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MG MGA - Trunnion Question

I am refurbishing a set of 1600 disc brake assembly and one of the trunnions is siezed on the spindle. My question is....with the spindle assembly on the car, the upper trunnion (shock mount one) turns clockwise to be put on the spindle and counter clockwise to be removed. What direction should I be turning the bottom one to remove it.

Gordon Harrison

The thread is the same direction for both top and bottom. i.e a standard RH thread.

The other side of the car has a LH thread for both top and bottom.

So all four trunnions are unique; top and bottom RH thread and top and bottom LH thread.
Neil MG

Perfect Thank you
Gordon Harrison

Now that I know which way to turn it, do you have any ideas how to get it loose. The one I am working on has the bushings removed and is either stuck by old grease or by rust. I tried a propane torch but I do not think that haets it up hot enough.
Gordon Harrison

Try the ATF/acetone mix as a penetrent . This has proved invaluable to free all kinds of stuck items on the MGA 50/50 mix.
C.R. Tyrell

Hi Gordon

I have a number of used ones in the cellar when you figure out what you need

dominic clancy

Thats good news. I am going to try and heat up the stuck ones and have a go at getting them to turn. I think it is mostly siezed by hardened grease and some rust. I find it hard to believe that the inside of the trunion would have no grease and would be completley seized by rust. I still have to remove the bushings first and that should not be too difficult, using a good press. Then some high heat and a solid bar thru the bushing hole , should get them to move.
Gordon Harrison

Hi Gord,

I believe the trunion on MGA is the same as on the T-series. Make sure you remove the steel tube (distance tube) before turning the trunion to remove it as there is a notch in the swivel pin for the tube and it will jam if you forget to remove it. As for pushing out the bushings once you have the trunion removed, I can lend you the piece you need to use in the press to push it out.

Dave Runnings

Im going to strip down my front suspension over the winter to give the swivel pins a good clean up and/or re-paint.
There is no appreciable wear on the pins and trunions but the grease seals have completely disappeared.
They fell apart after about 12 months (approx 3000 miles)
I have fitted some temporary seals made of amalgamating tape to try to keep the grease in and the water out but they look a mess to be honest.

Can anyone suggest a supplier of kingpin dust seals that are any good?
c firth

Make your self some fantastic penetration fluid. Take a mixture of 50/50 power steering or ATF and acetone. It's the best by far.


I had the same problem with the seals a couple of years ago. I tried several suppliers and am not sure any of them were very good. Bob West may have some better seals now although the ones that fell apart quickly were from him about 5 years ago. I also got some from B&G which looked ok.

John Francis

Dave, thanks for the offer. Hows your TD.

Sandy, That mixture sounds more like metal eater but I will try it. Is there a particular reason why it works better than other commercial types of rust penetrators.
Gordon Harrison

50/50 ATF to Acetone is all I use any more. Just keep it out of the sun as it expands when sun hits it. ( in a bottle ). I just keep the bottle 1/2 filled.. and cap a bit loose. I have been using for quite a few years and it has never let me down.
Ron Bissland

Gord - Had the TD out on Sunday. Missed the Saturday drive to Bob's place due to visitors so I tried to make up for the miss by driving on Sunday.

I'll dig out the piece for you. I recall that it sounded like a shotgun blast when the old bushings finally released from the trunion. You can use the same tool to press in the new bushings. You'll need to ream the new bushings to size after you put them in. Memory fails me but I recall .750 reamer.

Dave Runnings

Dave, thanks...maybe you could bring it to the next meeting if you are around. If not I will make a trip, and pick it up from you.

Ron, thanks for the info and the warning. I am going to mix up a batch, of this potion this weekend.
Gordon Harrison

Here is some info regarding penetrating fluids.
Here is a comparison of penetrating "oils". Hope this helps.

Machinist's Workshop magazine tested penetrants for break out torque on rusted nuts. They arranged a subjective test of all the popular penetrants with the control being the torque required to remove the nut from a "scientifically rusted" environment. The results are as follows;

Penetrating oil..... Average load
None ..................516 pounds
WD-40 ................238 pounds
PB Blaster ............214 pounds
Liquid Wrench ..... 127 pounds
Kano Kroil ............106 pounds
ATF-Acetone mix....53 pounds

The ATF-Acetone mix was a "home brew" mix of 50-50 automatic transmission fluid and acetone.

Amazing numbers. I am looking forward to soaking the trunnuion over night and giving it a go tomorrow. Sounds like it should come off rather easily.
Gordon Harrison

How many "scientifically rusted" fasteners did they test with each type of penetrating oil?

D Rawlins

Probably a "bazillion", Del.

Gene Gillam

Is it possible or wise to try and remove the cap (similar to an engine frost plug) that is at the top of a trunnion. My reason for asking it to try and get more access to pentrating fluid,into the trunnion. If I remove it safely,can it be re-installed. The reason I ask is that I am still having problems loosening one of the trunnions from the shaft. I may have to break down and take it to a machine shop.
Gordon Harrison

Gordon; Don't remove the plug. Remove the Zerk fitting if you can and get some of the penetrant in there with out the fitting in place. Just keep soaking it.... let stand... and soak again. This is one of these jobs that needs patience. Remember to remove the distance tube from the trunnion. That also keeps the trunnion from turning.
C.R. Tyrell

This thread was discussed between 20/10/2014 and 01/11/2014

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