To crankwalk or not to Crankwalk!

[Speed JUnkyz]

Ok we have recently fired up a debate on this forum that I am sure is all over other forums. Especially DSM forums(<hint).


Lets see who can solve this. Lets see who can prove themselves in the info that they have provided.

From Vibration? Or from what?


For the user who can prove with proper and legit information of what causes "crankwalk" in the DSM's, I will award 20,000 credits.
If more than one user puts a submission in, I will be the judge on who gave the most accurate, most clear, and fulfilled answer.

Everything is taken into consideration when judging.


Thanks for looking. I will sticky this thread until the contest is over.

I will give you guys one week to read this and research the answer. So you can not post any answers until 7 days from now. Any answers posted before 7 days from now will be disqualified.


So on Sunday the 16th at 2:00pm you may start posting. Anything before 2pm will be canceled out.

[JONPKA24]

bad oil squirters, mainly in 7 bolt tran i believe. the oil squirters arent sufficient enough to do anything really.

[Speed JUnkyz]

Thanks for responding Jon.... Noone else cares to share?

[Scrapy]

There are SO many theories it is rediculous. This is what my friends and I have come up with upon inspecting various 2g engines.

Lots of people think that matching the crank bearings will work. it will not, it is merely a bandaid. What we have come up with is that crankwalk is most likely caused by the main girdle not being correctly matched to the block. Depending on the block, the girdle is shifted either forward or backward. This causes the crank to ride either on the top thrust bearing or the bottom. Basically, only half the thrust bearing is taking the load. Now, the reason this is noticable on more 2g's than 1g's is because 2g's have the crank posistion sensor that gets messed up by the above problem. The tolerance between the crank position trigger plate and the crank position sensor is very tight so the crank walk can easily break the crank position sensor. Also, using a stronger clutch such as an ACT 2600 could help speed up crankwalk because all that thrust is pushing on the crank and and only half the thrust bearing is taking the load rather than the whole thing. Finally, the thrust surface on the 2g's thrust bearing is smaller than that of the 1g's, which does not help at all.

All those issues help to cause crankwalk.

(I WIN!)

[Vr4]

Incorrectly cut cranks primarily in 95+ 7bolt 4g63t engines.

[Sl3d0fR0ck3tz]

Having worked on quite a few DSM's professionally, and spending the better part of a decade owning, maintaining, and extremely modifying one, I'll chime in.

Many people have studied the failures, from backyard wrench monkeys to professional engineers. They have done everything from testing crankshaft size, balance, material, hardness and nitriding, which I believe the 7 bolt crank is not nitrided from the factory, to testing oil squirter operation; checking main and thrust bearing material, alignment, clearance, loading, and oiling; and cutting blocks apart on bandsaws looking for core shift and testing composition. Non harmonically dampened crank pullies were even blamed a time or two. Never has one issue consistantly been proven to kill the thrust bearing. There have been many hunches and much speculation, but never one solid answer.

Many fixes have been attempted, including line honing the mains then dowel pinning them in place, careful assembly and thrust bearing alignment along with bearing modification to increase oiling, removal and plugging of the oil squirters, possibly nitriding of the crankshaft. Lighter spring pressure clutches have been tried, but that can be negated by the fact that even some automatic transmission cars have walked, and they see minimal thrust load on the crankshaft. Aftermarket harmonic dampeners have been tried. Clutch switches are also disabled to prevent from pushing the clutch pedal in to start the car. I'm sure I'm forgetting a few that I've seen over the years too.

The issue in it's entirety is dang near impossible to pin down exactly what causes it, or what will fix it. It seems to be completely random, and if it's going to happen, it's going to happen. You will find some websites that claim to fix it, but in reality, maybe those blocks and cranks were never going to walk in the first place. Noone can say.

Mitsubishi did redesign the bearing in 1998, and it's said that if you are using a 7 bolt, the 98 and 99 are the best to get, yet still have a better chance of walking than the 6 bolt, from what I remember.

I also must state crankwalk is not as common as the internet makes it seem, it occurs in a very low percentage of the vehicles on the road with the 7 bolt 4g63, an even smaller amount of 6 bolts walk.

So after all of that, here is my answer to the question. No offence Speed JUnkyz.

I don't feel anyone on this forum is qualified to determine if the correct answer is given or not.