Welcome to our resource for MG Car Information.



TR parts and Triumph parts, TR bits, Triumph Car Spares and accessories are available for TR2, TR3, TR3A, TR4, TR4A, TR5, TR6, TR7, TR8, Spitfire and Stag and other TR models are available from British car spares and parts company LBCarCo.

Triumph TR6 - Trunnions: Oil or Grease?

I'm ashamed to admit I'm a trunnion greaser, but hope to get out of rehab soon as an oiler. The recent listing on ebaY of a modified trunnion oiler makes me wonder if it's possible to use an ordinary grease gun filled with 90W oil. Before I make a big mess, anyone done this before?

Rick Orthen

Hey Rick

I have always used 90w oil for the trunions. I buy a bottle of Marine gear oil with the correct weight and it is in already in a squeeze bottle with a nipple that you cut to size.

Failing that buy a restuarant grade sqeeze ketchup/mustard bottle from a rest. supply store and use that, it works great.

At 80,000 miles when I did my complete body-off restoration of my TR3A, I changed the trunnions. I had always used grease - the same gun I used to do all the other fittings. The trunnions were pretty bad, but then it may have been due to all that hard rally driving I used to do between 1959 to 1963 on rough loose gravel roads.

Since then (1990) with new trunnions, I still use grease as before and the trunnions are still like new with 67,000 miles of regular paved road touring.

I only heard about oiling them recently. Can anybody explain the advantages ?

Don Elliott, Original Owner, 1958 TR3A
Don Elliott

Steven--My trunnions each have a grease nipple on top; I guess you just squirt the oil on the exterior gaps between the pivoting surfaces huh?

Don--Perhaps grease is too thick to make its way down through the narrow gaps between the pivoting surfaces. I notice when I grease mine that the grease just exits at the uppermost gap and never comes out below (is there supposed to be a nipple on the underside of the trunnion?).
Rick Orthen

When I did my restore I filled the brand new trunnions with grease. Then I heard about "you are suppose to use oil". Well thank you Don have made me fell better. If you think about it I think grease is better than oil in this situation. There is a lot of "cutting" action going on here when you turn the wheel and since the trunnion is a screw mechanism, grease is better for this. Also consider that grease will not run down the threads like oil will. The idea behind using oil over grease I suppose is because it is easier to oil the trunnions in the future. It is easier to force oil down the screw rather than grease. If u get oil coming out the top seal then she has to be full. I am not sure how you force oil into a grease fitting nipple with a ketchup bottle...interesting steven. There is a special oil gun from Mercury Marine (sorry do not no part #) and is used for oiling lower ends of outboard motors with a grease nipple fitting...screw on the tube of oil and pump away. I recall seeing this on one of the TR web sites..maybe it was Zimermans.
Rick O, no there is no grease fitting on the bottom.
So who is right and who is wrong??
Rick C
Rick Crawford

On my 1958 TR3A, the grease fitting for my trunnions is at the bottom. When I grease them with my grease gun, my front wheels are off. I attach the fitting on the end of the hose for my grease gun to the bottom "zert". I give it a couple of lever actions and then I see the grease coming out the top where there is a round rubber ring seal - then I stop.

While the trunnion is made of brass, there is a long milled slot from the bottom to the top and the grease finds its way up in this slot. Each time I move the steering wheel, the rotational movement in the trunnion results in grease moving into the square threads from the slot that supplies the grease. This, I feel is what puts the grease into the threads that it is all riding on and supported by.

If you use oil, I would think that the oil would run out and it wouldn't be there very long to get from this full-length slot (in my TR3A trunnions) into the threads.

Maybe the TR6 trunnions are different ?

Don Elliott, 1958 TR3A
Don Elliott

Page 376 of the Official TR6 Workshop Manual....
"Using a 90 S.A.E. EP lubricant partially fill (25%) the trunnion. Fit the rubber boot and screw the trunnion into position ect ect...
The grease theory makes more sense. Having not done mine yet I'm going to do more research.
I love my Triumph !!

