VAC Rod bearing condition after 13k miles

[Doc Oc]

Don't I have the right to be pissed that they sent the incorrect bearings? Just because they worked doesn't excuse that. What if they hadn't? We've seen coated oem fail before and I certainly wouldn't have knowingly purchased and installed those bearings. How is that "distasteful"?

[Doc Oc]

Read post 96

http://www.m3post.com/forums/showthr...1253084&page=5

[anerbe]

Originally Posted by Gesler

But it looks like you proved "what's in stock" from VAC works. BE bearings don't have such 'proof' yet. This whole thing is getting even more distasteful by each post.

Agreed - there is particular evidence that VAC OEM sized bearings with ARP bolts showed zero wear. I expect similar examples of VAC Extra Clearance bearings with ARP bolts showing zero wear as stated from MRF.

What is still unknown is BE bearing wear results with both OEM bolts and ARP bolts from an unbiased source.

There is definitely some issues with VAC and their inventory management process, where if I was Doc Oc, I'd be pissed, especially if the bearings did cause a failure. However, there's also a lot of statements regarding both VAC bearing options (OEM and extra clearance) from BE sources that the clearances are not enough. If they weren't enough, I would expect wear patterns on VAC example bearings with ARP bolts.

The mere fact that VAC bearings with OEM sizing and additional layer of coating can be seen with zero wear, nobody still has the definitive root cause to this bearing issue.

[Doc Oc]

Originally Posted by anerbe

Agreed - there is particular evidence that VAC OEM sized bearings with ARP bolts showed zero wear. I expect similar examples of VAC Extra Clearance bearings with ARP bolts showing zero wear as stated from MRF.

What is still unknown is BE bearing wear results with both OEM bolts and ARP bolts from an unbiased source.

There is definitely some issues with VAC and their inventory management process, where if I was Doc Oc, I'd be pissed, especially if the bearings did cause a failure. However, there's also a lot of statements regarding both VAC bearing options (OEM and extra clearance) from BE sources that the clearances are not enough. If they weren't enough, I would expect wear patterns on VAC example bearings with ARP bolts.

The mere fact that VAC bearings with OEM sizing and additional layer of coating can be seen with zero wear, nobody still has the definitive root cause to this bearing issue.

The odd things is, Oem 702/703 bearings have been measured to give about .0015" of clearance. So how did the coated versions of these bearings give me .0016-7" of clearance? The only thing I can come up with is (like green eggs has been saying) that the additional clearance is caused by the bore distortion of the ARP hardware. If VAC knows this then they're not worried about which bearing they send because they know that the hardware will make it work....but what if someone doesn't buy arp hardware. Do they look like post 96 in the link?

[anerbe]

Originally Posted by Doc Oc

The odd things is, Oem 702/703 bearings have been measured to give about .0015" of clearance. So how did the coated versions of these bearings give me .0016-7" of clearance? The only thing I can come up with is (like green eggs has been saying) that the additional clearance is caused by the bore distortion of the ARP hardware. If VAC knows this then they're not worried about which bearing they send because they know that the hardware will make it work....but what if someone doesn't buy arp hardware. Do they look like post 96 in the link?

I don't know if added bore distortion could cause damage to other engine parts while making your bearing/journal clearances perfect.

Also, you probably answered this previously, but did you sand the parting lines? If not, perhaps this also added clearance and distortion to increase top and bottom clearances.

I'm really curious to gather wear data on these extra clearance bearings with OEM bolts, both VAC and BE. I have yet to also see poor bearing wear with ARP-2000 bearings.

Maybe with enough clearance, minimal bore distortion is fine? Or do you want a certain amount of distortion, adding additional clearances at certain locations to account for the different loads within the stroke cycle - which is why we see examples of OEM bolts causing more wear?

[Doc Oc]

Originally Posted by anerbe

I don't know if added bore distortion could cause damage to other engine parts while making your bearing/journal clearances perfect.

Also, you probably answered this previously, but did you sand the parting lines? If not, perhaps this also added clearance and distortion to increase top and bottom clearances.

I'm really curious to gather wear data on these extra clearance bearings with OEM bolts, both VAC and BE. I have yet to also see poor bearing wear with ARP-2000 bearings.

Maybe with enough clearance, minimal bore distortion is fine? Or do you want a certain amount of distortion, adding additional clearances at certain locations to account for the different loads within the stroke cycle - which is why we see examples of OEM bolts causing more wear?

Sorry I never answered your questions. No, we didn't sand the parting lines. They did not appear to have coating on them though...vac advised not to sand.

Here is some clearance info RG was kind enough to collect after sending him my vac's:
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I installed you're bearings into my rods with OEM rod bolts. They showed 0.0017 inch clearance. That's right about factory clearance. So the short answer: Yes, the VAC-ARP rod bolts did add extra clearance to your shells. It ranged from 0.00005 inch to 0.00065 inch. But all of them did have some degree of bore distortion that added extra clearance. So let's assume that if my rods were all within spec, and they all had 0.0017 inch clearance, the extra 0.00065 would give you 0.0024 inch clearance -- which is exactly what BE Bearings are spec'd at without bore distortion.