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
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