Essential when rebuilding your engine to ensure that the upper vertical bevel gear has the correct backlash and position in relation to the camshaft bevel gear, these camshaft bevel shims fit between the camshaft and the front cambox bearing (i.e. in the front cambox well).
Fitted in conjunction with the upper vertical bevel gear shim, the ideal positioning is acheved when the gears are in line and there is a just perceptible gap (backlash) between teeth.
This is for a set of 3 shims in the following sizes :
0.2mm/0.3mm/0.5mm. Note - shim steel is now supplied in metric thicknesses, but these are offered in the nearest equivelant to the old Imperial sizes that were commonly used - i.e.
- 0.5mm = 0.021" or 21 thou (for some reason the actual thickness is 0.53mm which = 21 thou)
- 0.3mm = 0.012" or 12 thou
- 0.2mm = 0.008" or 8 thou
It is common practice to measure initially with no shims fitted, then add one or multiple shims to reach the desired final positive backlash, measuring each time shims are added or subtracted
Note: The A11/788 back distance piece is sold seperately - see Item 0329, as can these shims in the individual sizes (Item 0328). The back distance piece is not used for shimming the camshaft bevel gear - it is for setting distance of cambox back bearing correctly.
Please note - Oct 2022 . . .in the past we used to get these made in 5 different thicknesses - but now only available in 3 most common sizes . . . but you may find it prudent to buy more than one packet or some additional individual shims - I normally keep a small tub of them, to ensure I can make up the right combination for correctly shimming the cambox I am making up, as over the 30 year period these cambox's were made, it is rare to find two cambox's with the same shimming requirement!
In the accompanyning photographs - the second photograph shows our shims on one of our camshafts in the position the shims would fit before the camshaft is slid into the cambox - the shims being fitted between the camshaft shoulder and the front cambox bearing (i.e. adding more shims pushes the large bevel gear out from the bearing more).
The final photograph shows a genuine pre-war (Manx) camshaft . . . having just been stripped for the first time in 50 years, and original Norton shims still in place (and a similar photograph is also shown in the listing for Item 0329, as the distance piece is also in situ in that photograph)