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      03-24-2015, 03:10 AM   #2553
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I completely misread the simple fact that this is rod without installed bearing. Ugh, sorry again.

Quote:
Originally Posted by regular guy View Post
Rod bores need to be round. There's no if's, and's, or but's about that.
Perhaps practically true but by no means necessarily true. What is essential is that the resulting/associated journal bearing shape maintains hydrodynamic lubrication across all shapes of the journal and journal bearing size and shape as they encounter varying mechanical and thermal loads and distortion. Of course also assuming that ovality isn't so severe that is causes bearing to sping. In short, small ovality effects very likely directly contribute to small eccentricity effects and that is what really matters.

Quote:
Originally Posted by regular guy View Post
yes it's OK to reinstall the bearings. The bearing backs are like spring steel. They interference fit into the bore hole. I would assume you can put them in and take them out almost infinite number of times.
I'm assuming that crush is indeed crush, a non-linear phenomena that involves material yield/plasticity. Such phenomena very well might have a hysteretic effect and hence my question. I think kawasaki also answered prior that both bearing diameters and eccentricity are highly consistent/repeatable during uninstall/reinstall.

Quote:
Originally Posted by regular guy View Post
I think I discovered I made a calibration error on the remanufactured rods. This is why I offered to get you involved
Not my area of expertise.

Quote:
Originally Posted by regular guy View Post
I am very comfortable saying that I believe as long as the bearing clearance is within the many decade-old general best practice -- and Clevite white paper specification -- of 0.001 inch clearance per journal-inch diameter + 0.0005 inch, then we won't approach anything near this "clearance is too large" safety factor you're talking about.
Recall that the exact spec is .00075 to .001 in/in and perhaps +0.0005. Also that spec is a general starting point, not a fixed rule. Using both the .001 in/in and the additional/optional .0005 in results in a clearance increase over nominal measured of 70%. I can't help but believe this huge increase in percentage has some deleterious effect.

Last edited by swamp2; 03-24-2015 at 03:26 AM.
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      03-24-2015, 04:26 AM   #2554
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Honing the rod end to a bigger diameter will have a direct effect on the assembled size of the bearing.

I'm not saying those rods are out of round. I expect they are perfect but you can't measure them properly for cylindricity with a bore gauge as shown in the measurement photos. That will only give you a basic size and not record out of roundness.
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      03-24-2015, 01:14 PM   #2555
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Quote:
Originally Posted by regular guy View Post
Part-1: Rod bolt clamping pressure:

M3post reader, kawasaki00 measured the OEM rod bolt clamping pressure, along with the clamping pressure of two different types of Carrillo rod bolts. As he discovered, the OEM rod bolts offer far more clamping pressure vs. Carrillo rod bolts, and it's believed the clamping pressure (or lack thereof) may cause the rod big end bore distortion and lead to increased bearing clearance at 90-degrees. Increased bearing clearance is a good thing, but bore distortion is not. I'm pretty sure that increased clearance at the cost of bore distortion is not advised. However, I'll let kawasaki00 and the other engine experts comment on that.

Here's the rod bolt clamping force data generated by kawasaki00:

At Torque
Over Torque
Bolt Type
53 in/lb
177 in/lb
130 degrees
+20 degrees
OEM Rod Bolt #1
1169
3075
10933
11570
OEM Rod Bolt #2
1101
2998
10855
11323
Bolt Type
22 ft/lbs
50 degrees
+20 degrees
Carrillo WMC #1
4200
8160
10211
Carrillo WMC #2
4189
8110
10301
Carrillo SPS
3270
7870


Notes:
Carrillo WMC bolts @ 50 degrees, 0.006 inch stretch
Carrillo SPS bolts @ 54 degrees, 0.0065 inch stretch


Part-2: Rod big-end ovality with different rod bolts:

With the rod bolt clamping data above, the next test will see which rod bolt creates the roundest circle. This will test for the "ovality" of the rod big end bore by checking the measurements at seven different points around the circle. Although the ARP-2000 and ARP-625 rod bolts were not tested above, I believe the two Carrillo rod bolts are of similar quality and specifications. (kawasaki00 can comment on that.)

For the most part, the OEM rod bolts create a near perfectly-round circle. Four of the eight rods I tested were 1/10000th of an inch or less out of round. That's probably what you would expect since these rods were honed (the process of making the circle round) with OEM rod bolts.

