Unofficial Royal Enfield Community Forum
Royal Enfield Motorcycles => Vintage Royal Enfield => Topic started by: 55firearrow on July 28, 2014, 05:20:46 pm
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Hi guys I'm new here, I've got a 1955 250cc Indian fire arrow made by Royal enfield and I believe it's the same as an RE Clipper. I'm looking for some advice regarding the crankshaft/flywheel sliding side to side in the crankcase. There's a local small engine guy who said I need to shim it. Not sure where to put the shims or even where to get them.
I am trying to do a full restoration on this bike. I noticed this issue before taking the crankcase apart but it's been split now so if you need any pictures I can try to get them.
Also would you change the bearings in the case halves even if they don't have any obvious problems?
Thanks, Jonathan
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Is there is side to side play in the crankshaft itself then it sounds like the main bearings are bad. If you already have it turn down take a close look at the crank and inspect it fir damage and wear where it rides on the main bearings. Also have a close look at the bearings themselves. I would plan on a complete rebuild. How long has this bike been sitting? Was it running before you tore it down?
Scottie J
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I don't know about the Clipper, but the Bullet takes up the crank end-play when you tighten up the alternator nut. Until you do that, the crank moves side to side about an eighth of an inch. When you tighten the alternator nut, it pulls it all out to one side, and then the crank is centered and doesn't move side to side.
As for the main bearings, yes, I always change main bearings when I have the cases split, regardless.
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If you don't already have it, here is a link to Hitchcock's in the UK.
http://www.hitchcocksmotorcycles.com/news/22616/Additional_Online_Parts_Books
They show parts for the 250cc Clipper and the Crusader and just studying the drawings can help you understand what goes where.
Although it's a PITA paying the shipping costs, their about the only good source for parts for many of the RE models like yours.
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+1 on sourcing parts from Hitchcocks. Tho I don't much care for the fact that most parts needed I'm forced to buy from their money hungry greedy fingers. After conversion rates and shipping you end up paying $3-$7 for a $.75 bolt. It's frustrating but can you do?....
Oh, and $120 for shipping on my last order.
Scottie J
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Is there is side to side play in the crankshaft itself then it sounds like the main bearings are bad. If you already have it turn down take a close look at the crank and inspect it fir damage and wear where it rides on the main bearings. Also have a close look at the bearings themselves. I would plan on a complete rebuild. How long has this bike been sitting? Was it running before you tore it down?
Scottie J
As far as wear on the crank I'm not sure what to look for. Here is a picture of the timing side of the crank where it looks like there may be an issue:
(https://farm6.staticflickr.com/5573/14775277034_993350f9d1_c.jpg) (https://flic.kr/p/ovDa6L)
(https://farm3.staticflickr.com/2915/14777636235_be5812fe09_c.jpg) (https://flic.kr/p/ovRfpD)
Do you see how it's not a 90 degree angle where the crankshaft drops down to a smaller diameter but rounded?
The bearing rollers are all about .249" in diameter according to my cheap digital caliper.
Should I get new rollers and cages or just rollers and should I go with the ones on Hitchcocks that are .2498 or should I try to get bigger ones to account for wear?
I was hoping to not have to replace the connecting rod bearing, so when the local small engine guy said don't worry about it unless it moves straight up or straight down I was ecstatic. What are your thoughts on this?
I really don't know how long it was sitting. The last registration sticker is 1973 but that doesn't mean it hasn't run since then. It was not running when I took it apart but I think it could have. It kicked over fine and everything. When I was taking it apart I noticed there was a wire disconnected from the alternator, so maybe it never ran after that came off?
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That radiused fillet you point out is not a problem. It is done like that to keep the crank from cracking there.
The area of concern is the inboard segment of the crank where the rollers run, and there are two black bands on there that look like burnt oil. That area must be completely smooth and round, and the proper diameter for the rollers to run on it properly. If it is not, then a new timing side shaft is called for, or a proper metal surface repair and heat treat for rollers should be done to that shaft you have. The clearance for the rollers is quite precise, and the surface needs to be quite hard, and it all needs to be perfectly round, and smooth and even.
Get a figure from a service manual, or from Hitchcock, on the proper diameter of that shaft in the bearing area. Then you know how close you are to being good, or how far out it is.
