Update on crankwalk fix

[Strm Trpr]

NosLaser, you're my hero....

 

[ItsStockOfficer]

Ah, but what if the misalignment is from the phenomenon of the block being made just that much too light? What if it's from them taking just 1/64" too much out of the main bearing and skirt webbing in the area of the center main?

I'm still waiting for a cw theory that fits all the way.

Thats possible. You assemble the engine, with all the torque thats ever goign to be applied in assembly applied, then if its in alignment, it shoud not walk...Is it possible the block is thin and misaligns at high rpms or under high load? That I do not know. But it seems to me that crank walk only happens to 10% of cars, and having the engine precision blue printed under all torque loads with cut that down dramatically. I think misalighnment is assembly is a serious issue, but this is why i said it hold water in my book.

It COULD still be wrong, and I would still go 6 bolt I think, but Im willing to grant this being a seriously good thing to do.

 

[JessesTalon]

Very Very Informative Aslan, Props to you.

 

[NosLaser]

ItsStockOfficer, the main scope to my reply to Defiant was the type of load the crankshaft experiences under 'revolving' load is not the same as the 'thrust load' where the problem of crankwalk lies. To prove that even further, the amount of horsepower the car has really has no bearing (pardon the pun) on whether the car crankwalks or not. It's all about thrust area; the side to side motion that is caused when the block tweaks thus mis-aligning the bearing. This also explains why some cars will walk, some never do, because assembly, even at the factory, is a crapshoot. The focal point is the fix eliminates the 'guessing' and adds to the 'exactness' by machining the block with all the load in that manner that it is ever going to see.

Bear in mind everyone, that this is another theory. In my opinion, it makes the most sense out of all I have seen, however I do not have the ability to provide conclusive results for said theory. All I can say is the few cars I have performed it on have number 1. not crankwalked, and number 2. during assembly measurement, the clearances were the best I have ever seen.

Regards,

 

[ballagsx]

i have one of those late 1gs that have the crank girtle and there is alot of clearence on the thrust bering, but still with in the service limit. you have me paranoied now.

 

[90LaZeRrst]

your info says a 90 dsm.... those do not have this problem, although 6 bolts can walk too

 

[ballagsx]

just my engine is a 94

 

[gotswrv]

Any thoughts on doweling a well seasoned engine before disassembly, that has not had CW ? I've got 185K+ and would like to freshen up a bit next spring.

 

[tommiman]

I'd like to hear 2 cents from a Mitsu engineer that designed the '95+ 4G63. I've been doing a lot of research on this issue but did not come across an acual Mitsu engineer's opinion. They all probably work at McDonald and will take this issue to their graves because of the humility.

 

[talon96tsi]

actually, i would really like to see one of the original mitsu designers involved. that could be a very informative asset in my book.

 

[jedi_light]

noslaser do you have any new updates for this i haven't seen one in a long time?

 

[ImportWarrior]

just found this thread. has anyone else tried this idea?

 

[BaliTSI]

Hello everyone, my freshly built motor just walked! Does anyone have further info on this fix? I mean has anyone performed it with good results?

 

[PieEyedPiper]

By what means was it assembled? Was it align-honed, and torque plated etc during assembly?
Supposedly those are the main deciding factors when concerning a build vs. crankwalk.

 

[Street Surgeon]

But you do have one advantage over the 6 bolts which is the full main girdle rather than cheeseball little main caps. The girdle design *is* much better, just flawed because the manufacturer cheaped out. Huh? Uh oh! Look what happens when you cheap out!! Maybe that should be a lesson to you and your 'cheap fix.' Just food for thought.

Regards,

If that were the case then why do the 2.4l's (of the 7-bolt variety) seem to nearly be impervious to "crankwalk"? They all sport the 7-bolt girdle that was thrown in the cheap way as well. I've never personally seen or heard of onewalking and the built examples seem to be running fine. as well as the other TONS of 7-bolt 4G64's out there in all kinds of cars! I'm not flaming nor am I being a smartass, just thinking out loud.

 

[interex]

There have been reports of 4g64 engines walking, as well as 6 bolt 4g63 engines. You see more and more people who claim "my 2g walked" so they're going to switch to a 6 bolt. More often than not the "crankwalk" people suffer from are their own carelessness, rather than failure to the thrust bearing due to any unknown reason. I've talked to quite a few people with 2g engines that claim it walked but yet the thrust bearing wasn't damaged, and the crank looked good, yet a rod bearing here or there was spun. Also most 2g walked engines happen after 160,000 miles, on a turbo engine and quite a lot of them are on engines running more boost than what the car came preset with from Mitsu. I believe that too is a factor, with kids getting these cars and just racing the shit out of them and then when something bad happens they jump up and yell "CRANKWALK!!!". </rant>

 

[Street Surgeon]

Sure there may be the occasional and completely rare random 6-bolt and 4G64 that walk, but nowhere NEAR as many as the 2G 7-bolt. The OP was reasoning that crankwalk might happen because the head was not installed and torqued down, the girdle not installed and torqued down etc. but the same can be said for 4G64's and they don't seem to suffer from near the failure rate. After reading your post it seems that you think crankwalk has something to do with racing your car or increasing the boost pressure but I have personally seen SEVERAL stock auto 2G's walk. Food for thought.

 

[Defiant]

This thread should be set on fire, but it's as good a place as any for ghost stories.

I've always wondered if the full-girdle bearing caps on the 7-bolt contribute to thrust bearing wear. Someone rich needs to cut that bearing free and do a study.

 

[interex]

After reading your post it seems that you think crankwalk has something to do with racing your car or increasing the boost pressure but I have personally seen SEVERAL stock auto 2G's walk. Food for thought.

Don't get confused with what I said... I am saying that more often than not people will spin a bearing, or throw a rod from racing and then claim they were affected by "crankwalk" just to have an excuse to why their engine blew up.

Yes I know there is a high rate of failure with the 2G engine, and I too with wonder if the girdle has anything to do with the failure rate. And if you check with organizations such as NASCAR and NHRA, they assemble their engines with a torque plate bolted on. My buddy's shop builds all his engines with the torque plate bolted on. How do we know that Mitsu didn't assemble the engines this way?

Originally Posted by

Someone rich needs to cut that bearing free and do a study.

I thought about cutting mine out and just bolting them down without the entire girdle.

 

[sophat34]

funny stuff this crank walking... I had my fresh built 4g64 (2.4) 7 bolt destroy the mains after 12 miles yes 12 thankfully the machine shop covered it. they blamed the clutch adjustment and replaced the mains with mains that were groved to promote oil flow. I only have 400 miles on the motor after that, three years. other than some non related problems it runs well. I am considering building a new motor and i will give the girddle alignment a shot with that one. seems silly to build a motor for preformance and not take advantage of an oprotunity to get consistant and more precise clearnces.