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Crankshaft end float

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Crankshaft end float

Posted by Andrew Wibmer at March 06. 2017

Does anyone know how to shim the crankshaft to eliminate end float and how to measure it?

Re: Crankshaft end float

Posted by peter_holland1 at March 06. 2017

Previously Andrew Wibmer wrote:

Does anyone know how to shim the crankshaft to eliminate end float and how to measure it?

Andrew, it is quite difficult to measure end float because all the bearing races are interference fits either on the crankshaft main journals or the crankcase bearing bores.

Lateral movement of the crankshaft is controlled and limited by the timing side ball bearing. When new, this bearing has no perceptible sideways clearance. It is secured rigidly by the interference fits of the journal and the crankcase. So, if all is in good order, there is no perceptible end float on the crankshaft and the rollers of the drive side bearing are running central on their tracks, not tight up against the shoulder of race. (I can't remember offhand which roller race has a shoulder, or it may be both.)

To measure crankshaft end float. (Remember to allow for the gasket between crankcases if you are using one)

1) Find a (used) timing side bearing with no perceptible endfloat.

2) With emery cloth, reduce the outer diameter and increase the inner diameter until the bearing is a free fit on the crankshaft and in the crankcase. A belt sander makes light work of the outer diameter if you put the axis of rotation about 95 degrees to the belt direction.

3) Do the same for the drive side races.

4) Assemble the crankcases with the crankshaft inside. Gasket?

5) Bolt the alternator rotor and engine sprocket in normal position. (this fixes the roller inner race on the crankshaft)

6) Bolt the triangular washer and pinion onto the timing side of the crankshaft. (This fixes the ball brg inner to the crankshaft.)

You can omit all the woodruff keys for the purposes of this exercise.

7) rigidly mount a dial gauge to the crankcases and use it to measure end float.

You MUST have endfloat or else the roller bearings are squeezed against the shoulder of the race.

As I explained, you want the rollers to run central in the roller tracks. A decent endfloat may be 5 to 10 thou in old units.

The endfloat can be reduced by inserting a shim, annular shape, behind the timing side outer race.

I can't see any satisfactory shortcuts or I would have used them myself. I admire your thoroughness.

Let me add a further piece of advice. All this will have been wasted effort if you don't fit bearings with enlarged radii to take the large radii on the crankshaft journals. Neglect this, and you will certainly end up with zero endfloat, damaged crankcases and tortured roller bearing. These are bearings specific to Norton lightweights.

Peter

 

 

Re: Crankshaft end float

Posted by Andrew Wibmer at March 06. 2017

Previously peter_holland1 wrote:

Previously Andrew Wibmer wrote:

Does anyone know how to shim the crankshaft to eliminate end float and how to measure it?

Andrew, it is quite difficult to measure end float because all the bearing races are interference fits either on the crankshaft main journals or the crankcase bearing bores.

Lateral movement of the crankshaft is controlled and limited by the timing side ball bearing. When new, this bearing has no perceptible sideways clearance. It is secured rigidly by the interference fits of the journal and the crankcase. So, if all is in good order, there is no perceptible end float on the crankshaft and the rollers of the drive side bearing are running central on their tracks, not tight up against the shoulder of race. (I can't remember offhand which roller race has a shoulder, or it may be both.)

To measure crankshaft end float. (Remember to allow for the gasket between crankcases if you are using one)

1) Find a (used) timing side bearing with no perceptible endfloat.

2) With emery cloth, reduce the outer diameter and increase the inner diameter until the bearing is a free fit on the crankshaft and in the crankcase. A belt sander makes light work of the outer diameter if you put the axis of rotation about 95 degrees to the belt direction.

3) Do the same for the drive side races.

4) Assemble the crankcases with the crankshaft inside. Gasket?

5) Bolt the alternator rotor and engine sprocket in normal position. (this fixes the roller inner race on the crankshaft)

6) Bolt the triangular washer and pinion onto the timing side of the crankshaft. (This fixes the ball brg inner to the crankshaft.)

You can omit all the woodruff keys for the purposes of this exercise.

7) rigidly mount a dial gauge to the crankcases and use it to measure end float.

You MUST have endfloat or else the roller bearings are squeezed against the shoulder of the race.

As I explained, you want the rollers to run central in the roller tracks. A decent endfloat may be 5 to 10 thou in old units.

The endfloat can be reduced by inserting a shim, annular shape, behind the timing side outer race.

I can't see any satisfactory shortcuts or I would have used them myself. I admire your thoroughness.