Regarding the big end, if it passes the no up/down play test, it is probably okay. However, we don't know how long it will stay that way. It is unknown for future lifetime.
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I don't know about the Clipper, but the Bullet takes up the crank end-play when you tighten up the alternator nut. Until you do that, the crank moves side to side about an eighth of an inch. When you tighten the alternator nut, it pulls it all out to one side, and then the crank is centered and doesn't move side to side.
As for the main bearings, yes, I always change main bearings when I have the cases split, regardless.
That is a very good point. I wish I had checked this before taking it apart. What year/what cc bullet would that be?
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That radiused fillet you point out is not a problem. It is done like that to keep the crank from cracking there.
The area of concern is the inboard segment of the crank where the rollers run, and there are two black bands on there that look like burnt oil. That area must be completely smooth and round, and the proper diameter for the rollers to run on it properly. If it is not, then a new timing side shaft is called for, or a proper metal surface repair and heat treat for rollers should be done to that shaft you have. The clearance for the rollers is quite precise, and the surface needs to be quite hard, and it all needs to be perfectly round, and smooth and even.
Get a figure from a service manual, or from Hitchcock, on the proper diameter of that shaft in the bearing area. Then you know how close you are to being good, or how far out it is.
Regarding the big end, if it passes the no up/down play test, it is probably okay. However, we don't know how long it will stay that way. It is unknown for future lifetime.
In my manual it says the engine shaft diameter is 1.0000/.9997 I don't know why there is a slash and then another number though. should I use steel wool or something to get the oil off and then measure it? One problem is my caliper only goes to 3 decimal places and these numbers go out to 4 places :(
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If you don't already have it, here is a link to Hitchcock's in the UK.
http://www.hitchcocksmotorcycles.com/news/22616/Additional_Online_Parts_Books
They show parts for the 250cc Clipper and the Crusader and just studying the drawings can help you understand what goes where.
Although it's a PITA paying the shipping costs, their about the only good source for parts for many of the RE models like yours.
I have been on that site before but I can't find one for the right year.
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In my manual it says the engine shaft diameter is 1.0000/.9997 I don't know why there is a slash and then another number though. should I use steel wool or something to get the oil off and then measure it? One problem is my caliper only goes to 3 decimal places and these numbers go out to 4 places :(
Those numbers are max/min dimensions. New is 1.0000" and minimum is .9997". If it is smaller than .9997", then it is out of spec and needs correcting. Crank size of 1.0000" is common with Enfield, and Bullets have the same size shaft.
The reason that the numbers are given to 4 places, is that roller bearings require VERY small clearance, and require very precision tolerances. These clearances are on the order of less than one thousandth of an inch(<.001"). You cannot do work on roller bearings with a cheap caliper that reads to 3 places. You need a high quality precision micrometer. Take that crank to a precision machine shop, and have them mic it for you, and check it for roundness and surface suitability for roller bearing use.
On a Bullet, there are inner races pressed on to the shaft, which are purchased with the correct sizes already there. Apparently on your engine, the rollers are running directly on the shaft, which requires precision shaft size, and surface hardness of ~58 Rockwell hardness.
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The two numbers represent the maximum and minimum size of the shaft. The difference between the max and min is known as the "tolerance".
Nothing can be made absolutely perfect so it must have some allowed variation defined to represent the absolute limits.
In the case of this shaft, the tolerance is three tenths of one thousandths of an inch.
That's about equal to the thickness of one piece of human hair cut into 10 equal pieces. It is written as 0.0003 inches.
This tolerance value is so small, it must be measured at a controlled temperature, usually 78 degrees F (25.556 degrees C). (Hotter or colder temperatures will give different values because the steel/iron will expand or contract as the temperature changes.)
This .0003 tolerance shown is a typical tolerance for a grade 5 roller bearing raceway and a brand new part may be any size in the range and still be acceptable.
Most applications where the bearing race is an integral part of something like a crankshaft also have a service limit that is greater than the new part tolerance. This service limit represents the maximum size variation allowed due to wear.
I'm sure somewhere in the world a Service Manual exists that gives this value but finding it would be difficult.
Lacking the recommended service limit I feel you can safely use a value of 1.0000-.9994 with the same rollers as long as the engine isn't going to be used for racing.
