The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Motoanimal on 24.10. 2012 20:29
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Guys,
can anybody tell me the correct configuration of the spring washers and plain washers on the rocker shafts?
According to the parts list there are only 6 (six) plain washers and 4 (four) spring washers in the rocker box? (or have I got it wrong?) So what end of the rockers dosen't get a washer? Perhaps I should just get rid of the spring washers competely and shim the endfloat with washers? What do you think?
Phil
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Phil,
Here you go.
So, do you have at least one manual? There might be a lot of debate over which is the best manual, but I think most here would agree that having at least one is a good idea.
Richard L.
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Phil, as you can see, it's 8 + 4, the 'usual' Engine A group parts manual does not show it as clearly as Richard's drawing (good quality, which publication is it from?).
Could maybe be shimmed, but what about clearance differences hot\cold ? I'd guess the springs takes good care of that dept.
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I'm just guessing here but tappets pushing down on valve stem against spring pressure could involve some movement sideways, however slight it may be the Thackery washer (is that the correct name for them) would accommodate this.
Butt of course I could be looking to close at the trees and missing the wood again *whistle* *sad*
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Richard,
What you are saying makes perfect sense, but my parts listing shows only 6 washers, i.e.
67-60 Thrust washer X 6 A 1950-62
and sure enough, there was only six in my rocker box, but you just don't know what has gone before!
Your drawing however is perfectly clear, my manual only shows one rocker shaft (with 4 washers) so I consider that the parts list is wrong and your line drawing is correct.
a10gf, I appreciate your point about hot/cold clearances, but this could be allowed for. Not sure how much extra noise this would produce when cold however, which is probably the reason for the spring washers in the first place. If I was tuning for power, I would definitely shim and not worry about some extra noise when cold.
Thanks for the info guys!
Phil
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Hope you dont mind Richard but I "borrowed" your pic.
Six of the hardened washers are the same but the two with the arrows are different, they have a smaller ID 3/8". This is to go over the smaller diameter part of the spindle.
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Brian,
Ah ha! Are these two simply the washers under the nuts securing the rocker shafts then? which would mean my original assumption is correct? i.e there are only six thrust washers and four spring washers?
Phil
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No these are hardened thrust washers that go inside the rocker box, same OD as the other six but smaller ID.
If you have a parts book the six are pt. no. 67-60 and the two in question are 67-61.
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Brian,
Oh right, now I get it!!! 6 X 67-60 and 2 X 67-61. Easy when you read manuals correctly *conf*
I can't help it you know, I blame my parents......
Thanks for all your help guys!
Phil
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Here's another scan.
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Brian,
Thanks for stepping in an filling in the info I left out.
e,
Good question about the book. I think the one that picture came from may not be well known in our group: Chilton's BSA Motorcycle Repair and Tune-Up Guide . I can't even remember where I got it; maybe, a used book store.
For laughs, I thought I'd show a picture of my BSA book collection. Seems like too many for someone with just one motorcycle doesn't it? The collection grew when my wife knew she could shop online at British Only and fill her Christmas list.
Richard L.
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R, thanks for the info, never seen that book before, will look for it on ebay.
Excellent scan from Brian as well, were's that one from? To not dilute the original topic, anyone with interesting or rare books not mentioned before, maybe post a little about it in 'BSA related Links & Service Literature'?
Regarding the washers, all doubt seems dissipated.
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That one was out of the 1960-61 parts book.
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Richard, I have one of those Chilton / OCee Ritch books- second print 1970- it's been very handy considering it covers so many models!
Phil, I also had a similar thought about just using plain shims as I figured that there is some 'torsional resistance' with the Thackeries in there,(Yay Bill you did get 'Thackery' right, the trees live another day *smile*) and confirmed when I did it, rockers move so easily, but probably not enough to matter unless racing.
Also I agree with Bills suggestion about side-play, and could affect pushrod/ valve travel, but think 'solids would counteract this more effectively than Thackery springs, as they will just cushion it without removing it.
I reckon the Thackeries are just a quicker,easier and cheaper way of pumping out the product, as shimming requires a few seconds more calculating
We had chat about it a while ago, Muskrat will set you straight
Cheers
Ps Thanks Brian for sorting that out- Phil, there are still two on the outside under the nuts, but that's a different story
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I use shims instead of springs in the cafe. Give them 2thou clearance. No noticeable noise increase. (can't hear myself think over the reverse cone megas)
Cheers
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Yeah, I think Dutch has hit the nail on the head here; from a design aspect, shimming would be the preferred method, but from a production/assembly angle, this would clearly take too long and the Thackerys effectively remove endfloat quickly and easily. The amount of friction they add is negligible and they cope with any expasion/contaction removing any noise (I don?t remember reverse cone megas being a factory fitment Muskrat, so this may have been important! *smile*)
I wonder what the graet Eddie Dow had to say on the subject?
Phil
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Phil Irving recommended it. I think he knew a thing or two. ;)
Cheers
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The thackery washers are there simply to reduce the cost of production.
A better alternative is thrust washers spaced to have the valve adjusters sitting dead central on the valve stem.
Sounds easy till you try to do it.
We did it on a B44 a it drastically reduced the head "clatter" but we are talking around 20 hours stoning down hard washers to get them to fit
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Just saw this on eBay. When I bought my various books the older ones were probably on close-out shelves, now they are unbelievably costly.
http://www.ebay.com/itm/1950s-1960s-BSA-A10R-A75-A65-A50-B31-B32-B40-B44-C10-C11-C12-C15-M20-M21-M33-/160923765716?pt=Motors_Manuals_Literature&hash=item2577cdcbd4&vxp=mtr
Richard L.
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G'day Richard. I got one of those from the states a few months back. Different seller and about $20. Now for sale at $100, any takers.
Cheers