main bearings

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Don
Posts: 46
Joined: March 24th, 2007, 3:40 pm

main bearings

Post by Don »

I recently rebuilt my engine. The new main bearings that I bought do not have a steel backed split bearing. Suppose it is a little late for the question (the engine is installedand broken in!)..........
Are the non steel backed bearings ok?

thanks, don
brian
Posts: 1348
Joined: June 26th, 2006, 12:31 pm

Re: main bearings

Post by brian »

Yes, they will be ok. Make sure the crank is straight and the bores in the cases are true. If there is a lip in the center of the case bores, it's likely the case will have to be line bored.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
sharplikestump
Posts: 183
Joined: January 12th, 2009, 2:28 pm

Re: main bearings

Post by sharplikestump »

I have pulled those out of stock engines where they were SHATTERED! That goes back to when I was building them in MI, so it is over 35 years ago, but I will not use them. When I learned they were going to those, I went on a buying spree, and now have well over 100 sets of brgs. on the shelf. Prices on the steel split-brg. sets has risen sharply, and it kinda hurt on some of them, but I see it as a cheap insurance policy. Will I share?..............heh heh.
I've got to think there are warehouses of the good ones out there, but I could not take the chance.
I would stongly suggest keeping the revs under 3,000. :shock:
brian
Posts: 1348
Joined: June 26th, 2006, 12:31 pm

Re: main bearings

Post by brian »

I pefer the Kolbenschmidt german bearings to the Brazilian Mahle product. The german bearings are a bit harder to find but worth it.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
SR Racing
Posts: 1205
Joined: June 24th, 2006, 1:58 pm

Re: main bearings

Post by SR Racing »

I think all the manufactures are now steel back splits. We haven't seen any of the aluminum ones for a while. However, I wouldn't worry much about it at this point. Torque (Ft Lbs force) on the shell is what hurts the bearing (assuming you have proper oiling.) We (FV) have less torque than a stock VW in our operating range. Plus a 12lb flywheel vs. a 15. Pop a clutch in a 2000lb bug at 2500 RPM and you have more bearing force than we (FV) will ever see.

While the ACVW isn't high tech, a properly balanced opposing 4 cyl has very little bearing forces on it. And other than crank flex (non-counterbalanced) it handles the load quite well. A bearing failure on an FV is always an oiling issue. (assuming it was assembled and sized properly.)

I suspect your non-steel backed bearing won't have the longevity, but with rebuilds as often as we normally do, I wouldn't worry about.
Don
Posts: 46
Joined: March 24th, 2007, 3:40 pm

Re: main bearings

Post by Don »

thanks all for your input, appreciated,
cheers, don
sharplikestump
Posts: 183
Joined: January 12th, 2009, 2:28 pm

Re: main bearings

Post by sharplikestump »

Looking for feedback on this issue. Got any?
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