The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: a101960 on 04.10. 2017 16:35
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My bike has never had a ski slope fitted for some reason. Anyway, I have now purchased one (a used genuine BSA item). The problem is the bolt through the upper rear engine plate (p/n 42-4474) seems to be a little to short when the extra width of the ski slope is taken into consideration. I can get the nut on, and it will do up (just) if I omit the spring washer, even then the nut is about two threads to long if that makes sense. So my question is what should the over all length of the bolt be? I want to check this out before I buy a new longer bolt, oh, and what thread is it supposed to be. I cannot measure the length of the bolt that is currently fitted due lack of access while it is still in place, and just to make things interesting the PO fitted the bolt in with the head facing toward the chain case, so that is going to have to come off to facilitate the bolts removal.
John
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I can't help with the length, but the thread probably should be BSC (3/8" ?), but I suggest the ski slope was left off because of that reason and maybe the bolts have been switched and you already have a longer one where it shouldn't be *dunno*
See if this is any help ;
https://www.draganfly.co.uk/index.php/bsa/bsa/a710--b3133--c101112--m202133/category/895-pre-unit-a-group (https://www.draganfly.co.uk/index.php/bsa/bsa/a710--b3133--c101112--m202133/category/895-pre-unit-a-group)
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Sounds like the bolt you have is a bit too short.
Originally there was a stud in this location with nuts and lock washers, but in 1959 the stud was changed to the bolt 42 4474 which was fitted with plain washer and self locking nut.
To take the lock nut the bolt needs to be at about 4 1/8 inches long, according to the measurement accross the ski slope on my bike.
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a101960, Why don't you take the nut off the bolt that is fitted at the moment tap it through enough to cut or grind the head off. Then you could extract it and fit the new bolt in its place. (job sorted) *smiley4*
ELLIS
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haaa butchery *work* but with a purpose *bright idea*, will save quite a lot of time, energy and swearing then you can *beer*