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Bearing tolerance slightly too big - Incorrect bearings?


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Hi guys,

I've measured the tolerances for my bearings and I have got the following values (I re-measured everything 7-10 times to make sure they're correct)

Location Lobe Upper Shell Lower Shell Bore Tolerance STD Min STD Max Max Tol
Main 1 46.988 1.956 1.961 51.038 0.133 0.016 0.048 0.8
Main 2 46.988 1.964 1.961 51.049 0.136 0.016 0.048 0.8
Main 3 46.987 1.958 1.957 51.030 0.128 0.016 0.048 0.8
Main 4 46.986 1.963 1.964 51.046 0.133 0.016 0.048 0.8
Main 5 46.992 1.950 1.957 51.046 0.147 0.016 0.048 0.8

 

As you can see my tolerances are out by about 0.5mm. I am using Standard Taiho bearings purchased from Japserviceparts.com.

Looking at the specs for bearings, my shell sizes should be as followed:

STD mark 1 = 1.995-1.999mm
STD mark 2 = 1.999-2.003mm
STD mark 3 = 2.003-2.007mm
STD mark 4 = 2.007-2.011mm
STD mark 5 = 2.011-2.015mm

 

Mine are about 0.05 too small by the looks of it - Looking at the spec sheet on Taiho's website (http://www.taihonet.co.jp/e/ebc/all.pdf) - the bearings I have got (Model T025A) are listed for the EP82 and EP85. My understanding these had 4E-FTE's as well - so this shouldn't be an issue?

If I were to get some OEM bearings/different aftermarket bearings - would this fix my issue?

I have an analytical balance (extremely accurate scales) at my disposal so I could check the weight of these bearings to make sure they're legit - however I don't know how heavy they should be! I'm also an idiot and threw out my old bearings so I have no way to check against the old ones!

PS. I am measuring the bearings from the corner with a micrometre - I've seen this method done before so is it okay still? - I don't have the tool to measure the centre unfortunately

Thanks!

Edited by bittenfleax
clarification
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4 hours ago, bittenfleax said:

Hi guys,

I've measured the tolerances for my bearings and I have got the following values (I re-measured everything 7-10 times to make sure they're correct)

Location Lobe Upper Shell Lower Shell Bore Tolerance STD Min STD Max Max Tol
Main 1 46.988 1.956 1.961 51.038 0.133 0.016 0.048 0.8
Main 2 46.988 1.964 1.961 51.049 0.136 0.016 0.048 0.8
Main 3 46.987 1.958 1.957 51.030 0.128 0.016 0.048 0.8
Main 4 46.986 1.963 1.964 51.046 0.133 0.016 0.048 0.8
Main 5 46.992 1.950 1.957 51.046 0.147 0.016 0.048 0.8

 

As you can see my tolerances are out by about 0.5mm. I am using Standard Taiho bearings purchased from Japserviceparts.com.

Looking at the specs for bearings, my shell sizes should be as followed:

STD mark 1 = 1.995-1.999mm
STD mark 2 = 1.999-2.003mm
STD mark 3 = 2.003-2.007mm
STD mark 4 = 2.007-2.011mm
STD mark 5 = 2.011-2.015mm

 

Mine are about 0.05 too small by the looks of it - Looking at the spec sheet on Taiho's website (http://www.taihonet.co.jp/e/ebc/all.pdf) - the bearings I have got (Model T025A) are listed for the EP82 and EP85. My understanding these had 4E-FTE's as well - so this shouldn't be an issue?

If I were to get some OEM bearings/different aftermarket bearings - would this fix my issue?

I have an analytical balance (extremely accurate scales) at my disposal so I could check the weight of these bearings to make sure they're legit - however I don't know how heavy they should be! I'm also an idiot and threw out my old bearings so I have no way to check against the old ones!

PS. I am measuring the bearings from the corner with a micrometre - I've seen this method done before so is it okay still? - I don't have the tool to measure the centre unfortunately

Thanks!

As far as I can research, the bearing shells are thinner at the parting line (where you are measuring) and should be measured at 90 degrees to the parting line with a ball anvil in the micrometer to get their true thickness.

I also thought that oil clearances are measured by installing the bearing shells in the main journals and caps, adding the caps and torqueing them down. Then measuring the the central bore with a bore gauge at 90 degrees to the parting line? This gives the size of the bore with bearing installed to check against the crank main journal size to check the oil clearance?

Never done it myself though.

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12 minutes ago, Claymore said:

As far as I can research, the bearing shells are thinner at the parting line (where you are measuring) and should be measured at 90 degrees to the parting line with a ball anvil in the micrometer to get their true thickness.

I also thought that oil clearances are measured by installing the bearing shells in the main journals and caps, adding the caps and torqueing them down. Then measuring the the central bore with a bore gauge at 90 degrees to the parting line? This gives the size of the bore with bearing installed to check against the crank main journal size to check the oil clearance?

Never done it myself though.

Oh yeah, so that's what the ball is for in the micrometre set 😆😅 I will do your method tonight and review the results cheers man!

I did install all the caps (torqued down as well), I just measured without the bearings to get the initial bore size. Then I just add the thickness of the bearings onto this. I then subtract this result from the lobe of the crank which gives me my tolerance - means I'm not scratching the surfaces of my bearings with a telescoping gauge!

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That sorted it - I measured the bearings at the centre point using the ball bearing supplied with my micrometre and also re-measured the lobes as it was the first set I measured (so was more likely to be inaccurate)

If anyone comes across this and is stick - I got the following after measuring the bearings properly:

Location Lobe Size Gauge Tolerance Total Lobe U Shell L Shell Bore Tolerance STD Min STD Max Max Tol
Main 1 21.988 25 46.998 1.993 1.991 51.038 0.056 0.016 0.048 0.08
Main 2 21.989 25 47.000 1.992 1.993 51.049 0.064 0.016 0.048 0.08
Main 3 21.988 25 46.997 1.992 1.991 51.030 0.050 0.016 0.048 0.08
Main 4 21.988 25 46.997 1.994 1.991 51.046 0.064 0.016 0.048 0.08
Main 5 21.992 25 47.002 1.992 1.991 51.046 0.061 0.016 0.048 0.08

 

Thank you @Claymore for pointing me in the right direction!

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On 1/22/2021 at 8:14 PM, bittenfleax said:

Oh yeah, so that's what the ball is for in the micrometre set 😆😅 I will do your method tonight and review the results cheers man!

I did install all the caps (torqued down as well), I just measured without the bearings to get the initial bore size. Then I just add the thickness of the bearings onto this. I then subtract this result from the lobe of the crank which gives me my tolerance - means I'm not scratching the surfaces of my bearings with a telescoping gauge!

i ll also confirm that for bearing clearance as mentioned you need to torque the mains with the bearings installed. Measure the crank lobe with the mic and then the bore 90 degrees to the parting line using the dial bore gauge. Substract accordingly

Your method seems logical on first thought but the bearing shells kinda distort to their apropriate shape once they are inside the bore

Keep us posted on the results! 0.133 would be way off

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UPDATE!

So I've double checked my measurements with plastigauge to be on the safe side.

The readings I got on the plastigauge were matching up perfectly with my measurements! Below is a picture of the 1st lobe for clarification.

 image.thumb.png.bb4705cc66212987f67b9d867fad4e50.png

 

I've also installed piston 1 - I checked the ring gaps (using TP rings) - they were in tolerance. I also checked the tolerance with plastigauge and the reading I got was the same as my measurements!

3 more to go now :D 

 

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