The ARP-2000 rod bolts did not create a perfectly round circle. The ARP-2000 rod bolts, with less clamping pressure produced bore distortion at 90-degrees. The bore distorts larger towards 90-degrees, and this would explain Malek's and Van Dyne's measurement of increased clearance when using the aftermarket ARP bolts. But is this enough to matter? Kawasaki00 told me privately, yes, this is a significant amount of ovality, and he would not use these bolts unless he was also able to rehone the connecting rod big ends to make them round again.

The data:

OEM Rod Bolt Measurements:

Torque Specifications: 20 Nm + 130 degrees

DegreesOEM Rod Bolts
R1
R2
R3
R4
R5
R6
R7
R8
Ambient Temperature
76.4
76.3
76.2
76.1
76.0
76.1
76.1
76.0
5.00
2.20490
2.20495
2.20520
2.20500
2.20510
2.20520
2.20515
2.20510
19.75
2.20490
2.20500
2.20510
2.20500
2.20500
2.20520
2.20510
2.20510
45.00
2.20500
2.20510
2.20515
2.20520
2.20500
2.20500
2.20500
2.20520
90.00
2.20510
2.20530
2.20515
2.20540
2.20515
2.20510
2.20515
2.20520
135.00
2.20500
2.20520
2.20520
2.20520
2.20510
2.20515
2.20500
2.20520
160.25
2.20500
2.20510
2.20520
2.20500
2.20520
2.20520
2.20510
2.20515
175.00
2.20500
2.20500
2.20520
2.20500
2.20520
2.20530
2.20510
2.20515


Ovality:

DegreesOEM Rod Bolts
R1
R2
R3
R4
R5
R6
R7
R8
Ambient Temperature
76.4
76.3
76.2
76.1
76.0
76.1
76.1
76.0
5.00
-0.00005
-0.00002
0.00000
0.00000
-0.00005
-0.00005
0.00003
-0.00002
19.75
-0.00005
0.00002
-0.00010
0.00000
-0.00015
-0.00005
-0.00002
-0.00002
45.00
0.00005
0.00012
-0.00005
0.00020
-0.00015
-0.00025
-0.00012
0.00008
90.00
0.00015
0.00032
-0.00005
0.00040
0.00000
-0.00015
0.00003
0.00008
135.00
0.00005
0.00022
0.00000
0.00020
-0.00005
-0.00010
-0.00012
0.00008
160.25
0.00005
0.00012
0.00000
0.00000
0.00005
-0.00005
-0.00002
0.00003
175.00
0.00005
0.00002
0.00000
0.00000
0.00005
0.00005
-0.00002
0.00003



ARP-2000 Rod Bolt Measurements:

Torque Specifications: 45 Ft-Lbs

DegreesOEM Rod Bolts
R1
R2
R3
R4
R5
R6
R7
R8
Ambient Temperature
75.4
75.2
75.5
75.8
75.6
75.2
75.7
75.3
5.00
2.20500
2.20500
2.20520
2.20500
2.20520
2.20515
2.20520
2.20515
19.75
2.20520
2.20535
2.20540
2.20535
2.20540
2.20530
2.20540
2.20540
45.00
2.20560
2.20560
2.20560
2.20560
2.20550
2.20550
2.20540
2.20560
90.00
2.20575
2.20580
2.20580
2.20580
2.20560
2.20560
2.20565
2.20580
135.00
2.20560
2.20540
2.20565
2.20560
2.20550
2.20545
2.20540
2.20565
160.25
2.20520
2.20520
2.20530
2.20520
2.20535
2.20535
2.20530
2.20530
175.00
2.20500
2.20500
2.20520
2.20500
2.20520
2.20520
2.20510
2.20510


Ovality:

DegreesOEM Rod Bolts
R1
R2
R3
R4
R5
R6
R7
R8
Ambient Temperature
75.4
75.2
75.5
75.8
75.6
75.2
75.7
75.3
5.00
0.00000
0.00000
0.00000
0.00000
0.00000
-0.00002
0.00005
0.00003
19.75
0.00020
0.00035
0.00020
0.00035
0.00020
0.00012
0.00025
0.00028
45.00
0.00060
0.00060
0.00040
0.00060
0.00030
0.00032
0.00025
0.00048
90.00
0.00075
0.00080
0.00060
0.00080
0.00040
0.00042
0.00050
0.00068
135.00
0.00060
0.00040
0.00045
0.00060
0.00030
0.00027
0.00025
0.00053
160.25
0.00020
0.00020
0.00010
0.00020
0.00015
0.00018
0.00015
0.00018
175.00
0.00000
0.00000
0.00000
0.00000
0.00000
0.00002
-0.00005
-0.00002


Graph(s):



Next Steps:

Next week, ARP-625 bolts will arrive. I will repeat this measuring process with the ARP-625 bolts and post the results when they are available.

