Post Number: 406
|Posted on Wednesday, 08 June, 2016 - 01:19 pm: |
I replaced a trunnion boot and observed that there was no source of gear oil, so I concluded that the gear oil in the differential stayed in the differential and did not migrate into the trunning housings. I further remember, possibly erroneously, comments about ports for adding oil to the housings, which would have made sense but I've looked without success.
How do I supply gear oil to the trunnions?
Thanks for the help,
Post Number: 1936
|Posted on Wednesday, 08 June, 2016 - 02:18 pm: |
You are indeed correct that the differential/final drive oil stays there. In fact, the trunnion/Detroit joint oil tends to slowly seep into the differential. It is not unusual to find the differential full to above the fill plug if the trunnion joints have been kept correctly lubricated and the differential oil has not been changed in some years.
On each Detroit joint, where it hugs the differential, there is a small bolt on one side of the oval shaped metal housing. You remove this to add oil to the trunnion joint. These should be checked yearly in an ideal world. I have found repurposed hair dye bottles to be the ideal size to fill about 2/3 full and get into the tight space you have to work with when the fill port is pointed almost upward.
Omar M. Shams
Post Number: 672
|Posted on Wednesday, 08 June, 2016 - 02:38 pm: |
Thanks for the tip Brian.
And thanks for jogging my memory to check my Detroit joint /trunion oil level Chris.
Post Number: 238
|Posted on Wednesday, 08 June, 2016 - 03:08 pm: |
Great stuff Brian,
Is there also a corresponding level hole?
Or do they get filled to the top?
Lastly is the oil used a typical 90 grade diff/gear oil?
Post Number: 2064
|Posted on Wednesday, 08 June, 2016 - 04:16 pm: |
The trick is to position the drain plug at the clock position for either 4 or 8 o'clock and squirt the oil in using a suitable squeeze bottle with spout attached to a clear PVC tube until oil starts to run out of the plug hole - any more is going to flow straight into the differential housing past the bearings.
From memory, the specified refill volume for each trunnion is 150ml.
I used Castrol SAE90 EP oil for both the differential and detroit trunnion.
Post Number: 239
|Posted on Wednesday, 08 June, 2016 - 04:34 pm: |
That's a great tip David.
I will be under the car this weekend.
Post Number: 1270
|Posted on Thursday, 09 June, 2016 - 01:06 am: |
Another great tip that Brian always gives on the related procedure of changing the diff oil is to always loosen the filler plug before removing the drain plug. This is because it is possible that having drained the oil you then find the filler plug is corroded in and cannot be removed.
Of course, the filler plug will have to be removed, but checking it first means the much longer job of freeing it off, with the possible removal of the rear cover and ordering of a replacement gasket, can be scheduled in better.
Post Number: 407
|Posted on Thursday, 09 June, 2016 - 01:38 am: |
On the topic of removing the filler plug, I didn't have a half-inch Allen wrench, so I used a coupling nut and a socket wrench. The coupling nuts came in a pack of three from Home Depot for $1.40. It turns out that a 5/16" threaded rod needs a coupling nut that is manipulated with a 1/2" wrench, and that fits the plugs in the differential.
I use the same trick for opening the Accumulator Control Valve.
Post Number: 1938
|Posted on Thursday, 09 June, 2016 - 01:58 am: |
Are you sure about that ACV comment? The ACV plug is a 1" hex and I do not think that even the large side of the Britool that comes with the car for the oil sump plug, differential plugs, etc., is anywhere near that and, if memory serves, the depth of the recess on the ACV will not allow the fattest part at the center of the Britool to drop in.
I always put in about 6 fluid ozs/175 ml of HP gear oil in to each trunnion joint with the fill hole positioned at the 2 or 10 o'clock position. Of course, if I hit "overflow" before that much fits in I stop.
Post Number: 408
|Posted on Thursday, 09 June, 2016 - 02:04 am: |
Well, there are two parts to this answer, because I was unclear in my statement.
Yes. I use a coupling nut to open the AVC.
No. It is not the same one I use to open the fill plug on the differential. (I haven't tried to open the drain plug, yet, as per suggestions previously offered, so it may even be a third size, but in my case, I have Allen wrenches up to but not including 1/2")
Post Number: 1272
|Posted on Thursday, 09 June, 2016 - 02:46 am: |
Here are my efforts:
The one on the left is for the drain plugs. On my car it fits the engine and diff plugs. It is a 14mm hex socket carefully filed down to 13.6mm across flats. It fits perfectly. If you put enough force on it, it would rip the sump off before rounding the flats.
The other is a 1" AF coupling nut that I bought from a local fastener specialist. Their minimum order was $5, a bargain at the price.
Post Number: 382
|Posted on Thursday, 20 April, 2017 - 11:10 am: |
Just refilled my trunions this evening.
Went to the dollar store and bought this.
Located the correct gear oil (because I have five gallons)
Rotated the trunion fill ports down to drain.
