Author Topic: Crankshaft end float  (Read 4247 times)

Offline huddie

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Crankshaft end float
« on: 06.10. 2009 17:15 »
Hi All, Hope you can help. My 57 Gold Flash engine is currently out of the frame for a frame paint job (now finished). Turning my attention to the engine and speciffically the crank, I do seem to have a lot of end float. I have read some of the old topics covering crankshafts and thought I had found the solution when it was suggested that the cush drive would take up the float. Alas I have put this back on to try it but the float is still there. It looks like as much as 40 thou !!!! but I am not sure how to proceed from here. At what point do you establish endfloat on a rebuild, should it disappear if I replace the timing side bush and the drive side bearing, or does one do that, reassemble dry, then check, restrip and shim. More specifically where do you measure the float, do you do it with the cush drive on or off?. Where do the shims go?.
I decided to do this strip and paint job as the engine had developed a top end rattle which turned out to be a con rod small end bush. The bottom end was not making any distinguishable noise all beit I felt the vibrations coming through the foot rest and handle bars was probably greater than it should be (no experience to draw on here).

While I've got your attention, what about cam shaft end float. If I measure between the timing side end and the bush it appears to be 2, no more than 3 thou. Is this OK?. If I have to remove the camshaft pinion what size and thread do the puller bolts have to be
Regards for now Huddie

Online bsa-bill

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Re: Crankshaft end float
« Reply #1 on: 06.10. 2009 17:53 »
Hi there
End float should be a max of 3 thou,  I measured my end float with a dial gauge and then deducted 1.5 thou this gave me the amount of shim I needed, old adage works here measure many times shim once because adding or subtracting shims requires removing the bearing.
Shim goes between crank and bearing on the drive side, I was lucky and got it right first time was left with 1 thou end float ( wasn't going to go through it all again for 1/2 a thou.
I measured at the drive end but should work at timing end also, the cush drive will pull everything over to the drive side but the end float is still there. 

Yes I replaced timing side bush and drive side bearing then assembled and measured end float, good point re the cush drive, did mine with it off as I said the end float is end float it should not alter with the cush drive screwed up unless the cush drive tightening squeezes the cases up to some degree.

All this said I have only rebuilt two engines and one of them has not been fired up yet although it turns ( turns rather than spins as there is new pistons, rebore, mains on so on ) ,

Camshaft - this I would like to here more of from some more knowledgeable than I, when I put the pinion on mine it would tighten to the point that it would lock so I slackened it a tad so that it turned, members here have said that the cork washer acts as shim to control end float, not sure about that it seems a bit iffy.

All the best - Bill 
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline huddie

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Re: Crankshaft end float
« Reply #2 on: 06.10. 2009 19:09 »
Thanks Bill,  I understood the cork washers role is to stop end float on the breather.  As a bye the bye when you split your cases did you remove the crank pinion first, and if so how, or did you split the cases with the crank still in the right side half and then knock the crank thru(carefully) the pinion.
Regards huddie

Online RichardL

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Re: Crankshaft end float
« Reply #3 on: 06.10. 2009 19:29 »
Yep, the cork washer compresses against the timed breather, and that's how camshaft float is controlled. It seems the theory here is that the cam takes a lot less abuse than the crank, the latter being a lot heavier and contiuously hammered by explosions in the cylinders.

