350 Forza front fork surprise

[Orcadian]

Further to my investigations regarding notchy steering head bearings - I eventually came across a workshop manual - albeit in the Thai language. The diagrams are very clear and self explanatory and even has torque settings, grease types and positions of fasteners on all body parts, well worth the 9 dollar download.
Anyway, it confirmed my suspicions that the steering head bearings are indeed cups and cones with balls - not taper rollers. The big shock (pun intended) came when I discovered that the front fork stanchions are only clamped in the bottom yoke and that's where they finish - no top yoke as such, just another bearing, so no wonder the bottom bearing is hard worked and doesn't last. A glorified bicycle set-up!

Ian

Anyone know if the ADV 350 has a top yoke and proper forks? I know they are USD type

[roadster]

Yes that is one of the benefits of the ADV - proper top and bottom yolks, makes it important to get the axle clamp tightened in an unstressed position though. At one time the horrible red sticky jelly that Honda used when assembling steering head bearings was notorious for its short life but I had hoped that was in the past. Head bearings, whether ball or roller, should never be adjusted with preload because if the rolling elements don't float the races get hammered in a fixed position causing a notch.

[Orcadian]

Thanks for that Roadster,
The problem for me is that I love the Forza - especially the electric screen, although I now have a larger Puig one. I led a tour from Orkney to Austria last year with 2 other couples (I was solo) and having had 1500cc GoldWings for many years, was greatly impressed. Have you had any experience of the Forza to compare it with the ADV? Mine's coming up to 9000 miles (bought new May 23) and I could be tempted by the ADV - especially with proper forks! I also have a Super Cub plus a few Classic Honda fours.
I like the idea of bar mounted mirrors on the ADV - the Forza ones are inadequate with my build when wearing bulky clothing.

Ian

[velocipede6295]

I don't know the ins and outs the different forks mechanicals, but the Showa forks on the ADV are definitely better than the Forza's. They give more confidence, handle better, absorb uneven surfaces better, and feel more like motorcycle forks. I prefer riding my ADV 350 over my 300 Forza, due to the better forks, increased power, and higher handlebars, which give more room, and makes the ADV feel more spacious to ride. The Forza, although still a good scooter is now my spare / winter bike.

[Orcadian]

Thanks for the honest comparison,
Looks like I might have to have a ride on an ADV. Does the screen offer any protection on the ADV (4 manual positions I think) or is there a larger one available which doesn't interfere with the bars or mirrors on full lock?
I fitted Honda heated grips on mine - not cheap and not very hot, even on max 5. Think I'll go for a decent pair of heated gloves next time - transferrable to any bike or even when walking in the cold.

Ian

[velocipede6295]

The standard ADV 350 screen ( smaller than Forza ) gives reasonable protection, but not as much as the Forza screen, plus it has to be raised / lowered manually ( 4 positions as you said), and you have to use both hands, so you need to be stopped. The Forza definitely has the better/bigger screen - electrically operated. I've not looked into getting a bigger screen for the ADV, as I only do half day or full day trips 50-150 miles, and it's OK for me.

[Dave Weller]

When you take the forks out, you have to fully remove the yoke pinch bolts holding them in.

[Orcadian]

Thanks for that Dave,
I saw from the diagrams that there is an annular groove around the stanchion top but perhaps there are also 2 grooves for the pinch bolts for exact location purposes. Quite surprised that the stanchions have no top yoke to spread the bearing load though. Far too much work to graft on the front end from an ADV - lots of stuff in the way, so will just have to put up with what I have - could mean bearing changes every couple of years! Must have a go on an ADV to see if I could put up with minimal screen protection. Wonder if they have taper roller steering head bearings?

Ian

[roadster]

Thanks for that Dave,
Wonder if they have taper roller steering head bearings?

Ian

I doubt that taper roller head bearings are used as the rollers have to be caged and this makes it more likely that they will not change position relative to the races in normal use. There is also the question of cost. Crowded ball bearings make most sense because the balls don't always return to precisely the same spot. The real killer is overtightening and for this application it is vital that there is no preload and there is plenty of grease.

This is fundamentally different to applications such as wheel bearings which rotate at high speed and will tolerate reasonable preload helped by the line contact of taper rollers. In the recent past new Piaggio MP3s suffered from notchy steering in less than 1000 miles because they used taper rollers for the kingpins and took the preload recommendation from wheel bearing standards which can't be applied to a bearing which spends most of the time in one position and is hammered by road shocks.

[Orcadian]

That's interesting Roadster,
Looking at the drawing on this manual download I got, the bearings are actually caged balls, so almost the worst of both worlds! Point loading from a ball, as the ball radius is less than the race radius rather than a line from a taper - AND a cage!
I still have a feeling that the design received more influence from accountants than engineers.


Ian