Thanks to Malek for loaning me the ARP-2000 rod bolts. Before returning them, I plan to measure bearing clearance.
Thanks for the measurement and gathering all the info. I wonder what this implies for those of us that used the ARP2000 rod bolts. Is that .0005 differential with the oem bolt that significant? If I recall, the bore is not exactly round once the bearing is in place anyway, right? Should we open up the engine and change the rod bolt asap? Will wait to see the result with the 625+ one. Thank you once again.
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      03-25-2015, 01:34 AM   #2556
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Well, I got to the bottom of the calibration error on the remanufactured rods. Ugh. Long story short, for 1.80 - 2.19 inch, I can use a calibration ring to calibrate the bore gauge. It's perfectly accurate. Measuring the rod B.E. bores is above 2.2 inches, and I don't have a calibration ring that big. I took a short cut and did something stupid instead of using a calibrated micrometer in a fixed position to calibrate the bore gauge. The other day, I discovered this method was off by a few tenths, and now that I think about it a little further, I understand why it's different.

Suffice to say, I learned a lesson on that.

The 702/703 bearing measurements were still perfectly valid because they were made with a calibrated bore gauge using the calibration ring. So those values are totally accurate. But the rod B.E. bore sizes were off by a few tenths, and those should be thrown out. (Emphasis: the clearance measurements were still valid.)

As I mentioned, I had borrowed those remanufactured rods, and it was a one-time thing over the weekend. There's no getting them back. That is...until today. Today I was picking up some parts and paying for some machining when I asked my kind benefactor if I could borrow the rods one more time...tonight. He was kind enough to allow it.

So using the micrometer method to calibrate the bore gauge to 2.2000 inch, I re-torqued and remeasured the rod B.E. bores. There was no need to remeasure the 702/703 bearings because there was nothing wrong with them. However, swamp brought up a good point that I should measure the 088/089 bearings in these remanufactured rods as well. Swamp, for the most part this isn't practical because it's an extra 3.5 hours of time for each set of bearings. But I thought the suggestion was important enough to make the time to do it while I still had these rods.

Virgin Bearings
R1
R2
R3
R4
R5
R6
R7
R8
Min
Max
Mean
Min Dev.
Max Dev
Rod B.E. Bore
2.20520
2.20480
2.20500
2.20480
2.20520
2.20490
2.20480
2.20500
Rod Journal Diameter
2.04650
2.04650
2.04650
2.04650
2.04650
2.04650
2.04650
2.04650
702/703 Bearings
2.04800
2.04795
2.04800
2.04800
2.04805
2.04800
2.04800
2.04800
702/703 Clearance
0.00150
0.00145
0.00150
0.00150
0.00155
0.00150
0.00150
0.00150
0.00145
0.00155
0.00150
-0.00005
-0.00005
088/089 Clearance
0.00150
0.00120
0.00140
0.00120
0.00135
0.00130
0.00140
0.00130
0.00120
0.00150
0.00133
-0.00013
-0.00017
VAC-Clevite Clearance
0.00210
0.00190
0.00190
0.00210
0.00210
0.00190
0.00210
0.00210
0.00190
0.00210
0.00203
-0.00013
-0.00008
VAC-Clevite Bearings
2.04860
2.04840
2.04840
2.04860
2.04860
2.04840
2.04860
2.04860
Rod Journal Diameter
2.04650
2.04650
2.04650
2.04650
2.04650
2.04650
2.04650
2.04650
Bearing Thickness Top
0.07840
0.07840
0.07840
0.07835
0.07835
0.07835
0.07830
0.07825
0.07825
0.07840
0.07835
-0.00010
0.00005
Bearing Thickness Bottom
0.07840
0.07840
0.07835
0.07835
0.07835
0.07835
0.07830
0.07825
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      03-25-2015, 02:24 AM   #2557
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      05-03-2015, 10:35 AM   #2558
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Many people know, I've been on a technical advising role on the "Custom Clevite" bearing project, providing all of the measurements and specifications we can find. Clevite didn't play dumb as if they didn't know some of the specs of the original BMW bearings they helped manufacture. They provided the "guide notch" size and locations, bearing thicknesses, etc.