My measuurement method was with the cush drive is off (as, I think it must be for any method).
1. Assemble the crank with the main bearing up against the crank web.
2. Assemble the crank cases with the crankshaft installed.
3. Block up the crankcases on your bench so that the end of the crank doesn't touch the bench. (Right now, I can't remember which end down I used, but I don't think it matters. Choose the side easier to block-up as the downward side.)
4. Lightly tap the up end of the crankshaft with a soft hammer.
5. Use a dial or electronic caliper as height gauge and measure from the crankcase to the end of the crankshaft. Mark the spots on the crankcase and crankshaft where you took the measurements.
6. Remove the blocks from under the crankcase and let the end of the crankshaft rest against your bench. (If the bench is not soft, protect the crankshaft threads.)
7. With the weight of the crankshaft and crankcase all resting on the end of the crankshaft, lightly tap on the crankcase with the soft hammer.
8. Measure from the crankcase to the end of the crankshaft using the points you previously marked. (All while balancing the works on the end of the shaft. Great fun.)
9. Subtract the smaller from the larger value and construct a shim stack of the same thickness minus 0.0005"-0.001". Try to put thick shims on the outside of each end of the shim stack.
10. Remove the bearing and locate shim stack between bearing and crankshaft.
11. Reassemble and test end float using the same approach.

In one post, I believe one of our members created a sacrificial bearing that could be easily pulled with a conventional puller. To see a home-brew puller I made, you could look at http://www.a7a10.net/forum/index.php?topic=368.msg1717#msg1717 .

Just remember, I am a kludger and there may be more elegant ways to get the job done.

Richard L.

Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Online RichardL

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Re: Crankshaft end float
« Reply #4 on: 06.10. 2009 20:26 »
Correction.

Now I recall. Other member's sacrificial bearing had I.D. ground out so as not to grip crankshaft.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Online bsa-bill

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Re: Crankshaft end float
« Reply #5 on: 06.10. 2009 21:45 »
As a bye the bye when you split your cases did you remove the crank pinion first[/color]

Removed the pinion before splitting the crank
1. remove nut ( lefthand thread) and tabwasher
2. remove the three nuts holding on the pump, note the packing washer under the front pump fixing
3. unscrew crank pinion while easing the pump outwards

one other thing that most of us have have done at one time or another is to forget the internal nut at the end of the camshaft trough

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline A10Boy

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Re: Crankshaft end float
« Reply #6 on: 07.10. 2009 11:07 »
When I did my last rebuild I left the pinion on the shaft and when I split the cases it came off easily. This is an easier way than trying to pull it off.

You might find that the roller bearing on the drive side is a "sliding fit" on the crank, they usually are which is why the cush needs to be tight to hold it all together. If it is, it will make it easier to shim the end float correctly because you can easily add/subtract shims to get it right, but you will need to apply some loctite "bearing lock" to the shaft on the final assembly.

You will be changing the timing side bush no doubt, this needs to be line bored properly and there are several years worth of very informative reading here on that subject.

good luck
Regards

Andy

1958 Super Rocket
Plus
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Online Minto

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Re: Crankshaft end float
« Reply #7 on: 27.04. 2020 01:07 »
Yep, the cork washer compresses against the timed breather, and that's how camshaft float is controlled. It seems the theory here is that the cam takes a lot less abuse than the crank, the latter being a lot heavier and contiuously hammered by explosions in the cylinders.

My measuurement method was with the cush drive is off (as, I think it must be for any method).
1. Assemble the crank with the main bearing up against the crank web.
2. Assemble the crank cases with the crankshaft installed.
3. Block up the crankcases on your bench so that the end of the crank doesn't touch the bench. (Right now, I can't remember which end down I used, but I don't think it matters. Choose the side easier to block-up as the downward side.)
4. Lightly tap the up end of the crankshaft with a soft hammer.
5. Use a dial or electronic caliper as height gauge and measure from the crankcase to the end of the crankshaft. Mark the spots on the crankcase and crankshaft where you took the measurements.
6. Remove the blocks from under the crankcase and let the end of the crankshaft rest against your bench. (If the bench is not soft, protect the crankshaft threads.)
7. With the weight of the crankshaft and crankcase all resting on the end of the crankshaft, lightly tap on the crankcase with the soft hammer.
8. Measure from the crankcase to the end of the crankshaft using the points you previously marked. (All while balancing the works on the end of the shaft. Great fun.)
9. Subtract the smaller from the larger value and construct a shim stack of the same thickness minus 0.0005"-0.001". Try to put thick shims on the outside of each end of the shim stack.
10. Remove the bearing and locate shim stack between bearing and crankshaft.
11. Reassemble and test end float using the same approach.

