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-   -   Reusing Main Bearings (http://forums.pelicanparts.com/911-engine-rebuilding-forum/920429-reusing-main-bearings.html)

arbita1 07-03-2016 04:44 AM

Reusing Main Bearings
 
Other than measuring. What would preclude me from reusing my main bearings. One of them has a scratch that you can catch a finger nail on. A few also have "hot spots" on them. Is it just safer to get new bearings?

If I was to reuse I was thinking of having them coated here. http://swaintech.com/race-coatings/automotive-coatings/automotive-coatings-price-sheet/

john walker's workshop 07-03-2016 09:34 AM

You can, but why go to all that work and put used bearings in?

Trackrash 07-03-2016 12:17 PM

If the bearings are more than a few years old, you are wasting your time, FMI, re-using them. (don't ask how I know)

930cabman 07-03-2016 01:20 PM

I have had the same thought, but Why? The cost of new bearings is slight in comparison to a full rebuild

arbita1 07-03-2016 05:30 PM

Others have recommended it. I hadn't even thought of it until then. Ok. New bearings it is.

Mark Henry 07-03-2016 06:27 PM

I've re-used #8
The tolerances on new number 8 bearings are horrid. At least the ones I've seen.

faapgar 07-08-2016 04:06 AM

Hi,to obtain a perfect fit they should only be squashed once and not reused.Fred

RedCoupe 07-08-2016 07:58 AM

Quote:

Originally Posted by faapgar (Post 9190981)
Hi,to obtain a perfect fit they should only be squashed once and not reused.Fred

Don't agree. In the course of a proper engine build, the rod bearings are assembled in the rods out of the engine and torqued to measure the ID "as installed" with a precision bore gage. Likewise, the case halves are assembled with bearings, but nothing else to measure the ID of the mains. Once the crank is mic'd and clearances are calculated to be acceptable, then final assembly can proceed for real. I have never heard of this trial fitting for measurement to cause any harm. Likewise, a couple of times I have dissembled engines that had very low miles to fix specific problems and reused all the bearings because they were virtually as new. Had no problems with that either. I'm not saying that I wouldn't replace the mains in this case - I would - I just have never experienced problems reinstalling bearing shells that have previously been installed and torqued.

arbita1 07-16-2016 05:48 AM

So I've seen some reinstall their number 8 bearing. How do I determine if I can reuse mine?


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al lkosmal 07-16-2016 08:18 AM

I recommend always installing new bearings...as JW said "why go to all that work and put in used bearings"........and I use the "trial fitting/bore gage" method to determine bearing clearances/specs etc.

regards,
al

Tippy 07-16-2016 10:03 AM

Quote:

Originally Posted by arbita1 (Post 9201140)
So I've seen some reinstall their number 8 bearing. How do I determine if I can reuse mine?


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I reused mine since:

1. It's a very large bearing with lots of load surface
2. It's way overpriced
3. There's very little load on it vs other vehicles

Didn't put much more than thought than that :)

Mark Henry 07-16-2016 01:10 PM

It should be measured with a bore gauge, but the down and dirty is it should slip on but have no play if you rock it side to side.

I bought 4 new 930 #8 bearings from different sources, they were all over spec with the worst being almost a full half mm too big.

Since my old bearing was in spec I DFL coated it and reused it.


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