Unusual damage on G'box sleeve gear bearing.

Reggie · Apr 7, 2009

I've just opened up the gearbox today, and found that 4th gear on the layshaft has slightly cut slightly into the sleeve gear bearing outer case (directly above it) at the bottom.

Unusual damage on G'box sleeve gear bearing.

Any ideas why? Is it just massive flex on the layshaft that has allowed this to happen?

I have tried to post a picture but it appears to have failed. Would anybody who is more computer literate be good enough to let me email this to them and then post it for me please?

L.A.B. · Apr 7, 2009

Your photo shows OK.

Possibly layshaft fourth gear was installed the wrong way around?

The shoulder on 4th gear should go against the bearing.

Reggie · Apr 7, 2009

That is odd, as the pictue isn't showing on my screen?

I've just checked and the gear is (still) on the layshaft the correct way around with the small shoulder against the bearing. Incidently, the bearing on the layshaft is No. RHP N203.

Shimming the layshaft wouldn't have any effect on this end of the shaft would it, unless it waas shimmed too tightly?

79x100 · Apr 7, 2009

It's strange but it looks as if the outer ring for the layshaft roller is sitting too deeply, which of course it can't, assuming that it's the correct bearing.

Is the sleeve gear bearing perhaps not fully home in it's housing ?

If you offer up the layshaft with just the 'fourth' gear and the bearing inner fitted, it should perhaps be clearer what's happening ?

Is the gear case original ? They couldn't have made one with an incorrectly machined depth, could they ? :shock:

Hortons Norton · Apr 7, 2009

I agree with 79x100 The sleeve gear bearing is not all the way in, Or could it be the wrong bearing and it's too wide?

Reggie · Apr 8, 2009

I've taken the sleeve gear seal and spacer sprocket out, and the bearing appears to be seated fully home.

When the layshaft is in, with fourth gear on, there seems to be sufficient clearance between it and the bearing case :?:

I am just wondering if the previous owner has had a layshaft bearing failure causing the damage, and left the sleeve gear bearing in, only changing the layshaft bearing :?: There is barely any evidence on fourth gear of grinding the bearing case away.

I'll get the bearings out next. If they are the correct size, I'll fit new bearings and check the clearance. The other thing as 79x100 says is incorrect bearing depth, but it appears to be the original casing as it has the matching numbers stamped on.

L.A.B. · Apr 8, 2009

Reggie said:
Incidently, the bearing on the layshaft is No. RHP N203.

If that's a bearing with its roller cage captive to the inner race, as I believe N203 bearings are, then I think it's the wrong bearing! As the N203 bearing won't control any layshaft endfoat. Your photo certainly shows an outer race without a captive roller cage.

The correct layshaft roller bearing is the NJ203(C3). As this bearing has the roller cage captive to the outer race, with a single lipped inner race on the gear side.

Correct NJ bearing: http://simplybearings.co.uk/shop/p49185 ... _info.html

Wrong N bearing: http://simplybearings.co.uk/shop/p51368 ... _info.html

Of course, Mick Hemmings recommends the special phenolic cage ball bearing, as he says a ball bearing is much better at controlling the layshaft end thrust.

splatt · Apr 8, 2009

I had the same thought as LAB while Iwas at work , the bearing rollers should still be in the bearing and not just the outer race left sitting there, we were a bit slow with the whats wrong with this picture.Ifind the gear box easer to assemble with the nj203 c3,but you need to control the end float,old britts give a very good description,when fitting the ballrace bearing,6203 tb I think it is,if the layshaft doesn't quite slip in you have to resort to giving it a mild wallop ,with the inner race being unsupported it makes you cringe a little.I believe the TB represents that the bearing has a polyamed cage which Iwas told resists vibration fatigue alot better as the rivetted steel cages may crack, good luck.

Keith1069 · Apr 9, 2009

FWIW I fitted the polyamide cage job from Mick. Expensive but with a needle race conversion on the K/S I needed a better way of controlling float. The needle race allows the shaft to go wherever it wants to as the existing shoulder is machined off and there is no longer a thrust face on the K/S shaft. The new bearing was a very tight fit on the layshaft though so makes any future disassembly more difficult, more than likely the shaft would come out with the bearing attached. Shouldn't have to go in there too often so not an issue really.

Reggie · Apr 12, 2009

Les, Splatt and Keith, thank you for your replies. Sorry about the delay replying, but I've been away for a short break 8)

Les, you are correct, I have got the "wrong" layshaft bearing in, not by me I might add, but the previous owner. I had left the gearbox alone when I rebuilt the rest of the bike, as the previous owner has a receipt from a well known Norton supplier (NOT M. Hemmings I might add) who had had the gearbox apart in-house and fitted a new camplate, bushes and one mainshaft bearing, and so as I was in a hurry to get on the road, I thought it was probably OK to leave it alone. Mmmmm, wrong again.

Thanks all, looks like I've found the probable cause of the damage.

P.S. Also thanks to 79x100 and Hortons Norton

Reggie · Apr 13, 2009

LAB wrote;

Of course, Mick Hemmings recommends the special Polyamide cage ball bearing, as he says a ball bearing is much better at controlling the layshaft end thrust.

Les, is this the bearing that he recommends;

Correct NJ bearing: http://simplybearings.co.uk/shop/p49185 ... _info.html

or is Micks a variant of this bearing?

On a more general theme, does anybody have opinions as to the quality of RGMs gearbox parts i.e gears, shafts and bushes as I am about to do some retailing of these? He is cheaper than other suppliers somehow?

L.A.B. · Apr 13, 2009

Reggie said:
is this the bearing that he recommends;

No, what Mick actually recommends a high spec. FAG 6203TB phenolic cage ball bearing.
As he says that a ball bearing is much better at controlling layshaft end float than the roller and that he's never had one fail.

Reggie · Apr 13, 2009

LAB wrote

No, what Mick actually recommends a high spec. FAG 6203TB phenolic cage ball bearing.
As he says that a ball bearing is much better at controlling layshaft end float than the roller and that he's never had one fail.

I'll get one of those then. Thanks (again) Les.

Hortons Norton · Apr 13, 2009

When I bought my gears from RGM they were Norton gears, But one thing I can tell you is be sure to brush the gears off with WD40 or something like that to get all the fine metal off them. It is amazing how much was on them, and not just small stuff but good size chips and other matter. And the only reason I did this is I remember a shop class teacher telling us to do this with all new gears. They do sell good stuff as far as I am concerned, The Hemmings layshaft bearing is something I wish I had done but heard about it after the box was finished. I did go with the roller though. It's kinda hard to see in the pictures but it was a lot of metal, Have a great day, Chuck.

splatt · Apr 13, 2009

Reggie,for the main shaft bearing try a NICE 1654DCTN it's a sealed bearing you can remove one seal.I figured it might hold more oil in an crap out a bit better.

Unusual damage on G'box sleeve gear bearing.

Reggie

L.A.B.

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Reggie

79x100

Hortons Norton

Reggie

L.A.B.

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splatt

Keith1069

Reggie

Reggie

L.A.B.

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Reggie

Hortons Norton

splatt

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