Relocated the ports up and refilled using the syringe. It looks awkward because I was trying to take a picture, in truth it was cake.
The syringe was 30ml so 5 syringes full and Bob's your uncle. I didn't even get any gear oil on the ground.
Post Number: 1456
|Posted on Thursday, 20 April, 2017 - 11:16 am: |
Nice work Ross.
A good thread that's for sure.
Post Number: 338
|Posted on Thursday, 20 April, 2017 - 09:03 pm: |
A possible alternative to the syringe (or the beauty salon bottle, which Brian recommended) is a wash bottle. Graingers have them (or any laboratory supply).
Wash bottle: http://tinyurl.com/n4ebqzv
Robert Noel Reddington
Post Number: 1389
|Posted on Thursday, 20 April, 2017 - 11:18 pm: |
I use a westcot squirty oil can wif 90 oil diff oil.
I put the filler hole at 12 o'clock squirt one can in then turn filler to 3 or 9 o'clock to allow excess to dribble out. 6 o'clock to drain oil.
One cup of tea job.
why oil and not grease anybody know?
Post Number: 1270
|Posted on Friday, 21 April, 2017 - 03:41 am: |
Bob, grease at speed it will settle in the wrong part of the rubber boot this can cause an imbalance at speed and not lubricate the required parts. Centrifugal force at play.
Post Number: 86
|Posted on Friday, 21 April, 2017 - 04:59 am: |
I am copying and pasting a document that I have on my computer. (probably written by one of our beloved Gurus on this forum!) Hope it is useful:
A SOURCE OF VIBRATION
The poor old rear axles one of which is pictured here are often quite neglected. They should have
grease nipples in the universal joints (Item 3 in the drawing) and a filler plug (17) for the trunnion
joints on the inner end. Removal is very simple involving undoing the two saddles and the half
dozen nuts securing the inner bearing flange (37) to the rear axle casing.
The inner trunnion joint was as you know
copied from Buick immediately after the last
World War. The joint was used on the front
end of the propeller shaft on all the Silver
Clouds and Phantoms V and VI and also the
very early Shadows. They are very expensive
to produce are fiddley to service and the
rubber sealing boots are very difficult to
replace. They were discontinued on the
propeller shaft shortly after the start of
Shadow production but continued to be used
on rear axles until the Spirit line got
As with any other joint they wear and vibrate
and on a Shadow this is often felt on
acceleration. One quick cure is to reverse the
axles which are identical. While doing so have a very good look at the boots ((7) to ensure they are
not about to puncture and consider replacing the universal joints. They are not expensive and can
be the cause of a pronounced ‘clunk’ when engine power is applied.
And seeing that you have the axles out why not pull out the inner bearings (38) and replace the oil
When did you last have a look at these dear old things stuck either side of your differential (read
final drive). They have quite a job to do are very expensive to replace yet the number I find utterly
empty of oil. If you haven’t been there get the car up into the air clean around the filler plug and
remove it preferably when the plug is at 3.00 o’clock. Ideally oil should just start to dribble out. If
not turn the trunnion down until it does dribble which will give you an idea of how much is there.
You may as well let the lot out and start again.
The required oil is the same as that you put in the diff of 90 viscosity and the quantity is 150
millilitres. That is about ˝ a coffee mug, the amount is not really critical. The easiest way I find to
get it in is to use a medical syringe available from most chemists. The most common size available
is 50ml. Buy three, fill them all and take them under the car with you. Pull the plunger out fill it
with oil pop the plunger back poke it in the hole and squeeze. The more clever among you will
also realise that the trunnion has the right amount of oil when it is just about to overflow when it is
While you are at it of course have a very good look at the rubber boot which keeps the oil in the
assembly any splits or holes and the boot has to be replaced.
Post Number: 87
|Posted on Saturday, 22 April, 2017 - 07:56 pm: |
interesting suggestion to swap half shafts over to even out wear and tear. I did that.
Robert Noel Reddington
Post Number: 1399
|Posted on Sunday, 23 April, 2017 - 03:22 am: |
Grease or oil.
Imbalance is a good answer also it's easier to get oil in.
the exhaust heats the lefthand drive boot up.
Post Number: 1477
|Posted on Sunday, 23 April, 2017 - 08:10 am: |
My 1925 Chev has a type of trunion/CV joint directly out the back of the transmission, that leads into a torque tube.
It requires "train oil" not sure what that is, plus it has an Alemite grease nippple, so I just pump grease into it.
Post Number: 2536
|Posted on Sunday, 23 April, 2017 - 11:03 am: |
"Train oil" aka "steam oil" was a very viscous oil for maintaining lubrication of moving parts on steam engines - if my memory is correct, it was also specified for lubricating items on pre-WW2 cars:
Robert Noel Reddington
Post Number: 1400
|Posted on Monday, 24 April, 2017 - 04:21 am: |
modern cv graphite runny grease might be better. depends on oil tightness