Crankshaft Failures

Message

cannondale27 · #61 Post by **cannondale27** » Wed May 19, 2004 1:52 pm

I believe it has been said that it is a rebuildable crank so I would assume it is press fit at normal pressures and if you wanted to have it welded you could have that done anywhere.The welding is normally done just for extra security.

bphillman · #62 Post by **bphillman** » Wed May 19, 2004 3:17 pm

a couple of things...

why couldn't we have "x" amount machined off the mating area of the pins before reassembly so as to require less force, and then have the pin welded? I personally think that resolves 2 issues. I have been told by a shop in the know that at thr RPM's our cranks spin, the pins should be welded anyhow, that the forces cause a sort of distortion. He stated he would NEVER no weld one of these cranks.

WolfmanGK · #63 Post by **WolfmanGK** » Wed May 19, 2004 4:55 pm

I hope a resolution is found. I want to stick with the Dale, but if reliability cannot be improved then it's better suited as a display, safely surrounded by plexiglass.

cannondale27 · #64 Post by **cannondale27** » Wed May 19, 2004 7:42 pm

Bp I agree.The damage to the pin could be occuring when it is taken apart.But at that point you should be able to magnaflux it .

bphillman · #65 Post by **bphillman** » Wed May 19, 2004 8:52 pm

I found that I am dropping letters off my posts... Sorry

Here's a resubmit corrected just in case....

QUOTE

why couldn't we have "x" amount machined off the mating area of the pins before reassembly so as to require less force, and then have the pin welded? I personally think that resolves 2 issues. I have been told by a shop in the know that at the RPM's our cranks spin, the pins should be welded anyhow, that the forces cause a sort of distortion. He stated he would NEVER not weld one of these cranks.

crawlr · #66 Post by **crawlr** » Thu May 20, 2004 4:09 am

I'm sitting here reading this whole thread thinking 'why doesn't someone build a roller crank for these things and eliminate the oiling issue'....then I get to the post that says it IS a roller crank!

This is definately not an oiling problem. Roller bearings need very little oil. What roller bearings need is a perfect surface to run on and that is clearly where the problem is. The pin being distorted is a good place to look. I think the Falicon cranks might be the best fix.

Another thing to consider is roller bearings need to be kept VERY clean. Any debris can kill them. With all the other parts of these motors getting ground up and contaminating the oil, I'm surprised more cranks didn't fail

kdeal · #67 Post by **kdeal** » Thu May 20, 2004 9:55 pm

QUOTE

Originally posted by cannondale27
Bp I agree.The damage to the pin could be occuring when it is taken apart.But at that point you should be able to magnaflux it .

Magnafluxing will not show distortion or any twisting, it will only show stress cracks.

bphillman · #68 Post by **bphillman** » Sun May 23, 2004 2:53 am

But they can check for distortion before the crank is reassembled. Generally, the pins are somewhat chewed up, and need to be filled and machined smooth. Heres what I am going to do.. I have asked Maz and/or Scott to ship me out a couple of bad stock cranks.. I am going to have the pins magnafluxed, reworked and machined down slightly at the mating surface of the crank web. I will have the pins welded and then spin balanced to have the balance point optimized for 10,300 rpm (my estimate of the average operating range I run). This will not be cheap, as it will require the crank to be pressed together and apart several times to balance it correctly. In the mean time, I am in negotiation with Oliver Rods to provide an incredibly light and super strong billet rod, also not cheap, but I think having less reciprocating weight will do nothing but help the situation, as the pin is getting the brunt of all the forces, and the weight of the rod and piston assembly is exponentially greater under load than it is when static. I will assemble my motor and tear the living heck out of it in the desert for the summer, mostly at wide open throttle, and under extreme heat. If this doesn't break it, I don't know what will. Anyone want to participate in the testing? As well, if anyone has a stock connecting rod laying around, please let me know as I need to get it to Oliver so they can take the measurements and produce it ASAP.

bphillman · #69 Post by **bphillman** » Sun May 23, 2004 3:08 am

the TBD? Cause it also is unproven, and I am not sure when it will be produced. As well, I like having alternatives. I was also told (people in the know please chime in) that it is similar in design to the yfz crank, being a full circular crank, and is balanced differently than the stock crank. It ability to work well with the stock counterbalanced has been called into question.. Again, I am not sure about this, and am interested in knowing.. BTW, the counterbalancer WILL be part of the balancing process with this upgraded assembly. As well, the cost to consumers of the end product will be comperable if not somewhat less than the new Falicon prices that have been posted. Itintally, it will be more expensive (for me).

cannondale27 · #70 Post by **cannondale27** » Sun May 23, 2004 3:42 am

Go for it!The more the better.I also would like to do a Q&A session with whoever is developing any new cranks.I personally believe the big rod side clearance was intentionally put in to get more oil to the piston pin and bottom of piston.A combination of less side clearance and a round web which would sling less oil might affect things more than we think(Falicon).
I assume the crank you are designing would be welded?Ballbearing main bearings?