Upright school boy trunion questions...

[shedmonkey]

Bare with me its been two years since the spitfire/upright/trunnion sagas and I have drunk a lot of cider since then refurbishing the TR6 Trunnions on my SE6a ...and have some school boy questions ...I could have posted this in the TR6 bit as a lot of our cars have trunnions I thought this would be ok..anyway

1- Would you re use the upright pictured? you can see the top two threads are a bit iffy

2-With the trunnion  screwed on in position dry -ie without any oil or grease - the Scimitar boys use Moly grease? Triumph circles recommend EP90 - discuss!!! :)  there is no play up and down but about .25mm left to right looking at the vertical link in the upright position if you see what I mean...anyway cant remember if this much is too much?
3-next daft question, is it those threads causing the play or the trunnion? not sure if those top couple of threads actually make it into the threaded section of the trunnion ?

Cheers in advance

[Nick Jones]

Don't use those unless you want to die!

It's not so much the missing top two threads.... though that is bad enough, but the rust pitting will act as stress raisers leading to cracking and fracture.......

Sorry if that is not the answer you were looking for!

Nick

[shedmonkey]

It was exactly the answer I was looking for -you know what its like just wanted it confirmed! so next question has anyone got a decent set of S/H TR6 uprights for sale? or am I going to have to buy something new for the shed? :(

[Greeks]

Remember Andy Mac had one let go on his TR6  :-/

We spent the weekend thraping it round the countryside, getting air of bridges and he kept saying "hmmm, front PS wheel seems strange" but couldn't figure it out.

Next week he came out of a roundabout and the wheel disappeared into the arch (luckily for him) and he came to a halt pretty sharpish!

[npanne]

Nick_Jones wrote:

Don't use those unless you want to die!

I'm glad you said that - I've just binned some GT6 ones that were MUCH better than those.

[uksnatcher]

Heres mine, looked ok until you see how the corrosion had burried itself causing a weak spot........:-/

[tiggrr1]

And another one

[JohnD]

Of academic interest, but still of interest, is to examine such breaks under a good magnifier and slanting light.    The development of the crack and final failure can then be seen.

See: http://www.metallurgist.com/html/MetalFatiguePt3.htm

John

[sparky_spit]

To answer the grease Vs EP90 question....  When under load there is a high degree of contact pressure between the upper faces of the trunnion threads and the lower faces of the vertical upright threads. EP oil is designed to maintain lubrication under this extreme pressure (that's why it's called EP oil) whereas grease isn't.

Simples. Mind you, I didn't know this until Kevin R explained it once.

[Hogie]

..and how was it calculated that the trunnion is under extreme pressure !!.
The thread in the trunnion has a good deal of contact with the vertical link attachment thread. If somebody would like to do the maths you may find that the pressure isn;t that great.
However lubrication is required all the time. Grease is a good lubricant in the correct application but doesn't flow like a thick oil - in fact it hardly flows at all.
You could use a semi-fluid grease (Penrite).

The Steel/Brass material combination allows for the use of grease as the lubricant can become embedded in the brass to maintain lubrication.
If you are going to use EP oil make sure that the bottom of the trunnion is leak-proof, if necessary solder it up.
EP140 may be a better bet than EP90.

Both oil and grease work well.

Roger

[JohnD]

I don't think I've posted this here before, excuse me if I have.

"Which Oil?" is an interesting and useful book, written by a Richard Michell, an Australian oil industry specialist and classic car owner.   The one big Q he didn't write about was the Trunnion one.  So I wrote to him, and he was kind enough to reply, at length, and to say I might copy his response to Triumph owners.
When reading, please note that Richard has never owned a Triumph.  Don't mark him down for not being familiar with details of the Triumph trunnion and where the oil/grease goes in.

