Crankwalk Sources

11-26-2003

JET's 1G engine had a major crankwalk issue last summer. It got to be so bad the block and crank were destroyed. It is not common for a 1G engine to develop crankwalk, especially the pre-92.5 engines. The 7-bolt engines with manual transmissions have a relatively high occurence of crankwalk, though. 7-bolt engines with automatic trannies have almost zero cases of crankwalk (I have not heard of one).

Crankwalk is the result of thrust bearing wear in the engine. The thrust bearing (a.k.a. the "center bearing") keeps the crank centered longitudinally so it can't move in and out over time. This is necessary to keep the forces presented by the rods on the crank within tolerance to prevent the crank from breaking.

Automatic trannies present virtually no end force on the crank so the thrust bearing has little to do to keep the crank in place. However, the force used to disengage the clutch in a car with a manual tranny also pushes the crank against the thrust bearing. AN ACT 2600, for example, presents as much as 700 pounds of force at the thrust bearing (stock clutches present about 400 pounds). The increased force ought to prematurely destroy the thrust bearing but the superior oiling system in the early 1G engines seems to stave off the inevitable, though it has no right to!

A thrust bearing will fail if the oil film between it and the crank fails. There is to be no metal-to-metal contact there. How an oil film breaks down is beyond the scope of this post, but suffice it to say that oil that is too thick or too thin for the application can result in thrust bearing failure. Thick oil will shear and leave air gaps where oil is supposed to be. This is especially true in engines that rev beyond their design limits. Added disengaement force from stiff aftermarket clutches only exacerbates the problem. Air gaps result in reduced load braing surface area which allows the two surfaces to move closer together which increases oil shear and the creation of even larger air gaps... runway failure!

Another ugly scenario has been discovered as a source for crankwaalk, although it often ruins the transmission first. On many modded DSMs the tranny has been removed many times. It happens that there are two guides that align the tranny with the block. If one or both of these guides is missing, the tranny can quickly become misalinged with the crank. The result is that the tranny input shaft is caused to wiggle around which leads to loosening of the tranny bolts. When this happens the misaligned tranny creates a continuous load on the thrust bearing.

The guides sometimes just fall out when the engine block is being handled. Sometimes they stay with the tranny, too. I have seen this several times and the results both times ruined the tranny input shaft bearing. I suspect this is the cause of JET's regrettable crankwalk, the subject of much debate and ridicule.

Anyway, before the implemenation of modified automatic trannies in drag cars with big block motors, it was common to have to replace the thrust bearings in those motors after just ten times down the track!

Rick

AJ · 11-26-2003

I am going to get in this right from the bat! If this turns into another go of the shit from MN DSM list in anyway, I won't pass any thoughts and just delete this. Otherwise lets discuss and help others out who need to undertand this in a cival matter.

Thanks,

Allan

**Kracka** · 11-26-2003

I love Shindley.

**JET** · 11-26-2003

I will play fair as long as Rick does. I thought we had already gone through this on MN-DSM, but here goes again.

My engine was crankwalked after 7k when I pulled the tranny off to put the Shepherd tranny in. Note that the tranny guides were in place until then. This means that the missing tranny guide had nothing to do with the crank walk.

When I put my Shep tranny in I had weird clutch engagement. I had been having this trouble for a long time and had talked to Rick about possible causes for it. He recommended bleeding my clutch a certain way, that didn't help.

Anyone at the shootout will remember me bleeding my clutch 10+ times trying to get the damn thing decent.

I do not know for sure when the crankwalk started, but I was having shifting problems within a month. I broke it in for 500 miles and had never been to the track.

The main culprit we came up with on MN-DSM was that the block was not align honed after the ARP main studs were put in. After much searching this has happened to many other people.

So, the lesson here is to get your block align honed if you are using ARP main studs. It ended up being a $3500 lesson for me, even though I asked Rick if I needed it and he said no.

TheBlizzard · 11-26-2003

NABR DSM ARCHIVE

For anyone that is a non believer in align honing when using ARP's here is one of the many many threads on NABR about the subject.

Just go to search and type in align honing and you will see many threads on this subject. Without the procedure being done even a 6 bolt can see out of spec crank movement withing 900 miles of a full rebuild.

And I can personally vouge for Jets car not shifting any differently with a 70,000+ tranny or a brand new Sheppard Racing Tranny. I drove the car just as much as he did and it shifted like shit with both of them. It didn't make any difference when the new tranny went in, it shifted the exact same as the one before it did.

So that would lead me to believe that it was crankwalked long before the tranny was even touched.

Also if you do some searching on the various boards you will see one of the signs of crankwalk is having major shifting problems.

Well there my two cents and that is just my opinion based on what I have read. But I can say one thing, I trust words spoken from the guys that I have recieved my information from though and would follow suit if I had a rebuild done. :jammin:

CRAIG

**Kracka** · 11-26-2003

Quote:

Originally posted by CUSTOMDSM@Nov 26 2003, 02:42 AM
Well there my two sense (you spelled this word wrong) and that is just my opinion based on what I have read. But I can say one thing, I trust words spoken from the guys that I have recieved my information from though and would follow suit if I had a rebuild done. :jammin:

Its too bad than none of the people who have recieved exceptional service and/or work from Shindley post up their every story. Didn't Shindley offer to help tear the engine apart and assist with the rebuilding process?