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Thanks for all the info guys! Measuring the shaft, is this something I shouldn't try at home? Or can I buy a micrometer like this one:
http://www.flexbar.com/shop/pc/DIGITAL-OUTSIDE-MICROMETER-2-3-0001--p5404.htm?gclid=CjwKEAjw0ueeBRCmhozc-_DRrlUSJABihBEEUnIGmU-7rT21VGxTNPgz6Jjbf5Vrk_M0ah1Qn0q4BRoCcITw_wcB
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That micrometer reads between 2 inches and 3 inches.
It can't measure your shaft, which is 1 inch.
It is a whole lot cheaper to take it to a good machinist and have it measured with a precision micrometer there.
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If it's a '55 Indian, it'll be a '55 Clipper. As for the two numbers on the diameter, that's the total wear you can have on the crank at that point which amounts to .0003 which is essentially none. Basically that just takes in manufacturing tolerances. If it's smaller than that, You probably have to get a new mainshaft.You can clean it up initially with a bit of very fine steel wool. But you only want to clean up the old oil stuff. If you get into the steel, you will loose that .0003 very quickly! If you're not experienced with engine building, obviously, do as ACE sez, take it to someone who knows how to take care of crankshafts and engine building, in general.
Bare
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I took it to a machine shop yesterday to have the shafts measured. The guy who I hoped would be there wasn't and this guy didn't check the temp or anything. It was a little cooler that day so I would say the crank was 60 to 70 F when he measured it. Anyway he got .9995 where the inner drivers side bearing would ride, .9996 where the outer bearing would be on the drivers side, and .9991 on the timing side. The guy didn't seem to think it was any big issue but then again he doesn't know anything about these motorcycles. What are your thoughts?
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I say live with it.
The roughly 18 degree temperature difference will only cause the journal to appear to be .0001 smaller than it actually would be if measured at the correct temperature. Actually, if the measuring equipment and its calibrating gage blocks were at a similar temperature they would also be that much smaller so the reading you got would be still be accurate.
As I mentioned before, the .0003 tolerance (1.0000-.9997) is for a brand new journal size. It is anticipated by the designer that there will be some wear during the course of the journal's life and these hardened steel journals can not be "built up" to enlarge them.
For that reason a limit lower than the original new size is allowed before scrapping the crankshaft would be required.
The service limit of .9994 I suggested in my previous post will effect the radial clearance in the bearing assembly by allowing it to be .00015 looser than a brand new journals lower limit. The oil film between the rollers and the journal will eliminate any perceptible play in the bearing even with this added clearance.
I'm assuming the journal that measured .9991 diameter is on the lightly loaded side of the crankshaft? If so, it should still work for many miles as long as the engine is not run hard.
As a side note, if this wasn't a surface with rolling element bearings running against it, it could be repaired by "thin dense chrome" or "electroless nickel" plating. These repairs could be used on a shaft that was going to have a full bearings inner ring pressed onto it, for instance.
These methods of repair cannot be used with your engines design because the direct contact between the rollers and the journal would rapidly chip off any plating that was applied to the crankshaft.
As I said, live with what you've got. Run the engine easy and it should last for many years. :)
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I say live with it.
The roughly 18 degree temperature difference will only cause the journal to appear to be .0001 smaller than it actually would be if measured at the correct temperature. Actually, if the measuring equipment and its calibrating gage blocks were at a similar temperature they would also be that much smaller so the reading you got would be still be accurate.
As I mentioned before, the .0003 tolerance (1.0000-.9997) is for a brand new journal size. It is anticipated by the designer that there will be some wear during the course of the journal's life and these hardened steel journals can not be "built up" to enlarge them.
For that reason a limit lower than the original new size is allowed before scrapping the crankshaft would be required.
The service limit of .9994 I suggested in my previous post will effect the radial clearance in the bearing assembly by allowing it to be .00015 looser than a brand new journals lower limit. The oil film between the rollers and the journal will eliminate any perceptible play in the bearing even with this added clearance.
I'm assuming the journal that measured .9991 diameter is on the lightly loaded side of the crankshaft? If so, it should still work for many miles as long as the engine is not run hard.
As a side note, if this wasn't a surface with rolling element bearings running against it, it could be repaired by "thin dense chrome" or "electroless nickel" plating. These repairs could be used on a shaft that was going to have a full bearings inner ring pressed onto it, for instance.
These methods of repair cannot be used with your engines design because the direct contact between the rollers and the journal would rapidly chip off any plating that was applied to the crankshaft.
