oil not grease but why?

[thomas]

There's a consensus that oil is better than grease to use in the trunnions but can somebody explain, why, to me please?
I've had a Minor for 16 yrs. and unlike Triumph, Morris recomended grease. I mostly used a molybdenum type and failing a lithium based lube and had no problems.
Speaking of which ,of these two types which is the best for wheel bearings and what is the lightest viscosity least drag grease you can get generally for wheel bearings?

[Deleted User]

Because car manufacturers spend millions of pounds designing a car and researching all the lubricants to use.

Triumph would not have specified EP90 oil unless their research showed that it was far superior to grease in the Triumph suspension design, so we use EP90 oil today because that is WHAT THE MANUFACTURER SPECIFIED.

[GT6 M]

Grease by its nature  does no flow well, so cannot get every where at once, and when some thing is only turning ..most of the time.. a little either side of a point, so in this case, there would be no lube thea

and also , after a time grease goes ..hard.. so gives even less lube qualitys :-/ :-/

where as oil, will be ..flooding.. the area, cos the whole inside of the trunnion will,or should be, filled with oil

and also it should be done very regularly,if you use your car in the wet alot

as ..oil floats on water.. so when water  gets in, the oil goes out the top  :-/ :-/

in my opinion this is a job that should be done on a monthly basis, its no a hard job to do,
and may also save you frae having a bad bang, cos the trunnion has snapped off,

Marcus

[bxbodger]

I never had a Minor or Marina threaded trunnion fail because it was greased rather than oiled, but then again grease was specified- pump the new grease in and watch the old grease get expelled through the seals.

It was the same with all those BL cars that had the balljoints that you used to have to shim every so often to take up the wear, they were all specified for grease as well, so quite why Triumph specified oil for their threaded trunnion I don't know, possibly for metalurgical reasons perhaps..but whatever,  the book says use oil so that's what I do!

Quote:

and what is the lightest viscosity least drag grease you can get generally for wheel bearings?

...I doubt it's measureable but lithium grease is sold as suitable for bearing use so that's what I'd use: moly grease is used in chassis applications- handbrake pivots, that sort of thing, I don't think it's suitable for bearings.

[G.in_Lux]

I vaguely remember somebody hypothesising that any debris in the trunnion would sink to the bottom in oil and therefore not score the trunnion itself.

I cannot guarantee the veracity of the above statement though.

[Casper]

There is a high vertical load on the threads and as they slide, grease is forced out from the contact face.  And stays out, leaving metal to metal contact, with resulting high wear.
EP Oil (note EP = extreme pressure) is also forced out of the contact face to some extent, but the clever design causes the oil to be pumped up from the 'resevoir' at the bottom, up the oilways so that the bearing faces are continually replenished with oil.  Hence reducing wear.

Vertical link failure is another issue - the lower steerings swivel needs to move in the wishbone - check the geometry (which is why failures normally occur on sharp turns).  Failures are perhaps more likely if maintenance is poor, due to corrosion caused when the metal is not protected by lubricant.

Edit:   Not being familiar with the Morris setup, I have had a Google.  I notice that:
a.  The thread seems finer, perhaps leading to the contact area being larger, therefore pressure lower.
b.  There is a section in the middle of the thread which is relieved.  This will act as a resevoir for grease and allow it to be picked up as the v. link turns.
Different design, different requirements?

C.

[thomas]

Kevin,
I'm well aware of what you said,  as I'm sure are most heads on here. The question I asked was why? As in why did Triumph specify oil ,after their resarch when other's , BMC  for example specify grease in a similar design (i.m.o.) with no problems. Apperantly it's considered wothwhile to question matters and not accept blindly what you are told.
Oh, check that cap lock, as using capitals in a sentence is considered shouting on line and yes I know this topic is around since '62 but I don't care,as I'm not.

[JohnD]

thomas,
Tribology is a science, and not just a load of old craftsmen passing on generations of knowledge - which is what any science is, except the knowledge is based on an understanding of the basic processes involved rather than witchcraft.