TheBlizzard · 11-26-2003

Sorry almighty spelling police it was 1:30am when I wrote that

. Anyway, I am pretty sure he told Jet to bring it up there and they would look at it. But then stuff took a turn for the worse, just like AJ described that this thread is not going to turn into. I was there when he talked to Rick on the phone and Rick said that the tranny shouldn't have anything to do with the crankwalk. And then within a couple of days he posted on MNDSM that it was the tranny and the "monster clutch" that caused it. And then all hell broke loose and things got out of control. And with that, all civil communication between them was lost and nothing was going to be done about it.

I can vouge for JETS feeling on the whole subject. My consensus is that he has taken in the fact that he is just going to have to eat this one no matter whos fault it was. Like he said, theres a $3,500 lesson that was learned from this. Just do things yourself and then if something doesn't work out according to planned you don't have anybody to blame but yourself.

But all that is a mute point anyway, like AJ said this should be a educational post so that this doesn't happen to anyone in the future no matter who is doing the rebuild. Thats why I posted the thread to NABR, if you don't trust the information that is on there, who do you trust?

And Chris you are probably right. I am 100% sure that there are far more happy people with Ricks work than that are unhappy. But the only way to be the best at what you do is to admit when you have overlooked something and then learn from it. And if something is being overlooked when rebuilding with ARP's, well then it should be addressed and the proper precautions should be taken so that problems don't occur in the future. Right?

CRAIG

**JET** · 11-26-2003

Quote:

Originally posted by TalonTSiDude@Nov 26 2003, 02:09 AM
Its too bad than none of the people who have recieved exceptional service and/or work from Shindley post up their every story. Didn't Shindley offer to help tear the engine apart and assist with the rebuilding process?

Rick did offer to take the crank out of the block if I took it up there. The next day on MN-DSM he said that there was no way this was his fault. That is the only thing that made me mad. How can you say this is 100% not your fault if you have not even looked at the engine?

During the whole thing I said that Rick does good work on most things. I would probably still take a timing belt change to him if I didn't have time to do it. He does a better job at most things than most people around. I was just pretty amazed that he said he would not stand behind his work before he even looked at the engine.

**Kracka** · 11-26-2003

Quote:

Originally posted by CUSTOMDSM@Nov 26 2003, 05:03 AM
Sorry almighty spelling police it was 1:30am when I wrote that

Just fucking with ya :stick:

TheBlizzard · 11-26-2003

Quote:

Originally posted by TalonTSiDude+Nov 26 2003, 09:51 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (TalonTSiDude @ Nov 26 2003, 09:51 AM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-CUSTOMDSM@Nov 26 2003, 05:03 AM
Sorry almighty spelling police it was 1:30am when I wrote that

Just fucking with ya :stick: [/b][/quote]
I know me too.

niterydr · 11-26-2003

I thought issues like this were already resolved, I figured this would be an informative post, not a summary of common knowledge. Any search of dsmtalk, dsmtuners, nabr private and public forums, any of the yahoo lists, any dsm related list in general, will list the 'monster clutch' theory of crankwalk. I know that besides a 'monster clutch' crankwalk has been linked to improper building techniques, improper block preperation (ranging from line hone, to clogged oil passages). The point is, fingerpointing on a public forum is useless. Crankwalk is as much of a 4g63 problem as spun bearings are to the 6g72. What saddens me is is the fact that it is always someone elses fault for a faulty rebuild. Fingerpointing gets people nowhere, lets turn this into a shared community thread of ways to 'prevent' crankwalk. Personally i've seen cases of nearly every tranny/motor/mods list out there crankwalking.
The things I personally believe that help fight against crankwalk are:
-line honing blocks w/torque plates still attached
-pinning caps
-proper assembly techniques (which I think is common knowledge, using plasti-gauge, etc).
-Making sure everything else 'attached' to the crank is in working order (from undampened pullys to improperly attached transmissions)
anyone have any other theories/ways to 'help prevent' crankwalk, please post them up.
Its unfortunate that this situation occured pubically once, and its unfortunate that it involves trusted members of the dsm community, but lets let by-gones be by-gones.

TheBlizzard · 11-26-2003

Doesn't the clutch only accelerate an already existing problem? I mean a ACT 2100/2600lb clutches are like stock clutches these days. I wouldn't think many people would put in a stock clutch when it goes bad unless the did know any better. I mean shit if they were that bad on motors they should put a warning label on the box just like a pack of cigarettes.

Another question has to be asked. Why is it then that crankwalking usually occurs after a rebuild? I have done searching and couldn't find that many that walked unless they have been worked on.