"“First I must confess to having never owned a Triumph vehicle although I did once seriously consider a Dolomite Sprint.   Plenty of other British cars – MG TC and TD, Morgan 4/4 Competition, Austin A30, A40 and Seven amongst them.   In fact my first car was a one-fifth share of a Standard Flying Twelve, a name that would fall foul of Trades Practices legislation today.   Perhaps as a consequence of my Triumph abstention, I had not heard of the trunnion lubricant controversy until you raised it.   Also, I have never seen the tunnion concerned so I may not fully understand the design.
At first sight, this would seem to be an application where a grease would be the preferred means of lubrication.   The nipple would preferentially be located at the bottom of the trunnion and the seal at the top.   The trunnion would be regreased at appropriate intervals and the fresh grease would displace the old.   Grease would be preferred over oil for the same reason it is elsewhere on chassis, it does not leak out.   It also does a better job where surfaces settle onto each other when not in use, as is presumably the case in these trunnions.   Oil is squeezed out whereas grease soap is not.
So why did Triumph change from grease to oil?   From a quick Google search, apparently it was because grease was drying out and a hard white powder was being formed.
All greases will bleed some of their oil when put under pressure, particularly if there is a large ratio of surface contact area to grease volume, as would be the case in the trunnion.   However, in the layout that I have suggested, the outcome should not be catastrophic.   The oil would remain in situ and would not evaporate.   It would require gross neglect to cause failure of the type observed and, as such failure requires loss of the oil, switching to oil as the lubricant would not seem an immediately-logical corrective step.
The following is pure speculation.   Back when these trunnion designs came into being at Triumph, the lubricating grease specified for them was presumably chassis grease.   Such greases would have been based on Calcium chemistry at that time.   A “feature” of calcium greases is that they require some water to be present in them if they are to retain their structure.   Without water they separate into oil and a solid soap phase.   This soap is a “gritty” solid, white or pale amber in colour.    This behaviour is part of the reason that the upper operating temperature of calcium greases is about 80C.
If Calcium greases are held at elevated temperatures – say over 65C – for extended periods they can slowly lose their water content and separate in the manner described.   As Triumph vehicles became faster - and particularly with the introduction of disc brakes - the increased heat generated under braking may possibly have regularly brought the trunnions up into this temperature danger zone.   Once the grease destructured, regreasing would not necessarily fix the problem.   The new grease would tend to displace only the separated oil, leaving the gritty soap behind.   Over time, soap would build up and the vertical link could bind in the trunnion.
Turning to Triumph’s solution - moving from grease to oil - it appears that the objective was to have the trunions sitting in a bath of oil.   The oil addition  “nipple” is at the top, as is the seal.   This design will control the friction when the vehicle is under way but will not be as good at controlling wear or initial friction (for the “squeeze out at rest” reason I mentioned earlier).
To overcome this, Triumph specified use of an Extreme Pressure (EP) gear oil.   It is here that they got a little confused, in my opinion.   If you have digested the relevant bits of ‘Which Oil?’ you will be aware that EP additives are used to control wear and friction in boundary lubrication conditions – the conditions that apply in a starting-from-rest Triumph trunnion or when it suffers an impact when motoring, such as a pothole.   However, Triumph seem to have missed two critical points.   The first is the one that current Triumph owners have cottoned on to – EP additives can be chemically aggressive to “yellow metals” such as bronze.   However, this chemical attack does not become significant until temperatures of over 100C and so it is not a significant concern in the bronze trunnion application.   Also, modern EP oils are far less aggressive than those of 40 years ago.
The big howler, at least to me, is that EP additives work only on ferrous metals.   They have no impact on non-ferrous, other than the potential for corrosion.   For the same reason, moving to the GL-4 specification for the gear oil, to reduce the possibility of corrosion, does not necessarily give any wear protection to the bronze trunnion.   The GL-4 wear tests are also on ferrous metals.   So we appear to have the situation where, if anything is being protected from boundary layer wear, it is the harder steel vertical link rather than the softer brass trunnion.   The protection of the bronze wear surfaces is solely by the oil portion of the gear oil, not the EP portion.
To my knowledge there are no chemically-active EP additives designed for bronze.   An oil film is an excellent lubricant for bronze where full hydrodynamic lubrication conditions  can be maintained but designers usually avoid the use of bronze where boundary, non-film conditions will exist regularly.   Bronze will wear and may even distort.   I presume that Triumph used bronze in this location to avoid binding between the two threads, e.g.  from corrosion.   Also, the softer bronze would sacrificially shear relatively easily if it should bind at any localised spot.
So what alternatives are there for the lubrication of a Triumph trunnion?   Solid lubricants could be helpful, molybdenum disulfide being the obvious first candidate.   Using a gear oil with some truly-colloidal moly in it - at a few percent - could be beneficial.   Some moly will stay between the surfaces when the trunnion/link are at rest and give a soft, easily-sheared protective layer on both the bronze and the steel surfaces.   It will also protect the surfaces against impact loads.   However, the moly would have to be truly-colloidal – completely stable in the oil – or it could settle out and ultimately lead to binding problems of its own.
I don’t know whether it is feasible but the design I described earlier – a grease nipple in the bottom of the trunnion – would be the preferred way for me.   The top oil addition plug could then act as the vent while the trunnion is being greased.   The grease I would suggest is a CV joint grease with 2- 3% moly.   Modern greases will not separate out into a solid soap phase and an oil phase in the way a calcium grease could historically.  However, regular regreasing should be carried out at the standard chassis maintenance intervals.

