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Discussion Starter · #1 ·
HI i have been rebuilding a 1973 vw bug 1500 engine.the measurments are .40 bore .10 thrust .50 crank.orded .25 over main bearings.all the bearings fit except the small one by the flywheel.it would not slide on easly had to force it on.then put crank in the case got all bearings to sit except the small one would not sit.took it off it was destroyed.if anybody could help it would be appreciated.thanks alot
 

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67 Bug. 2275cc, 10.1:1, 48IDA,Eagle2242Cam,2300Lb clutch, 3.85 diff. Lowered,roll bar, 5pt, swaybars
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Little confused. Usually the measurements are in Imperial size like .040". I assume you have given metric sizes. So you are saying the case has been bored to .4mm (.016") over and the crank was ground .5mm (.020") smaller, right? If so the bearings must be sized to these exact sizes. The outer diameter of the bearings is .4mm larger than Standard and the inside of the bearings is .5mm small than Standard. 0.25mm over bearings would be the wrong size for either the case or crank, unless you meant that the crank was actually only cut down .25mm making it .5mm smaller diameter.

All the bearings should fit the crank with a slide on fit. You should be able to turn the bearing (which is installed oiled) with one or two fingers or the size is wrong. Second if you take a bearing and place it in the case half, it should fit snug. No need to force it in and it should not be loose. Forcing a bearing means it is the wrong size. Also if you bolt the case together, the crank should be loose enough to be able to turn by hand. If you cannot turn it, the main bearing outer diameter is too big or the inner diameter is too small. If you can feel any side to side movement or it seems really loose, the inner and/or outer diameter is wrong as well. If the thrust surface has been cut .1mm, then the thrust bearing needs to be .1mm narrower between the inner surfaces of the sides. If it is not right the crank will be able to move .1mm in and out regardless of the crank end-play setting (which should be about .005" to .006"). Even if it seems to have no in/out play (due to the positioning pin holding it in place), it will move over time allowing the crank to move in/out as well. The flywheel end is the front and should have the largest bearing installed on it with the flanged sides. The rear of the engine/crank takes the smallest bearing, which is the end you mount the pulley to.

I think you need to remeasure the crank diameter and the case bore diameter and compare to the sizes of a new set of bearings.

Also, the 73 had a 1600cc engine not a 1500cc, unless you have an older engine in the car. The letters/numbers stamped on the engine case below the generator pedestal will allow you to look up the year and size of the engine as built by the factory. If no letters are present or no letters/number combination, then the case is an aftermarket case.
 

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67 Bug. 2275cc, 10.1:1, 48IDA,Eagle2242Cam,2300Lb clutch, 3.85 diff. Lowered,roll bar, 5pt, swaybars
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Also, good to see you are back to working in the engine again after your last set of problems.
 

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Discussion Starter · #5 ·
Little confused. Usually the measurements are in Imperial size like .040". I assume you have given metric sizes. So you are saying the case has been bored to .4mm (.016") over and the crank was ground .5mm (.020") smaller, right? If so the bearings must be sized to these exact sizes. The outer diameter of the bearings is .4mm larger than Standard and the inside of the bearings is .5mm small than Standard. 0.25mm over bearings would be the wrong size for either the case or crank, unless you meant that the crank was actually only cut down .25mm making it .5mm smaller diameter.

All the bearings should fit the crank with a slide on fit. You should be able to turn the bearing (which is installed oiled) with one or two fingers or the size is wrong. Second if you take a bearing and place it in the case half, it should fit snug. No need to force it in and it should not be loose. Forcing a bearing means it is the wrong size. Also if you bolt the case together, the crank should be loose enough to be able to turn by hand. If you cannot turn it, the main bearing outer diameter is too big or the inner diameter is too small. If you can feel any side to side movement or it seems really loose, the inner and/or outer diameter is wrong as well. If the thrust surface has been cut .1mm, then the thrust bearing needs to be .1mm narrower between the inner surfaces of the sides. If it is not right the crank will be able to move .1mm in and out regardless of the crank end-play setting (which should be about .005" to .006"). Even if it seems to have no in/out play (due to the positioning pin holding it in place), it will move over time allowing the crank to move in/out as well. The flywheel end is the front and should have the largest bearing installed on it with the flanged sides. The rear of the engine/crank takes the smallest bearing, which is the end you mount the pulley to.

