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Hi Chris, don't know if that shortening is significant, but I'd change them anyway. While you've the head in bits. it's easy. If you re-assemble and there's a misfire or suchlike, you'll be wondering about those springs and kicking yourself because you didn't change them. If they are original, after 50 years of heat cycles and millions of compressions, they are bound to be a bit weary. Change 'em.
 

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Hi Don,
tracking wear after doing the washer mod. While it might improve things. I see more wear than you’d like after 9 k miles. Not like cutting wear to really good.
Mmmm ... but the top end oil supply also isn't great?

How has the wear changed in your experience.
No experience. Triples' rockers were assembled correctly, the guy who put the basics of my T100 together assembled the rockers correctly.

I only advised @Rusty1 Chris to check because of the wear photos. he posted, he's found his bike's rockers assembled incorrectly. :(

If you think about it, the incorrect assembly was a real top-to-bottom management failure - it went on for years after it should've changed, it actually took more different parts (the smaller-ID washer at one end) to do it wrong than to do it right! 😖 Barmy.

Many cars used similar adjuster screws that lasted 100k miles.
Otoh, both Porsche and MB likely didn't use something obviously more expensive just for the hell of it?

I hope some of the old dealer mechanics will share their experiences.
I believe John Healy started out as a dealer mechanic (when God was a boy)? He's always advised correct assembly. ;)

Hth.

Regards,
 

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Discussion Starter · #44 ·
I only advised @Rusty1 Chris to check because of the wear photos. he posted, he's found his bike's rockers assembled incorrectly. :(
And I think more evidence of poor lubrication here Stuart. They look worse than they feel, there are no wear ridges and the rockers slide on without excessive play (in my humble opinion) but if I could find the grooved version I’d replace them. A few sellers are advertising 71-3301 but from the pictures I’ve seen they appear to be the same as what I have, 70-3748. Will correct assembly improve oil flow to the rockers even without the grooved spindles?

Oh and I also have an inlet rocker arm with a loose ball so something else added to the shopping list.
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Has anyone seen grooved small unit spindles? I have certainly seen them on 750 twins, but as far as I can see, the change from 70-3749 to 71-3301 was to change from BSCy to UNF thread on the end. The new spindles would all be Harris manufacture anyway, but some NOS ones don't appear to be grooved either. Assemble with the new 1/2" washer as per Stuart's note and I doubt you'd have any problem this side of soil.
HTH
 

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Hi Chris,
Will correct assembly improve oil flow to the rockers even without the grooved spindles?
Afaik, no. Oil's delivered to the centre of the rocker-box, the spindle's the only way it gets from the centre of the 'box to the rockers; if not by a groove on the outside, through the spindle centre ... but there aren't any holes from the spindle centre to the outside in way of the rockers?

It should've been a package of dependent modifications made during '68: rocker arms not drilled plus other different machining, Thackeray and plain washers positions changed, spindles 'scrolled' (machined spiral grove around and along the exterior) to carry the oil to where is would be 'squirted' at the ends of the rockers by a combination of the differently-machined rockers and the plain washers against them.

In reality ... the rockers were changed, the washers positions and the spindles weren't. Moreover, unhelpfully, Triumph didn't change the part numbers of the rockers ...

Assemble with the new 1/2" washer as per Stuart's note and I doubt you'd have any problem
... so, aiui only changing the washers positions won't get the oil to travel along the spindle ...

as far as I can see, the change from 70-3749 to 71-3301 was to change from BSCy to UNF thread on the end.
Apologies for any bum information here, Meriden didn't change the domed nut part number between the '72 and '73 500 parts books, and did change the 650/750 spindle part number from '72 to '73.

There aren't any basic differences between 350/500 and 650/750 rockers/spindles principles. The spindles should've changed to grooved during '68 as part of the aforementioned package; if 650/750 spindles were finally grooved '73-on, so should 500 ones.

Hth.

Regards,
 

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Hi Chris,

Afaik, no. Oil's delivered to the centre of the rocker-box, the spindle's the only way it gets from the centre of the 'box to the rockers; if not by a groove on the outside, through the spindle centre ... but there aren't any holes from the spindle centre to the outside in way of the rockers?

It should've been a package of dependent modifications made during '68: rocker arms not drilled plus other different machining, Thackeray and plain washers positions changed, spindles 'scrolled' (machined spiral grove around and along the exterior) to carry the oil to where is would be 'squirted' at the ends of the rockers by a combination of the differently-machined rockers and the plain washers against them.

