Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board 71 T100R and the Thackeray Unpleasantness

I realized too late that my workshop manual had the error on the order of assembly of the rocker arm spindles. I took the boxes apart again this last weekend and made it right. In the process I devised a way that seemed to work well to keep the spindle O rings intact when pressing the spindle home:

http://bullfire.net/Triumph/Triumph15a/Triumph15a.html

Nice work Ed.
Bill

Hi Ed -

Just curious....I notice you have the later arms with the machined notches to direct oil flow. From your photos tho, it appears that there are no oil grooves in the spindles themselves....

Did they ever change this for the T100's like they did with the later T140's? Might be a worthwhile enhancement some point down the road....

Steve

Hi ed,

Nice work.

I have a few suggestions.

1) Make the photos a smaller file size (less resolution) so they load faster for dia up world.

2) You ground the valve adjusters? I would be careful of that. I think only the tip is hardened. In fact the allen replacements I have, I noticed that the end was actually smushed a bit, kinda like a campfire roasted marshmellow would appear... Confirming in my mind's eye that only the outside of the tip is hardenend, as it should be or the thing would be brittle and break. This is in fact what does happen with some of the available "mushroom" head adjusters. They break. Yikes.

2a) Speaking of breaking. We might also want to consider the lowly "lock nut" on the adjuster. The after market replacement ones which are available: how hard are they? Do we, any of us know the grade of steel used originally on these? And what the new ones are? I have word of mouth from some who have worked on a lot of bikes, that they have never ever cracked one of them, having had they strip first. And yet, I had a replacement one, crack in three places (not stripped threads), and the cracks did not come apart until 500 miles down the road from adjusting. So we must be aware and use very careful torquing on these after market lock nuts, if one is used to the old ones, and what worked for them.

3) Your camfer appears quite deep. How did you determine how far one could go? I would suggest it might vary, because as you point out the "caps" are pressed on, and that might vary as to how far. I have noticed that these stick out a different amount as I look at other bikes.

4) I have no idea how one made of steel as the originals were, and not aluminum, as some now are, could possible come off.

While not all rocker boxes were chamfered during production, there is a 15° chamfer shown on the factory rocker box drawing.

This chamfer can be cut easily using a sharpened three corner file - often referred to as a machinist's scrapper. We have illustrated this in a rocker box article some years ago in Vintage Bike. If you haven't made yourself a three corner scrapper (or don't know what I am talking about) you can but them from several sources:

http://grizzly.com/products/3PC-MACHINIST-S-SCRAPER-SET/T10086

http://www.google.com/products/catalog?oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&q=machinist+scraper&um=1&ie=UTF-8&cid=8464923610114008828&ei=G-sITZzXG8GqlAfajomBAg&sa=X&oi=product_catalog_result&ct=result&resnum=2&ved=0CBsQ8wIwAQ#

Steve also makes a good point about the shafts themselves. For the later rocker arms (cuts on the side instead of hole in arm) and flat washers to work, the update must include some way for the oil to travel down the shaft. The rocker arm oiling was changed mid-year 1969 and should have included a change to the rocker shafts.

All this change came about with the design of the Trident/Rocket III and included an important detail of the new system which is required for the system to work: a groove the length of the shaft.

While Meriden adopted the cuts in the rocker arms, there was always confusion (except for Rod Coates 1969 Service Bulletin) about the position of flat and thackeray washers. They never addressed the groove in the shaft It wasn't finally adopted on the 1973 750 twin, but was never incorporated into 500 production. We covered all this recently in Vintage Bike - Autumn 2010...

Hi Ed,
I hope that you chose Viton type O rings otherwise they will be goo a few miles down the road.
The taper makes sense and I doubt if you will have too many problems but I always put some sealant on the shaft before sliding in.
I was rather hoping that you would tackle the other leaky problem of the tappet inspection covers on the side as there is no really satisfactory way to get a long term seal on these with the stock plugs. There are two sealing methods. One is a special compressible copper washer like on a spark plug. This is ok to start with but funnily enough it compresses over time and the seal is lost. The other way is to use a viton O ring but you cannot tighten up too far otherwise the O ring spreads and either gets damaged or compromises the seal and then in use loosens. I have resorted to the most successful method for me and that is to use an O ring, thoroughly clean the threads with solvent and then apply a little loctite (the blue type)on the thread and tighten the plugs to the right compression. This usually works for longer than other methods but is far from perfect. What it really needs is a plug with a groove in the cap to prevent the O ring spreading and then the seal would keep the cap from loosening. This would be similar in principal to the rocker caps I purchased from Dave Degens which work perfectly in that application.
PS Just leave the high resolution pictures as they are and Bob get a decent internet connection - Its probably cheaper in the long run!

Easier said than done in some remote parts of the US.....

And while the taper helps installing the "O" ring it isn't a panacea. Some "worrying" is still required to get the "O" ring in place without cutting it. We use P-80 to lubricate the "O" ring to ease assembly. Unless you know that the sealant is compatible with the material used to make the "O" ring it is best to avoid it.

Oh...And if you don't have the groove, either parallel or spiral, you will not get any oil flow through the rocker box! So going to the effort of changing the position of the flat washer turns out to be a wasted exercise.

Hi Twiny,

In frustration, with the valve lash adjusting inspection hole plugs (whew), coming loose and leaking/weeping, I tried the Kopper spray coat stuff. On the washer, with the slit in it, and on the plug threads. Seems to work just fine.

With a razor knife or other slender tool one can re-open the slit in the copper washer and get it to work again.

Problem solved.

The other problem is the adjusting caps themselves. The larger plugs. Here a viton ring with a brass "sealing" washer, of the appropriate size, from a plumbing store, works very well indeed. Two problems solved.

