Crankshaft Failures

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josborn · #11 Post by **josborn** » Wed May 12, 2004 4:06 pm

LIMIT THE RPMS! It's pretty simple, I know for Mx I don't ever touch 10-11 grand, unless I miss a shift. It's probably what killing the cranks. High Rpms shorten crank life.

haydug · #12 Post by **haydug** » Wed May 12, 2004 4:22 pm

OK, here is one issue that I have noticed, 7 out of 10 motors the wrist pin need knocked out, they appear to be starving for oil. Posted is a picture of one I just took apart. Usually you could re-use a wristpin and get by with it no problem, but this one is obviously a shot.

haydug · #13 Post by **haydug** » Wed May 12, 2004 4:47 pm

I would also like to take a moment and commend John for his comment, seems Diamond Racing has found a problem, and will try to correct it. That is good business. Jim is a nice guy, and easy to get along with. I hope this crank issue doesn't get the best of him. Have a nice vacation Jim!!

claas900 · #14 Post by **claas900** » Thu May 13, 2004 10:49 am

..I have an idea,and might sound really gay..and let me say first that im not 100% sure on how the oil flows threw on theses motors, But i think itd be really nice to find a way to use the gear oil to oil the head,and have to motor oil only for the crank,bottom end......
I dunno might be dumb,but hey thats ok cuzz its 3;40 am right now..

bphillman · #15 Post by **bphillman** » Sun May 16, 2004 3:09 pm

I too had a failure on my Winky crank. Big end. Roughly 10 hrs or so of riding. Pics attached. Notice the side clearance at the rod. As well, notice the missing pin plug. That = no oil pressure to the big end bearing.. No evidence it was ever there. I certainly hope he does do something, while appreciate and applaud the efforts he put forward, I cant stomach another $1800 rebuild. The sleeve and piston have wear (scoring) from the lateral forces exerted when the crank failed. So I get to do that again as well.

bphillman · #16 Post by **bphillman** » Sun May 16, 2004 3:11 pm

and the other.. note that the evidence of the pin plug not ever being installed is there was no damage to the cart. plate. No rub marks, nothing at all. It just wasn't there.

Canniboomer · #17 Post by **Canniboomer** » Sun May 16, 2004 3:25 pm

Perhaps there is a routing we can actually drill a hole through the motor casing and insert a threaded nipple to route more oil from spar directly to crank and near wristpin? There HAS to be a way?
I hope they come up with a solution soon -- afraid now to install and ride my new motor.

Question, if we stop and lay our rigs on their sides every 20 minutes, would that assure some "bathing" of oil to the crank and wristpin?
Or maybe losing control and tumbling down a hill? would that get all the internal parts oiled again? JEEESH

Wow , could it really be that all these expensive fixes all these months are directed at over-compensating for a more basic weakness of poor internal lubing..?.

Just think... what if we can all rest assured again that the WHOLE motor is getting constantly lubed? What if that could make all these risk factors go away, or at least be same with other Quads?
Yep, we sure need "ALL HANDS ON DECK" to solve this problem.

Canniboomer · #18 Post by **Canniboomer** » Sun May 16, 2004 3:36 pm

bphillman, thanks for your posted pics --

that burned discolored area in middle of crank? any evidence of it getting oiled? Or did high friction there burn it up anyway?

bphillman · #19 Post by **bphillman** » Sun May 16, 2004 3:56 pm

I assume you are talking about the blu-ing of the rod big end. It obviously got real hot with no oil and discolored. Honestly, the fact that it lasted the 10 hrs is an absolute miracle. What oil it did get was from centrifugal force, and not pressure.

cannondale27 · #20 Post by **cannondale27** » Sun May 16, 2004 6:10 pm

This is the kind of info that will solve this problem.Obviously the lack of plug started this.But it looks to me like one of your thrust washers actually is gone!Or is this one with 02 rod and no thrust washers?In that case the halves seperated or werent put together enough but I doubt it.
Lots of heat there but for washers to actually disintegrate shows a weakness.I suspect there is plenty of oil pressure but it is being directed to the wrong places.Needs to be oiling Rod and Cams the most.Check out the hole in pic below.That is a awful big hole just to oil a main bearing it is also before the rod bearing.What do you guys think?