I think you need to remeasure the crank diameter and the case bore diameter and compare to the sizes of a new set of bearings.

Also, the 73 had a 1600cc engine not a 1500cc, unless you have an older engine in the car. The letters/numbers stamped on the engine case below the generator pedestal will allow you to look up the year and size of the engine as built by the factory. If no letters are present or no letters/number combination, then the case is an aftermarket case.
I got the numbers wrong the case is 0.40 crank was turned to 0.10 or 25mm thrust should be 0.25mm i think.
 

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If the other bearings fit the crank then it is possible the crank has had all journals turned but not the small rear one. Before you waste any more time, you need to use a micrometer gauge to measure all the bearing journals and see if they are all turned to the right sizes. If you buy a set of bearings that are for a crank turned .010, then all the crank journals must be .010 smaller than the stock size. I would start by looking up the standard size of the stock crank journals. Then check the small journal to see if it is still at the stock size or .010 less than the stock size. Next, I would measure the inside diameter of all the bearings and make sure they are all .010 smaller than stock. There is not a mystery here if you measure all the journal sizes and the bearing inside diameters. You will see something wrong in the sizes.
 

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Discussion Starter · #10 ·
If the other bearings fit the crank then it is possible the crank has had all journals turned but not the small rear one. Before you waste any more time, you need to use a micrometer gauge to measure all the bearing journals and see if they are all turned to the right sizes. If you buy a set of bearings that are for a crank turned .010, then all the crank journals must be .010 smaller than the stock size. I would start by looking up the standard size of the stock crank journals. Then check the small journal to see if it is still at the stock size or .010 less than the stock size. Next, I would measure the inside diameter of all the bearings and make sure they are all .010 smaller than stock. There is not a mystery here if you measure all the journal sizes and the bearing inside diameters. You will see something wrong in the sizes.
okay i will do that and let you know.thanks alot
 

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Discussion Starter · #11 ·
Hi the small end measures 0.040 the big journal is .50mm stock is 2.164.the inside diameter of small bearing is 0.040 so i don,t think it would fit.
 

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67 Bug. 2275cc, 10.1:1, 48IDA,Eagle2242Cam,2300Lb clutch, 3.85 diff. Lowered,roll bar, 5pt, swaybars
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Still a little hard to understand your measurements. I am looking for the actual diameter measurements in inchs, not in MM or what the bearings say they are tuned down by.

Generally all the journals on a crank are turned down by the same amount. If it is a .010 under crank then the big journals should be 2.154" in diameter (OD). The bearings for the big journals will be slightly larger in inside diameter (ID) by a couple of thousands such as 2.156" to 2.158". The small journal would be 1.564" OD and the bearings should be 1.566" to 1.568" ID. With oil on the bearings, the bearings should go on and spin with only the oil resistance. No force is ever needed for crank or rod bearings.

What are the actual full size measurements in inches? Once you make these measurements, you can see what is wrong and you can order the correct bearings. It sort of sounds like the crank was turned down in different amounts so one set/size of bearings will not fit on the crank.
 

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Discussion Starter · #13 ·
Still a little hard to understand your measurements. I am looking for the actual diameter measurements in inchs, not in MM or what the bearings say they are tuned down by.

Generally all the journals on a crank are turned down by the same amount. If it is a .010 under crank then the big journals should be 2.154" in diameter (OD). The bearings for the big journals will be slightly larger in inside diameter (ID) by a couple of thousands such as 2.156" to 2.158". The small journal would be 1.564" OD and the bearings should be 1.566" to 1.568" ID. With oil on the bearings, the bearings should go on and spin with only the oil resistance. No force is ever needed for crank or rod bearings.

What are the actual full size measurements in inches? Once you make these measurements, you can see what is wrong and you can order the correct bearings. It sort of sounds like the crank was turned down in different amounts so one set/size of bearings will not fit on the crank.
Hi the measurments are all the same your numbers are write but that small bearing wont,go on smoothly.should i go up a size just for that one bearing.all the others fit.
 

