Britbike forum
I thought you would like to see a copy of a 1969 Service Bulletin put out by Rod Coates The Triumph Corporation Service Manager.

He discusses the change to the placement of the flat and thackerary washers where the flat washer goes against the rocker arm.

The problem is he only partially discussed the change as he didn't mention for the need for the grooved shaft as introduced with the first T140.


Click here to see the Bulletin:
Triumph Service Bulletin
So without the washer against the rocker there is nothing to direct the oil toward the button. yes?
It must have been a manufacturing expense decision. It costs more to drill a deep small hole and plug it than grind or cut a small notch in the edge of the rocker.
The rocker may be stronger without the drilling.
Interesting the emphasis on ANY and MUST, as he then goes on to say that "The rocker ball ends could have insufficient lubrication..."

Why not "The rocker ball ends WILL have insufficient lubrication..." ??

I suppose if these are the questions that keep me up at night, I should be grateful!(?)


So how far backwards should this update apply?

Can't say how far back from the top of my head, but it can be found in JR Nelson's "Bonnie" book and others.
John Healy will know of course. From a feeble memory I'd say either 1970 or 71.
I ran my 71 Bonnie for 17 years and maybe some 150.000 km with the washers assembled the wrong way. The bike is still out there running just fine, so I don't believe this is a killer, but I didn't know better and would have fitted them correctly if I knew. In fact, on my next unit engine project, a 70 engine with a 72 head, I'll even splurge for a set of T140 scrolled rocker shafts to really get the juices flowing.
Originally Posted by R Moulding

So how far backwards should this update apply?

Which update?

The Service Bulletin states the engine numbers for the 650's and 500's that production for the drilled rockerarms stopped.

As John said, the grooved spindle was introduced with the first T140's.

You can swap spindles and drilled rockerarms easily enough on 650's with the later grooved spindle and machined rockerarms, just be sure to use the proper acorn nut as the thread changed...


Thank you Steve. Tried reading the Bulletin without my glasses and missed useful chunks of it!

So if you " change the order of assembly", I gues you need to find some extra flat washers to protect the aluminum from the spring washer ends. The letter doesn't mention extra parts, but implies the same if I read right. I have some '69 rocker boxes apart as we speak, still fighting the O-rings, so good time to look this over too! Thanks John.
...there s no extra space to fit another washer between the spring washer and the box.
I think that will be a damage in that area of the box.
Originally Posted by KC in S.B.
you need to find some extra flat washers to protect the aluminum from the spring washer ends.

Seems counter-intuitive, but the thacker(a)y washers don't foul/gouge the aluminum rockerbox.

Not sure about the earlier spindles, but the grooved ones have a shoulder on the thread end. Three 1/2" ID thrust washers and one 3/8". Toss the one 3/8" washer and replace with another 1/2" or it will foul on the shoulder when you swap with thacker(a)y.

This placement of the flat and thackeray washer came about when they were updating the triple during the early design phase. The thackeray, or spring, washer against the aluminum rocker box continued from the first to the last of the BSA and Triumph triples. It has never been a problem nor have the worn into the side of the rocker box!!

The adoption by Triumph in 1969 was not their idea. Development in this period fell upon the engineers at Umberslade Hall who did most of the development work on the Trident and Rocket Three. The rocker arms were a part of this design exercise and made by a BSA subsidiary. Why Triumph didn't choose to adopt ALL of the parts to make it work, or choose to install the washers as they always did would consume a lot of time, but they did. As I said above it wasn't until 1973 did they combine the new rocker, a slotted rocker shaft and the proper position, as used on all triples, of the washers.

...hello Mr Healy, I changed the placement of the spring washer as per your recommendation in my 79; however, as I mentioned in other threads, I had dismantled 4 later engines in these years (2 78s and 2 79s) and all had the flat washer to the box.
I do not live in US so may be the "local or export" models did not changed? or may be there were batches that leave the works this way?
Originally Posted by reverb

I do not live in US so may be the "local or export" models did not changed? or may be there were batches that leave the works this way?

My bike was 'unmolested' (purchased new by my father) and had the assembly wrong. Built in Dec '76 and purchased in late '77.

