front wheel bearings

neil · Post by **neil** » 02 May 2009 12:07

Just mot'd my 350 and I was given an advisory on the front wheel bearings. Bought new bearings and taken the wheel off but have no idea how to get the old bearings out. I've removed the circlip from the disc side but the speedo drive seems to be in the way on the other side. Any advice gratefully received!

EVguru · Post by **EVguru** » 02 May 2009 17:20

There are a couple of ways of getting the first bearing out. You can push the spacer tube (part 15) to one side and then use a drift onto an inner race, or you can use a rawl bolt inside the bearing/spacer.

It helps a lot if you heat the hub up, a hot air paint stripper works very well.

neil · Post by **neil** » 05 May 2009 19:47

Thanks for the advice Paul.
The disc side bearing was easy to remove and replace but the speedo side was just the opposite and required use of a drawbolt to remove and replace it and more use of the hammer than I was happy with. After replacement I found the inner ring of the bearings quite stiff and difficult to turn with a finger. The wheel doesn't seem to spin very freely and there is a slight noise, from the speedo drive I think. Haven't had a test ride yet. Do things need to bed down or have I done something wrong?
Neil.

Steve Brown · Post by **Steve Brown** » 06 May 2009 17:27

Hi Neil, that does sound wrong, sorry! The wheel and bearings should be quite free to turn. If you used sealed bearings there is a very small drag from the seals but not enough to stop the wheel on its spindle, you would feel a resistance if you turned them with your finger in the inner race, but that's all.
It could be that one or more bearing has gone in slightly cock-eyed, or perhaps not in far enough? Spin the wheel on it's spindle out of the forks, then you can see if the speedo drive is contributing or not.
It's likely you'll have to remove one or both bearings again to get it right, and that will nearly always wreck the new bearings, so expect to change them again.
The wheel should be free from the moment you put it back, nothing will settle in like this, only cause some other problem. I guess you've made sure the spacers and calipers are all back in place and not causing this?
As Paul (I think) said, it will help a lot if you get the hub really hot before fitting the bearings and also put the bearings in the freezer over night! Makes life a lot easier!
Good luck with it!

Steve

neil · Post by **neil** » 06 May 2009 19:14

Thanks Steve.
Well everything seemed ok until I tried to fit the circlip on the disc side but the bearing needed another tap to seat it enough to get the circlip in. That was when the bearings seemed stiff to turn.
Guess what I'll be doing this weekend? Good job the weather forecast isn't up to much!

EVguru · Post by **EVguru** » 06 May 2009 22:13

You've probably just got too much preload. In theory the bearing housing and spacer should be the same length, but often they aren't.

I've usually found the bearings will settle themselves, but if not the preload will just shorten their life. Since removing bearings damages them also, you might as well just leave them alone.

Steve Brown · Post by **Steve Brown** » 06 May 2009 22:44

The bearings cost pence, (relatively) I'd much rather take them out, find out what was wrong and do the job right. This is the front wheel we're talking about, after all. They are a simple bearing and not meant to be 'pre-loaded' at all. If they are, they will at least get a bit too warm, and die sooner. If they got 'pre-loaded' when you had to drive them in a bit further against the inner spacer tube, they will already be slightly damaged in the same way they get damaged when you take them out. Your wheel and bike, your choice!

3potjohn · Post by **3potjohn** » 07 May 2009 05:46

Just to second the use of something to warm up the hub ( yes even boiling water on bath towels!) and cooling the bearings. I used dry ice because I had some last time but this is probably overkill.

robint · Post by **robint** » 07 May 2009 07:48

...........and if you can find the right socket, piece of pipe, old very slightly smaller bearing or similar to use as a drift on the outer ring only so much the better (along with heat/cold etc).

Post by **morini_tom** » 07 May 2009 11:54

Not wishing to teach anyone to suck eggs but since it hasn't been mentioned in this post- when you put the new bearings in you must only drift them on the outer race so find a socket or similar which contacts only the outer race and tap the bearing in with that. Hitting the inner race will wreck them.

And for the record for the sake of a couple of quid I'd fit new bearings.

neil · Post by **neil** » 07 May 2009 19:59

Wow, that's provoked some responses! Had another look this evening and maybe the wheel spins freely enough but there is some noise which may be the speedo drive. I will take the wheel out at the weekend and have a closer look. Yes bearings are cheap enough but I don't want to put another new set in and have the same problem(if there is one). I used a hot air paint stripper but worried about damaging the paint.Is the speedo drive available from NLM? Anyway it's all part of the learning curve,once I've done it a couple of times I'll wonder what I was worrying about!
Thanks again for you replies.
Neil.

EVguru · Post by **EVguru** » 07 May 2009 20:16

The inner spacer is often a couple of thou longer than the bearing housing so that when the spindle is done up tight it's the inner races that are held solid not the outer. If you drive new bearings in on the outer race alone then you end up with a bit of preload.

It is only a couple of thou though and unless the outer races were very tight in the wheel, they will move and settle. If the bearings rotate smoothly, but a little stiff, you really should be fine. If you want to play extra safe and try then again without the preload, then you only actually have to change one bearing.

To prevent the same thing happening again, you have to drive the bearing in on BOTH races, definitely not the inner (since that would put the load through the balls), but not the outer alone either since that allows you to put in that little bit of preload.

Speedo gears are in short supply, but you should be able to dismantle and clean everything.

neil · Post by **neil** » 10 May 2009 19:49

Just an update if anyone is still interested! Took the wheel out today and realised that, as has been suggested, the bearings are nipped up against the spacer tube so the tube rotates with the inner bearings. Cleaned and regreased the speedo drive, put it all back together and it all seems ok. Had a short test ride with no problems so I will just keep an eye on it see how things go. Thanks again for everyone's input.
Neil.

3potjohn · Post by **3potjohn** » 11 May 2009 06:02

Glad that's done.I have yet to do my front bearings on my Morini so will retain this info.I have done them on BMWs but as they are taper rollers this involves some bu**ering about with a nasty thing known as a wedding ring.(there maybe a joke here somewhere but I've avoided it.)