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      09-23-2013, 10:18 PM   #7
regular guy
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Crankshaft Machining

S65/S85 Bearing History:
Quote:
Originally Posted by GIdriver View Post
Hmmm. I was under the impression these parts were the same since 2008. Good to know. Do you know in what month and year they changed these parts. Sorry if this has been discussed before.
Quote:
Originally Posted by Leonardo629 View Post
crankshaft bearings have been different since 2008/10, but conn rod bearings are still the same...at least that's what realoem.com tells me.
We all thought the same thing and many arguments have been fought over this topic. But a few weeks ago, I got to the bottom of it. Realoem removed the old part number from their database, and this is why we all thought the rod bearing part number had not changed.

Got a lot more information. There have apparently been three different S65 crankshafts, and two sets of connecting rods. Maybe somebody with better BMW connections (hint, hint, Tom@EAS) can fill in the blanks. You will be surprised, I even found +.001 bearings and they are currently available!

BTW, this wasn't easy to track down. Had to look in catalogs out of country, etc. Called local dealer and confirmed they are all valid part numbers, and +size bearings are still available using these part numbers.

Crankshafts:
11 21 7 838 641 Crankshaft, Ended (no date given), no weight given
11 21 7 841 658 Crankshaft, Ended (October 2008), 20.400 kg
11 21 0 443 639 Crankshaft, Current production, 23.840 kg

Main Bearings:
11 21 7 841 488 Main Bearing Top, Yellow, Ended (October 2008)
11 21 7 841 609 Main Bearing Top, Yellow, Replaced 488 bearing
11 21 7 841 489 Main Bearing Top, Green, Ended (October 2008)
11 21 7 841 610 Main Bearing Top, Green, Replaced 489 bearing
11 21 7 841 490 Main Bearing Top, Violet, Ended (October 2008)
11 21 7 841 611 Main Bearing Top, Violet, Replaced 490 bearing
11 21 7 841 483 Main Bearing Bottom, Yellow, Ended (October 2008)
11 21 7 841 605 Main Bearing Bottom, Yellow, Replaced 483 bearing
11 21 7 841 484 Main Bearing Bottom, Green, Ended (October 2008)
11 21 7 841 606 Main Bearing Bottom, Green, Replaced 484 bearing
11 21 7 841 485 Main Bearing Bottom, Violet, Ended (October 2008)
11 21 7 841 607 Main Bearing Bottom, Violet, Replaced 485 bearing

Rod Bearings:
11 24 7 838 089 Rod Bearing Blue, 53.000 mm, +0.000 mm, Ended (no date given, but hints at July '08)
11 24 7 841 703 Rod Bearing Blue, 53.000 mm, +0.000 mm, Replacement for 089 bearing.
11 24 7 838 091 Rod Bearing Blue, 52.750 mm, +0.250 mm, Currently available

11 24 7 838 088 Rod Bearing Red, 53.000 mm, +0.000 mm, Ended (no date given, but hints at July '08)
11 24 7 841 702 Rod Bearing Red, 53.000 mm, +0.000 mm, Replacement for 088 bearing.
11 24 7 838 090 Rod Bearing Red, 52.750 mm, +0.250 mm, Currently available

I have verbal confirmation that some bearings replaced at another SoCal shop have 088/089 stamped on the back. So this would be pretty strong evidence along with information posted by Tom & B767capt that the rod bearings have indeed been superseded since production began. Most likely they were superseded in October 2008 when the crankshaft and main bearings were superseded. I will take pictures when I see these bearings in person.

Since I posted this, I ordered and received samples of each of these rod bearings including the oversized bearings. Yesterday, I measured and photographed all of the rod bearings.

Rod Bearings:
11 24 7 838 089 Blue, 53.000 mm, +0.000 mm, 0.07890" Thick, Ended
11 24 7 841 703 Blue, 53.000 mm, +0.000 mm, 0.07890" Thick, Replacement for 089 bearing
11 24 7 838 091 Blue, 52.750 mm, +0.250 mm, 0.08370" Thick, Currently available

11 24 7 838 088 Red, 53.000 mm, +0.000 mm, 0.07875" Thick, Ended
11 24 7 841 702 Red, 53.000 mm, +0.000 mm, 0.07875" Thick, Replacement for 088 bearing
11 24 7 838 090 Red, 52.750 mm, +0.250 mm, 0.08370" Thick, Currently available

Here's a photo of the old and new bearings side-by-side with part numbers shown. As seen in the photo, the bearing surfaces are quite different. More Photos Here.


S65/S85 Bearing Hardness Issues:

From Kawasaki00:
http://www.m3post.com/forums/showpos...&postcount=246

Regular Guy was gratious enough to send me bearings to look at and measure and hardness test.
What has been observed is the original 088/089 bearings are a copper/lead content while the 702/703 bearings are of an aluminized tin/silicon compound.
Measurements with my mic are as follows, I am in no way saying what is right or wrong but there is always a tenth or two between different people, just because I measure one way is not to say another measurement is incorrect. What matters is the same guy measuring the crank and the clearance for the final outcome.
088 .07875
089 .07885
091 .0837
090 .0836
702 .07855
703 .07875
Measurements are pretty much in line with what others have documented up until they get polished.
What is a MASSIVE change is the hardness of the bearings. I will not get into the difference of what is right or wrong here but just know the new 702/703 bearings are a huge jump in hardness
The average hardness for the 088/089 bearings are the same at 16.2B Scale
The average hardness for the 702-703 bearings are the same at 61.8B Scale

This puts to rest the theory that one bearing is harder than the other relative to the old vs new ones.
We can work bearings to get a few tenths when needed at our shop. The big one here is not only are we gaining on the average .0002-.0003 by going to the 702/703 but we are also gaining .0003 more by our polishing method. In essence a rod that was .001 clearance before with 088-089 can now be installed with the newer polished bearings and be AROUND .0016. Bearings that were in at .0013 should be able to get to .0019. It is not the end all be all but it will help.
Also remember I have one smaple of each bearing. From our experience ther can be +-.0001 from shell to shell. Not every bearing will turn out the same as these measurements. Here are some pics for comparison. I did not do pictures of the before polishing sizes, they were measured but not photographed.





















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I have noticed this before also. The last time I changed the tws I only had 3k miles on it and it came out very black and smelled really bad. Couple thoughts I have are it is the high Ester package in the oil that breaks down pretty quick and turns black or maybe there is more to the rod side clearance thing and it really is baking the oil inside the rod bearings. The evidence is all over the place that they are cavitating. I am still looking into it.
Here is a little teaser pic of a rod bearing I have been working on...I have multiple bearings that I am hardness testing and doing some processes that we do to our race bearings.

Last edited by regular guy; 01-15-2014 at 03:00 PM..
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