And Swanny all them steps up listed to prevent crankwalk are right on. But then you would agree then that skipping over any one of them steps could mean a certain death of a motor right?

And isn't a "monster clutch" is only going to make matters worse when something is not done right to begin with.

If somebody with valid proof of any of these questions can fill me in that would be great.

CRAIG

**Shane@DBPerformance** · 11-26-2003

100% stock cars with stock clutches that have never had the tranny removed have crankwalked. The whole way the tranny has to support the weight of the motor on a 2G might be part of the problem. You rarely have stock 1G 6-bolt or even 7-bolts crankwalking.

**JET** · 11-26-2003

Quote:

Originally posted by niterydr@Nov 26 2003, 01:04 PM
The things I personally believe that help fight against crankwalk are:
-line honing blocks w/torque plates still attached
-pinning caps
-proper assembly techniques (which I think is common knowledge, using plasti-gauge, etc).
-Making sure everything else 'attached' to the crank is in working order (from undampened pullys to improperly attached transmissions)

This is the exact list of things that I have come up with. I have already talked to Mike about renting the torque plate when you guys get it. I am also installing the CRCO dowel kit. The only other thing I would add is the piece that John posted up from NABR that went over the alignment of the crank bearings, but that only matters if it is not doweled.

I have been toying with the idea of putting a torrington bearing in place of the clutch side of the thrust bearing. I know they will take a pretty good amount of force on them. For anyone that doesn't know, basically it is a set of needle bearings. I am thinking of machining down my dead crank and block to make room for the bearing. That is the major problem with putting a torrington in, I have not been able to find one that thin because that will decrease the surface area of the bearing which means it will hold less pressure.

The other issue with that is that the block is cast iron and I don't think it will like a needle bearing rolling around on it. To solve that the block has to be machined down even farther and a bearing surface mounted. .100" would probably work. Food for thought and I don't know if I will ever get to it or not, but it is interesting.

MustGoFaster · 11-26-2003

I have also thought of the torrington bearing idea. The biggest thing I hit was you can't just slip it over the crank, you would need a two piece bearing that bolts together around the crank. I don't know if they exist or not. Then I started wondering if it would be possible to add one somewhere else.

The other thing I encountered was a modification to the thrust bearing it self. It's on this page for those of you that haven't seen it. The idea is basically adding an oil passage right to the thrust surface.

12-17-2003

I regret Jet's crankwalk problem. I have rebuilt about 20 or so 1G DSM engines over the past three years and several (I don't keep track) of them had ARP mains installed. No line boring was necessary and they are still running well today.

Claiming that using ARP main studs without line honing (not "align honing" as someone stated earlier) causes crankwalk is no different that claiming green paint causes crankwalk. If you want to claim something then provide the tech info to back it up! Opinions don't mean squat!

Dr ****

12-17-2003

"Another question has to be asked. Why is it then that crankwalking usually occurs after a rebuild? I have done searching and couldn't find that many that walked unless they have been worked on."

I cut and pasted this from a previous reply in this thread. It is not a true statement. Crankwalk also happens after 50k! Actually, I found a stock 2G than had it at 43k! From my own experience I find maybe 30% of the 2G's I have worked on came in with some amount of non-spec crankwalk. I have seen only one 1G with it, a '93.

I helped a friend buy a clean, stock '95 GSX that was in a Mitsu shop at 106k torn down due to crankwalk. The car was a 1-owner and driven by a 30-year old nurse/single mom. (It was not abused whatsoever. She even had her car named... who could abuse a car with a name?) She explained that the car developed crankwalk at 53k and was repaired under warranty! Funny that at 106k (2 X 53k) it was in the shop again for crankwalk! Mitsu has a problem with that 2G motor design.

A big block engine builder told me that crankwalk was a problem for the drag cars with manual trannies back before auto trannies became popular in drag cars. He said that the thrust bearing in the big block engines had to be replaced after just ten runs down the track! Most Mitsu thrust bearings last a little longer than that now so maybe science has advanced a little?

Rick

1Fst14B · 12-17-2003

Quote:

Originally posted by rick shindley@Dec 17 2003, 01:46 AM

Claiming that using ARP main studs without line honing (not "align honing" as someone stated earlier) causes crankwalk is no different that claiming green paint causes crankwalk. If you want to claim something then provide the tech info to back it up! Opinions don't mean squat!

Why does ARP say that it must be done?

There has to be a reason everyone, including the machine shop that rebuilt my engine, says that it should be line honed.

?? i dunno, ive heard enough horror stories just from watching the MNDSM list about engines grenading in the past, im not really sure what to think.
who knows how many people arent on the list, or on here, that get screwed and end up taking it elsewhere

Adam

PSI2HI · 12-20-2003

Blah, blah, blah............

It's fucked up, it needs to be fixed, it's my fault can this topic EVER end!!!!!!!!!!! Haha, errr wait no, not guilty....

Stock motor are the bomb!! I strongly recomend them.

Nick

2003eclipse · 12-27-2003

BUY A 3g you wont have the problem, cause you wont be fast enough.