The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: v8ivor on 21.11. 2015 20:32
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Are these nuts the correct way around because the bolts don't finish flush and cover the shake proof part of the nut ?
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Hi, V8
That aint right *problem*
What engine is that?
The nuts look too big to accomodate a socket to tighten them??
Are the bolts seated properly in the rods?? as they look short ???
Also judging from the punch marks (heathen PO*eek* ) the bolts have been reused several times ???
Not too clever looking at this point in time *sad2*
John
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It's a 52 A10 plunger and I cant get even a 3/8" drive socket on them, so I wouldn't be able to torque them up after, and may damage the threads if I undo them past the punch marks.
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Hi, V8,
So you have found it like that ??
ON the early engines the nuts were smaller hex castellated ones with a built in shoulder if I remember correctly
I would remove the bolts and bin the lot *eek*
You may need to enlarge the spotfaces where the nuts sit to accomodate the new bolts
I would not run an engine with bolts/nuts like that
New ARP bolts are really the only solution
John
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I largely agree with John, the bolts and nuts need to come off, even if you could fit a socket you cannot trust a torque setting on threads that have been punched and they are too short...
So whoever assembled it cannot have torqued it up and the shells should typically be replaced as a matter of good practice even if they are not as mickey mouse as those big end bolts.
Pull it down, flush the sludge trap, and sort out as a minimum new bolts and nuts (yes ARP a good option)
When you start seeing bad practice like that it suggests treating everything with question. ie get the rods checked for straightness and consider shot peening them to relieve stress - or get fresh rods...
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Assuming you go with ARP bolts, you will see in their instructions that they are more interested in bolt stretch when tightening than in torque. They offer a specialized measuring tool for this, though I measured mine with a micrometer. If, after used and removed, the bolts return to the specified length then they are OK to reuse.
Richard L.
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Sorry to disagree folks but I think the nuts are correct, If they didn't have the corners taken off the bottom of the nut they would risk catching the crankcase
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There are plain washers under the nuts (The same thickness as the bolts are recessed ) And the end of the bolts are machine finished as opposed to cut off .
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I just looked at what you said Bill, and the outer edge of the nuts are in line ( Or a few thou past ) With the flywheel.
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Sorry to disagree folks but I think the nuts are correct, If they didn't have the corners taken off the bottom of the nut they would risk catching the crankcase
Well, Bill is correct that those are rod nuts, but they are not correct for those rods. As John mentioned, the castellated nuts have a shoulder that fits the landing and a smaller hex that clears the case. There are some other twists (maybe the wrong word) on this, but inability to securely use a socket and engage all the threads in the nut are not among them.
Richard L.
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they are not correct for those rods
yes there are several types, I've had the castellated ones before also, not that it helps V8ivor except to point out the machined bit is correct at the bottom.
two other types here one self locking the other not but looks like made from a nut with a pin,
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Did you mean the nut to go this way on or up the other way Bill ? These bolts haven't got a hole for a split pin.
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Yep that the right way.
The nut with the hole for a pin is (I think cause it's a while ago) one of a set came with bolts from Mike Cheyne (dont know if your in here Mike), mike asked for them back as someone had found they caught the crankcase, so he kindly sent another set with a bit more machined off
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Ivor,
I think one dfference between the nut in your picture and the picture from Bill, as well as the picture from deGroot (below), is that the points on your nut are not chamfered where they come against the rod cap as are the other two. The unchamfered points seem to contact the recess in the cap. I will, and should be, corrected if I'm wrong, but I think washers are not used under the type nuts we're showing here (Triumph type?).
Richard L.
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Hi All,
Whatever has happened ????? V8's setup is clearly wrong *sad2*
maybe the bolts are from something else????
Some years ago there were a lot of poor quality big end bolts on the market, these were machined not forged head
At the time C&D had the correct forged bolts, presumably these sold out and were not replaced??
After that the only properly made bolts available are ARP (as far as I know)
Another issue came to light a couple of years ago the replacement Triumph type nuts that were commonly sold were made of cheese !!! WTF
HTH
John
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Another issue came to light a couple of years ago the replacement Triumph type nuts that were commonly sold were made of cheese !!!
*lol*
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This the surviving big end on my small journal crank. The rods look tech same as yours Ivor, but not the nuts an bolts etc.
I believe the nuts and castle bolts with the split pin to lock are original factory fittings.
Guy
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I rebuilt a small journal motor S/W arm by fitting the internals of a plunger . They had the same nuts as those shown by Guy. never had any problems with the st up.
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Just for interest....as I have lightning engineering billet rods in my SJ engine and have dodged the question.
If new rod bolts are used with original rods, what determines the torque they should be done up to? Is the determined by the bolt supplier? Or by what BSA originally stated was the correct torque?
I'm thinking the rods may distort if bolts exert too much pressure on them.
Do new bolts like the ARP bolts have the same thread spec as the original bolts? As that could affect the torque setting..... *dunno*
(Anyone else noticed the "more" emoticons have stopped working? They have on my iPad! It just comes up blank after clicking "more"....).
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I did a search and this might answer my question above....
http://www.a7a10.net/forum/index.php?topic=4388.msg29989#msg29989
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Hi Kiwi and All,
There was a discussion on the use of ARP bolts here on the forum some time ago and recommended torque's
and bolt stretch figures given.