So what I'm saying...is that I've seen all the blueprints Clevite generated for this project (there have been a few sets reviewed and rejected). One of the blueprints contained a very interesting "mistake." Clevite was supposed to update the rod bore diameter (with newly discovered official BMW specifications), but they forgot to adjust the bearing thickness to match the new clearance specifications (that's why this was rejected). But that "mistake" gave the discovery of something very significant. By forgetting to adjust the bearing thickness in the blueprint, I believe we back doored our way into discovering the official BMW bearing clearance specifications.

This blueprint takes into account ALL of the tolerance stacking for every affected part from bearings manufacturing tolerances, to rod journal diameter tolerances, to rod big-end bore dimensions. With this simple mistake, I can now give the official BMW rod journal bearing specifications on the original Clevite 088/089 bearings.

Min clearance: 0.015 mm; 0.0006 inch
Max clearance: 0.055 mm; 0.0021 inch
Target clearance: 0.035 mm; 0.00135 inch

The blueprints gave two more pieces of interesting information. My measurements for Clevite bearing eccentricity were dead accurate and all within tolerance, as were my measurements for bearing thickness.
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      05-03-2015, 03:45 PM   #2559
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Quote:
Originally Posted by regular guy View Post
Many people know, I've been on a technical advising role on the "Custom Clevite" bearing project, providing all of the measurements and specifications we can find. Clevite didn't play dumb as if they didn't know some of the specs of the original BMW bearings they helped manufacture. They provided the "guide notch" size and locations, bearing thicknesses, etc.

So what I'm saying...is that I've seen all the blueprints Clevite generated for this project (there have been a few sets reviewed and rejected). One of the blueprints contained a very interesting "mistake." Clevite was supposed to update the rod bore diameter (with newly discovered official BMW specifications), but they forgot to adjust the bearing thickness to match the new clearance specifications (that's why this was rejected). But that "mistake" gave the discovery of something very significant. By forgetting to adjust the bearing thickness in the blueprint, I believe we back doored our way into discovering the official BMW bearing clearance specifications.

This blueprint takes into account ALL of the tolerance stacking for every affected part from bearings manufacturing tolerances, to rod journal diameter tolerances, to rod big-end bore dimensions. With this simple mistake, I can now give the official BMW rod journal bearing specifications on the original Clevite 088/089 bearings.

Min clearance: 0.015 mm; 0.0006 inch
Max clearance: 0.055 mm; 0.0021 inch
Target clearance: 0.035 mm; 0.00135 inch

The blueprints gave two more pieces of interesting information. My measurements for Clevite bearing eccentricity were dead accurate and all within tolerance, as were my measurements for bearing thickness.
TIA for your vigilant work on this issue Regular Guy.
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      05-03-2015, 04:40 PM   #2560
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Quote:
Originally Posted by regular guy
Many people know, I've been on a technical advising role on the "Custom Clevite" bearing project, providing all of the measurements and specifications we can find. Clevite didn't play dumb as if they didn't know some of the specs of the original BMW bearings they helped manufacture. They provided the "guide notch" size and locations, bearing thicknesses, etc.

So what I'm saying...is that I've seen all the blueprints Clevite generated for this project (there have been a few sets reviewed and rejected). One of the blueprints contained a very interesting "mistake." Clevite was supposed to update the rod bore diameter (with newly discovered official BMW specifications), but they forgot to adjust the bearing thickness to match the new clearance specifications (that's why this was rejected). But that "mistake" gave the discovery of something very significant. By forgetting to adjust the bearing thickness in the blueprint, I believe we back doored our way into discovering the official BMW bearing clearance specifications.

This blueprint takes into account ALL of the tolerance stacking for every affected part from bearings manufacturing tolerances, to rod journal diameter tolerances, to rod big-end bore dimensions. With this simple mistake, I can now give the official BMW rod journal bearing specifications on the original Clevite 088/089 bearings.

Min clearance: 0.015 mm; 0.0006 inch
Max clearance: 0.055 mm; 0.0021 inch
Target clearance: 0.035 mm; 0.00135 inch

The blueprints gave two more pieces of interesting information. My measurements for Clevite bearing eccentricity were dead accurate and all within tolerance, as were my measurements for bearing thickness.
Not bad considering you aren't an engineer. You must have had someone review the prints for you, Right?!
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      05-03-2015, 05:16 PM   #2561
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Quote:
Originally Posted by BMRLVR View Post
Not bad considering you aren't an engineer. You must have had someone review the prints for you, Right?!
Yes, multiple people, including engine design engineers have reviewed the blueprints.

