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TR4A bottom trunnion problem


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Recently been attempting to grease the front suspension of my TR4A, not something I've done before, and I found that a couple of the nipples were not keen to take the grease. As I was ordering some other bits from TR Revington I added new nipples onto the list. Came to fit them, wrong size, slightly bigger than the originals, they need a 3/8" AF spanner where the originals are more like 5/16" AF. Ok not a problem take off and clean the nipples make them work. Came to the right side lower trunnion and found that the cap on the bottom of the trunnion was missing. It was there 2 weeks ago but could have been the 'falling off, metallic tinkling sound,' heard on a run at the weekend, in a place not handy to go back and look. My basic question is do I have to replace the complete bottom trunnion assembly or is possible to find a suitable cap only? If the whole lower trunnion needs to be replaced is it relatively easy? Any improvements I can make whilst I'm in that area? Another observation in this area is that the grease nipples are on the sides of the trunnion, not on the bottom cap as shown on the parts books. Any thoughts there?

 

Les

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Hi Les,

there are a number of different shapes and sizes for the grease nipple.  Whenever you see a nipple grab it and put it in the spares box.

The cap on the trunnion ir swagged in place and often soldered as well.  You could make a new cap from sheet mild steel and solder it in place.

There may also be a core plug of the correct size lurking around.

To replace the TRunnion  you need to safely remove the damper and spring and then battle away with the large bolt that passes through the TRunnion.

In theory it is an easy job but with many pitfalls.

Good luck

Roger

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4a Trunnions dont have grease nipples fitted to them anyway so you must have non standard ones. The grease nipple is part way up the upright and the grease path feeds down through to the trunnion thats probably why the supplied ones dont fit. In that case I would just fit two new ones and see where the grease nipples are on your uprights.

Stuart.

 

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Roger, Stuart, many thanks for your interest and replies. The core plug idea sounds good, and cheap, failing that a penny washer soldered on, with a grease nipple fixed in the hole!

 

Thanks

 

Les

 

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Hello Les,

Having once had an upright snap I treat things like trunions and uprights with great respect. I’d do what Stuart suggests and replace both sides with new ones. At the same time you can check for any wear marks in the upright and replace them if need be.

If you don’t want to buy new at least remove them both and clean out the old grease and the parts where the grease flows from the nipple down to the trunion. If you have never greased them before then there is a possibility that the old grease may have become hard and it would be impossible to get new grease down into the trunions through the upright passageways.

If you do reuse your old ones you would need to replace the bottom "Caps" with holeless blanks, as you should be using the side entry nipples in the uprights.

What sort of grease are you going to use?
Ask here and you will get 101 different answers…

Charlie.

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Good morning Charlie  I was driving a Hillman Imp about 50 years ago when I came to a 90 left bend and turned left as you do, the wheel refused to come back after the bend resulting in a 180 left into a field. Drove back out without a scratch, that was something in the front suspension seized, so yes I take your words (and Stuart's) on board. My lower trunnions do have the side nipples not bottom ones, adding to my confusion as to what is correct. I'm using a LM grease. When I greased the left side a black oil came oozing out of the bottom, but there seems to be only grease in the right side.

 

Les

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Did Les say that his trunnions had grease nipples or that he was trying to grease them in the usual manner via the nipple on the upright.

A trunnion seizing is a scary experience, had it happen on  a Scimitar SE5a which essentially uses TR front suspension parts.

Unless the trunnion is newish I would replace it and fit new trunnion bushes as these do wear quite quickly. A pain of a job but probably worthwhile to allow the upright to be inspected too.

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2 minutes ago, Andy Moltu said:

Did Les say that his trunnions had grease nipples or that he was trying to grease them in the usual manner via the nipple on the upright.

A trunnion seizing is a scary experience, had it happen on  a Scimitar SE5a which essentially uses TR front suspension parts.

Unless the trunnion is newish I would replace it and fit new trunnion bushes as these do wear quite quickly. A pain of a job but probably worthwhile to allow the upright to be inspected too.