The ARP bolts have UNF threads so the BSA torques do not apply
ARP send instructions with the bolts and special lube for the threads
Aftermarket rods that use ARP bolts require higher torques than on BSA rods
I fitted ARP bolts to the last A10 engine I built and followed the torque figures given, and the bolt stretch was correct.
I rebuilt a small journal motor S/W arm by fitting the internals of a plunger . They had the same nuts as those shown by Guy. never had any problems with the st up.
Topdad
How were you able to torque them? as there no room for a socket to fit in the photos shown ?
Did you get a full depth of thread on the nuts?
The nut has to go fully onto the bolt to get full strength and security
Cheers
John
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Here's a pic of the ARP bolts. I contacted ARP's techinical department some time ago regarding the torque figures for them and when fitted to std BSA rods they recommended 28 ft/lbs.
I will only use these bolts these days, mainly because they are a "known factor". Genuine ones are not available and the rest are all of a unknown origin so not worth the risk.
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Brian,
Did they also tell you the dimensions for the stretched bolt when tightened?
Richard L.
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I dont think so Richard but it was some years ago so they may have.
When I bought the bolts they came with a slip of paper recommending a very high torque figure, I cant remember exactly but it was 36 or 38 ft/lbs which i thought was way too high for a BSA rod so I contacted them and they recommended the 28 which is what I used and have used ever since.
Its worth the expense to put quality bolts in as if they fail it will cost a whole lot more, I think its called the big bang theory !
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Good morning John, there was no problem torqueing them ,as a complete novice to bike engine rebuilding (,this was my first shot at an A10 ) plus I was flying in the face of advice from supposedly wiser heads than mine ie you can't do that etc, I took extra care even to the point of polishing everything and getting every thing absolutely spotlessly clean .The only problem I remember having was getting the correct new washers for the big end bolts so as the holes for the spit pins lined up when torqued ,I remember my Dad suggesting taking them slightly pas tthe hole then back slightly whilst my basic torque wrench was clicking .I was blessed with the best kit I could get and the socket fitted perfectly ,if you look at V8's nuts ( no pun intended *whistle*) you'll see as you pointed out a real problem whilst the ones of Guys are well proud and can be tightened correctly, cheers bob
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Hi ALL,
Topdad,
Apologies I misread you r earlier post, mixing up V8 and guys pics in my head *red*
Yes it can pe problematic getting the pin holes to line up, sometimes you can over come this by swopping nuts around
On that point, were not the torque settings for early engines less than later ones ???
Richard.
Did they also tell you the dimensions for the stretched bolt when tightened?
Yes, I got instructions with the bolts I bought, also instructions about cycling the bolt torques a couple of times ,
measure, tighten - measure stretch, loosen, measure again !!
so the stretch is measured, and also that the bolt returns to its original length when loosened
Regards
John
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about cycling the bolt torques a couple of times ,
similar instructions to those I got if memory serves I think torqued to 27 three times
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I'm confused. If I use these super new Big End bolts can I torque them up or must I use the stretch technique?
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Hi GB,
I found that the 28ft lbs on the ARP bolts on BSA rods (with their lube) gave the required "stretch"
HTH
John
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I'm confused. If I use these super new Big End bolts can I torque them up or must I use the stretch technique?
Part of the instructions that are sent with the bolts is to keep a record of the original length of every bolt so that you know if it has gone out of spec (that is, experienced plastic deformation). As I recall, you don't own a 2" - 3" micrometer. Might not be a bad time to invest, but you shouldn't have to spend a lot, just be sure you get one that reads to 0.0001" precision. While you're at it, might as well get a 1" - 2" for those pesky journals. Otherwise, beer for your nearest friendly machine-shop owner.
Richard L.
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In my recollection, the rods with castellated nuts had the washer there so that the washer could be dressed with a file to get the castellations to match a split-pin hole.
Late large journal BSA rods did vary quite a bit in the amount of clearance left for a socket spanner to tighten them (I bought numbers of these rods back in the '60s straight from BSA). On the later rods the spanner clearance was very small and I have a socket spanner turned down to "quite thin" to undo these little so-and-sos. 28 lbs ft and red Loctite always kept them happy. Two types of nut were fitted, firstly ones with a crimped on interference washer then the type with 2 slits in them, with the slits closed up to interfere with the bolt threads. In the 70s and 80s there were some truly awful bolts around, I once bought some where the threads were all torn - clearly not rolled threads, and cut with a blunt die. These went into the circular filing cabinet. I have never seen washers fitted under self-locking nuts.
In the early 2000s I went over to the ARP bolts sold by SRM and they really are fine engineering. Because the nuts are quite tall I had problems with their tips catching the inside of the crankcase but some filing saw to that. I think if you want to stick to 5/16" bolts then these are the best choice. ARP's reputation rest on their bolts!
My current motor has the billet rods made by R&R in the USA and sold by Wassell (I never thought Wassell would get into that territory!). These are very good rods, CNC with corrugated joint faces and 3/8" x 24 ANF bolts (no nuts) made by ARP done up to something like 50 ft lbs - twice the pressure of any 5/16" bolt.