It's funny don't you think? That simple mistake inadvertently gave us the equivalent of the original BMW factory blueprint for rod bearings, including tolerances and target clearance. That blueprint also kind of closes the door on all the guys questioning the measurements, methods, and saying nothing is proven and it's all just speculation. I guess I can quit collecting data now. Post-1, Table-1 updated with new specifications.

BTW, I would post this blueprint matching the original factory specs...but Mahle asserts ownership over the blueprint and does not allow posting without written permission. So you'll just have to take my word for what it contains.

I would say now, there's only two remaining "debatable" topic:
  1. Is the target clearance of 0.00135 inch too small for this engine with 10W60 oil and 2.0468 inch rod journal?
  2. Does 0.0006 inch to 0.0021 inch bearing clearance (tolerance stacking) explain why some engines fail early and others last a long time? That's 0.00029 to 0.00103 inch/inch journal clearance.

Last edited by regular guy; 05-03-2015 at 08:52 PM.
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      05-04-2015, 12:26 PM   #2562
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Quote:
Originally Posted by regular guy View Post
I would say now, there's only two remaining "debatable" topic:
  1. Is the target clearance of 0.00135 inch too small for this engine with 10W60 oil and 2.0468 inch rod journal?
  2. Does 0.0006 inch to 0.0021 inch bearing clearance (tolerance stacking) explain why some engines fail early and others last a long time? That's 0.00029 to 0.00103 inch/inch journal clearance.
Great find.

Are you really certain that the resulting "target clearance" takes into account all variation on the rod bores, bearing thicknesses and crank journal diameters? Do you have official ranges for all of these contributing dimensions? Remind me (since the OP has changed) how does this official .0006 to .0021 range compare to the measured range? IIRC it is pretty close but nothing was measured that low. 702/703 measured is .00115 - 0.0020.

From my perspective we can't really compare the resulting .00029 to .00103 in/in official specification without a similar range known for a baseline (hopefully similar) engine. Unfortunately, despite prior claims from kawasaki, I believe such information is not at all readily available.

A remaining issue could also be - do all measured BMW parts adhere to their acceptable/specified/official ranges (i.e. is the manufacturing "perfect")? I think it is likely but worth keeping on open mind on.
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      05-04-2015, 02:37 PM   #2563
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Quote:
Originally Posted by swamp2 View Post
Great find.

Are you really certain that the resulting "target clearance" takes into account all variation on the rod bores, bearing thicknesses and crank journal diameters?
Yes, absolutely certain within the caveat I will discuss below.

Quote:
Do you have official ranges for all of these contributing dimensions?
Yes, there is a range for every contributing dimension. There are ranges for the following: rod bore diameter, rod journal diameter, bearing base metal thickness, bearing material thickness, etc. Everything that contributed, had a range.

I knew you'd ask this question, so here's the caveat. The rod journal diameter is from our measurements, rod bore diameter provided by BMW specs, everything else provided by Clevite. But this is the same process and materials as the original 088/089 bearings, so the tolerance stacks will be the same. The only place it could differ, is the use of our rod journal diameters. But we can be intuitive here and realize that if they get any bigger outside of our measured range, then the minimum clearance gets even smaller than 0.0006 inch; and visa-versa on the larger side.

Quote:
Remind me (since the OP has changed) how does this official .0006 to .0021 range compare to the measured range?
By intentionally stacking tolerances, my previous spreadsheets show between 0.0009 to 0.0019 inch clearance. I believe my original measurements (original thread) deduced nominal clearance at 0.00125 inch, then the updated virgin bearing tests changed that to 0.00145 inch. As you will correctly point out, these sample sizes are too small to draw meaningful conclusions. But I think we can agree that all my measurements on 088/089 bearings seem to be dancing right around that 0.00135 inch target shown in this blueprint.

Quote:
IIRC it is pretty close but nothing was measured that low.
Correct. Looks like the lowers I've measured is 3/10ths away from theoretical minimum, and largest I've measured is 2/10ths away from theoretical maximum.

Quote:
702/703 measured is .00115 - 0.0020.

