Still Noisy Burman Gearbox

[Matty]

A couple of years ago I rebuilt my Series C Comet Burman Box with a new layshaft and bronze bearings plus both 3rd gears because it was noisy (whining) in 3rd. It was and still is quiet in top. It was filled with semi-fluid grease as sold by Draganfly for Burman boxes when rebuilt.

It seemed little better and after about 5000 miles including a couple of 1000 mile round trips to the Manx Rally it now is very noisy in 3rd and not too good in 2nd.- though working OK.

I now think the problem is probably the very expensive gear 50/15, which is part of the final sprocket drive and/or the small gear 50/28 which meshes with it - these gears only do any work in 1st, 2nd, and 3rd, spinning fastest in 3rd!!.

Has anybody had and fixed a simular problem please and could I just change the small gear which is fairly cheap from VOC spares because this has the advantage of being possible to change without removing the gearbox - and in any case I do not want to spend about £250 on what may not be the problem. Both the above gears did not appear to be unduly worn when I had the box apart before, but the noise is a rather horrible whining/grinding one after about 50mph in 3rd.

Matty

 

[chankly bore]

duplicated, sorry

 

[chankly bore]

Richardson mentions adding 1/2 pint of engine oil to gearbox to cure "screeching noise".Worth trying before you do owt else! Cheers, F5AB/2A/7945 since 1970

 

[chankly bore]

Richardson mentions adding 1/2 pint of engine oil to cure "screeching noise". Worth trying before you do owt else! Cheers, F5AB/2A/7945 since 1970

 

[Matty]

Have had this "screech" some years ago when box was filled with grease and adding oil certainly cured it then.

Present noise is not the same and is the noise that sraight gears make but much louder than I like.

Have ordered the small 21 tooth gear at the end of the layshaft which meshes with the final output gear with the chain sprocket on it.

Will change this gear and refill with thixotropic grease and if this does not fix it, I will either have to live with the noise or pay £200+ for the output gear I suppose!!! - all other bearings, the layshaft and both 3rd gear having already been replaced.


Thanks

Matty

 

[redbloke1956]

Hi Matty, it might be worth looking at parts from a B52 Burman box from an AJS or Matchless (much more common and cheaper than BAP boxes) I am ALMOST certain that most parts are interchangeable, try Jampot Spares...please let us know if it works out.
Kevin

 

[Matty]

Thanks REDBLOKE, but the Comet box has practically no parts in common with AJS, Matchles, Ariel etc which is a pain because I have some of these.

The only other Burman box I am told which has much the same parts as the Comet is the one used in the Panther 600.

Semper in excretum!! - but hopefully not too deep.

 

[Matty]

Thanks all - see my reply to the 4th gear meltdown question for my progress on the noisy 3rd gear which seems a bit quieter now.