In reality ... the rockers were changed, the washers positions and the spindles weren't. Moreover, unhelpfully, Triumph didn't change the part numbers of the rockers ...


... so, aiui only changing the washers positions won't get the oil to travel along the spindle ...


Apologies for any bum information here, Meriden didn't change the domed nut part number between the '72 and '73 500 parts books, and did change the 650/750 spindle part number from '72 to '73.

There aren't any basic differences between 350/500 and 650/750 rockers/spindles principles. The spindles should've changed to grooved during '68 as part of the aforementioned package; if 650/750 spindles were finally grooved '73-on, so should 500 ones.

Hth.

Regards,
Me not making myself clear, the important bit is aligning the holes as you explained.
 

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Discussion Starter · #48 ·
Thanks Stuart/Mick (is Mike ok?),

I’ve been over to BritBike and read the latest thread on this subject (several times) and I think I’ve got it now. Long story short oil has to get to these crescent shaped reservoirs via the rocker bearing surfaces, a groove in the spindle facilitates that. I can see why correct assembly alone wouldn't be ideal but that's where I am at the moment, there must be hundreds of late sixties/early seventies Triumphs being run like this?

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Hi Rusty1, Overall length is approximation of spring only. But the test you can do without spring tester.

Spring should also set straight on both ends.

The spring should be tested in valve spring tester. You compress spring to specific length & read pressure.

It is advisable to test new springs as well to verify they are up to standard as well. The highest quality suppliers springs are up to standard. These days I trust nothing.

Now that spring is to spec, fitted length is important. The distance from top of spring seat to to underside of spring cap. Meaning how long is spring when installed with valve closed.

4000 rpm all this is fairly forgiving. 6-7000 it’s very important. All it takes is one trip to 7000 or less... Valve floats & hits piston you have a lot of damage.

Valve float is where motor is spinning so fast the spring pressure cannot close valve fast enough. At high rpm there is a lot of momentum in valve train. Takes good spring & fitted length to control this.
Don
 

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On a side note. Both my inner & outer springs were longer than spec. These are from new 1973. Don’t know why. This was 6 years ago. Covered 36k miles on them from new.
I don’t have spring tester. I didn’t take to machine shop for testing
I lightly lapped valves & reused old springs.
I think about this all the time. I don’t dare take to near 7000. Nor even 6000. Would it blow up? I’m not going to find out.
During overhaul I’ll test springs. I expect a fail. I’ll test new also.
Don
 

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Hi Chris,
oil has to get to these crescent shaped reservoirs via the rocker bearing surfaces, a groove in the spindle facilitates
Ye-ea-ah ... but it's the groove that gets the oil to the "crescent shaped reservoirs" in the first place.

there must be hundreds of late sixties/early seventies Triumphs being run like this?
True but, given we have the knowledge and either ability or contacts, and we don't have the time-cost pressure, like the electrics, are we not doing things better than Triumph did?

In your place, my pov would be: I don't know whether the rocker spindles were replaced at the last rebuild; if they were, they're in their current state in relatively-few miles; I've taken my Triumphs more than a thousand miles in one trip; irrespective, I don't want a rocker to seize if I have to give the bike some welly down a motorway or autoroute/bahn for the sake of a groove any competent machinist can make.

that's where I am at the moment,
If this is a prelude to rebuilding either with the existing shafts, or new shafts without grooves:-

. Have you considered emailing or ringing Harris to find out if there's a reason current production shafts don't have the grooves?

. If there isn't a sound engineering reason, have you considered ringing, say, @Andytheflyer's contact in Wrexham, or P&M in Brentford (020 8847 1711, open 'til 6 pm today according to Google) and asking if one could machine the groove in a couple of new spindles posted?

Hth.

Regards,
 

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Hi M,ick,
dunno why my name should cause a spitting of dummies,
VerticalScope - who own the TriumphRat site and a large number of others - Admin uploaded a new list of "hate speech" words on the 15th and are currently a world-wide laughing stock for their stupidity - e.g. while "M,ick" without the comma is "hate speech", "Dick" isn't; "n,egro" is "hate speech" but "honky" isn't; we can't mention F,AG for bearings but "tranny", "queer", "gay" etc. intended as insults aren't "hate speech"; the ten-letter word beginning with C and ending in R, that is never not an insult, isn't "hate speech" according to the new VS list ...

