Question for you motor guru's.

[tipafew]

I have a 5 mill stroker with a cast 7 port R&D cylinder. I don't put on a lot of hours, but decided it should probably get a top end this winter. I pulled it apart and the cylinders and pistons look amazing. Everything on the crank is tight and quiet EXCEPT the very center bearing.
It looks like it has been moving around quite a bit and left some heavy pitting all over. It still spins quiet but has slight play up and down. Everything else on the crank is dead quiet and tight.

Any input what is happening here?
Also, I was planning on boring it and doing a new top end. As clean as everything looks is there any reason not to just do new rings and a hone?

Somehow I added these pictures twice....sorry

Chad

 

[badvinny]

Those bearings and the center lab ring are done! rebuild that crank completely.The cases look real rough, the lower case is foocked!

 

[tipafew]

What do you think caused it though.....It spins super quiet. to me it doesn't seem like it was caused by shrapnel from the bearing. Looks more like the bearing was siting there loose vibrating around.....

 

[Big Kahuna]

What may feel tight to you might be loose to that crank. It was chattering around!

 

[tipafew]

Well guess it was a good call to tear it down before it grenaded then..... Who does a good job with crank rebuilds???

 

[stefan]

ADR has 5 mil crank brand new, think they a 599 USD

 

[Jr.]

Crank has twisted / out of phase tolerance. Rebuild / replacement is mandatory !

 

[High Speed Industries]

Well guess it was a good call to tear it down before it grenaded then..... Who does a good job with crank rebuilds???

Competitivecrankshafts.com

They are the best in the business. Second option would be to buy an ADR 5 mil crank.

 

[ajmps1]

Jeff at competitive crank shafts rebuilt an old blown 5mm for me last winter in 3 days. Doesn't get better than that!

 

[Kyle Chandler]

Yep. Competitive Crankshafts is the way to go.

 

[sjetrider]

Definitely do not run those cases either. Either the cases or the bearing itself or both have worn and not seating properly. I wish you could get + .010 or .020 bearings and have cases line bored when this happens like you can on a auto engine, unfortunately it is not an option. I feel for you as I have had to toss ported cases and rebuild cranks for this very reason in the past, it feels like throwing $$$$$ out the door as the shiot ran LOL. But no need in risking a top end as well.

 

[sjetrider]

And x4 on Jeff at competitive cranks. When you can get him on the phone he is awesome. If you have the time and he is under $400 then worth calling him, If not just get the ADR for $600 . The cases (assuming they were ported to your Cyl.) is the real head ache in that mess. $250 and some epoxy / grind time involved BLAHHHHHHHH!

 

[DAG]

Can you catch a fingernail on the step in the cases? The look worn out to me.

ADR has partnered with Competitive Crankshafts so best of both worlds cant go wrong sending it to Jeff or Aaron

 

[john zigler]

Lots of chattering. Do as suggested above.

Is it possible someone switched out the bottom case 1/2 at some point, and they are not matched? Agreed you need new cases.

 

[tipafew]

Lots of chattering. Do as suggested above.

Is it possible someone switched out the bottom case 1/2 at some point, and they are not matched? Agreed you need new cases.

John, they were all ported and set up by Tim Judge about 4 years ago.

 

[john zigler]

John, they were all ported and set up by Tim Judge about 4 years ago.

OK, good. Still need to replace......

 

[badvinny]

OK, good. Still need to replace......

I just saw the bottom case pics, top didn't look too bad but the bottom is wasted!!

 

[tipafew]

What causes a bearing to chatter around like that though...... Seems like the race would be held tight in place by the cases regardless of if the bearing is grenading. Do the bearings sit fairly loose in there? I always assumed the cases held them pretty snug.
I looked closer at it last night and everything on the cases is build up above the surface. I was hoping a good machine shop could smooth out the high spots. Sounds like I'm dreaming???

 

[sjetrider]

Either the cases were machined from factory wrong or the Bearing on that crank had a slightly smaller OD for some reason or just years of vibration wearing one or the other down. I have seen this twice in all the years I have messed with these motors and it both baffles me and pisses me off every time. However the end result is always SCRAP them or have the same issue again soon unfortunately.

 

[tipafew]

Either the cases were machined from factory wrong or the Bearing on that crank had a slightly smaller OD for some reason or just years of vibration wearing one or the other down. I have seen this twice in all the years I have messed with these motors and it both baffles me and pisses me off every time. However the end result is always SCRAP them or have the same issue again soon unfortunately.

Thanks.....Good feedback. Had me a little baffled.