There are 2 grease nipples on each side of the car. One on top of the upper ball joint and another on the side of the bottom trunnion assembly. Both the same size requiring a 5/16" AF spanner to remove them. All smaller than supplied by TR Revington which are 3/8"AF. (please note I'm not knocking the supplier)

 

Les

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I’m by no means an expert on different types of TR trunions, but I’ve never seen one with nipples on the side.
If you have got oil coming out of one and grease coming out of the other then it sounds like a bodger has worked on them previously, and well worth a strip down to inspect.

On the 4/4A it is a bit of a pain, but nowhere as long-winded as on the sidescreen cars where you have to remove the lower wishbones to remove the trunion. On then 4/4a there is a simple bolt going through the trunion that can be pulled out. (After carefully removing the spring using a special spring compresser. Advice on that bit is mentioned several times in previous threads. DO NOT try using a conventional spring compresser.)

I use Penrite “Semi fluid & steering box lube” in mine.

Charlie

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Everyone, my apologies, I've just realised that the parts I was looking at I've wrongly described. The lower grease nipple is on the side of bottom end of the vertical link, just above the trunnion. So sorry about that. Off to go and sit in dark room until tea time.

 

Les

 

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3 hours ago, RogerH said:

The TR4 uses the same trunnion as the TR3A with the inbuilt attachment shaft for the lower wish bones.

Ahhh…

Thank you Roger.
Apologies for the confusion.

So the trunion changed for the TR4A then.
Fortunately that is what Les has got.

I have often wondered if the previous version of trunion could be drilled out to the correct size/shape to take a simple bolt and bush.

Charlie.

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18 minutes ago, Charlie D said:

Ahhh…

Thank you Roger.
Apologies for the confusion.

So the trunion changed for the TR4A then.
Fortunately that is what Les has got.

I have often wondered if the previous version of trunion could be drilled out to the correct size/shape to take a simple bolt and bush.

Charlie.

Read this for info on trunion thread size.

https://www.tonydrews.com/Front_Suspension/tr4_front_suspension_upgrade.htm

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I don't know what the current thinking is on greasing the trunnions, but many years ago I was discouraged from using grease simply because it sits in the tortuous route from the steel vertical link to the brass trunnion and hardens off, a bit like ear wax in a blocked ear. Attempts to then add more grease then proves futile and the screw thread portion of the trunnion/vertical link subsequently runs dry and seizes up. Older members will recall seeing Morris Minors with their front wheel folded under the car as a direct result of this type of failure mechanism. I was told always to inject hypoid oil into the vertical link via the grease nipple. This is what I've done for many years, in fact I use a blend of hypoid oil and Molyslip.

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To avoid the grease hardening off, one should grease frequently.

I have always (for 60 years now) used Castrol LM everywhere on my TRs.

Ian Cornish

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If you do let it set, gentle heat from a blowtorch, avoiding melting the seal allows it  to flow again.

But as Ian says do it more often and the grease setting isn't an issue. Flushes out any debris before it blends with the grease and becomes grinding paste. The same comment applies to the use of oil if you use that but for me unless the bottom of the trunnion is perfectly sealed oil drains away very quickly.

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On 5/16/2022 at 5:31 PM, twostrokekid said:

I don't know what the current thinking is on greasing the trunnions, but many years ago I was discouraged from using grease simply because it sits in the tortuous route from the steel vertical link to the brass trunnion and hardens off, a bit like ear wax in a blocked ear. Attempts to then add more grease then proves futile and the screw thread portion of the trunnion/vertical link subsequently runs dry and seizes up. Older members will recall seeing Morris Minors with their front wheel folded under the car as a direct result of this type of failure mechanism. I was told always to inject hypoid oil into the vertical link via the grease nipple. This is what I've done for many years, in fact I use a blend of hypoid oil and Molyslip.

As I have a steering box car I use the same semi fluid grease in the trunions 

http://penriteclassicoils.co.uk/product/semi-fluid-and-steering-box-lube/

 

PS I silver soldered the steel caps into the bottom of the trunions to be sure they were fluid tight.

Edited by BlueTR3A-5EKT
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29 minutes ago, BlueTR3A-5EKT said:

As I have a steering box car I use the same semi fluid grease in the trunions 

http://penriteclassicoils.co.uk/product/semi-fluid-and-steering-box-lube/

+1

It may well have been you who suggested it before !

I actually bought a small grease gun just for the steering box/trunion lubrication.(Along with a flexible coupling to get it to places other grease guns could not reach.)

Charlie.

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