Normal wear?

fiatfan · Dec 3, 2020

Am in the process of removing the inner races of the main bearings, and saw this wear. Should I take some action apart from measuring and put the appropriate amount of shims in when I put the whole thing together again? This is on the reg side and there were two shims there with a total thickness of 0,45 mm, about .018".

Time Warp · Dec 3, 2020

Do you mean the what looks like rubbing on the crank cheek ?
If you have the outer removed from the engine case put it on and check for rubbing. (It would normally be around 0.020" clear of the cheek)

The replacement crankshaft I got had one spot of rubbing so I surface ground that area. (It was the cheek itself at fault)
You might want to check the height of the raised area the inner goes up against also.

I elected to machine my own shims to go in the engine case (under the outers) over putting them behind the inner races.
0.25 mm each side for 0.3 mm / 0.012" axial.

Fast Eddie · Dec 3, 2020

I do not believe that’s normal. Do you recall how much end float there was? Maybe it had been shimmed too tightly?

fiatfan · Dec 3, 2020

Time Warp said:
Do you mean the what looks like rubbing on the crank cheek ?
If you have the outer removed from the engine case put it on and check for rubbing. (It would normally be around 0.020" clear of the cheek)

The replacement crankshaft I got had one spot of rubbing so I surface ground that area. (It was the cheek itself at fault)
You might want to check the height of the raised area the inner goes up against also.

I elected to machine my own shims to go in the engine case (under the outers) over putting them behind the inner races.
0.25 mm each side for 0.3 mm / 0.012" axial.

View attachment 20187

Yes, the markings on the cheek. To place the shims under the outer half of the bearing seems like a good idea, are there no such shims to buy somewhere?

fiatfan · Dec 3, 2020

Fast Eddie said:
I do not believe that’s normal. Do you recall how much end float there was? Maybe it had been shimmed too tightly?

Sadly I didn´t check when I took it apart..... I´ll have to check everything carefully when putting it back together.

Time Warp · Dec 3, 2020

fiatfan said:
Yes, the markings on the cheek. To place the shims under the outer half of the bearing seems like a good idea, are there no such shims to buy somewhere?

Old Britts have shim kits but no longer post internationally, there are also online options where you can enter the dimensions and have shims made.
It is much easier for me to make my own, that also avoids the drama aspect which I have had to contend with to many times.
What should be straight forward becomes anything but and in Australia the general policy is the customer is always wrong even if you were to buy a square online and were sent a circle.
#

Where is a picture of the shims removed please ?

That rubbing is basically not possible as there is a gap between the bearing and the crank cheek due to the raised portion of the crank the inner race seats against. (About 0.5 / 0.20")
The shouldered step on the inner race stops the outer moving inward from that contact point onward.

>>>>>>That makes me wonder where the shims you removed were placed. <<<<<<

The shims are either under the inner race, not removable without removing the inner itself or they are under the outer in the engine case bearing bore itself.
I use machined dummy bearings to check the end float.

Fast Eddie · Dec 3, 2020

For the less able and less equipped, you can linish or grind down and old bearing outer to achieve the same as TW did.

For the shims:

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.

andover-norton.co.uk

Time Warp · Dec 3, 2020

This raised portion of the crank cheek would normally give a gap bearing to cheek.

Time Warp · Dec 3, 2020

Fast Eddie said:
For the less able and less equipped, you can linish or grind down and old bearing outer to achieve the same as TW did.

For the shims:

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.

andover-norton.co.uk

Those are the shims for under the inner, I have plenty still in the AN bags free to a good home.
I have to wonder if the FF crank had some form of home made shim that went over the inner race to get that rubbing.

Fast Eddie · Dec 3, 2020

I did wonder about the AN shims. Are you sure they’re the inners? The exploded drawing definitely shows them as going in the case and therefore outers?

concours · Dec 3, 2020

fiatfan said:
Am in the process of removing the inner races of the main bearings, and saw this wear. Should I take some action apart from measuring and put the appropriate amount of shims in when I put the whole thing together again? This is on the reg side and there were two shims there with a total thickness of 0,45 mm, about .018". View attachment 20185

Could be from a previous (not perfectly done) grinding operation.

kommando · Dec 3, 2020

I had the same on a Combat crank, end float was 30 thou so I put a 10 thou shim under the main bearing inner on that side. The witness mark was not fully round indicating it was from a whippy crank taken to high revs.

