Stuck gearbox bearing

George. Maybe a PO used bearing fit-type Loctite to hold it in place, if it was a poor fit. Are you sure that the bearing needs replacing? If so, more heat, more bashing on a lump of softwood....

I think I'd go for the drilling 2 holes method. As long as you do that where there's plenty of meat.

You could then tap them and fill with a couple of grub screws. In fact once they're tapped you could use them as bearing extractors in the future.....

I had to get my dolls head casing really hot to move the bearing. You know when it is hot enough when you spit on it and it bounces!

Colin

You can buy/borrow/rent blind bearing pullers which might help if you can get one in there. Iâve also heard of people making one using a large Rawl bolt.

dan

I used a steel rawbolt expanded in bearing until grips then heat to 400 deg in oven and soak then pull on extractor. Tip put tray in oven to collect oil and best done when wife is out.

I've never failed on gas mark 6 but the casing has to be hot enough for spit to bounce off. Local heating with a small source doesn't seem to get it hot enough all round.

Are the studs out of the box ? If so then you can give it a full two-hander from above your head down onto a softwood block.

Swearing at 'em helps too.

A good cuss at it also makes you feel in charge of the situation even if you may not be!

Each type of Loctite loses strength when hot. At varying temperatures for different types. Its on their web site. Somewhere about 150C I seem to remember but anyway it OUGHT to let go even if it was glued. Anyway if it is hot it probably isn't the Loctite holding it. In theory.

The hot air gun may go up to 600c, but, it is localised heat. The oven heats the whole assembly, however, it will probably take about an hour to heat completely. Make sure "her indoors" is just going for the weekly shop!

Maplin (while they still exist - shame!) sell an infrared thermometer which is very handy to confirm the temperature of bits of your bike. Ideally I believe it is more accurate when used on a black (or maybe dark grey) surface but I don't really know. Also I don't know what effect heat has on the alloy casting! It might make it stronger ('artificial aging') or weaker. Are there published maxima? And can they be reached in a domestic oven?

I use it at Christmas to check the oven before the turkey goes in!

I remember reading somewhere that 200C was about the limit for LM30 alloy which is one of the common ones.

I have one (well 2 as I temporarily lost the first) of those infra red thermometers and it's useful for all sorts of things. You can get them for a tenner or so from ebay. Probably not very accurate but near enough.

Previously George Phillips wrote:

Yes David, I have one. Used it in my job when I was gainfully employed. Mike Pemberton on his DVD blasts the casing with a pretty hairy blow torch flame and doesn't seem to wqrry about any "heat effect" other than expansion? I've now invested in a Rawlplug (big spender!) so whichever way I heat the box I should be able to get the last part of the bearing out. When it does come out I shall start a new thread on correct bearing size (C2 CN etc). Cheers

George

George; largestexpansion of the alloy will occur up to 230 degrees. I am banned from the kitchen but as the oldgas barbecue is not in use it and itâs got a window in the lid, ideal tool to use with the infrafed temperature gauge.... just sayin

Hi George

I have a hand-written note in my maintenance book showing that the layshaft bearing that I removed was a Hoffmann 117 V2 (or maybe VZ). It also says "same as front wheel 6203". Unfortunately no dimensions recorded or what I replaced it with. I am fairly sure that there is a spherical roller bearing only at the clutch end of the layshaft, the other end runs in a plain bush inside the kickstart shaft. Unless someone has come up with a bearing conversion for that end?

You could try these guys:

Vintage Bearing Company http://vintagebearings.co.uk/home/2528957

Hoffmann https://www.hoffmannprecisionbearings.com/

I can't see on-line ordering for either of those so give them a call.

Cheers, Ian McD

George

The layshaft L/H bearing is a metric one. The size is 17mm x 40mm x 12mm.

If you look at the WD Norton workshop manual (free download from the WD Norton site) it gives this size. The bearing size did not change throughout, including the AMC box. The later Commando used a roller bearing the same size because the ball type couldn't handle the torque. Not a problem (despite our aspirations) with an ES2. You measured your shaft at 0.669". Multiply this by 25.4 and you get 17mm! (Or as close that matters). It was tight in the casing because they have to be!

I can't help you with the R/H layshaft size but as it runs in the K/S shaft there is no bearing to change.

The WD book quotes the R/H mainshaft bearing as 5/8 x 1 9/16 7/16. This should have a bearing code LJ5/8. Again, I don't think this changed throughout.

Hope this helps.

Colin

It's my understanding that the layshaft and front wheel bearings (6203) were always metric. No idea why......