No spitting of dummies, just schadenfreude ... ;)

Regards,
 

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Discussion Starter · #56 ·
If this is a prelude to rebuilding either with the existing shafts, or new shafts without grooves:-
Yes it is Stuart. If they were readily available I'd buy the improved shafts, I have e-mailed LF Harris but don't think I'll be asking a machine shop to modify standard new items, I wouldn't know what to ask them to do - dimesions position etc. If nothing comes of the Harris query my original spindles will be re-fitted, scotchbrite has removed most of the staining and they really aren't worn or pitted, if I was in any doubt I'd replace them. I've a few days wait for the new rocker to arrive so there may be developments.

If any kind soul is willing to recieve two new shafts from me, have the machining done and return them I'd be very grateful and there'd be a drink in it for them.

Chris
 

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A few sellers are advertising 71-3301 but from the pictures I’ve seen they appear to be the same as what I have, 70-3748. Will correct assembly improve oil flow to the rockers even without the grooved spindles?

Oh and I also have an inlet rocker arm with a loose ball so something else added to the shopping list.
Here are the differences between the earlier 70-3748 and later 71-3301 rocker shown in the '74 500 parts book.

744830

If you have the later rocker boxes (with the side adjustment access plugs), the later shaft will be needed to fit correctly when installing the Thackerays and shim washers in the correct orientation, without a shim washer at the shoulder of the shaft bearing against the rocker box wall. The slight taper on the shoulder at the threaded end, bears directly against the rocker box and assists in preventing the rocker shaft from turning at the dome nut is tightened. The older shaft will sit below flush at the o-ring end and will protrude in the inside against the Thackery, holding it clear of the rocker box wall.
I came across this issue when BrianG and myself (both with500 Daytonas) did the rocker shaft groove mod last year. That mod CONSIDERABLY increased the oil flow to the rocker boxes and is well worth the effort.
 

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Yes it is Stuart. If they were readily available I'd buy the improved shafts, I have e-mailed LF Harris but don't think I'll be asking a machine shop to modify standard new items, I wouldn't know what to ask them to do - dimesions position etc. If nothing comes of the Harris query my original spindles will be re-fitted, scotchbrite has removed most of the staining and they really aren't worn or pitted, if I was in any doubt I'd replace them. I've a few days wait for the new rocker to arrive so there may be developments.

If any kind soul is willing to recieve two new shafts from me, have the machining done and return them I'd be very grateful and there'd be a drink in it for them.

Chris
Draganfly have the 71-3301 shafts "Good Stock level" for £19.60 no doubt plus VAT. That's where I got mine.

The groove dimensions are not critical and can be done with a Dremel. An alternative is to grind a shallow flat on the shaft. Whether using a groove or a flat on the shaft, they should be positioned at the top in the unloaded area between the rocker and the shaft. I made a pop mark at the outer end of my shaft to able to confirm the correct position of the shaft when assembling and tightening things up.
 

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Hi Chris,
don't think I'll be asking a machine shop to modify standard new items, I wouldn't know what to ask them to do
P&M are far from any old "machine shop", they're one of about three well-known triple engine builders in GB. There aren't any major principal differences between triple rockers, spindles, etc. and the same parts on a 500. Even if P&M haven't done it before, if they're prepared to do it, they only have to reproduce the oil 'scrolling' they're familiar with on triple rocker spindles. The reason I also included @Andytheflyer's contact is I gathered from his recommendation they're also experienced with the engineering requirements of old Triumph motorcycles?

That mod CONSIDERABLY increased the oil flow to the rocker boxes and is well worth the effort.
The groove dimensions are not critical and can be done with a Dremel. An alternative is to grind a shallow flat on the shaft. Whether using a groove or a flat on the shaft, they should be positioned at the top in the unloaded area between the rocker and the shaft. I made a pop mark at the outer end of my shaft to able to confirm the correct position of the shaft when assembling
... as I also suggested earlier in the thread.

Hth.

Regards,
 

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Discussion Starter · #60 ·
Thank you Shippy, that’s helpful.

My rocker shafts have a slight chamfer at the threaded end, it’s not a square shoulder, is this what you mean by a taper? From that shoulder to the other outer end of the shaft is 120mm, total length of the shaft is 140mm. I may already have 71-3301 (don’t know the thread) but if I end up buying replacements can I simply cut a groove or file a flat along the gaps in the tape (see pics).

Chris
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