Author Topic: B40 steering head bearings 1965  (Read 53 times)

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chaz

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B40 steering head bearings 1965
« on: 14 February, 2020, 11:34:34 »
I need to replace the head bearings on a 1965 B40, having a problem finding which ones I need, according to Draganfly web site , the BSA parts book and my suppliers there are around 3 or 4 options. Ive seen a taper roller option, pricey  but got cheap bearings but would need to grind the o/dia down to 1.906".
the other options are 3/16" or 1/4" bearing ones. some have top cone on its own or part of a dust shield.
Does any one know if the cup and cone options are the same sizes just ball size difference and dust shield or are the outside diameters physically different?
cant seem to find diameters on any listings.

JulianS

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Re: B40 steering head bearings 1965
« Reply #1 on: 15 February, 2020, 11:19:17 »
The swan necked frames used on the standard B40  used 2 x cups 40 4074, top cone with dust cover 40 5029 and bottom cone 40 5027. These take 3/16 inch balls. Same parts as C15 standard swan necked frame bike.

The welded competition type frames used on the B40 enduro WD B40 use different parts. Cups 66 4149 (same as A10 pre OIF A65) and 1/4 inch balls. Cones 40 5143 and 5144.

The parts dont interchange.

chaz

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Re: B40 steering head bearings 1965
« Reply #2 on: 15 February, 2020, 13:41:06 »
thanks Julian
Ive put a cup and cone together with 3/16 balls and it seems to move about too much, steering parts , cones and balls  are from one bike and the cups are from another frame. so I suspect we have one of each frame although both came from america.
any idea if they were the same outside diameters for the cups? ours is 1.906"
« Last Edit: 15 February, 2020, 14:30:24 by chaz »