Article [13] ST1300 - Maintenance - Fitting Wheel Bearings - What the manuals don't tell.

[Sidekick]

Very confusing as to why the spacer isn't a few mm shorter, to prevent the problems you made us aware of.....

I still have the same question, why is the spacer not shorter or equal as the hub shoulders distance?
Is the spacer acting as a seal, preventing dust and water to get from the hub to the bearings, or something else? This question is not answered yet and stand as a key point to understand the installation procedure.
Everything that have been said on this thread is very straight forward, but I keep wondering about the design of the spacer.
Thank you @jfheath for bringing clarity on the practical side of the installation, as always your work is very much appreciated!

 

[jfheath]

I still have the same question, why is the spacer not shorter or equal as the hub shoulders distance?

It is a good question - one that I have pondered a number of times, and have not been able to find an official answer. Or any answer other than the one that I have come up with for myself.

The hub of the wheel is a cast alloy. I know next to nothing about the structural properties, but I have a few experiences.

• For many years I rode a pushbike with a frame that was made of Reynolds 531 tubing. I never knew much about it but I knew it was supposed to be good - light, strong and had a certain amount of flex in it. I never appreciated how good this was until I replaced it with a more modern aluminium alloy frame. It is rigid. Absolutely no flex in it at all. It is a bone shaker.
  
  
• At one time, I used to build and true my own wheels and used a cast alloy wheel truing frame. On one occasion, too lazy to turn the threaded rod the held the wheel axle in place the extra fraction I tried to 'spring' the two legs apart, as I would when trying to get the wheel hub between the bike's fork legs. The entire arm of the truing frame snapped off.
  
  
• The rear ABS sensor on the ST1100 is a small cylinder which slips inside a hole in a short, cast alloy stalk - part of the rear final drive housing. It is a good, slide-in fit. Over the years the sensor rusts and the alloy corrodes, and it gets stuck. Faced with a failed sensor, it had to be removed, but would not budge. There was a slight gap at one point where the metal shim fits to adjust the air gap between the sensor and the pulsar ring. Enough for the tiny wedge shape blade of a modellers screwdriver. Armed with the experience years back of the snapped alloy truing frame, I knew that this had to be a very delicate procedure. I very gently gave my tiny wedge a tap into the gap, with nothing heavier than a toffee hammer, and a very light touch. I was being ultra cautious. Second tap, the bracket snapped off. Honest, it was a serious over-reaction to the slightest of taps. It was nothing.

So my thinking is that the cast alloy hub isn't really designed to take 78Nm or 108Nm force that is applied to the centre races of the wheel bearings when tightening the axle.

If that is the case then I reckon that some other things have to be true:

1. The squeezing force has to be taken by the spacing tube. This means that the tube is clamped between the two bearings and is not free to rattle around.
2. The length of the spacing tube must always be more than the distance between the hub shoulders to allow for temperature expansion / contraction of the alloy hub. (Heat / cold from tyres, brake discs, bearings, exhaust, sun, rain.... )
3. As a result of #2, one bearing has to identified as the one to be driven in first, otherwise the wheel will be slightly off centre.

Years back, I used to wonder why there was a spacer at all on my previous bikes - it just seemed to be something that rattled around between the bearings when I went over bumps. But I never changed the bearings on any of those bikes.

 

[John OoSTerhuis]

If it’s shorter, the bearings would be side-loaded when the axle nut is torqued, causing early bearing failure! The inner races would be forced to move laterally, relative to the outer races, to close the gap between the shorter distance collar and inner races.

John

 

[jfheath]

If it’s shorter, the bearings would be side-loaded when the axle nut is torqued, causing early bearing failure!

I forgot to mention that pretty crucial point.

Here are some diagrams and more detailed explanation from me.

https://www.st-owners.com/forums/attachments/st1300-wheel-bearings-pdf.269292/

 

[Sidekick]

I forgot to mention that pretty crucial point.

Here are some diagrams and more detailed explanation from me.

https://www.st-owners.com/forums/attachments/st1300-wheel-bearings-pdf.269292/

Can the first bearing hub shoulder be considered as the reference alignment point for the front wheel on the axle?
I am in the process of replacing the front wheel bearing for the second time after having done it incorrectly recently. The first time, I heard a whining sound coming from the hub and the wheel was misaligned.
Thank you!

 

[jfheath]

You drive in the first bearing to the shoulder.

The spacer goes in and then the second bearing goes in until the inner shell meets up with the spacer. Making contact is enough, you don't drive it beyond that if you want your bearing to last longer than your tyres. But they must meet up.

BUT

You do not choose which bearing is first. Which side you drive in first is specified in the workshop manual. I try not to write it down anywhere because I will think that I have remembered, and I know that the day will come when I remember incorrectly. Next Thursday.
It is the left hand side for one wheel and the right hand side for the other - and yes it matters. The difference could affect (say) the front disc rotor clearance through the brake caliper.

Probably not quite, but if you believe that, you will remember that it is important enough to get it right.

Or you could watch the video of me putting one in. I did that one correctly. The side of the wheel with the abs pulsar ring is the right hand side.

I'll look it up and post it here, but Ive just got off the pushbike and right now, standing up will be quite a challenge.

Rear wheel - drive in the left bearing first. (it doesn't help that the manual then says drive in the left bearing - but I have checked this out with the diagrams and left first is correct.
Front wheel - drive in the right bearing first, then the left.

But you should never trust information that you get from someone on the internet . Always check it out.

 

[ST1100Y]

You do not choose which bearing is first. Which side you drive in first is specified in the workshop manual.

yep...

Rear wheel - drive in the left bearing first. (it doesn't help that the manual then says drive in the left bearing - but I have checked this out with the diagrams and left first is correct.

From a mechanical POV it might seem strange to have the narrow, LHS bearing going in first as alignment reference, and the heavier, double-row, load bearing RHS one to be brought home gently till inner race "touches" the spacer tube, but the brake/rotor side is in focus there...

 

[John OoSTerhuis]

Rear wheel - drive in the left bearing first…
Front wheel - drive in the right bearing first…

Yep, clearly stated in the Honda ST1100 Service Manual. Additional info noted in the Honda Common Service Manual, Section 1.

John