One can use the newer style rocker boxes with the big window to the valves adjusters, but then one needs to have a lot of the special gaskets, and the good ones, too. Then one avoids the above problems. But with a bonne, the carb is such a place that getting one of the screws started for the big cover is a huge pain.

So which is better?

Hi John,

Do I have the spindles with the groove? I do not remember noticing it.

The T140 spindle is a direct interchange with the 650 except for the acorn nut which is UNF instead of CEI.

Am I to understand that if I have a spindle without a groove, the position of the springs and washers is moot because the rockers get no oil anyway?

Thanks, Mike

Hi Mike,



I wouldn't say they get NO oil, but perhaps you could say not enough oil in the right places, i.e the valve tips and push rod tips....


I suspect you'd do well to either replace the spindles with ones with the spiral oil galley groove, or cut your own as this will significantly increase the oil flow and perhaps lengthen the service life of the valve tips.

Steve

The best "O" ring cure I have seen lately is the one posted to BritBike where the owner cut the shaft for a second "O" ring. All of the Triumph rocker shafts are two piece.

I think Steve described what happens without the oil galley groove. While a small amount of oil makes it to the rocker shaft to lubricate the rocker and its shaft, there is no appreciable flow of oil through the rocker as before.

On the models envolved (mid-1969 through the end of 1972) with stock oil tanks put a clear plastic tube in the over head oil line. You will see that the oil just sort of gurgles until you loosen one of the acorn nuts holding on the oil fitting. Then you can see oil flow freely through the tube.

Replace the shaft with one with a oil galley groove or spiral and you get the same results as loosening the acorn nut. Oil flows like it should.

Oh, great, John and Steve, now you've got me considering taking it apart again to add grooves.

Was this purely a design oversight, or did they think that the small amount of oil reaching the ends of the rockers was enough? The drawing in my Shop manual that shows oil flow in the rocker box shows the end grooves in the rockers, but no grooves in the shaft.

Also, John, you've convinced me. I subscribed to Vitage Bike today.

To answer a few other questions--
btour (2)--I wouldn't really call it grinding the valve adjusters. More like smooting the surface and polishing. I did it in a few minutes with wet silicon carbide paper.

btour (2a)--in keeping with a general policy, I reused the stock valve adjuster lock nmuts since they were still in good shape.

btour (3)--The chamfer maximum depth was determined by careful measurement of where the O ring groove would end up when the spindle was in place. It was important to press the spindles into place instead of pulling them with the acorn nut. In my case, pulling them in displaced one of the caps. This might explain your observation that the caps stick out varying abounts on differnt bikes--possibly the caps have moved from their fully seated positions on the spindle. It would be interesting if John or someone could tell us how deep the chamfer went on the factory drawings.

twinspin--the O ring material is Buna N. Viton does have a higher temp rating but the material I used has a continuous temp rating of 250 degF, which I believe should be high enough. I believe what you get from most parts suppliers for this part is Buna.

'twinspin--the O ring material is Buna N. Viton does have a higher temp rating but the material I used has a continuous temp rating of 250 degF, which I believe should be high enough. I believe what you get from most parts suppliers for this part is Buna.'

I hope that was a slip of the keyboard and you meant deg C. Otherwise it will end up being liquid. It gets pretty hot up there!

'Hi Twiny,

In frustration, with the valve lash adjusting inspection hole plugs (whew), coming loose and leaking/weeping, I tried the Kopper spray coat stuff. On the washer, with the slit in it, and on the plug threads. Seems to work just fine.
With a razor knife or other slender tool one can re-open the slit in the copper washer and get it to work again.
Problem solved.'

Kopper Coat Spray has been withdrawn from sale in the UK now as it is considered too dangerous!

Made one 23 years a ago when I served my time as a machinist. Such a versatile tool, I'm still using it.

Hi Ed -

It seems the design changes were made at the engineering end (BSA/Umberslade), but for various reasons (John could elaborate on this part) the changes either didn't make it to Meriden or were ignored....hence the confusion in the parts books, workshop manuals and service bulletins...

Now, if you look at the triple manuals that originated in the BSA group, you'll find the correct information for these three changes (machined rockers, washer placement and grooved oil galleys).

Steve

Steve

I wonder just how much difference the grooved shaft makes. As a longtime (almost 30 years) owner of a 71 T120, I can't say that I've experienced any problems in the rocker area aside from 2 valve jobs I've done in 30K miles.

A soultion looking for a problem?

Mike

Hmmm, I think you answered your own question.

The rocker arm bearing surface gets adequate oil and I personally haven't seen any rocker arm/rocker shaft bearing problems/failures because of this.

But think of the rest of the kit: Rocker buttons and push rod cups, valve tips and rocker adjusters and valve stem and valve guide.

It is the oil FLOW that distributes lubricating oil to these surfaces. Without the flow, and there is little without the oil galley cut into the shaft, how do these get lubricated?

Well, I did the first VJ about 20000 miles ago and the second just this summer. From what I've understood, getting 15/20K is about the norm?

Mike

I got 24K - 26K out of the originals, this with the grooved shaft, but incorrect washer placement. Now, if you hunt up my valve job thread from last April, you'll see that the valve tips and rocker adjusters were totally knackered! All due to the incorrect placement of the washers....

The push rod cups and rocker buttons were fine, but only because they relied on the oil galley in the spindle and the relief machined in the rocker arms....

I replaced the guides and valves with quality material (Black Diamond) and corrected the washers....remains to be seen, but I hope to get upward of 30K out of the top-end through regular road riding...

Steve

Interesting, Steve
I saw no evidence of the wear you had on my motor. My problem was seriously worn guides and valve stems.
Mike

Are the spindle oil grooves spiral?

ed -

Yes. I'll try and hunt up a photo of mine....

Steve