We have a WD B40 that won't go into first gear.
It changes up the box from neutral just fine and changes back down the box to neutral, but it will not select first gear.
Anyone had a similar problem?
Or any ideas what could be the cause.
All of the internals look fine and the selector springs appear to be ok.
Any suggestions would be greatly appreciated.
Check the gearchange spring is centrally aligned on the gearchange quadrant in terms of the eye of the spring, the centreline of the spindle and the centre of the spring anchor peg are in a perfect straight line. If the eye of the spring is biased to one side it will effect gear changes in one direction.
The other possibility is the fit of the selector fork roller in the camplate track in the first gear position. Too much wear mens insufficient movement to engage 1st gear dogs.
Thanks Rupert, we will check that.
Ok, all of the pinions and selector forks are fine, the cam plate and selector mechanism are good.
The selector spring is ok and adjusted correctly.
With the assembly on the bench all 4 gears can be selected, but when fitted back in the engine casing, 1st gear is not selectable. The gear change lever won't go below neutral.
Anyone got any ideas?
Would it be worth buying a new selector plate?
I'm not familiar with the B40 gearbox but it sounds like the camplate plate is not not aligned properly. I've had a Quick Look at the manual but it's not very clear about this. All it says is that the "T" mark must be at the top and that the camplate must be replaced with the bottom gear notch at the bottom.
Fix some sort of pointer to the end of the gearchange shaft and fit it alone with its spring into the crankcase with the inner cover on. The gearchange shaft should turn an equal distance both clockwise and anti clockwise from its at-rest position, the pointer will help you to see that it is doing so. If it doesn't, there's the start of the solution to your problem.
If it does, fit the camplate only and verify that engages in all four gear positions and neutral...
We appear to be getting somewhere.
There seems to be at least two different types of gear change quadrants in the B40 gearbox over the years.
Unfortunately because BSA didn't cast the part number on the quadrant it is almost impossible to know if you have the right one for the year of manufacture.
Anyway it looks like the castings differ in that the angle of the quadrant castings is greater on some than others.
So if you get the larger one when the gearbox should have a smaller one, the quadrant fouls on the gearbox case and won't travel far enough to engage bottom gear.
We used engineers blue and a Dremel to remove some of the quadrant edge and have finally got the damned thing to engage first gear.
So be aware, not all B40/44 gearbox quadrants are the same.
Yep, original BSA gearchange quadrants usually no problem, pattern gearchange quadrants usually troublesome.
I have checked the parts catalogues for the B40, B44 and B50.
The gear change quadrant part number changed four times from 1961 to 1973.
Whether the actual part changed I can't say.
B40 (1961 - 1964) part number: 14140-3140.
B40 (1964 - 1965) part number:14440-3192.
B44 (1966 - 1967) part number:40-3321.
B50 (1971 - 1972) part number:40-3321.
B50 (1973) part number:57-2692.
I seriously doubt that the quadrant in our gearbox is a pattern part as I can't find anyone selling this as a pattern part.
Most dealers are offering to supply a replacement splined gear change shaft to weld into the original quadrant head.
Plenty of pattern gearchange quadrants were in circulation in the 80's-90's and still cause problems. If you fit one, good luck with it!
As well as the rotational travel being a problem the plungers protrude further than the original BSA part.