Roller bearing runout

[Reinhoud]

Gents,

 

I'm busy building up a GS1000 crankshaft, stronger con-rods.

 

According to the specs the runout should be 0.1mm max.

The sideway runout I've got to 0.04mm accurate, but the up and down (factory) runout is 0.28mm.

 

This far out of spec, does anyone had this seen before? I did mark all the parts, but even if I hadn't, it shouldn't be out this far..

 

Thanks

[Dezza]

Maybe there is variation in bearing manufacturers. I say this because when I recently rebuilt a small two stroke and replaced the main bearings I had to source a thinner end float shim or otherwise the crankshaft locked when I tightened the cases. Presumably this was due to different manufacturing tolerances between different bearing manufacturers, even though I used good quality bearings (SKF).

[Arttu]

What you are actually measuring and how?

I haven't done much measuring by myself but a local crank builder said that many stock cranks are over that 0.1mm spec. Any way, 0.28mm sounds quite a lot.

[Fazz711]

Have you some how ended up with extra clearance bearing. Not sure what std is but bearings come with a choice of clearance eg c2 fairly std use c3 for extra clearance when something runs a bit hotter then c4 for a lot hotter eg oven fans. 

[markfoggy]

I would be interested in what you are measuring here. Or rather trying to.

Is a roller bearing crank, so when it is spinning it should center on the bearings.

If that tolerance is lateral float, maybe the manual is misleading you and you have already got it crazy tight.

[Reinhoud]

I don't think it's a bearing thing..

[Gixer1460]

I think thats gonna need some persuasion with the heavy engineering adjustment mallet! Is it welded yet or just pressed - could have pulled with the welding (if it was!)

[no class]

deffinately  some issues with concentricity !  hopefully it is not welded yet as it can probably be indexed / trued .

[Reinhoud]

Look, this is adjustable, and is within spec.

[Reinhoud]

This is fixed, and this is out of spec, that's the issue.

The manual says 0.1mm max run-out,  sometimes this has 0.15mm run-out, but 0.28mm I haven't seen before..

 

Anyone have seen it before being this far out?

[Arttu]

Yep, that's clearly over the spec and you should fix it before using it So is this something that you have rebuilt or did it came from a running engine like that?

Edited January 7, 2019 by Arttu

[Reinhoud]

I think that's the crank what came out of my bike, but not sure, I had another engine laying around, could be from that engine too..

[Gammaboy]

Are you locking it down to the stand? Doesn't look like it where the centre bearing supports are. Clamp it down, measure, and then take it out and fix with a tree stump and a  BFH (Brass faced Hammer, well, copper actually). wear eye protection!

[Reinhoud]

So... Got myself another crankshaft....

 

After pressing it together I had the same problem, only the runout wasn't as bad as the previous crank...

That means the mistake must be me

 

Did some measuring, turned out pressing it together didn't go as straight as I hoped for.

A little bit on an angle causes the runout, now all is within 0.03mm.

 

Problem solved.

[RickC]

There's a lot more to putting a crank together that I ever realised.

 

 

[Reinhoud]

I did do the indexing completely different.

I have a set of old crankcases and cylinders and pistons, I build that all up, and used 2 dial indicators to see when the pistons stopped and started to move.

The thing was that the pistons could stop equally, but started differently, it doesn't sound logic, but I had to find a way in between that.

It wasn't very hard, mostly time consuming, it was a very interesting job to do.

[Reinhoud]

The bike with the crankshaft from this topic is running again, and there are no excesive vibrations, actually less as before..

I'm pretty happy with that.