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Gtir Motorsport club » Tech room » Help and Advice » Selecting big end bearings

Selecting big end bearings

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1 Selecting big end bearings on 21st February 2016, 8:34 pm

burrows1980

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I read somewhere a while back that the nissan part number is only for one half of the bearing:

Con rod bearing - 12111-54C01-  x 4    Type 1                  £7.97
Con rod bearing - 12111-54C00-  x 4    Type 0                  £7.97


So all the rods are 0 and the crank has 1111 so am I right in thinking I need to order 4 of the above type 1 part number and 4 of the 0 part number?

Fast shows it as two seperate items



In the manual I cant find a reference of ordering two per rod:



Main bearings were easy to work out although still need to plastigauge the crank before ordering them!

Gaz

2 Re: Selecting big end bearings on 22nd February 2016, 8:35 am

Mr B

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gtir technician
gtir technician
They sold as each half so you need buy 8 for full set. You need grade 1 for all. crank grade represents crank pin size & rod grade represents rod bore size grade . on later sr engines you crossed these on chart to select bearings so outer & inner diameters of shells match correct.
I would still mic everything to check all in tolerances or use plastiguage . I think the grading of rods on 54c was normally always 0, ones i've built have been & spare set I got are also all 0 stamped .

3 Re: Selecting big end bearings on 22nd February 2016, 1:17 pm

burrows1980

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Cheers again Mr B!! I ordered plastigauge a few months back to check the main bearings but will do the rods as well.

Gaz

4 Re: Selecting big end bearings on 22nd February 2016, 3:53 pm

Mr B

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gtir technician
gtir technician
when order bearings get parts staff confirm order quantity for full engine set as then if get any issues on what finally supplied they more obliged to help correct it rather than blame you or me :-)
rod shells i've order have always been bagged as one half & thus 8 for full set .

5 Re: Selecting big end bearings on 22nd February 2016, 9:19 pm

burrows1980

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Im a bit confused now Mr B, popped a bearing out tonight and on the back the part number is grade 0 , checked the rest and there all 0



I'll measure it with plastiguage this friday.

6 Re: Selecting big end bearings on 23rd February 2016, 7:16 am

Mr B

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gtir technician
gtir technician
if you got 0 fitted then I would probably go with same again, with such a small difference in grades 0 or 1 will still be in spec but mic or plastiguage to get the figures. Someone been in your engine before perhaps !

7 Re: Selecting big end bearings on 23rd February 2016, 8:17 am

burrows1980

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Might explain the valve shim floating around! Will see what it measures on Friday.

8 Re: Selecting big end bearings on 23rd February 2016, 10:46 pm

burrows1980

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The plot thickens tonight! Cleaned everything up tonight ready for the plastigauge and notced the main journal bearings are all the same grade, 0? the part numbers on the back of the bearings are:

12223-54C00- cap bearing
12215-54C00- block bearing

Weirdly this part number doesnt exist in fast and the grade 0 bearing is 12207-54C00- maybe the above are a disc part number superseeded by the 12207-

But from the numbers on the block and crank:

00001 Block

11001 Crank

The bearing grades should be 11002. Confused I googled the part numbers on the bearings and got a few results one forum post with exactly the same bearing grades and part numbers as me but no replies doh!

Ive had the car since being imported in 2004 with 33k miles and never stripped the engine down this far, so surely this has to be from factory, but whats the point in stamping the crank and block with the correct bearing spec if there not going to use the right ones. Guessing mine was a monday morning or friday afternoon build Laughing

Will see what results I get with the plastigauge and report back

Gaz

9 Re: Selecting big end bearings on 25th February 2016, 8:18 pm

burrows1980

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Finally got round to using plastigauge on the crank this evening:



The rods measured:

Rod 1: 0.050mm
Rod 2: 0.050mm
Rod 3: 0.038mm
Rod 4: 0.038mm

Crank Measured:

Journal 1: 0.038mm
Journal 2: 0.038mm
Journal 3: 0.038mm
Journal 4: 0.038mm
Journal 5: 0.038mm

The journals were slighly tighter towards 0.025mm



0.038mm was to small on the gauge but 0.025mm was to big.

There all way in spec, but i dont know what size bearings to order?  As in the above post, all the journal bearings are the same grade 0 but makes no sense to whats stamped on the crank and block.  Does anybody know the ideal clearance spec for journal bearings?

With regards to the rod bearings, Mr B said about ordering type 1's, which Ive also read on the SR20 forum that only type 1's are used but again mine are all type 0  loopy

Think what im trying to say is do I just order type 0's for everything?

Final question(s) Laughing how do they classify the bearing grades? ie is 0 the thinnest and 6 thickest...  what does each grade increase by thickness wise?