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This is going to be an interesting problem.

It is important that the bearings are the right size. If the bearing will fit on the crank but is really tight, then it is probably a few thousands too tight. ...or it could be that the bearing is not completely round, possibly damaged in shipment. If you have already tried putting it on the crank, it might be that you cannot return it where you bought it. If it is non-returnable, then you could try very lightly sanding the inside diameter with 200 to 400 grit sandpaper, to take off some of the gray babbet material. Just a very small amount and see if it will fit as smoothly as the other bearings. It might work this way. If you take off too much (can see some of the metal under the babbet material, then it is a throw-away.

You could try the next size but remember that it will be 10 thousands larger ID than the one you have, which could be a little too loose. However if it fits as smoothly as the other bearings on the crank, then you have found your problem. In this case the person that turned the crank did not turn all the journals down by the same amount.

If you find that one size is too small and the very next size (10 thousands larger) is too loose then the crank work was not done correctly. Options then would be to have the crank turned to the proper size (might just need sanding and then polishing the journal on a lathe), or trying to sand the smaller bearing just a little to get it to fit. Either way some work will need to be done to get the bearing size to match the journal.

One other thing to look at is the outside (rear) edge of the journal to see if it is even with the rest of the journal. If it has a slight edge to it, the bearing might be the right size but there is a slight lip on the edge of the journal that will not let you put the bearing on. You might be able to feel the lip/edge with your finger or try laying a straightedge across the journal, in a couple of places, and see if you can see light under the straightedge near the edge of the journal.
 

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Will give you another piece of advice. Take the bearings and crank to a local machine shop and explain your problem and ask them for advice. They will have the crank and bearings in hand and can look them over for you. You don't need to find a VW machinist since cranks, crank turning and bearing fitment is the same regardless if it is a Chevy, Ford, BMW, Nissan or Toyota crank. The work is all done the same way and clearances to allow for oil are identical for all cranks. Someone who turns cranks should almost immediately know what the problem is.
 

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Discussion Starter · #16 ·
This is going to be an interesting problem.

It is important that the bearings are the right size. If the bearing will fit on the crank but is really tight, then it is probably a few thousands too tight. ...or it could be that the bearing is not completely round, possibly damaged in shipment. If you have already tried putting it on the crank, it might be that you cannot return it where you bought it. If it is non-returnable, then you could try very lightly sanding the inside diameter with 200 to 400 grit sandpaper, to take off some of the gray babbet material. Just a very small amount and see if it will fit as smoothly as the other bearings. It might work this way. If you take off too much (can see some of the metal under the babbet material, then it is a throw-away.

You could try the next size but remember that it will be 10 thousands larger ID than the one you have, which could be a little too loose. However if it fits as smoothly as the other bearings on the crank, then you have found your problem. In this case the person that turned the crank did not turn all the journals down by the same amount.

If you find that one size is too small and the very next size (10 thousands larger) is too loose then the crank work was not done correctly. Options then would be to have the crank turned to the proper size (might just need sanding and then polishing the journal on a lathe), or trying to sand the smaller bearing just a little to get it to fit. Either way some work will need to be done to get the bearing size to match the journal.

One other thing to look at is the outside (rear) edge of the journal to see if it is even with the rest of the journal. If it has a slight edge to it, the bearing might be the right size but there is a slight lip on the edge of the journal that will not let you put the bearing on. You might be able to feel the lip/edge with your finger or try laying a straightedge across the journal, in a couple of places, and see if you can see light under the straightedge near the edge of the journal.
okay you gave me a few things to look at appreciate it thanks alot.
 

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Discussion Starter · #17 ·
okay you gave me a few things to look at appreciate it thanks alot.
okay you gave me a few things to look at appreciate it thanks alot.
Hi i got the bearing on after polishing crank and the inside of the bearing,but now i am back to the same problem where the bearing will not seat on the dowel pin.the number 3 bearing is seated but loose.the bearing with the flange i took out of the box was too small would not fit ,so i put the old one in and fit perfect and is seated.I think it is time to take it to somebody .
 
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