RGS Corsa head bearing adjuster nut. Which way is up?

Ventodue

Ventodue

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Location
France
Ok, here's a dumb question ...

This here is the head bearing adjuster nut from my Corsa. As you can see, one side is plain, while the other has a rebate machined into it. But I can't see for what purpose ...

So, which way is up? Plain side or rebate side against the bearing dust seal? Or does it not matter in the slightest? And why is there this rebate anyway?

All thoughts and opinions most welcome ...

Thanks
 

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Ventodue said:
Ok, here's a dumb question ...

This here is the head bearing adjuster nut from my Corsa. As you can see, one side is plain, while the other has a rebate machined into it. But I can't see for what purpose ...

So, which way is up? Plain side or rebate side against the bearing dust seal? Or does it not matter in the slightest? And why is there this rebate anyway?

All thoughts and opinions most welcome ...

Thanks
Click to expand...
Often wondered that myself, Craig. Haven't worked out a feasable reason yet.

I place the plain side to the dust seal, ensuring full contact to the bearing race underneath, the underside of the top yoke is wide enough to cope with the small rebate.

piet
 
Thanks Piet.

Yep, I reasoned the same: plain side against the seal. Good. Will carry on like that.

Maybe Laverda bought these as a readily available, off-the-shelf item originally intended for another application - ? Who knows.

(JFI, I'm chasing an annoying acceleration headshake. I suspect that the head bearings aren't involved; but on the principle, 'start with the last thing you touched', I've pulled it down again.

Nothing untoward that I can see. It's probably nothing more than a worn front tyre!)
 
I've found the front shakes violently once the tyre has worn about 20-30%, irrespective of tyre make or size! The Conti Something Attack has fared slightly better, now at around 40% wear and head shake is steadily rising.

Always sets in at around 80kmh and settles again at 90. Tried every trick in the book, to no avail. Reckon weight distribution could be a major factor, as it became worse when the panniers were fitted!

piet
 
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The first time I rode an RGS it wobbled just like that at 80kph, you could feel strong lateral pulses through the bars and if you took your hands off it would oscillate badly, it was fine at 60 and 100, just horrible at 80. The owner said it was the tyre. Never noticed that on my 3c.
 
Vote one for the tyre of wobbles, almost like the old days, chronic on some Japanese bikes, tank slapper in the true meaning for those affected 70's bikes. Goodness if you put dropped bars or flat bars, pinned your thumbs against the tank sides. Back to Laverda, mostly RGS and cases of 180's, Piet has it correct, greater chance the tyre is mostly to blame, with a modicum of steering/frame assistance. Happened on the BT45 when not all that worn, Macadam used to "slip" in roundabouts, more worrying tyre behaviours.

Going out of town here, is the mad mile, fast sweepers where the RGS would wobble so bad you thought it would launch you... coming back later, no wobble and for laughs we would ride the same outbound road, same day, no wobble? Tyre temp perhaps, warmed working front suspension, perhaps, it was unnerving all the same.

Like all old riders, we ride through it with skill ( relative ) and hope... been onboard huge tank slappers for the kettle ( Suzuki GT750K ) renowned for them.... let hands loose and hold out until it stopped.. like the sound barrier, above speed the tank slapper all was good, until you had to come back through the sound/slapper barrier and the alarm rising again... j
 
In my case it didnt get beyond those pulses you could feel in the bars and a high-frequency wobble if you took your hands off. It was nothing like a big tank slapper, only ever had one of those very early in my 3c ownership. I was passing a 5 car lineup down near the Benboki turn-off of The Princess Hwy and ficked the bars a bit aggressively crossing back over the painted centre line and got a big rear slide, corrected that and it slapped back hard a couple of times. I learned what not to do, being aggressive on the bars and got a big don't do that again response. I wasn't as clever as I thought I was, good to be humbled every now and then and thankfully not in a physical way.
 
sfcpiet said:
I've found the front shakes violently once the tyre has worn about 20-30%, irrespective of tyre make or size! <snip>
Click to expand...
sfcpiet said:
Reckon weight distribution could be a major factor, as it became worse when the panniers were fitted!
Click to expand...
Huh, well what d'ya know?! Same, same ... The first time I noticed it was when I took the top box off after Breganze (!).

(I hate riding with a top box, but sometimes practicality wins out ...)

Kinda suggests that as the tyre wears, the front end starts losing traction/grip/call it what you will. Dropping pressure worked for a while, but it wasn't long before it came back.
 
Never use a top bag, more like a tank bag which gives more load to the front.
With my RGS I did not have any front wheel shaking at 80 K. Just with this scrappy BT45 I had a hard bumpy front at 120 k and higher speed. Like more the Contis.
Generally one point are the headstock bearings, better to have them at the loose side, not too tight. When you adjust the bearings and have no play and then you fix the main nut, it is too tight. There is some play in the threads which will increase the preload. So, when all is fixed the steering should move easy and fall to the side by its weight.
 
Found exactly the same when tightening my top nut on the 3c. You need to creep up with the adjustments a tiny step at a time and hold the bottom nut as you tighten the top one. Slightly loose is better. More art than science.
 
My 81 Jota scalloped front tyres like no tomorrow. I put the 80 -95klm wobbles down to the scallops. And a horrible head shake at about 80-60 with hands off bars, usually pulling my gloves up coming into a town.

Not to mention the rear end weave around bends over 180kph.
 
Scalloped treads are usually caused by insufficient pressure in the tyres Chris, the tread blocks warp under braking because they are not supported properly and thus wear unevenly. Also one of the reasons front tyre treads are often shallower than dedicated rear tyres! I haven't found the scallops to effect the wobbles. The 180 can require a bit more of your lane than usual with worn swingarm bearings.

piet
 
Any thoughts on the following making a difference? As yet unridden by me RGS Corsa. Headstock bracing as per factory mod bikes at 80k and has no cracks but as it’s stripped now for a refurb so I am getting it done. Secondly it has had emulators and progressive springs fitted and was tuned to a 115kg rider so I will cut the preload spacers down 5mm at a time to suit my weight. Could both of these improve the wobbles?
 
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