Steering head bearings and fork oil

[embee 7,288]

Following on from another thread regarding head shake, my Integra had recently started to show signs of doing it so I decided it was time to do the front end sooner rather than later.

 

It's all pretty straightforward on this bike, the only specialist tool needed is a socket for the head bearing adjuster and lock-ring. You could probably use a C-spanner on the others, but I did try one on the Integra and the bodywork is just a bit close really.

 

I didn't take many photos since I just wanted to get the job done.

 

I took the screen off which allowed easier working access. The Integra gloss black handlebar centre panel lifts off vertically, there are 4 plastic spring clips which are tight first time and you're sure you'll break something. I used a thin blade kitchen knife under each corner to prise them up one at a time. This pic shows it lifted. I applied some silicone grease to aid future removals.

 

 

The plastic handlebar trims come off easily, remove the 2 allen button head screws (one seen here) and 3 crosshead screws, 2 at the outer ends underneath and one in the "well", then unclip the 2 halves. The top lifts off and 2 more bolts hold the lower onto the bracket welded on the centre of the handlebars.

 

I removed the handlebar clamps (note they have a dot marking the front on the top face) and held the bars up to the screen mount area with a bungee (rags used where necessary to protect).

 

I place a couple of bags of sand on the pillion seat (tied on to make sure they don't slide off) which just about balances the weight, and used a car scissor jack under the engine to ensure it couldn't tip forward again. Be safe!

 

Removing the front wheel, caliper, and mudguard is simple, a few bolts. Support the caliper with another bungee. There's one bolt holding the brake hose clip to the lower yoke.

 

At this point slacken the centre nut on the top yoke. It's fairly tight and it makes it easier while everything else is still tightened together.

 

Slacken the top yoke pinch bolts and just loosen the top caps (the pinch bolts will prevent them undoing if left tightened).

 

You can then slacken the bottom yoke pinch bolts and remove the fork legs. NOTE!! - they will drop out if not supported, so hold the leg firmly while slackening the lower pinch bolt.

 

The fork top caps are lightly spring loaded so keep them held down while you undo them, it's not a lot so don't worry but just keep them held down. You now know why you loosened the caps while still clamped in the yokes.

 

I checked the oil level in both legs. With the cap off and spacer tube removed, and the leg fully compressed and vertical, the oil was 52mm down from the top end in both legs. I used this measure for refilling.

 

Use some bent wire to hook out the washer and spring, the washers in mine were "round side" upwards (stamped washers with a flat and a curved side). The springs are progressive with close coils downwards.

 

With the springs out the oil level was 125mm down, but bear in mind a small amoubnt of oil is lost when taking the wet springs out. My guess is 122mm would be a refill level at this point. Invert the legs and drain the oil, pumping the fork to eject the oil from the bottom end. Fortunately these forks don't "lock" when fully compressed (unlike some bikes!).

 

My favoured fork oil is Silkolene PRO RSF. http://www.peterverdone.com/archive/lowspeed.htm'> This chap has done all the hard work. Half way down there's a white table showing fork oils and properties. Assuming the NC forks are Showa, my guess is the std oil is their SS8, or maybe it's Honda PRO HP 10W, but anyway something like 35cSt at 40C viscosity will do the job. A high Viscosity Index (VI) is good, so the Silkolene PRO RSF 7.5W fits the bill nicely. This is what I use in my bikes that need a 35cSt oil. Note that this is typically a 10W range value, but ignore the nominal number and check the actual viscosity.

 

So, forks refilled with Silkolene PRO RSF 7.5W up to 52mm with the springs and washers installed, tubes refitted and caps put back. Usde a socket and ratchet to be able to apply some downward pressure while turning the caps and they go in easily. DON'T cross thread them!

 

Next the steering head. The top yoke will just lift enough to come off the stem while wiggling the cables from the ignition switch, and can be held forward enough to access the bearing locknut. Now the interesting bit.

 

When I bought my Deauville I found the locknut was finger tight. On the Integra, the locknut was properly loose, when I undid the tabs on the tabwasher, I could turn the locknut 5 notches before it made contact, that's fully 5/8ths of a turn loose. The securing nut with the dust cap was actually nipped tight against the bearing, so it still had some preload which had saved the bearings from damage.

 

I removed the nuts, tabwasher, and top cone and lowered the yoke and stem down and out. There was actually a reasonable amount of grease in both top and bottom bearing, and both were in perfect condition. This shows the grease as found. I always prefer to fully pack steering head bearings, so I simply added a load more to what was there already since it was all perfectly clean.

 

When reassembling, I applied about 10Nm preload to the retaining nut, then fitted the tabwasher and nipped the locknut down against it until the slots aligned for the tabs. It doesn't need to be all that tight since the top yoke nut will clamp it down hard against the retaining nut. This ended up with about the right "feel" for the bearings when it was all back together. I have a castle socket which I made out of a piece of scaffold tube and a 3/8" socket welded in an end plate so I can torque the locknut etc, but you could get away without.

 

Reassembly is, as Mr.Haynes would have it, the reverse of what you've just done.

 

Bottom line is -

 

the Silkolene PRO RSF 7.5W fork oil is just right, giving a nice feel.

The head shake has 99% gone. You can sense there is a tendency for it to want to shake as you coast down through 40-30mph hands free, but unless I was looking for it I'd not know it was there now. As someone else has said in another thread, any bike with a "castor" front end will have a tendency to shake, it's simply the physics of a castor system depending on the numbers in the equations, but this service has sorted my Integra.

[embee 7,288]

Sorry, the link to the fork oil info didn't go into the post above, and it won't let me edit it for some reason. Anyway, look at the table halfway down the page here

http://www.peterverdone.com/archive/lowspeed.htm

[michael 324]

Concise and an easy read. You're as talented an author as mechanic! Thanks for posting this.

[Guest duk2n]

Thanks for sharing, very clean!

[embee 7,288]

Thanks for the comments, comes from years of writing tech reports!

 

Hopefully here's a few more thumbnails showing the steering head, the top seal, the retaining nut with dust shroud, and the tab washer arrangement.

 

The socket was made from a piece of scaffold tube, it happens to be just the right diameters. It doesn't need to be hardened or anything special since it's only dealing with small torques (and I don't intend to use it that often anyway!)

 

[djsb 491]

Thanks Murray,

Do you know the size of the socket needed for the tope yoke nut? Are these bearings a cup and cone or taper roller bearing design? Also is it possible to mark the original relevant positions of the nuts with a scriber/punch/dab of paint in order to assist in reassembly? Thanks.

[Tex 36,817]

Excellent 'How To' article, Murray. It needs to be bookmarked and kept safe for future reference.

[embee 7,288]

Sorry I haven't got the size of the top yoke nut to hand, it's hidden on the Integra by the cover arrangement so I can't get to it to measure, and I know I used an old imperial socket which is a very nice fit, I think that was 1 1/4" A/F but can't be sure. That would be equivalent to 31.75mm (plus a little for wear and tear), and I think it's a nominal 32mm nut size but can't swear to it  You'd best measure it unless someone else can confirm it.

 

It is straightforward. There's no point marking anything for reassembly, it adjusts to where it adjusts.

 

The std bearings are cup and cone, and are caged so they don't fall apart and drop all the balls out, different sizes top and bottom but that's obvious. As mentioned these are designed to have a significant preload applied, tapered rollers aren't (due to the very different pressure angles).

[Grumpy old man 4,673]

Come back @embee

[RC166 694]

Another example of embees excellent posts. I agree with Lloyd, please come back!