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Looking for opinions on main bearings / rod bearings. For boosted and non boosted applications.
What brand did you use?
Why did you choose them?
Coatings?
How long have you had them or used them for?
Would you pick differently if you where to do it again?
Where did you get them from?
What was the cost (does not need to be exact)
Any additional information on the bearings you used or want to use I would like to see.
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I use dlc coated oem main and rod bearings on all my builds. Wouldn't change a thing.
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u owe my mule an apology
the same ones you took out
86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
best time 9.06 @ 151.8 mph, best 60 foot 1.30
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I'll take that as a vote for " who needs bearings when you have a machines surface "Originally Posted by someguy2800
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I used Glyco. Bearings don't seem to be a problem on these motors, assuming the clearances are correct.
M54B30 Inside
DLC is the opposite property you want on a bearing. Are you sure you don't mean just "coated"?
u owe my mule an apology
What I mean is the oem ones are of very good quality and if you haven't worn the tin plating off them there is no reason to not reuse them
86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
best time 9.06 @ 151.8 mph, best 60 foot 1.30
Member
Got it Misinterpreted my bad,
I would agree with you on reusing them but I will be doing a fresh build. I'll keep the bearings for someone that needs them. Just interested in seeing and hearing what everyone have to say about different bearings.
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In 12 years here, I have not read of any particular bearing working better than others on these motors. These motors, unlike some other BMW motors, do not suffer bearing issues. If you had an S54 or S65 or S85, all of which have bearing issues, things would be different. You can put stock or aftermarket in. The expensive ones won't do any harm and may make you feel better. I run WPC treated stock bearings in my lightly modded S65 and standard aftermarket glyco in my fully built S52.
ßMW///MµrÐêr§þðr†
Kolbenschmidt mainly (popular here)
OEM rodneys
but some might prove that a coated would last longer and be stronger with datalogs?
Plastigauge is a friend
Last edited by milKt; 07-13-2017 at 11:16 AM.
boost pls
Threads like this reminds me I need to measure my crank to order a set.
ßMW///MµrÐêr§þðr†
likely not...(but better safe)
the STD size will usually fit.
Our cranks take minimal wear.
Last edited by milKt; 07-13-2017 at 11:44 AM.
boost pls
Yea but even std varies on colors. I’ve seen plenty of different sized std bearing sets. Plus although I’m not gonna boost it any time soon I’d rather know it’ll last me for years
Member
I used standard size Kolb main bearings and glyco rod bearings. Plastigauge said they were all within spec.
ßMW///MµrÐêr§þðr†
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Sorry I meant coated ... I use the ones from VAC
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This is very timely. I was debating the very same thing yesterday. I am doing a full refresh on my motor. It's not boosted but it is built around a grossly lightened - read minimal counterweight S52 crank. 40lbs down from 52. I'll take pics later today. The motor is torn down for other reasons and I see some aluminum transfer on some of the bearings - read "other reasons". Otherwise all the main bearings are in fabulous shape. The rod bearings are also in great condition, all except for #5 which has some odd wear - past the tin to the copper on the edges by the chamfer. That rod (Molnar) is going to the machine shop for checking. All the bearings are Glyco. The motor has 25,000 miles on it and I do pound the piss out of it a lot (7,800 rpm in 1st and 2nd).
Anyone think it's worth the extra $100-$125 to go with the Calico coated bearings? I would prefer not worrying about this for the next 50-60,000 miles.
Last edited by jakermac; 07-23-2017 at 03:10 PM.
ßMW///MµrÐêr§þðr†
If everything is right to begin, the crankshaft will rarely, if ever, touch the bearings anyway.
It's like that a majority of M/S5x BMW engine bearing failures can be traced back to assembly.
If our cranks were known to "walk" or our bottom ends known to have bad harmonics
(for those of you revving high)
then coating may offer a .00035% more confidence.
Change your oil.
If you're rich, $pend away.
2¢
Last edited by milKt; 07-23-2017 at 04:23 PM.
Member
I was worried that harmonics were going to kill the bearings. I guess I'm not getting enough harmonics or crank flex to do any damage. I was VERY relieved to see the condition of the bearings when I took it apart (other than #5). I'm also using an ATI damper.
ßMW///MµrÐêr§þðr†
Whatchya revvin to?
Member
The moon.
Member
7,800, but only in 1st and 2nd. 3rd-5th it's limited to 7,200.
Here's the #5 bearing - top half. The bottom half is in much better condition.
40lb S52 crank:
Last edited by jakermac; 07-23-2017 at 07:26 PM.
Member
what FW you gonna run? RHD CrMo?
its odd about that 1 rod bearing showing alot of wear in a short amount of time, im assuming this engine was built and check before? was it mic'd or just plastiguaged?
i'm tossing up running ACL or KS on my molnars
Last edited by digger; 07-25-2017 at 11:58 PM.
Member
I've been running the same UUC II 8.5lb flywheel for 15+ years now. I've now discovered that what I though was aluminum transfer on the crank journal/rod bearings actually appears to be pitting of the journal surface. Anyone have any feedback/experience with grinding journals undersized on a BMW crank? In the Honda world years ago, we always looked for better condition replacement cranks when dealing with journal wear/damage in race motors. Seemed that the journal hardening process on the Honda cranks did not go deep enough to permit longevity when grinding them.
The rods and crank were checked for roundness before the bottom end was built. The assembly was only plastiguaged because of this.
u owe my mule an apology
The forged BMW cranks do appear to have a nitriding or surface hardening
86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
best time 9.06 @ 151.8 mph, best 60 foot 1.30
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