From my perspective we can't really compare the resulting .00029 to .00103 in/in official specification without a similar range known for a baseline (hopefully similar) engine. Unfortunately, despite prior claims from kawasaki, I believe such information is not at all readily available.
That's why I put the Ferrari and other engines comparison on the front page. They are decent analogs IMO.

Quote:
A remaining issue could also be - do all measured BMW parts adhere to their acceptable/specified/official ranges (i.e. is the manufacturing "perfect")? I think it is likely but worth keeping on open mind on.
That's an unknown, and I don't think we'd disagree on that. I agree it's possible some parts are outside of range and we just don't know it unless we find and measure one.
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      05-04-2015, 02:44 PM   #2564
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One of the more interesting things on the blueprint was the eccentricity. Eccentricity seems to be set by the manufacturer, but I'm sure BMW could override this if they want. But it appears they did not because my measurements on their bearings match this blueprint exactly.

There is a target value for eccentricity. Then the blueprint has three measurement points and mentions maximum range for those points:
  1. Bearing center should measure nominal bearing thickness (range: 3/10ths).
  2. Approximately 20 degrees from parting line has a specific value, with range: 4/10ths. I believe of my eccentricity measurements hit this target within 4/10ths. If there were any at 5/10ths, then I would assume I wasn't measuring at the proper location.
  3. Within a few thou of the parting line. There is a range for this too, but I don't remember what it is. I do remember my measurements hit that target as well.

So the eccentricity specifications on the blueprints was pretty interesting to me, not only how it's specified, but also how it's also measured. By choosing approximately 20 degrees measuring point, I think I got lucky because it matches the measuring location on the blueprint...or maybe kawasaki recommended I measure there?
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      05-04-2015, 11:55 PM   #2565
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Originally Posted by regular guy View Post
I knew you'd ask this question, so here's the caveat. The rod journal diameter is from our measurements, rod bore diameter provided by BMW specs, everything else provided by Clevite.
No concerned about any "inaccuracy" here at all. You measure well and as you know BMW is controlling this particular dimension incredibly well.

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Originally Posted by regular guy View Post
By intentionally stacking tolerances, my previous spreadsheets show between 0.0009 to 0.0019 inch clearance.
Pretty darn consistent in range and mean with the new official specs. Your attempt to widen the range with "intentional stacking" was a reasonable approach and turns out to be even more reasonable in light of the new data.

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Originally Posted by regular guy View Post
That's why I put the Ferrari and other engines comparison on the front page. They are decent analogs IMO.
The table does not appear to be updated for the S65 in light of the new data. Not a huge deal but it lists .0012 - .0018 (clearance, not in/in) for the S65 rod clearance. Although the 328 might be the best analog you have outside of other BMW numbers, it's some pretty old tech overall/relatively, developed in the early 80s.

The only thing that is a bit of an "itch" for me is the sheer size of the official acceptable range. Overall it seems really wide, right? Obviously it is easier to control a crank journal diameter manufacturing range than a bearing thickness, but this roughly 3/10th all the way to about .001 in/in is quite a bit larger than seems comfortable/correct. No data here, just gut...

Again, excellent find/calculations/conclusions. Thank you for sharing.
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      Yesterday, 01:36 AM   #2566
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The table does not appear to be updated for the S65 in light of the new data. Not a huge deal but it lists .0012 - .0018 (clearance, not in/in) for the S65 rod clearance. Although the 328 might be the best analog you have outside of other BMW numbers, it's some pretty old tech overall/relatively, developed in the early 80s.
I know there's pieces of the table that are not updated. I've converted most of it to pull live data from my other spreadsheets. That's one section that hasn't been converted. I know about it...haven't forgotten...just been swamped (pun intended).

Quote:
The only thing that is a bit of an "itch" for me is the sheer size of the official acceptable range. Overall it seems really wide, right? Obviously it is easier to control a crank journal diameter manufacturing range than a bearing thickness, but this roughly 3/10th all the way to about .001 in/in is quite a bit larger than seems comfortable/correct. No data here, just gut...

Again, excellent find/calculations/conclusions. Thank you for sharing.
I totally agree. That range is huge. I was pretty shocked by it as well.
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      Today, 01:05 PM   #2567
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rg: Will you be able to offer a guaranteed tighter spread in clearance or only the same range along with a larger mean value? I guess it begs the question as to which component, if any, is the key contributor to this seemingly broad range? It certainly is not the crank journals.
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