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#849315 05/19/21 10:40 am
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Kevin E Offline OP
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Hi all,

Has anyone ever replaced the ball pins in the A65 rocker arms?

I'm just wondering what is involved. Is it simply a case of pressing, or drifting the old ball pins out and new ones in?

How tight is the interference fit and is there anything else that need to be done, or is cause for concern?

Cheers,

Kev E

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Interestingly I’m sure the ones on my rockers have been drilled through the ends (they are on the Lightning, I didn’t check the thunderbolt ones) I assume this is so oil can flow to ball and socket. Never seen any cause to replace them though.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Kevin E Offline OP
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Hi Allan,

I'm a little confused by the rocker arm subject.

None of my A65 parts books mention a ball pin until you get to the 1973 publication, which has no illustrations but lists the ball pin as part number 71-0070

Interestingly the 1973 parts book doesn't list part numbers for the inlet rockers. There are only exhaust rockers there, unless I'm missing something?

All the other parts books list the rocker arms as: -

Inlet L/H - 68-0147
Inlet R/H - 68-0149
Exhaust L/H - 68-0151
Exhaust R/H - 68-0153

I haven't checked my inlet rockers yet but the exhaust ones have the numbers 68-0152 and 68-0154 cast into them? Numbers that I can't find anywhere in any of the parts books but if you google them 68-0152 comes up as a BSA L/H exhaust rocker arm and 68-0154 doesn't result in anything specific. I know casting numbers are not always the same as the listed part number so I'm not too concerned about that. They fit and line up with everything and that's what matters.

The ball pins however are drilled as you can see in the attached photograph and this allows oil fed into the rocker shafts to travel through and lubricate them and the tops of the valve stems.

Worryingly, none of the ball pins I can see advertised on the web have this hole drilled in them. I'm also wondering what the hole is in the end of the rocker arm that is drilled in at 90 degrees to the ball pin?

My ball ends look a little ''chipped' almost as if they are chrome and the chrome is pitting a little. You may be able to make this out on the attached photograph.

As I have brand new valves, brand new mushroom headed adjusters and new a brand new SRM high strength chrome moly pushrod set. I didn't want to skimp on the ball pins if there was something that I could do about them.

I may just leave it as is and give them a polish up?

IMG_E1794.JPG IMG_E1795.JPG
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Never seen one like that before.

I’m using the SRM chromolly pushrods in two of my bikes (granted one set has yet to be run) they are a nice pushrod. Well made!!


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Kevin E Offline OP
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Originally Posted by Allan G
Never seen one like that before.

I’m using the SRM chromolly pushrods in two of my bikes (granted one set has yet to be run) they are a nice pushrod. Well made!!

Yes they do look the business and I'm hoping they work well.

Back in the 80's after I had just rebuilt the bike I was out on a short run and heard a bit of a nasty racket just before losing power on one cylinder. After pushing the bike home and investigating, I found one of the end caps on the pushrods had split in two. I managed to retrieve all the parts and ordered a new pushrod. I should have realise that something was wrong with the tappet adjuster being so different to all the rest but I wasn't as experienced back then. Fortunately I was fitter so the 4 mile push home wasn't so bad. I'd never manage it nowadays frown

It turned out that for some reason the pushrod end cap socket wasn't big enough for the cam follower to seat properly and eventually it split into two.

I've never really trusted the end caps since and when I saw the SRM pushrods I thought I'd have a set.

I'm sure the standard ones are ok really, I cant recall hearing of any other problems with them from anyone?

Cheers,

Kev E

Last edited by Kevin E; 05/19/21 11:55 am.
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Hi Kevin,

The hole at the end of the rocker arm is the oil way drilling through to the spindle. lt is blocked off when the "ball pin" is pushed into place. The "ball pin" has a hole drilled in on one side which matches up with the hole from the spindle side and a hole from the centre of the cap up to that side hole, this allows the oil from the spindle to flow to the top of the push rod cup.

Hope this helps

Keith.

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Here is a typical rocker end ball from a BSA, showing the oil hole which must be aligned with the oil passage in the rocker arm.

[Linked Image from i.postimg.cc]

Also beware of pushrods that are too long or too short. This photo shows an Alloytech pushrod end that has been broken because the cap on the Alloytech contacted the shoulder on the ball. Also shown is a Smith Bros. pushrod that has a larger end cap which won't contact that shoulder, but is heavier.

[Linked Image from i.postimg.cc]

I use the heavier Smith Bros. ones which gives me a little more assurance that this won't happen again. You can, of course shorten the Alloytech ones if they are too long, but you can't make them longer.

Tom


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I have an identical pushrod with the same issue as yours has. The pushrod continued to work fine and wasn’t noticed as an issue until I had the rocker cover off.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Joined: Sep 2020
Posts: 243
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Kevin E Offline OP
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Originally Posted by Keith Miller
Hi Kevin,

The hole at the end of the rocker arm is the oil way drilling through to the spindle. lt is blocked off when the "ball pin" is pushed into place. The "ball pin" has a hole drilled in on one side which matches up with the hole from the spindle side and a hole from the centre of the cap up to that side hole, this allows the oil from the spindle to flow to the top of the push rod cup.

Hope this helps

Keith.

Hi Keith,

Thanks for that, it makes perfect sense and I should have realised what it was for.

It would be hard to get a drill in to the correct place without doing it that way.

Cheers,

Kev E

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Kevin E Offline OP
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Originally Posted by koncretekid
Here is a typical rocker end ball from a BSA, showing the oil hole which must be aligned with the oil passage in the rocker arm.

[Linked Image from i.postimg.cc]

Also beware of pushrods that are too long or too short. This photo shows an Alloytech pushrod end that has been broken because the cap on the Alloytech contacted the shoulder on the ball. Also shown is a Smith Bros. pushrod that has a larger end cap which won't contact that shoulder, but is heavier.

[Linked Image from i.postimg.cc]

I use the heavier Smith Bros. ones which gives me a little more assurance that this won't happen again. You can, of course shorten the Alloytech ones if they are too long, but you can't make them longer.

Tom

Hi Tom,

Thanks for the photos and information. They're very helpful.

I wonder why all of the ball pins I can see on the web site have no oil holes in them?

Have you any idea where I can get hold of some with the correct oil holes>

Also I assume that you have had your ball pins out. Are they difficult to get in and out?

Cheers,

Kev E

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It could be they are substituting triple pins for the A65. Triple pins do not have the drilling.

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Kevin,

I just have a one-ton arbour press and they are not hard to press out.

I broke that push rod cap on my 600cc B50 because the pushrod was too short. Having said that, today I took my T100 out for the first time since I rebuilt it for the second time, having replaced the exhaust valves, and didn't get 5 miles (running very well with no oil leaks) before the left cylinder got a tap-tap-tapping noise. I turned around to limp home, but didn't make it. Removed the valve adjustment cover on the left exhaust rocker to find it wasn't moving. I'm sure it's a broken pushrod cap, so I'm not immune to having it happen again. So off with the rocker box again to check it out. I just put in new oversize exhaust valves and had the seats professionally done, so I'm at a loss to know what is causing this problem. Too long or too short or WTF!

I used copper rocker box gaskets this time, so maybe the pushrods are too short now?

Tom

Last edited by koncretekid; 05/19/21 11:20 pm.

Life's uncertain - go fast now!
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