Let me add a further piece of advice. All this will have been wasted effort if you don't fit bearings with enlarged radii to take the large radii on the crankshaft journals. Neglect this, and you will certainly end up with zero endfloat, damaged crankcases and tortured roller bearing. These are bearings specific to Norton lightweights.

Peter

 

Hello Peter,

many thanks for your comprehensive reply, just what I needed, I had not thought to resize my old bearings. It is the interference fit that makes the measuring difficult, just as you say. This particular bike had a gasket separating the crankcases (made from an old weatabix box of all things), so the end float would never have been right, on top of this one of the bearings (the ball race one) had spun on the crankshaft, so will need to be loctited on. Thanks for the reminder re the ground bearings. I wonder how they ever got it right at the factory, perhaps the crankcases being pinched up forced the roller bearing into the case and it all just found its "correct" position.

Presumably the less endfloat the better as the case will grow more than the shaft, or is that wrong? Point taken about the race and shoulder. This is something I would prefer to get right first time as expensive to do again. As for a gasket, I was proposing to use the cotton thread trick, that would give me a few thou.

Andrew

Re: Crankshaft end float

Posted by Jonathan Soons at March 06. 2017

Once you do up the oil pump worm the crankshaft will be clamped hard against the main bearing inner race and there will be no end float.  It might be off-centre though and I don't know what you would do about that.

Re: Crankshaft end float

Posted by peter_holland1 at March 07. 2017

Jonathan,

The timing side bearing will slide in the crankcase because the OD has been reduced with emery cloth. (Step 2) So end float can be measured.

You are correct that with a new bearing, the fits don't allow measurement of end float.

Peter

Re: Crankshaft end float

Posted by Andrew Wibmer at March 07. 2017

Previously peter_holland1 wrote:

Jonathan,

The timing side bearing will slide in the crankcase because the OD has been reduced with emery cloth. (Step 2) So end float can be measured.

You are correct that with a new bearing, the fits don't allow measurement of end float.

Peter

If I understand you correctly Peter, having ground clearances on the bearings to allow them to slide in the cases and on the crank, then it is just the bearing thickness that remains, allowing me to work out the end float with a dial gauge. The measured float then being taken up with a piece of shim, allowing for 5 to 10 thou. The only other thing I am inclined to try is to make sure the final fit bearings are tight in to the crank cheeks (or whatever they are called), I might try to measure them to make sure they are.

Andrew

Re: Crankshaft end float

Posted by anna jeannette Dixon at March 08. 2017

hello do use your over to warm the crankcase before any fitting of your main bearing, do not fit any main bearings  crankcases when the are  cold   or hit them with a hammer   the only hammers used in construction of an engine are a copper hammer or a rubber dead blow hammer    or copper ended punches 

            yours anna j 

Re: Crankshaft end float

Posted by Andrew Wibmer at March 08. 2017

Previously anna jeannette Dixon wrote:

hello do use your over to warm the crankcase before any fitting of your main bearing, do not fit any main bearings  crankcases when the are  cold   or hit them with a hammer   the only hammers used in construction of an engine are a copper hammer or a rubber dead blow hammer    or copper ended punches

yours anna j

Thanks Anna,

hot case and cold bearing, though the Timken bearing is very tight on the crank and will probably need "encouraged" with a brass or ally tube. Thanks for help.

 

Regards Andrew

Re: Crankshaft end float

Posted by peter_holland1 at March 08. 2017

Previously Andrew Wibmer wrote:

Peter

If I understand you correctly Peter, having ground clearances on the bearings to allow them to slide in the cases and on the crank, then it is just the bearing thickness that remains, allowing me to work out the end float with a dial gauge. The measured float then being taken up with a piece of shim, allowing for 5 to 10 thou. The only other thing I am inclined to try is to make sure the final fit bearings are tight in to the crank cheeks (or whatever they are called), I might try to measure them to make sure they are.

Andrew

Andrew, You understand correctly.

As you pointed out the bearings can be very tight on the crankshaft journals. It makes checking the fit up to the crank cheeks very hard to establish. Is a large clearance because the bearing is not driven full home? or because the radius on the bearing inner is smaller than the radius on the crank journal? And are you going to damage bearing in removing/replacing and having another go?

Better to use a radius gauge to ensure the radius, ground especially on the Norton Lightweight inner race, is as large, or larger, than the radius between crankshaft cheek and journal. If so, all should be well if the bearings are pressed fully home.

Try the shank of drill bits pressed onto the crank radius to establish best fit and the radius here. Use that drill to drill a hole in some sheet metal. Cut the sheet exactly through the hole centre with shears. Then again so a quarter hole is left at the corner of your sheet metal. Now you have a radius gauge to check the bearing inner.

Let us know how you get on.

