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MG MGA - Swivel pin ceased

Should read; Swivel pin seized.

Today I started the rebuild of my front suspension.
I changed the seals in the upper swivel pin, with no problems. The threads were good (well lubricated) and put in some new thrust washers which were missing.

Then I went to do the same on the lower swivel pin. I took the big bolt off that links it to the A-arm, and the distance tube looks in good condition (well greased and no grooves.
When I went to unscrew the lower swivel pin to change the trunion seal, I was not able to uncrew it more than a quarter turn (i.e. the travel it regularly does when the wheels turn). It can't be further screwed or un-screwed, and is a tight fit on the small travel it does.
I suspect with time some water, may have gone in the threads locking them together. Trunion seal is perished but seems like there is still grease inside.

I don't necesarily need to take it off completely for any reason because the thread seems to be ok, but I wanted to change the trunion seal.
Do you have any ideas about how to take it off?
I tried levering it with a bar through the distance tube but it will not move further.
Anyone else experienced this?
I guess the elegant solution would be to take it all off and put it in a vice, and use a big lever... but have no access to a vice, and was wondering if there was a shortcut solution.
Any other way to install the trunnion seal? cut and install a small clamp?

Ideas appreciated. Tomorrow I will give it another go!
Gonzalo Ramos

Gonzalo, don't try to remove the swivel links with the distance tubes in-situ, you will damage the threads on the king pin. Top and bottom swivel pin links are un-scewed with the distance tubes removed. I presume you have removed the brake backplate.
Lindsay Sampford

No back plate on mine with Disc brakes.
I removed the distance tube before trying to undo it, but still would not move.

It worked fine on the upper one.. ;S
Gonzalo Ramos

Nevertheless, don't resort to force until you are certain that is the answer. They should unscrew easily. The distance tube should line up with the centre of waisted part of the kingpin. The swivels should turn about 1 1/2 turns in each direction with the distance tubes in position.
Lindsay Sampford

I don't think I would use force either. Because it is tight like that I would definately want to take it apart to make sure there is no major problem.

First thing I would check would be to make sure the cutout in the bushing is there and in the proper location. Can't imagine how the bushing could rotate so the cutout was in the wrong position but have found stranger things.

Hard to believe the pin could rust to make it that tight without any rust on the distance tube. On mine the distance tube was fused to the bolt with rust but the swivel pin was free of rust. If it is just rust, then removing the grease fitting and cleaning out the grease and soaking in rust penetrant would probably be the best thing. I would try to work it back and forth with the penetrant in there without using extraordinary force.

Jeff Schultz

Left Hand Thread? Aren't they handed. May be you have been trying to tighten it.

Steve
Steve Gyles

Steve, exactly what I was going to say...LHD?
Gary Lock

It going to give it a go now.
This is the right wheel so I undestand RH thread. However it does not move in any direction....

Will try to follow Jeff's directions.
Gonzalo Ramos

Jeff, Iv'e been thinking about what you said about the bush turning. If the bush were too long so that it nipped between the thrust washers, then it would turn and give Gonzalo his problem. No doubt he will find out if he has a good look with a strong light. When I fitted a new top swivel housing to my car a few weeks ago and bolted it up, the suspension wouldn't move at all. I had to take a file to the thrust faces of the bronze casting to get some clearance. So it seems like these things come in different sizes, maybe something similar has happened to Gonzalo's car and it wasn't rectified.
Lindsay Sampford

Bush was in the right place...
Could not find the solution so I just put everything back together. I works for the moment so I will leave it as it.
Gonzalo Ramos

Sounds like a good attitude Gonzalo!
Lindsay Sampford

Just thinking that it is possible that your kingpin is bent. Barney has an article about this - causes and remedies, etc. Someone just had this problem on one of the other boards.

JIM in NH

AJ Mail

Indeed this came to my mind but I was not able to identify it from basic inspection.
Also I find it hard to believe the king pin would be bent RIGHT at the point where the thread comes out of the swivel pin (which would unable me to unscrew it).
Gonzalo Ramos

You could pop the plate (item 6) off the swivel pin link (item 4) and have a look if there is any grease, loose metal or rust under the plate that might give you guide to why it has siezed.

You could also clamp blanking plates on both sides of the swivel pin link where the bottom wishbone bolt passes trough using a vice or G clamp (with the distance tube - item 46 - removed)- then force grease through the system to ensure the swivel pin (item 2) threads are well lubricated and any contaminants are flushed out.

Once this is done and it still wouldn't budge I would be tempted to clamp the swivel pin in a vice and apply a large pipe wrench to the swivel pin link - I could not sleep not knowing why it would not screw off as it is meant too!

Mike
Mike Ellsmore

Gonzalo,
Before to remove or turn the trunnions you must remove the bushings, (to remove the bushings remove also the distance tubes, nothing to do with backing plate that you mentioned at the beginning of the thread) if you turn the links with the bushing in you will damage the thread of the swivel pin as Lindsay mentioned above.
That happens to me and I damaged the threads!
R Garcia

My swivel links don't have pop plates (welsh plates). They are made out of brass, so it seems that they may have been changed.
I understand that the 1600 MGA should have cast iron swivel links.
It was not the distance tub that was fouling on the threads, since I was still able to take the distance tube out easily with the swivel link seized in one direction.
I suspect the copper bushing 'MAY' have rotated slightly, and this is what is fouling on the threads. Looking through the hole the bushing hole seems to be in the right direction, but it may have rotated minimally.
I can find no other explanation.

I'll put this one to bed, drive the car for a bit and try to take if off during the next maintenance when I have access to a vice and a big lever... ;)
Gonzalo Ramos

Gonzalo,

The assembly procedure to install the trunnion in the swivel pin you must: thread the trunnion in the swivel pin all the way and then return something like 1 1/2 turn, then insert the copper or brass bushing, next the distance tube then you can install the assembly in the suspension arm !

Para desarmarlo tienes que hacer todo a la inversa, de lo contrario el bushing de bronce o cobre se atascará en la rosca del swivel pin, dañando la rosca. Los extremos del swivel tienen dos roscas y entre las roscas existe una superficie ahuecada, esa parte deberá quedar exactamente en medio de la perforación que tiene el bushing y es por donde entrará la grasa para lubricar el ensamble. Pero insisto en que el bushing debe ponerse hasta el ultimo antes de atornillar el link.
Yo tuve que desmontarlo con el bushing puesto porque estaba totalmente atascado por tantos años sin moverse y por esa razón la rosca del pin se acható.
Ahora si el link o trunnion se mueve sin problema te recomiendo que lo dejes así, nada mas bien lubricado, porque para poner el bushing es otra bronca, porque tienes que desbastar el bushing con una rima para que pueda entrar.

Saludos
RG
R Garcia

Gracias RG por los consejos! los seguire!
Por ahora se mueve y tiene grasa asi que lo dejare estar.
Gonzalo Ramos

This thread was discussed between 05/06/2010 and 10/06/2010

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