As I said, live with what you've got. Run the engine easy and it should last for many years. :)
I'm not sure what you mean by lightly loaded side, it's opposite the clutch/drive sprocket side.
I think I'll take your advice and just go with it, replacing only the rollers and cages.
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By "lightly loaded side" I was talking about the force the bearing must resist to keep the crankshaft centered in the engine crankshaft bores.
Usually, driving the camshafts and the ignition gears doesn't require much horsepower so the force that the crankshaft must produce to rotate the gears is not very large. This sideways force on the crankshaft produces the "load" that the bearing must resist to keep the crankshaft centered, hence the term "lightly loaded".
The clutch side of the crankshaft must deliver the full power that the engine can produce to the clutch thru the primary drive chain. This produces a large sideways load on the crankshaft which its bearing must resist so I refer to this side as the "heavily loaded side". Because the force needed is large, the bearing on that side will be "heavily loaded".
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That makes sense, thanks.
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55firearrow
I've been doing a bit more reading and if you really have a 1955 250cc firearrow it should be basically the same lower end as the old 350 bullet and the transmission is mounted on the rear of the engine in a similar manner.
I'm not sure where I got the idea that the bearing rollers were running directly on the crankshaft but according to what I've read, the bearings have a hardened inner race which is pressed onto the crankshaft. Of course, I could be wrong about this.
If the bearings have inner races that are just pressed onto the crankshaft journals, you could have the one(s) that are undersize plated to bring it up to spec.
The processes I'm familiar with are called "electroless nickle plate" and "thin dense chrome plateing".
Both of these plating processes can be applied so they will only increase the steel or iron journal a tenth of a thousandth of an inch or two in the area that is undersize.
Because it is a slow process where the plating fluid is applied directly to the metal with a soaked wand or stylus, there is no machining involved or required. (Actually, these plating processes can add up to .0005 per surface without a problem).
The difficult part is finding a plating company who can do the process and will work for someone who does not work for a large company that will give them a production order.
If you are beyond this level in your rebuild, don't worry about it.
As long as the bearings inner race is a press fit on the crankshaft journals you have no problem.
If one of the bearings inner races is a slip fit, not requireing a press to install it you can clean the surfaces of all oils or preservatives and apply locking compound specially made for this type of application. If you can't find any of this, good old Blue Loc-Tite will work.
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55firearrow
I've been doing a bit more reading and if you really have a 1955 250cc firearrow it should be basically the same lower end as the old 350 bullet and the transmission is mounted on the rear of the engine in a similar manner.
I'm not sure where I got the idea that the bearing rollers were running directly on the crankshaft but according to what I've read, the bearings have a hardened inner race which is pressed onto the crankshaft. Of course, I could be wrong about this.
If the bearings have inner races that are just pressed onto the crankshaft journals, you could have the one(s) that are undersize plated to bring it up to spec.
The processes I'm familiar with are called "electroless nickle plate" and "thin dense chrome plateing".
Both of these plating processes can be applied so they will only increase the steel or iron journal a tenth of a thousandth of an inch or two in the area that is undersize.
Because it is a slow process where the plating fluid is applied directly to the metal with a soaked wand or stylus, there is no machining involved or required. (Actually, these plating processes can add up to .0005 per surface without a problem).
The difficult part is finding a plating company who can do the process and will work for someone who does not work for a large company that will give them a production order.
If you are beyond this level in your rebuild, don't worry about it.
As long as the bearings inner race is a press fit on the crankshaft journals you have no problem.
If one of the bearings inner races is a slip fit, not requireing a press to install it you can clean the surfaces of all oils or preservatives and apply locking compound specially made for this type of application. If you can't find any of this, good old Blue Loc-Tite will work.
Sorry I dropped off the face of the earth for almost a month. Things have been crazy here. The transmission is mounted at the rear of the motor. And I do know there is an outer race that is pressed into each of the case halves, but I don't think there is an inner race pressed onto the crankshaft. Here is a parts blowup of a 1956 look on page 7 of the pdf or 11 of the manual:
http://www.klassiekrijden.nu/techniek/re-1956-clipper-sparepartslist.pdf
I believe it's virtually the same engine and it doesn't appear to be any kind of inner race except for the crankshaft itself, which is what it looks like to me when I look at mine.