Gaz

10 Re: Selecting big end bearings on 26th February 2016, 7:56 am

Mr B

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gtir technician
gtir technician
0.025 to 0.035mm is ideal range . i always like aim for high 0.02? to 0,030 max
I reckon your bearings been swapped at some stage in japan during a bit of a refresh for some reason, I remember machinist I use who does a lot of sr20 builds once said it common see all 0 shells fitted in a jap rebuild as gives larger clearance & lazy way of being sure not going pinch a bearing & possibly track use precaution .
On a high mile motor only way be spot on when using nissan grades is use quality digital mic & bore gauge & do at least 4 measures to each journal & bore. Plastigauge is really not very accurate but a good last safety test before final build.
Out of plastigauge & nissan stamped grades I would trust nissan grades more when parts still super condition
I would deffo look at grade 1 on rods & would be more inclined head towards nissan stamped sizes than go with all 0 grades BUT nissan grades were measured thousands of miles ago so only way know what best for sure is measuring with decent mics & bore gauges.

couple images & the pdf data doc to help ...



PDF LINK

What you also can consider is likes of ACL that only done one size which is about same as grade 2-3 works on most builds well but oem nissan way done right is better as can get more even clearance over all bearings without bodging or just living with off clearances, most people including your average back street engine shop just can't or can't be bothered measure accurate enough to be oem precise & part of reason most rebuilds spin bearings in a month or struggle see 10,000miles of life while a oem build can see 10x that .

11 Re: Selecting big end bearings on 26th February 2016, 8:48 am

burrows1980

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Thanks once again Mr B! I've got what I think is a decent mic that I inherited from my dad, brand new Moorse & Wright, only problem I've got is its imperial 2"-3" and not got a clue how to read it Laughing

I've always said from the day I got it that I thought it had been used for track use in Japan, just by how it was setup in terms of strut braces on top and underneath, negative camber angle, as well as various other things I noticed over time... Not the end of the world I guess!

Ive got a bore gauge but can't remember if I have a small enough attachment to check crank bores, would imagine there is!

12 Re: Selecting big end bearings on 26th February 2016, 9:09 am

Mr B

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gtir technician
gtir technician
Is worth anyone rebuilding an engine to invest in decent 0-25mm, 25-50mm, 50-75mm digital mic & bore gauge set with 0.001 resolution , good thing with digital is memory hold channels & switch metric/imperial.
Heavy investment though & pro gear measuring 0.0001 resolution is scary money if not used a lot.
Being your engine in good order it should be quite easy measure all jourmnals-pins/bores and use the oem measures & grades s a safety guide to how good your gear & measuring is .
I would deffo look at borrowing or buying decent measuring gear as does job right & tool for life .
Won't go far wrong using nissan stamped grades though as jdm factories were very anal on their measuring :-)

13 Re: Selecting big end bearings on 27th February 2016, 5:29 pm

burrows1980

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So I spent the last hour measuring the journals with the imperial mic that I have, impressed myself learning how to read it and cant get over how acurate it is!  I practised on the 2" calibrating bar to get the feel of the pressure needed.

Here's the results I got:

Journal 1 - 2.150 + 0.014 + 0.0002 = 2.1642"
Journal 2 - 2.150 + 0.014 + 0.0002 = 2.1642"
Journal 3 - 2.150 + 0.014 + 0.0004 = 2.1644"
Journal 4 - 2.150 + 0.014 + 0.0004 = 2.1644"
Journal 5 - 2.150 + 0.013 + 0.0007 = 2.1637"

The numbers stamped on block and crank add to: 11002, going off the spec sheet in the workshop manual the above measurements fall into the correct size shells needed.

Also measured the pins and they consistently measured 1.8885", again the spec shows this is top end of type 1 but bottom of type 0, might explain why I have type 0's instead of the more common type 1's.

Gaz

14 Re: Selecting big end bearings on 27th February 2016, 7:21 pm

Mr B

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gtir technician
gtir technician
You can't beat proper measuring, if fit caps & measure you can get good idea of oil clearance with shells & if do again with shells you can get very accurate oil clearance measures.
Bet your Dad would be pleased see that decent mic getting used too ... thumbsup

15 Re: Selecting big end bearings on 7th May 2016, 6:18 am

burrows1980

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Meant to update this last week, when I came to install the crank and big end bearings, although they were all the correct sizes type 2,1 & 0 for crank and type 1's for big end, the part number on the back of the shell was the same as I took out! So it looks like they were right to start with.

Weird why they put a different part number on the back to what's on the box! Anyway plastigauge the crank bearings and all in spec now Cool

16 Re: Selecting big end bearings on 7th May 2016, 8:16 pm

Spark plug spike

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What did you get the clearances down to compared to the original clearances you posted?

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