You might like to read this article before you accuse others of blindly following tradition. http://www.copper.org/Applications/industrial/bronze_bearing.html
In particular, the sections on Boundary Lubriation Mode and Material Properties.

If you have taken a trunnion apart, you will have observed that the threads in the casting are interrupted by lands that cut right through them vertically.     This is to allow wear particles that would otherwise accelerate wear if they became embedded in the threads to drop out and down into the base, a process that will not happen if the trunnion is filled with grease.
Steel-on-bronze, in a sliding application, is a well known engineering solution to extreme pressures.  For instance, this is from article about a power station that burnt pulverised coal:

"Pulverizer Gearbox
The pulverizer gearbox design dates back to the early 1960s. A steel worm gear driven by a large 800 rpm electric motor powers a bronze bull gear that is directly connected to a grinding table. The sump holds 255 gallons. The gear oil temperature is controlled by an integral water-cooled heat exchanger. The unfiltered ISO 320 EP gear oil is recommended by the gearbox OEM to provide the bronze lubrication for steel gears and bearings."
You will note the use of an oil, a gear oil, as recommended by Triumph.    The article was about how wear on the bronze gear was reduced by keeping coal dust out of the oil, when the owners were aghast at the cost of maintaining it.   This was an oil change every 12 months, rotating the gear every ten years and replacing it every  twenty  years!  Not too bad, you might say, except that it cost them about $25,000, $300,000 and $450,000 when lost production was included.

Read the full article at: http://www.machinerylubrication.com/Read/959/wear-particle

John

[Lord Sorbington]

1136 wrote:

Oh, check that cap lock, as using capitals in a sentence is considered shouting on line and yes I know this topic is around since '62 but I don't care,as I'm not.

Quite.  It's far better to use italics when trying to place emphasis on particular words.  :)

I'm fortunate that my 2000 doesn't have trunnions but I understand that, as explained, the EP properties of the specified oil provide better lubrication than ordinary grease.

[thomas]

John,
it seems ,as I thought ,that this topic has ruffeled some feathers, lol!
Tribology,I presume is a general study of friction and lubrication solutions but you might feel the need to correct me.
As far as you saying " a load of old craftsmen passing on knowledge -which any science is,except the knowledge is based on an understanding of basic processes involved instead of witchcraft" these are your words not mine (and I would imagine this is obvious anyway) leaves me only to conclude that you misunderstood my question.God forbid I would give even the merest suggestion that those good engineeers at Standard Triumph all those years ago were practicing witchcraft!
I was n't denying that gear oil is a superior lubricant in this case but just wanted to know why.based on my empiracal knowledge with other brands of automobile.
It's all good fun anyway.

[Deleted User]

The trouble with debates like this is that very few people really know the real answer.

In this case, the only people that that really know  the real answer are the engineers at Standard Triumph who did the original research, if they are still alive.  

Did they fully document the research ?
Is the fully documented reasoning behind why they chose an EP oil available in the public domain ?

If the answer to either question is no then all anyone can do is to speculate.

And you will always find someone that is 100% convinced that snake grease is better, and the ST engineers got it wrong, based on their 10 minutes of research and use on their own car for the last 10 years.

If people outside "the industry" really understood how much research goes into the selection of a lubricant for a specific aplication, then they would quickly understand that they are never going to find something better in their 10 minutes of research.

On a project that I've been involved with, it took 5 years of research and experiments to optimise the choice of grease for a specific oscillating shock loaded frequently water immersed part.  We researched hundreds of greases and performed hundreds of lab tests to get a short list of greases, and then field tested them for 3 years before deciding on the correct grease for the application.

[JohnD]

1136 wrote:

John,
I was n't denying that gear oil is a superior lubricant in this case but just wanted to know why.based on my empiracal knowledge with other brands of automobile.
It's all good fun anyway.

