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Apparent damage to new bearings- problem or not? by Taijiguy
Started on: 02-10-2015 09:40 AM
Replies: 7 (147 views)
Last post by: Taijiguy on 02-10-2015 08:48 PM
Taijiguy
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Report this Post02-10-2015 09:40 AM Click Here to See the Profile for TaijiguyClick Here to Email TaijiguySend a Private Message to TaijiguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I assembled the bottom end of my motor and then pulled it apart after turning it over by hand a few times to inspect things. There were some minor imperfections in the crank that left narrow radial scratches in the bearing surface, just enough to scratch away the dull top finish of the bearing. I think if I hit the spots with 1000 grit polishing pad that should resolve that problem.

What has me a bit more concerned is that the rod ends seem to be slightly out of round. When I pulled them apart the bearings were worn at the ends where the two pieces meet. I'm on the fence about whether this is severe enough to be concerned about or not. Obviously I would prefer it if everything were perfect, but I have to balance between perfection and expense. If I have to have the rods reworked then I'll most likely need to have the crank re-balanced, as the bob weight will change. So, b e anal and fix 'em or run with it?

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Report this Post02-10-2015 09:57 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Might as well have everything checked for proper roundness and alignment while getting the rebalancing done. No point in saving the few extra dollars to do it, just to find out later on that it was bad, when stuff breaks.
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Taijiguy
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Report this Post02-10-2015 10:21 AM Click Here to See the Profile for TaijiguyClick Here to Email TaijiguySend a Private Message to TaijiguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Everything has already been balanced. The shop honed these when they had my parts, but apparently they didn't cut the caps down and bore them. So if I have these worked on I'll have to have everything RE-balanced. That's the only reason I'm asking the question- I've already paid to have the whole rotating assembly balanced and would really like to not pay to do it again.

[This message has been edited by Taijiguy (edited 02-10-2015).]

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Report this Post02-10-2015 10:43 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Taijiguy:

The shop honed these when they had my parts, but apparently they didn't cut the caps down and bore them.


Have you checked with them, is that normal procedure?
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Report this Post02-10-2015 11:21 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Taijiguy:

Everything has already been balanced. The shop honed these when they had my parts, but apparently they didn't cut the caps down and bore them. So if I have these worked on I'll have to have everything RE-balanced. That's the only reason I'm asking the question- I've already paid to have the whole rotating assembly balanced and would really like to not pay to do it again.



Sounds like you should show the shop what the problem is, and get them to fix it if they messed it up.
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Taijiguy
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Report this Post02-10-2015 11:46 AM Click Here to See the Profile for TaijiguyClick Here to Email TaijiguySend a Private Message to TaijiguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:


Sounds like you should show the shop what the problem is, and get them to fix it if they messed it up.


I just left there. I showed him that same pic. He didn't seem overly concerned, but did say to bring them in and they would double check them. He asked about the bearings I was using and I actually couldn't remember the brand, they came from CarQuest, they had to have them delivered from their machine shop.....it's amazing to me that you can no longer walk into an auto parts store and just buy SBC parts off the shelf any more...what's the world coming to?

I did buy new bearings, but this time I got Sealed Power CP series which are probably far better than what I originally had.

[This message has been edited by Taijiguy (edited 02-10-2015).]

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Lou6t4gto
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Report this Post02-10-2015 12:44 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
The Shop Honed the big end of the Rods Without cutting them first ? (honing them makes them bigger, even if it's only .001 of an inch). Were there any "edges" left on the rod Halves after honing ? Did you happen to MIC the rod Ends after you got them back ? did you Mic the bearing shells ? I've found .0005-.001" difference between bearing Pairs and even More when you compare different Brands ! You cannot trust that ANY machine shop does it right 100% of the time. I ALWAYS check the work. Chances are, you can get away with them like they are, but......
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Taijiguy
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Report this Post02-10-2015 08:48 PM Click Here to See the Profile for TaijiguyClick Here to Email TaijiguySend a Private Message to TaijiguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto:

The Shop Honed the big end of the Rods Without cutting them first ? (honing them makes them bigger, even if it's only .001 of an inch). Were there any "edges" left on the rod Halves after honing ? Did you happen to MIC the rod Ends after you got them back ? did you Mic the bearing shells ? I've found .0005-.001" difference between bearing Pairs and even More when you compare different Brands ! You cannot trust that ANY machine shop does it right 100% of the time. I ALWAYS check the work. Chances are, you can get away with them like they are, but......


I can't say about the hone job, according to the guy at the shop (Mike) they did cut the ends down a bit before honing them. I didn't mic the ends, although I did use a telescoping inside diameter tool to check the ends. That's not a perfect method, and it wasn't far off enough that I could detect any variation or eccentricity using that tool. I did just measure a couple, including the one in the pic, the bad end is a couple thousands less than one that isn't worn. I might take another one of the originals and set them in that rod and torque it to the crank and see what happens.
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