Charlie--What rubber boot? Mine don't have any.
Rick Orthen

the rubber boot is a seal between the trunion and the vertical link and keeps dust, dirt and water out of it. It is clearly illustrated in all manuals and on pg 219 of the TRF catalogue item DD34. This boot is a must.

Oil is recommended because of the material of the trunnion. It's bronze, not brass, and has a steel upright running in it, that will inevitably cause some wear. Bronze particles will be suspended in grease, forming an abrasive mixture, but will gradually fall to the botton of the trunnion out of the way if oil is used. The vertical slots provide a "bronze fragment elevator" when they would otherwise need to migrate along the thread.

As for 'grease is better than oil', you are supposed to use Hypoid 90, the same as the diff. If the pressure in the trunnion is greater than that between crown wheel and pinion then you have stronger arms than I!
At least that's what I've been told.

Thanks John, that makes sense. But since we're dealing with bronze, you shouldn't use any of the modern (high sulfur content) hypoids, right?
Rick Orthen

John, Thanks for the correct answer as supplied by an old timer I talked to once. Rick O., that is not a grease nipple but an oil nipple and the Mercury part # Quick silver Grease Gun # C-91-37299, about $14.00
Don K.

I lifted this from the quiller triumph web site (FAQ page )
What lubricant do you recommend for the trunnions Ive heard differing views and Im confused? We recommend and use Penrite Semi-Fluid grease. The original Triumph handbook just recommended standard grease, however we find that although standard grease does an adequate job at lubricating it tends to wear the trunnions out quickly. This is because due to their brass/copper construction they are prone to tiny particles chipping off, in grease these particles remain in solution and with suspension movement tend to exasperate wear in a vicious circle, as grease is too viscose to allow the particles to sink to the base of the trunnion where they are relatively harmless. Alternatively, the use of gearbox oil does allow the particles to sink, but may not provide adequate lubrication. We find the Penrite product (which Penrite claim is designed for this job) a happy compromise.

R. Campbell

On high sulphurs - I'm too much of an oldtimer to know anything about them! Are they supposed to attack bronze? Any other metals?

Well, Quillers would recommend it, wouldn't they? They sell it, at a high price.
That's what is so great about this sort of site - any bias is readily detectable, and challengable
Yours cynically,

John is correct - use SAE90. If for no other reason the grease will not circulate adequately. When oiling you should use the 'grease' (nothing is better than a wanner) gun filled with SAE90 until it exudes from the rubber boot (spitfire). This was a MONTHLY job on the spit - you will notice how light and free the steering remains.


I knew something was wrong when I stuck the grease
gun on the "oil nipple" gave it one good pump and blew the steel seal off the bottom of the trunion.
I seal it back up but was still puzzled.
I'm walking out the garage with a lug nut wrench in hand as I type ...
Christopher Trace

Wow, trunnions receiving a well-deserved discussion it seems. Having never oiled mine, when do you know you've pumped enough oil in? Where does it come out?
Rick Orthen

Chris - If that's what happened, you have to ask what created the resistance to the new grease going in that it popped the end cap off. The grease in your trunions must be so hard that it's blocking the passage to the other end where the rubber seal is supposed to open a bit on each shot of the grease gun to let the excess old grease out.

I suggest you may have to remove your trunnions and clean out all the caked in grease. Whether you use grease or oil after that is up to you, but at least they will be clean before you decide.

Don Elliott, 1958 TR3A
Don Elliott

Don , sorry , but,
Brand new trunions, new grease, new seals.
It might have been a bit cool in the garage the day
I did it.
Still I think I 'll do the oil thing.
Stange, my other two vehicles I'll keep in running
order. I do required maintenance and so forth, but
not much else. When it comes to the TR6 if I think
I can gain 0.01% improvmemt, then out to the gararge
I go to do the work. And afterwards I'm always SURE
that I can feel the difference.
Christopher Trace

For past twenty odd years I only used molybdenum grease and am on third set of trunnions (in 200,000 miles). The last set of trunnions i bought leaked where the steel disc is pressed into the bronze trunnion- I doubt oil would be retained more than a minutes.
Peter Cobbold

This thread was discussed between 07/08/2002 and 25/08/2002

Triumph TR6 index