I'm delighted to have answered your question.

John

[Jonny-Jimbo]

Well I've certainly learned something from all this...

[junkuser]

Would Moly greases, as mentioned by Thomas, have actually been available for evaluation back when this type of vertical link was designed?

[Deleted User]

junkuser wrote:

Would Moly greases, as mentioned by Thomas, have actually been available for evaluation back when this type of vertical link was designed?

Moly greases were available before WWII, but were properly developed in the late 40's and early 50's by the US Government nuclear research labs, and these ones hit commercial market in 1953 and were marketed as "Wonder Greases".
I would be astounded if ST had not tried and dismissed moly greases when developing the trunion

[esxefi]

just adding to john d's earlier post is that as far as i remember from working on my wifes minor she had years ago,the morris trunnions are iron or steel and not brass as in the triumph part so this may back up the reason for grease over oil. :)

[Pete Lewis]

but  if you dont maintain them properly they  all will fail, be they Moggie,Marina or your trusty  Triumph

most general purpose grease does not have the  Extreme Pressure properties of an EP oil

and in their   60's and 70' s haydays  there were more Moggies sitting on the kerb with a shot trunion you never saw any Triumphs  even if production volumes were unequal  

now they are more aged  most trunions fail due to being fitted to already corroded uprights , it just files  the new threads to bits  oh so quickly and  cracks start to eminate from the corrosion , then its hello hedge,
Pete    

[Mj17]

I read somewhere recently (think it was the TSSC mag. but not certain) that when first used the Triumph trunnions were greased but, very early on following a number of failures due to lack of lubrication Triumph switched to EP90.  And by early on I think they were talking possibly pre-Herald (anyone know what system Standard 10's, etc used?).

[Goody]

The answer may come in part form days of old when greese was not bold.
Haveing owned and restored CJ2A Jeeps vintage 46 to 48 the front axle U joints use oil and not greese.  While the outer houseing's have upper and lower roller barrings the factory mandated OIL!  Everything is lubed by the splash system.  Greese of ole had a very short service live.  Those who own old cars know the factory recomends re packing the front berrings every 1,000 miles.  To re pack the front axles of a Jeep would require a majoy dissassembly.  If you have stock Jeep then this works well.  Like a Triumph adding oil often is the key.  If you install free wheeling hubs then the splash system does not work and modern greese is the way to go.  Land Rovers of ole have the same set up.  But for what ever those of us who oil our Triumphs have no problem and those who greese do.  Kinda like what we all put on our hair.  Those of us who have hair.

[heraldcoupe]

Mj17 wrote:

I read somewhere recently (think it was the TSSC mag. but not certain) that when first used the Triumph trunnions were greased but, very early on following a number of failures due to lack of lubrication Triumph switched to EP90.  And by early on I think they were talking possibly pre-Herald (anyone know what system Standard 10's, etc used?).

The Standard 10 and Atlas used the same upright casting as the drum braked Herald. The machining was slightly different, with no provision for a nipple or associated oil channel. In this early application, the nipple was fitted into the trunnion itself, and you are correct, at this time it was lubricated with grease. It's some years since I've looked at the earlier upright, I couldn't comment on whether the threadform matches the complex style of the Herald parts.

The move to lubrication by oil was evidently seen as progress at Standard Triumph. I believe that similar changes were made in the TR range, however that liese well outside my area,

Cheers,
Bill.

[rotoflex]

Goody wrote:

Greese of ole had a very short service live.

That checks with the industrial machinery I've seen in difficult-to-reach places surrounded by scores of empty grease tubs in corners, etc. and even discarded worn-out grease cups and grease feeders scattered around.  Equipment that now wouldn't seem to have gluttonous lubrication needs did specify going by once a week and giving the grease cups a twist.

[Deleted User]

Must admit i use semi liquid grease (cv joint grease) and havent had a worn out item or a failure in 20 years and 160000 miles ill stick with it

h