gear box

[Cookie2050]

Hi guys
Has any body had to replace or repair their 41 tooth countershaft low gear? I am finally rebuilding my engine and ordered new chains and piston rings and seals etc.
 started re build and the first problem i found was the low gear is very worn with loads of wear on the brass bush, none in stock at david silver and not made any more. Has any one replaced the brass bush? or am i going to have to wait for a decent one to turn up at DS or E-Bay.
Thanks
Russ

[AshimotoK0]

Do you mean this ...item # 145 ?

Don't think the bush is available separately or ever was. It may be the same bush as a CB350K gear in which case its possible I may have one.

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[Chris400F]

You could try Steve at http://www.400fourbits.co.uk/ - he may have the gear available.

[Cookie2050]

hi
yes ashimoto thats the one , im on holiday from work this week and i havent got my vernier calliper to measure the size of the bore or the shaft so i cant be sure the 350 one would fit. Chris ill have a look on the site and see if he has anything in stock. it may be easier to buy one than try and get one made where i work.

[mike the bike]

I'll have a look in the shed.   Give me a day or so.

[AshimotoK0]

This 750 gear has the correct ID bush if any use .

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[Cookie2050]

sorry for the delay in replying

i measured the diameter of the bush and its about 0.20 over size, the shaft is around 0.15  down.

there is also a lot of sideways play on the gear, i can get a 30 thou feeler guage between the gear and the 20 mm spacer and this removes a lot of the wobble in the gear. i may have to get or manufacture some new spacers.

i did some investigating into the bush itself and they look very similar to a wrapped bush

 http://www.bowman.co.uk/products/wrapped_bronze_bearings

if you look at ashimoto's pic you can just see the line where the bearing is split at the top right,

steve at 400 four bits has got a gear in stock so im going to e-mail him  and see what he wants for it and i will also find out a bit more info on the bushes themselves

Russ

[AshimotoK0]

You can have that Gear FOC BTW if the bush is of any use .. & yes its a rolled bush

[Cookie2050]

thank you ashimoto, thats a great offer you'll hve to let me buy you a drink surely.

[AshimotoK0]

thank you ashimoto, thats a great offer you'll hve to let me buy you a drink surely.

No worries Just pay the postage & send me your address. I have a 13.7 mm and a 16.7 mm deep one . Which one is best for 400?

OD is just under 27 mm ?  Since I have pressed out don't worry about postage just put the cost of a stamp in your local charity box.

[AshimotoK0]

Russ told me it's the 13.7mm one on the 400/4. The bush when I pressed it out had similar markings to SOHC crank shells on the OD probably made by the same company.
In the post today Russ

[Cookie2050]

Cheers ash

Working nights this week so i should be able to get on with it.

[Greg65]

Ok, have the same problem. So can anyone tell me the dimensions of the bush required so I can try and source a replacement.

Thanks,
Greg

[Greg65]

Had a session with the micrometer and the shaft measures up at a fraction under 20mm and using a digital calliper I think the outside diameter of the bush will be 23mm but this is a bit of an estimate, can anyone give me a more precise figure?

Greg

[ttr400]

I make these bushes all the time for that gear, but i match the new bush to the gear and shaft. I use Bronze.

Best is to take the gear and shaft to a local machine shop, they will turn one up in no time.

Kevin