Rebuilding 7bolt

[pur97tsifwd]

ok if i get a new crank and bearnings and everything will a 7bolt still have crankwalk problems and be strong b/c you dont see to many built 7bolts

 

[GVR4592]

There's always a risk of crankwalk with any engine, 2g 7 bolt's are more prone to getting crankwalk than 6 bolts are. Having a good engine builder can make a little difference, but there's no guarantees.

 

[2fastTSi]

By all means correct me if I'm wrong, but I was under the impression that the crankwalk issue was due to a bad batch of crankshafts made by Mitsubishi and that after replacement everything was okay. Is this not the case?

 

[Wildeclipse2000]

By all means correct me if I'm wrong, but I was under the impression that the crankwalk issue was due to a bad batch of crankshafts made by Mitsubishi and that after replacement everything was okay. Is this not the case?

Thrust bearing failure is what causes the crankwalk problem, not bad cranks.

 

[2fastTSi]

Sorry, I thought that a batch of cranks were machined slightly out of spec, causing the thrust bearings to wear prematurely.

 

[hereitcomes]

No they changed parts on all crankshafts for 7-bolts. The 95-95 models have the worst aspects of crankwalk, and there is a different part # for 97-99 models. So lots went on.

back to the question, since the thrust bearings are what wear and move around causing the crank to walk, then reinforcement around the crank should be a good start.

 

[lookin4dsm]

ok if i get a new crank and bearnings and everything will a 7bolt still have crankwalk problems and be strong b/c you dont see to many built 7bolts

If your crank is still in good shape and the end play and journals are in spec, I would just have the machine shop polish the journals. I would also replace the crank bearings with new ones from Mitsubishi.

Replacing a perfectly good crank with a new one is no guarantee of avoiding crankwalk. The best minds in the DSM community can't agree on what the causes it. Some say it is the smaller oil squirters. Some blame a bad batch of cranks. Mitsubishi actually changed the design of the thrust bearing in 1997. They are probably all correct.

I read numerous posts and articles about the subject and decided to rebuild my son's 7-bolt anyway. So far, so good.

Mike

 

[Locutus78]

I am in the process of replacing my second 7bolt lost to CW. There has been no tried and true proof of the exact causes. Some say out of spec cranks, some say not chemicaly hardened cranks, bad oil squirters. but by replacing the crank will not for sure fix the problem. That is what I did the first time, and here I am again. And this case being the worse of the two. We changed from crankwalk to crankrun with this one. it moved 1/8 of an inch when we dug into it. Then again a another car at the same shop has a 7bolt that is putting 732awdhp. but if you are rebuilding then do a 6bolt swap it is near the same cost as a full rebuild with crank and such, and you will be happier. This website says they can fix CW www.overbore.com