Headstock bearing woes

[shielsy]

Changed the headstock bearings on my KTM LC4 yesterday. Other than the old bearings being a bh to remove, every thing came off and went back together OK.

I have an issue though. If I tighten the steering head nut enough to remove play (forwards/backwards) the steering is too tight. If I loosen the nut enough for the steering to be free, I get play in the head

I've not done this job before so any tips on what the fk to do next?

[V8 FOU]

Check that the bearings are in straight. What sort of bearings are they? Taper roller or sealed ball?

[shielsy]

Tapered ones

[shielsy]

I've been dicking around with the steering nut tension this morning. I've got it too a point where the steering is not too tight, but there is somewhere between 0.5-1mm of play when pulling on the forks with the bike in the air. If I tighten the but any more it starts effecting the steering.

With the bike on the floor I can't feel the play.

[kev b]

Set it so that with the front wheel off the ground the bars do not move under their own weight but will flop when given a slight nudge. Check with yokes bolts etc fully tight.

You definitely do not need any play or movement, but they must not be too tight, it is more art than science.HTH

[shielsy]

Something is not right. The bars don't move freely even with a slight amount of play.

[V8 FOU]

Daft question. You do have the bearings the right way round? i.e. with the narrow sides pointing towards each other?
Also, when you are setting up, is the top yoke loose? Once you have removed the free play, then tighten the yoke pinch bolts.
I usually slightly overtighten the stem nut, loosen it, the turn it until I feel resistance of it all tightening up, then add approx 1/2 flat of the nut preload. Works on all the bikes I do....

[Steve Bass]

Are the bearings properly greased?
Once the bearings are fitted, grease the steering stem bearing faces and stem and slide the steering stem up from underneath and fit the threaded collar. Tighten this to the specified torque or to remove any play.
Make sure the bottom tripe ( and forks if still in the bottom triple) turn nicely with no notchiness or slop. This should be WITHOUT the top yoke fitted
Now fit the top yoke and tighten the top nut.
Remember the top nut should clamp the top yoke against the bearing collar underneath, NOT force the top yoke onto the bearings....
There's 2 nuts to consider.. The bearing collar which sits UNDER the top yoke and the top nut which sits on the yoke.
Unless it's a Ducati. Which it isn't

Edited by Steve Bass on Sunday 26th June 16:15

[shielsy]

I think I have found the issue. One of the seals wasn't seated correctly and was getting chewed up. There is a little bit of damage on one side.

I've put it back to gether properly now and its a lot better. However I think I will be ordering a new seal tomorrow to be on the safe side.

Cheers all

[graham22]

If it's the bottom seal I wouldn't be too worried about replacing it.

I deliberately leave them out on dirt bikes as they seem to trap moisture rather than let it drain out, to me that's why the bottom race is usually more rusty than the top one.

Not sure how you tapped the outers in but I use the old outers to do this, usually gives a good indication if they've gone in square. As said above, pack them well with grease.