                                             Richard Michell, Jan 2012"

Richard is currently rewriting his book the second edition of which will include an item on the Triumph trunnion, so you're geting an exclusive preview here!

John

[nang]

Bite the bullet and fit the trunionless conversion. A bit expensive but no more trunnion/upright worries.
Tony.

[Nick Jones]

nang wrote:

Bite the bullet and fit the trunionless conversion. A bit expensive but no more trunnion/upright worries.
Tony.

Yes, maybe.  Quite tempting.  Suspect that in the end we'll just end up with a different failure mode - probably of the unsealed spherical joint.  However, it it fails in a more graceful manner than a snapped trunnion (wear= excess play + clonks) it would still be a big improvement!

Nick

[Velocita Rosso]

The cost of new vertical links are getting quite close to the modern/trunnion less version and also the new vertical links were ,at one time, hard to find

[junkuser]

Thank you for that John.
It may help those of us who have been using Moly grease in the trunnions (In my case since 1976) from the criticism so often leveled.

From the letter it would seem that Richard may not appreciate that, by fitting a grease nipple and pumping in grease, the trunnion is effectively being greased from the bottom as he suggested it should be.
It would be good if he could have a look at a vertical link before re-writing his book to see if the design satisfies his ideas.
I'm 90 Klms north of Sydney and would be happy to take him a link and trunnion if he is anywhere near.

My interpretation of the failures of the vertical link is corrosion from water, particularly salted water, sitting on/in that fairly hopeless seal on top of the trunnion.

[uksnatcher]

Also the age of the upright, it could be 30-40+yrs old...! A new standard upright should be as good as a trunionless kit....depends how flush you are as the spherical ball joints will have a useable life span too .

I have started using FG30 autolube grease in my uprights as we have plenty spare at work and its good enough for brass spring eye and king pin bushes on heavy goods vehicles....


Any pros/cons using this over GL4 EP90?

[yorkshire_spam]

I was considering using "one shot swivel grease" from a Land Rover for mine.... since that is an application that was originally specified EP90 and now uses a grease I was "guessing" that the grease might be good for trunnions.

[Nick Jones]

The trunnions are oiled from the bottom in fact as the threaded section is hollow with a drilling from the nipple to its base so any oil (or grease) pumped in through the nipple enters the threads from below.

Nick

[bxbodger]

I use oil because the book says so, but every other trunnion'd car I've had was specified for grease. I suspect I could use a modern grease with no problems but since the oil goes in without any difficulty I'll stick with it. I would suspect though, that many of our cars have spent the banger phase of their lives with little or no trunnion lubircant of any sort or maybe the occasional squirt of whatever grease was to hand.

I personally wouldn't go near those trunnionless uprights, at least not until someone can tell me exactly how the bottom bearing is located........the original trunnion should pivot at the bottom around the bottom bolt as the wishbone moves, I can't see how the trunnionless version is supposed to work other than being clamped as tightly as possible in the wishbone, it only has one bolt to fix it, it just doesn't look right- the movement is taken by that balljoint rather than the pivot bolt in the factory design- for it to work the bolt would need to be phenomenally tight as there's only one- why not two??   I know they sell a lot but I'm not convinced and it doesn't look as safe long term as a properly maintained original trunnion.


