Trunnions - how slack is slack

[ColinChandler]

Morning all,
After asking "how slack is slack" for a torsion bar, I'd like to ask how slack is slack for a trunnion. I'm methodically going through a front suspension rebuild and set up and have bought a pair of new swivel pin/uprights. Having read on here that its best to change both the uprights and the trunnions at the same time, I've got the swivel pins kits which come complete with the trunnions included. Dismantling them ready to clean and paint and out of curiosity, I reassembled them without any seals to see how much slack they had in them. There was more than I thought there would be. There is none up and down ie if the trunnion were to pull out in a wheel in the wing manner but there is noticeable side to side clearance. is this usual? I have no problems with renewing everything as I appreciate that new trunnions with old swivels might not give the maximum thread engagement in the joint so I just wondered if anyone has any comments.
Many thanks, Colin.

[philthehill]

There has to be some slack between the threads but there does seem to be a trend towards more clearance between threads. So long as there is no up and down movement with grease free threads that is all you can ask for.
Original BMC trunnions do seem to be a better fit than the aftermarket trunnions.
The side to side clearance - is it when you rock the trunnion on the swivel or is it sideways movement elsewhere on the front suspension?

[ColinChandler]

Hi Phil and thanks.
Yes, it's as you say. When holding the swivel firmly, there's a little bit of rocking in the trunnion. As you say, old stock will be of a better quality but I'm assuming that the newly made parts probably all come from the same source regardless who sells them. In other words, sending them back and getting another set from somewhere else wont improve anything. I appreciate there has to be some clearance in there to allow the things to turn but I'd forgotten about the need to let the grease get through to the ends of the trunnions. That'll be useful.
Thanks again for your help.
Regards, Colin.

[philthehill]

Before you fit the new trunnions I would advise that you drill and tap the trunnion to take an additional grease nipple.
Below is a photo my efforts to determine the best place to fit an additional grease nipple.

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The additional grease nipple should be placed near the bottom of the trunnion opposite the machined/broached grease channel.

Between the bottom trunnion pin bearings there should be a baffle tube to make sure that some grease is directed to the swivel threads - it is not always there on after market trunnions. If it is not there grease will just exit via the trunnion pin bushes with very little if any going to the threads.

If the baffle tube is in the old trunnions the bushes can be pressed out and the baffle tube recovered and fitted into the new trunnion.

100_1984.JPG (894.62 KiB) Viewed 706 times

I would recommend that you use Declan Burns swivel seals. He can be contacted via a PM.

[ColinChandler]

Thanks Phil.
The photos speak a thousand words so I'll add an extra grease nipple and check the baffle tube. I also have a set of Declan's seals "in stock" ready for this overhaul. Obviously I've not used them yet but they do look very professional and that they'll do a good job.
Thanks once again for your help. Its much appreciated.
Best wishes, Colin.