Advice Please: Head stock bearing tightening?

[Bibio]

my pleasure

just keep an eye on the rebound, the wear should not get any worse than what it is now and if it does then just notch the adjuster up a 1/4 turn. when setting the 'bounce' on the front add 20ml for each top up from the initial 60 and keep a record till its about right. dont try and get perfection, better a little overshoot than too much.

[johnnyrod]

Glad you got it looked at. It's a job I've done a number of times and it's very Zen. I once was wrestling with the same on a mountain bike, and asked a mate of mine if he had any tips (he was an ex-MTB racer so must have known a mechanic at some point). He said you need to find a little old man in a back street shop who has reached 10th dan, that sort of thing.

[Craigg]

Originally Posted by Bibio

my pleasure

just keep an eye on the rebound, the wear should not get any worse than what it is now and if it does then just notch the adjuster up a 1/4 turn. when setting the 'bounce' on the front add 20ml for each top up from the initial 60 and keep a record till its about right. dont try and get perfection, better a little overshoot than too much.

couldnt get any 20w oil, so got some 15w, and topped up to 90mm airgap with that (instead of the 7.5), mixed it then extracted 60ml and topped up with 15w to 90 again. that seems to be spot on for the bounce test.

after having the front end apart and back together, the bike does feel much better.... maybe its all in my head?

will get some miles on it an see where we are at. miserable ride into work this morning so didn't spend any time messing about!

[Bibio]

having a think about it the vague feeling could have been due to the rear sitting low causing the front to be nose up.

with what you have said above as regards to the oil mix i done a quick calc and it looks like RSF 10w (47cst@40c) will be just about right for your setup when it comes time to change the oil.

[650]

Elaborate on the calculation you did, Bibio? Interested to know about that....

[Bibio]

its easy. you need to find the CST ratings of the oils (will be in the spec sheets or online charts) you then divide the CST @40c by 100 then multiply by what you use.

lets take some RSF 2.5w and RSF 5w then mix to get showa SS-05 oil. lets say the SS-05 is 15.52 CST@40c. RSF 2.5w is 13.6 CST@40c. RSF 5w is 26.7 CST @40c

to mix 1ltr of 15.52 CST@40c you would use 16% of RSF 5w and 84% RSF 2.5w

RSF 2.5w. 13.6/100 = 0.136 x 84 = 11.424
RSF 5w. 26.7/100 = 0.267 x 16 = 4.096

11.424 + 4.096 = 15.52 CST@40c

its not an exact science but its close enough.

why use Silkolene RSF oil? simple, RSF has larger CST@100c figures so there is less movement of the range as the oil heats up compared to other oils.

spot the mistake

[650]

haha, I'll decipher that when I'm home - too much going on at work at the moment! But thanks

[21QUEST]

Originally Posted by Bibio

its easy. you need to find the CST ratings of the oils (will be in the spec sheets or online charts) you then divide the CST @40c by 100 then multiply by what you use.

lets take some RSF 2.5w and RSF 5w then mix to get showa SS-05 oil. lets say the SS-05 is 15.52 CST@40c. RSF 2.5w is 13.6 CST@40c. RSF 5w is 26.7 CST @40c

to mix 1ltr of 15.52 CST@40c you would use 16% of RSF 5w and 84% RSF 2.5w

RSF 2.5w. 13.6/100 = 0.136 x 84 = 11.424
RSF 5w. 26.7/100 = 0.267 x 16 = 4.096

11.424 + 4.096 = 15.52 CST@40c

its not an exact science but its close enough.

why use Silkolene RSF oil? simple, RSF has larger CST@100c figures so there is less movement of the range as the oil heats up compared to other oils.

spot the mistake

You are such a Nerd

I use this.... http://www.widman.biz/English/Calculators/Mixtures.html.

[Bibio]

cheers Quest thats well handy

[philbond07]

Originally Posted by 650

It's the bearings. Too tight will cause wobble and weave at low speed. Too loose and you'll get clicking and vague steering. You can also encounter the feeling you're getting if the forks are twisted in the clamps or the spindle is too tight. But my money's on the bearings.

Bearings needs adjustment with the front wheel off the ground. You should also loosen the lower clamp pinch bolts so the forks can turn in the triples while making the adjustment.

Torque settings are high for the lock nut and the top triple clamp.

40Nm tends to be the torque setting for the steering nut, 80Nm for the lock nut, 90Nm for the top yoke.

Feel is important on the steering stem, at least more so with tapered bearings than the stock roller bearings...so are you definitely using roller bearings or have they been changed out for tapered? Tapered require a 0 preload so the steering nut should only just be nipped up from finger tight.

Hey all,

Sry for reviving old thread.

I wanted to check out stock head bearings of my naked k3 and also tighten up a bit cause it felt a bit loose. So regreased the bearings; races up/down looked still ok. But cannot seem to put right final tension on it. Even when leaving the bottom adjuster nut very loose, after torqueing the locknut/80Nm the steering becomes too hard. Then after torqueing stem top nut/90Nm it gets even worse. Thought maybe the upper inner race could have been mis-seated, but everything looks ok. I use a c-spanner to adjust/torque the castle-nuts. How did you get right torque by using hammer&drift Craig?