Peter

 

Re: Crankshaft end float

Posted by Andrew Wibmer at March 09. 2017

Previously peter_holland1 wrote:

Previously Andrew Wibmer wrote:

Peter

If I understand you correctly Peter, having ground clearances on the bearings to allow them to slide in the cases and on the crank, then it is just the bearing thickness that remains, allowing me to work out the end float with a dial gauge. The measured float then being taken up with a piece of shim, allowing for 5 to 10 thou. The only other thing I am inclined to try is to make sure the final fit bearings are tight in to the crank cheeks (or whatever they are called), I might try to measure them to make sure they are.

Andrew

Andrew, You understand correctly.

As you pointed out the bearings can be very tight on the crankshaft journals. It makes checking the fit up to the crank cheeks very hard to establish. Is a large clearance because the bearing is not driven full home? or because the radius on the bearing inner is smaller than the radius on the crank journal? And are you going to damage bearing in removing/replacing and having another go?

Better to use a radius gauge to ensure the radius, ground especially on the Norton Lightweight inner race, is as large, or larger, than the radius between crankshaft cheek and journal. If so, all should be well if the bearings are pressed fully home.

Try the shank of drill bits pressed onto the crank radius to establish best fit and the radius here. Use that drill to drill a hole in some sheet metal. Cut the sheet exactly through the hole centre with shears. Then again so a quarter hole is left at the corner of your sheet metal. Now you have a radius gauge to check the bearing inner.

Let us know how you get on.

Peter

 

Thanks Peter,

I will do. A few weeks away yet, but getting my ducks lined up.

Re: Crankshaft end float

Posted by robert_tuck at March 09. 2017

The late very practical John Hudson of the Norton service dept advocated rubbing down cranks to allow the bearings an easier fit .A very tight bearing can loose its internal clearance and wont last.

Re: Crankshaft end float

Posted by Andrew Wibmer at March 09. 2017

Previously robert_tuck wrote:

The late very practical John Hudson of the Norton service dept advocated rubbing down cranks to allow the bearings an easier fit .A very tight bearing can loose its internal clearance and wont last.

Hello Robert,

I can see that, the old one was a real bstd to get off, a lot of heat and force on a puller, I can see that you will get one shot at fitting it too. I will give a good polish with fine emery to clean up and perhaps loose a thou.

Thanks

Andrew

Re: Crankshaft end float

Posted by Andrew Wibmer at March 27. 2017

Previously Andrew Wibmer wrote:

Previously peter_holland1 wrote:

Previously Andrew Wibmer wrote:

Peter

If I understand you correctly Peter, having ground clearances on the bearings to allow them to slide in the cases and on the crank, then it is just the bearing thickness that remains, allowing me to work out the end float with a dial gauge. The measured float then being taken up with a piece of shim, allowing for 5 to 10 thou. The only other thing I am inclined to try is to make sure the final fit bearings are tight in to the crank cheeks (or whatever they are called), I might try to measure them to make sure they are.

Andrew

Andrew, You understand correctly.

As you pointed out the bearings can be very tight on the crankshaft journals. It makes checking the fit up to the crank cheeks very hard to establish. Is a large clearance because the bearing is not driven full home? or because the radius on the bearing inner is smaller than the radius on the crank journal? And are you going to damage bearing in removing/replacing and having another go?

Better to use a radius gauge to ensure the radius, ground especially on the Norton Lightweight inner race, is as large, or larger, than the radius between crankshaft cheek and journal. If so, all should be well if the bearings are pressed fully home.

Try the shank of drill bits pressed onto the crank radius to establish best fit and the radius here. Use that drill to drill a hole in some sheet metal. Cut the sheet exactly through the hole centre with shears. Then again so a quarter hole is left at the corner of your sheet metal. Now you have a radius gauge to check the bearing inner.

Let us know how you get on.

Peter

 

Thanks Peter,

I will do. A few weeks away yet, but getting my ducks lined up.

 

Hello Peter,

update.. having ground the bearings to a close sliding fit, I used the solder trick to measure the gap, rather than fix a dial gauge and wiggle. the measured thickness of the crushed solder is 30 thou and the bearings are tight, so I will make a shim at 20 thou and allow the 10 to be the clearance. At least that is my intention. I could not see the point of adding all the crankshaft components. What do you think?

Re: Crankshaft end float

Posted by peter_holland1 at March 29. 2017

Andrew,

Sounds good to me. You don't need to add the crankshaft components . It's a while since I did the endfloat measurement so forgive my poor memory.

The aluminium crankcases will expand more than the steel crankshaft at running temperature, increasing the endfloat slightly. So your 10 thou will grow, not shrink.

So onward.

Peter

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