My own thery on trunnion failure-there's nothing wrong with the design, other than it's a victim of age and sloppy maintenance. I reckon a bit of corrosion gets into ye olde trunnion threads, plus the bottom pivot point seizes over the years and no longer pivots with the wishbone, this causes stress as the trunnion takes the movement of the lower wishbone rather than just pivoting with it..........by the time we've rebuilt these assemblies and got them working properly, the years of neglect have already done the damage.

That's my theory anyway- plase feel free to shoot it down!!

[yorkshire_spam]

Since the threaded "peg" at the bottom of the front upright (the bit that snaps off) is hollow to allow lubrication - how dumb would it be to thread that hole, screw in a HT bolt and then lubricate with something like the "one shot" swivel grease from a land rover?
Not that I'd ever do it... jut wondering how bad and dumb it would be?

[sparky_spit]

6797 wrote:

Since the threaded "peg" at the bottom of the front upright (the bit that snaps off) is hollow to allow lubrication - how dumb would it be to thread that hole, screw in a HT bolt and then lubricate with something like the "one shot" swivel grease from a land rover?
Not that I'd ever do it... jut wondering how bad and dumb it would be?

Exactly this is a mod that is/was being investigated by "Vegas Steve" (not sure his username on here) but I'm not sure where he's got with it.  His idea was to drill out the oilway right up the threaded part and well into the main part of the casting, tapping it and then screwing in a long HT bolt, about 6 to 8mm dia. He was then going to drill and tap a nipple hole near the top of the trunnion.

I think one of the issues was being able to mount the link accurately enough to drill and tap it, although I would think the existing hole would act as a pretty good pilot and it would almost align itself.  I was going to give it a try too, on a scrap one to start with, but it's currently at about 150 down my "things to do" list.

[bxbodger]

But to what end? There's nothing wrong with the voriginal design, provided it's maintained properly and in good condition. Snapped trunnion syndrome is an age related thing, it comes from years of use and abuse and extended periods of total neglect, and there isn't a car of 45 years old that won't have been kerbed and potholed at least several times by now, it's not something that was a common occurence when the cars were current and in everyday use, and it didn't send the many competition cars that used the same set up flying into the bales on every corner.

Surely the best option if there's any doubt about them would be to replace them and then maintain them, after al,l I don't suppose anyone foresaw the things still being in use 40 odd yearts down the line!

[Hogie]

As just mentioned the best practice is for some form of regular maintenance. Keep the grease/oil going in at least annually and perhaps every2/3/4 years strip it down. If there are signs of corrosion then cleaning and crack checking (MPI) would be a good idea.
Where do you go for MPI (magnetic particle Inspection) - there are quite a few places out there that do it but the best place is an aircraft maintenance area -
Heathrow, Stanstead, Gatwick - you must know somebody who works there.

Roger

[yorkshire_spam]

"To what end" well in my case the idea of reinforcing a potentially weak area of the car was interesting.
Also the idea that I might be able to do something that meant I didn't have to shell out significant money to repair something.

[JohnD]

junkuser wrote:

Thank you for that John.
It may help those of us who have been using Moly grease in the trunnions (In my case since 1976) from the criticism so often leveled.

From the letter it would seem that Richard may not appreciate that, by fitting a grease nipple and pumping in grease, the trunnion is effectively being greased from the bottom as he suggested it should be.
It would be good if he could have a look at a vertical link before re-writing his book to see if the design satisfies his ideas.
I'm 90 Klms north of Sydney and would be happy to take him a link and trunnion if he is anywhere near.

My interpretation of the failures of the vertical link is corrosion from water, particularly salted water, sitting on/in that fairly hopeless seal on top of the trunnion.

No probs, junkuser, I am the mere messenger.
   I have pointed out to Richard how the trunnions are made, and no doubt he will take that into account in his rewrite.

On your last point, of course water would sit on top of oil, or grease if the boot leaked. The position of the corrosion often seen ona failed trunnions shows that it occurs at the top and regular oiling or whatever should lift out that water.  Maintenance has to be the key, whatever lubricant you use.  Moderns have been designed to need little or none of this dirty hands type fettling so it's a mental shift for anyone coming into classics.

John