Time Warp · Dec 3, 2020

Fast Eddie said:
I did wonder about the AN shims. Are you sure they’re the inners? The exploded drawing definitely shows them as going in the case and therefore outers?

The other thing is 0.003" shims are not much use and stacked up in that location would be a no no for me. (imho)

Time Warp · Dec 3, 2020

kommando said:
I had the same on a Combat crank, end float was 30 thou so I put a 10 thou shim under the main bearing inner on that side. The witness mark was not fully round indicating it was from a whippy crank taken to high revs.

On the replacement crankshaft I got it was the cheek itself.
There was a small area of contact (just) and marks from when the journal was ground at the factory were visible at the outer of the cheek in that section.
It meant the bearing outer had 0.019" gap to the cheek in 3 positions but 0 at that one location, clocking the cheek confirmed the cheek material was high so I surface ground it enough for clearance.

Fast Eddie · Dec 3, 2020

Time Warp said:
The other thing is 0.003" shims are not much use and stacked up in that location would be a no no for me. (imho)

View attachment 20198

I agree, I think Comnoz posted pictures once of shims that had basically worked themselves out of that position due to flex.

kerinorton · Dec 3, 2020

From what I understand, the only safe place to fit inner shims is on the timing side because the bearing is compressed and held against the crank cheek by the oil pump gear [ nut ]. The drive side bearing is only pressed on, and has not means of holding it rigidly in place as the theory goes. I would only fit one thick shim. I fitted a 10 thou shim on my 750 and ended up with 10 thou end float. That seemed a lot when you consider auto engines mostly only have 2-3 thou end float, but that is usually on one journal. The length of the crankshaft dictates more clearance and 10 though was the minimum in the book I got the info from.

fiatfan · Dec 3, 2020

Time Warp said:
Old Britts have shim kits but no longer post internationally, there are also online options where you can enter the dimensions and have shims made.
It is much easier for me to make my own, that also avoids the drama aspect which I have had to contend with to many times.
What should be straight forward becomes anything but and in Australia the general policy is the customer is always wrong even if you were to buy a square online and were sent a circle.
#

Where is a picture of the shims removed please ?

That rubbing is basically not possible as there is a gap between the bearing and the crank cheek due to the raised portion of the crank the inner race seats against. (About 0.5 / 0.20")
The shouldered step on the inner race stops the outer moving inward from that contact point onward.

>>>>>>That makes me wonder where the shims you removed were placed. <<<<<<

The shims are either under the inner race, not removable without removing the inner itself or they are under the outer in the engine case bearing bore itself.
I use machined dummy bearings to check the end float.

View attachment 20196

The shims were under the inner race. It could be traces of an older "mistake" maybe, I like your method with dummys.

fiatfan · Dec 3, 2020

Time Warp said:
This raised portion of the crank cheek would normally give a gap bearing to cheek.

View attachment 20197

View attachment 20199

Yeah, there´s nothing wrong there on my parts, looks the same.

fiatfan · Dec 3, 2020

Fast Eddie said:
I did wonder about the AN shims. Are you sure they’re the inners? The exploded drawing definitely shows them as going in the case and therefore outers?

I looked at that and have to agree that it looks like they fit in the case, and I also wondered about the thickness of them. Can´t be good to stack them.

Fast Eddie · Dec 3, 2020

I’d email AN to clarify for sure. The pic definitely shows case fitment. But maybe thats not what they actually supply?

Personally, I’d also research a bit more on the end float topic. Comnoz gave an OK figure of up to 0.035”. Mick Hemming doesn’t usually shim any road engines apparently.

The Commando has a big old crank in some big old cases that suffer a lot of flex and a lot of expansion. It ain’t no modern tight tolerance kinda thing !

Normal wear?

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Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Time Warp

.......back to the 70's.

Time Warp

.......back to the 70's.

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Fast Eddie

concours

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Time Warp

.......back to the 70's.

Time Warp

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Fast Eddie

kerinorton

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