Hi, I would appreciate some guidance on correctly assembling the cush drive on a B31 1953 plunger.
I have "51- distance piece 65-2529" but do not have any of "52 - bearing alignment washer 66-1707/1708".
Is there a service sheet which describes how to select the correct part?
Or could someone describe how to?
Thanks
The washers "52" are used to improve the primary chain alignment.
I normally do a dummy build and check the alignment of the sprockets, a good steel rule will help.
https://pesltd.uk/?product=66-1708
https://pesltd.uk/?product=66-1707
Mark
Use a steel ruler as straight edge to check primary chain alignment between clutch sprocket and engine sprocket.
Add shims to move engine sprocket out as required.
I had opposite problem with DBD type and had to have the new engine sprocket faced off to move sprocket closer to crank case (I've got NEB clutch alloy sprocket so alignment has to be spot on).
Fingers crossed you only need shims.
You've reminded me, when I was assembling the cush drive on my 59 A10 I has several sprockets to choose from. The bearing face on one was about 20 thou stepped up compare to the other. I did a bit of looking and I wonder if some of the aftermarket ones have a raised surface? I too was looking at machining the sprocket down but I found one with the correct teeth and a near flush face that gave perfect alignment. I never got tot he bottom of what was going on as I'd fixed the immediate issue.
Quote from: limeyrob on 13 Jul, 2026, 17:28 You've reminded me, when I was assembling the cush drive on my 59 A10 I has several sprockets to choose from. The bearing face on one was about 20 thou stepped up compare to the other. I did a bit of looking and I wonder if some of the aftermarket ones have a raised surface? I too was looking at machining the sprocket down but I found one with the correct teeth and a near flush face that gave perfect alignment. I never got tot he bottom of what was going on as I'd fixed the immediate issue.
Yes I think that the newer pattern parts have more of a raised lip. I've got 17,18 and 19 that are virtually flush but the 20 and 21 I've got both had a lip - I'm going with a 20 for my 600 (19/42 rear) and 5 speed box.
I guess the O/P has a 4-lobe cush drive?
Thank you all for replying that's been very helpful