In one post, I believe one of our members created a sacrificial bearing that could be easily pulled with a conventional puller. To see a home-brew puller I made, you could look at http://www.a7a10.net/forum/index.php?topic=368.msg1717#msg1717 .

Just remember, I am a kludger and there may be more elegant ways to get the job done.

Richard L.

Great description Richard, just what I was looking for. I feel a little less daunted by it now, just need an extra pair of hands and a dial gauge.
Thanks
Jase
52 A10 plunger
Aprilia RSVR

Offline bikerboy

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Re: Crankshaft end float
« Reply #8 on: 27.04. 2020 02:10 »
I find you are better of putting a lever between the crank web and the crankcase rather than tapping with a hammer personally and watching the dial gauge as you do it.

The only tip I would give is dont be tempted to leave out any of the crankcase bolts or nuts thinking that you will get a true reading.

For me I have always found that you need to do up every nut and stud making sure the crankcases are well and truly tight or you will end up redoing it.

I also bearing lock the main bearing and put the cush drive on immediately. It does hold the bearing and in the past I have known many people who have found buts of shim in the bottom at their first oil change where the shims have spun. you have to obviously slide on the sprocket and the spacer etc to torque it up.

Thats why I put the cush drive on, do it up to 65 foot pounds and leave it overnight for the bearing lock to go off. It possibly makes no difference but I have never found bits of broken shim in my sump so I stick with that method :)

Online RichardL

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Re: Crankshaft end float
« Reply #9 on: 27.04. 2020 05:03 »
Bikerboy,

Not sure of the benefit of the lever versus letting gravity do the work. A "soft hammer" (that is, rubber mallet) doesn't hurt anything. The dial gauge at the end of travel should be the same if you sneak up on it or get there quickly. I've made the assumption that tightening the four studs that surround the crank centerline was good enough. Really, not sure if tightening everything wouldn't be better, but not clear to me how the mechanics of that helps.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline Swarfcut

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Re: Crankshaft end float
« Reply #10 on: 27.04. 2020 08:46 »
I will add a note of caution concerning the crank pinion. Don't attempt to drive the crank through the timing bush, as a quick method to remove the crank pinion.  This practice  risks bending the relatively weak area of the end of the crank with the left hand thread, as well a mushrooming the thread. If you protect the thread with the nut, there's the chance of damaging that as well.

 All is needed is a thin jawed puller, the usual angle iron homespun design will do, the pinions aren't tight, but the simple convenient smack with the big hammer carries an expensive risk.  Yes, it was me that found out the hard way.

 Swarfy.

Offline bikerboy

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Re: Crankshaft end float
« Reply #11 on: 03.05. 2020 11:40 »
A "soft hammer" (that is, rubber mallet) doesn't hurt anything

I have found that tapping it just disrupts and jars the whole thing its not about possible damage.

I just push the crank hard towards the bush side, stick my dial gauge on the bearing end then stick a lever inside and gently lever the crank over fully. All nice and gentle like. Just my preferred way I find it easier thats all.

Online RichardL

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Re: Crankshaft end float
« Reply #12 on: 03.05. 2020 14:42 »
Sounds like it works just fine. I may (meaning, probably will) try it.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline muskrat

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Re: Crankshaft end float
« Reply #13 on: 03.05. 2020 21:09 »
G'day Fellas.
If you tap the crank with a mallet the dial gauge will jump and possibly move giving a false reading. Push pull by hand or light lever action is best.
Cheers
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Online Angus

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Re: Crankshaft end float
« Reply #14 on: 04.05. 2020 09:35 »
Thanks Musky, I was getting worried for a bit there thinking I had done it wrong and I would have to pull the A10 down again to remeasure.
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