wingnut86 Nov 11 2012, 10:10 AM

This won't help the broken one, but I have read about many racers or at least frequent builders, who create additional slots or holes in the tray to allow for faster oil drainage back to the sump. Not sure that's a great idea with normally aspirated blocks, but if you are running AX or Track, have larger oil demands and have outfitted your block with a stronger oil return system with extended sump and similar, maybe this would diminish this happening in the future?

You need more oil in the twisties, turns and climbs, but not at the loss of oil in other areas without proper volume and pressure to go with it.

Just ruminating here...

Posted by: wndsrfr Nov 11 2012, 11:39 AM

ttt

Posted by: NORD Nov 11 2012, 12:24 PM

I'm wondering? Did the broken crank break the windage tray or the windage

tray break the crank??

Sorry you broke down.

Posted by: brant Nov 11 2012, 12:30 PM

I don't think the tray could do that to the crank...
I'm guessing your crank broke first and then caused the tray as collateral....

Posted by: zambezi Nov 11 2012, 03:08 PM

I agree.

Posted by: messix Nov 11 2012, 03:27 PM

who did your crank?

i would have them take a look...... or may be another engine builder.

for the crank to break there, there had to be some thing really wrong with the crank before machining or with what they did while maching it!

Posted by: Valy Nov 11 2012, 04:31 PM

Look at the journal of the rod next to the crank. That crack goes to the oiling channel. What size is it? Looks 80mm to me, correct?
This failure is typical for poorly welded and enlarged cranks. The oiling channel is too close to the wall and weakens the crank.
For your next crank, make sure the oil channels were correctly relocated.