The guys building the engines didn't know or care where the finished bikes would end up
And quite possibly no one told them of the change so they carried on doing it as they had always done----
A mistake to confuse the old Brit bike factories with the antiseptic robotic cathedrals to computerized engineering that you see on TV these days.
There were a lot of things done on the assembly line that made no sense. This is only one of them. There was a lot of "not designed here" attitude held by the Meriden workers especially when it came to technology forced upon them by Umberslade Hall.

If you look at the rocker box with the object to understand how oil gets into the rocker box, how it gets out of the turned down section of the rocker arm shaft and where it needs to go once it leaves the rocker arm. As I said above, this was the standard way all of the three cylinder machines were assembled right through the T160. Triples are much less prone to excessive valve guide wear.

My original thoughts about this came about on a 15 hour road trip to do seminars at Mid-Ohio with Don Hutchinson. To pass time we spent a lot of time talking about problems and possible solutions. One observation both of us brought to the conversation was the lack of seeing oil flow to the rockers on 1969-up Triumph 650's when you put a clear hose on the over head oil line. Previous you would always see at least some oil flowing. We kept exploring why when we started tracking the path the oil follows. What was blocking the flow. Well, first the original path through the rocker arm itself out the rocker button had been blocked. This left oil getting to the turned down section of the rocker shaft, but it seems no further. I had spent a lot of time working on triples when it dawned on us: the triple has a groove the length of the shaft. The oil could escape in volume from the turned down section of the shaft and the end of the rocker where it could be diverted to the front and back of the rocker box.

Thus the oil on the triple could reach the the end of the rocker and the two milled grooves. This led us to explore the arraignment on the triple. All of the Workshop Manuals, parts books and rocker boxes themselves illustrated the shaft was grooved, the flat washer went up against the rocker and the spring washer sat adjacent to the rocker box (you don't want the end of the spring washer to locate itself, thus diverting the oil flow, in one of the milled grooves).

Why the line workers assembled the washers the way they did, and the department that made the rocker shaft didn't cut the groove, is lost. But isn't lost is when they removed the drilling from the rocker arm, and didn't follow through with the grooved rocker shaft, they blocked almost all flow of oil to the top end. Speculation be damned all I want is a steady stream of oil flowing through the rocker box (lubricating and removing heat) and down on the tappets.
John doubt that the materials are good and that no needs of too much oil or pressure etc in that part due to thousands and thousands of kms done in these machines and the problem normally is a hole in a piston and not so much more (except carburation, electrical problems)
Hi All, I am at the stage where I will putting the top end back together on my 1970 T120. Am I right that the washer positions are fitted wrong at the factory and need to be altered but also that there needs to be a grooved shaft fitted.
I have not been able to view the bulletin as it won,t load and can't find it elsewhere.
Thanks Paul
ok, I found the link on another older thread, You do need to replace the plain shaft with a grooved one which can be got from later triumph parts numbers. 73 on 750 models.
Can anyone advise if the later 73 on 750 shafts/spindles fit on the 1970 t120
Some things that went on are hard to believe.
Thanks Paul
I did this yesterday, I used a 3.175mm tungsten carbide cutter and milled a 10 thou deep slot onto 2 rocker shafts, assembled a rockershaft with rockers and washers and forced oil into the shaft and got oil coming out of all the right places.

[Linked Image]
Hi Kommando, yes I am considering this option also, seems fairly easy and effective.
The case hardening is tough, everytime the cutter got to a change in diameter I had to slow the feed right down or the cutter broke, but at 60p each not too big a problem, cut very well on the long sections.
Have done the same thing now and oil is coming through perfect, I was asking questions a while back on the forum concerning oil not reaching the top of the rocker feed pipe (there was nowhere for it to go) but never had any replies that related to the lack of grove in the spindle and placement of washers.
I doubt if I would ever of thought of this and would of been chasing all sorts of other causes, oil pump, external filter reducing pressure, changing restrictor position/ size etc etc.
It seems so obvious and simple now I have been shown.
Great thread, fantastic forum, enormous respect for John and gratitude to all
© Britbike forum